HIPPARCHOSHIPPARCHOS The Hellenic Astronomical Society Newsletter Volume 2, Issue 2
Society News Science News The Antikythera Mechanism Skinakas observatory Spectroscopic Diagnostics of Galactic Nuclei Eclipsing Binaries
ISSN: 1790-9252 ʸ˱ˤ˳˶˱˹˯˩˭ˮˬ˰˱˙
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ISSN: 1790-9252 Message from the President. . . . . 3 REVIEWS Hipparchos publishes review papers, news and comments on topics of in- 8th Hellenic Astronomical Skinakas observatory, Crete, Greece terest to astronomers, including mat- Conference, 13th-15th September A General Description ters concerning members of the Hel- 2007, Thassos, Greece ...... 4 of Infrastructure and Activities, lenic Astronomical Society by Yiannis Papamastorakis ...... 14 SOCIETY NEWS Eclipsing Binaries: Editor: Kostas Kokkotas General assembly Tools for Calibrating Department of Physics, and elections of Hel.A.S...... 5 the Extragalactic Distance Scale, Aristotle University of Thessaloniki, by Alceste Bonanos ...... 18 Thessaloniki 54124, Greece. Members in new positions...... 5 Mid-Infrared Spectroscopic Tel: +30-2310-998185 New members of Hel.A.S...... 5 Fax: +30-2310-995384 Diagnostics of Galactic Nuclei, Email: [email protected] Human Resources in Astronomy, by Vassilis Charmandaris ...... 23 Astrophysics & Space Physics in Editorial Advisors Greece, by Vassilis Charmandaris. . . . 6 CONFERENCES • V. Charmandaris (Crete) The prospects of employment The Athens Solar Orbiter • D. Hatzidimitriou (Crete) for young astronomers in Greece Workshop, by Kanaris Tsinganos. . . 28 • M. Plionis (Athens) by S. Kitsionas...... 7 • J.H. Seiradakis (Thessaloniki) X-ray summer school, September 18-20, 2006, • N.K. Stergioulas (Thessaloniki) BRIEF SCIENCE NEWS • K. Tsinganos (Athens) by I. Georgantopoulos ...... 29 Decoding the Antikythera Recent Developments in Gravity, Printed by ZITI Publications • www.ziti.gr Mechanism, by John H. Seiradakis . . . 9 NEB XII Nafplion 29/6 - 2/7/2007, The Astronomy top stories by Theocharis Apostolatos...... 30 of the year for 2006...... 11 The Schutz Symposium Dark Energy on Gravitational Waves at Redshift z=11 ...... 13 and Relativistic Astrophysics ...... 30
Message from the President
Dear Hel.A.S. fellows, ready established good tradition. As a matter of fact, in the 2006 elections the Formally the Governing Council of GC of the Hel.A.S. was considerably re- Hel.A.S. is elected every two years but juvenated with younger members rich the officers can serve a maximum of two Cover photo: with fresh ideas. consecutive 2-year terms, i.e., up to a The Antikythera Mechanism. total of 4 continuous years. Last sum- Among the first measures taken by See related article on page 9. mer (2006) the fourth 4-year period this new GC is the external appearance of the Governing Council (GC) of Hel. of the Society. The webpage has been A.S. started since the first council was conveniently named Editorial help is badly elected in 1994. The three previous 4- www.helas.gr needed! year terms (Presidents: G. Contopoulos, while its content is also drastically re- J. Seiradakis, P. Laskaridis) made an enor- formed: the layout has a profession- Please volunteer, feed us with mous contribution to solidify the Hel- al and very useful structure, its style is information related to your Insti- lenic Astronomical Society and inherit more pleasant and youthful, the new lo- tute or with exciting news from us a strong, well organized and peaceful go of the Society is artistic, etc, all con- your field of research Society. The obligation of the present 4th veying to the reader the appropriate as- term is to take Hel.A.S. a further step tronomical excitement which a Hel.A.S. forward adding new elements in this al- webpage should do. Our thanks go to
HIPPARCHOS | Volume 2, Issue 2 3 Message from the President (continued)
Vassilis Charmandaris for coordinating he previous seven Hel.A.S. Pan- of IYA2009 activities will take place on all this effort. Next, we are waiting for T hellenic Astronomical conferenc- several levels: locally, regionally and na- the second surprise, which has to do es have become already a tradition on tionally. Several countries have already with the new appearance and format of their own and the forthcoming 8th Hel- formed National Nodes to prepare ac- another popular contribution of the Hel. lenic Astronomical conference will be no tivities for 2009. Paul Laskaridis is coor- A.S. to our members –but at this point exception. They combine reporting the dinating the Hellenic node together with I should rather cut it short ... Finally, as latest in research in astronomy, meeting V. Charmandaris, I. Daglis, J.H. Seiradakis, you can also witness by yourselves, the other Greek and foreign colleagues and E. Theodossiou and myself as mem- present second issue of the second vol- also exploring other regions of Greece bers. In particular, the conference enti- ume of HIPPARCHOS is also the second and diffusing to them the astronomical tled “Communicating Astronomy with one with the new more professional and experience. This summer, the 8th Hellenic the Public 2007” will take place in Ath- better style, a result that has to be cred- Astronomical conference will take place ens, Greece, from 8 -11 October 2007: ited to Kostas Kokkotas. in the beautiful northern Aegean island http://www.communicatingastronomy.org/ of Thassos, between September 13th to cap2007. his summer, the aided Hellenic As- 15th, 2007. Fr George Anagnostopoulos T tronomical eye will be consider- is chairing the local organising commit- nother direction we can move in the ably upgraded too. Aristarchos, the 2.3 tee and promises a memorable local or- A years ahead is to expand the Direc- meters new telescope will be fully in ganisation. At the same time the conven- tory of Hel.A.S. by including in it every operation atop Mt Helmos, at 2350 m. ors of the scientific organizing commit- Greek astrophysicist working anywhere More than 90% of the tests have been tee are already preparing their sessions in the world, regardless of being a mem- performed and they are to the satisfac- and the Hel.A.S. GC has already invited ber of the Society. I would thus ask anyone tion of the NoA telescope committee. several distinguished plenary speakers. It who knows such scientists to notify them At the same time, at a common meeting will be a good opportunity for all of us to contact the Secretary, or vice versa, in of the National Astronomical Commit- to be there and exchange views about order that their name and affiliation de- tee and the GC of Hel.A.S. a strong sup- the latest astronomical news, etc. tails are included in the Society Directory. portive letter for ARISTARCHOS was Our aim is to make Hel.A.S. really the As- signed and handed to Christos Goudis, has been declared by UNESCO tronomical Society of everyone of Hellenic the IAA/NoA Director for facilitating his 2009 and the International Astro- origin, or, everyone who shares the Hel- meetings with the government and oth- nomical Union the International Year of lenic cultural and historical values. er involved officials in taking care of the Astronomy (IYA): last necessary actions for the operation http://www.astronomy2009.org/ hus, till 2009, there are many astro- of the telescope this summer. Christos The IYA2009 will be a global celebration T nomical events expecting all of us manages well the effort to bring the tel- of astronomy and its contributions to to participate. Till then, I wish to all and escope project to completion and so we society and culture, stimulating world- everyone of you good health, good skies are indeed looking forward to this in the wide interest not only in astronomy, but and good ideas. coming summer. in science in general. The vast majority Kanaris Tsinganos
8th Hellenic Astronomical Conference
13th – 15th September 2007, Thassos, Greece http://www.ee.duth.gr/hac/index.htm
he Conference will take place at the Hotel “Makryam- T mos bungalows” located in the island of Thassos, Greece. Makryammos is the most picturesque beach in the Limenas area, in beautiful surroundings with forest all around. Set in a pretty bay with shallow water and fine sand. Very well organized. Conference Sessions will cover most areas of Astronomy and Astrophysics: – Sun, Planets and Interplanetary Medium – Our Galaxy: Stars, exo-Planets and Interstellar Medium – Extragalactic Astrophysics – Dynamical Astronomy, Relativity and Cosmology – Instrumentation and Methods in Space and Astronomical Ob- servations – History and Education in Astronomy
HIPPARCHOS | Volume 2, Issue 2 4 General assembly Members in new positions
and elections of Hel.A.S. • We would like to congratulate Prof. Christos Goudis, who was recently unanimously reelected as the director of the In- D uring the 24th General Assembly of Hel.A.S. which took place stitute of Astronomy and Astrophysics of the National Ob- on September 22, 2006 the President of the Society Prof. P. servatory of Athens. Laskarides presented a summary of the activities of HelAS during the • Dr. Panayotis Hantzios was recently appointed to the level last two years, the Treasurer Assoc. Prof. E. Theodossiou a detailed ac- of Researcher-C (Associate Researcher) at the Institute of count of the finances. The Secretary Prof. K. Tsinganos presented an Astronomy & Astrophysics of the National Observatory of update on the HelAS membership status over the past year. Athens. In the elections that followed the 24th General Assembly of Sep- • Dr. Ioannis Bellas-Velidis was recently appointed to the tember 22, 2006, the members of Hel.A.S. voted for a President, as well SOCIETY NEWS as a new Council and Auditors. The total number of eligible to vote level of Researcher-C (Associate Researcher) at the Institute members was 82 and an equal number of ballots were collected. of Astronomy & Astrophysics of the National Observatory of Athens. The results were: • We would like to congratulate Dr. Kleomenis Tsiganis, who President: Tsinganos Kanaris (73 votes) recently commenced his appointment as Lecturer in the Dept. Council: of Physics of the University of Thessaloniki. 1. Kokkotas Kostas (39 votes) • We would like to congratulate Dr. Nektaria Gizani who re- 2. Plionis Manolis (37 votes) cently commenced her appointment as Lecturer in the Section 3. Charmandaris Vassilis (32 votes) of Astroparticle Physics of the Hellenic Open University. 4. Mastichiadis Apostolos (28 votes) • We would like to congratulate Dr. Christos Efthymiopou- 5. Daglis Ioannis (25 votes) los, for his recent promotion to the position of Main Re- 6. Papadakis Iosif (20 votes) searcher (Researcher Bv) in the Research Center for Astron- 7. Anagnostopoulos Georgios (19 votes) omy of the Academy of Athens. 8. Efthymiopoulos Christos (19 votes) • We would like to congratulate Dr. P. Patsis, for his recent Auditors: promotion to the position of Director of Research (Research- 1. Xilouris Emmanuel (53 votes) er Av) in the Research Center for Astronomy of the Academy 2. Vlahakis Nektarios (45 votes) of Athens. 3. Nindos Alexandros (23 votes) • We would like to congratulate Dr. Manolis Plionis who was Following the constitution of Hel.A.S. the new Governing Council recently promoted to the position of Director of Research for the 2006-2008 term is: (Researcher Av) at the Institute of Astronomy and Astrophys- President: K. Tsinganos ics of the National Observatory of Athens. Council: • We would like to congratulate Prof. Harry Varvoglis who 1. K. Kokkotas (vice-President & Hipparchos’ Editor) was recently promoted to the position of Full Professor at the 2. V. Charmandaris (Secretary) Department of Physics of the University of Thessaloniki. 3. A. Mastichiadis (Treasurer) • We would like to congratulate Dr. Manolis Xilouris who 4. M. Plionis (member) was recently promoted to the position of Researcher Cv at 5. I. Daglis (member) the Institute of Astronomy and Astrophysics of the National 6. I. Papadakis (member) Observatory of Athens. New members of Hel.A.S.
Members of Hel.A.S. moving from Newly elected Ordinary members: Newly elected Junior members: Junior to Ordinary status: 1. Dr Zacharias Ioannou (PhD University 1. Panagiotis Gavras (Graduate student, 1. Dr Olga Bitzaraki (PhD 2003, Univer- of Keele, UK) University of Athens) sity of Athens) 2. Dr Styliani Kafka (PhD 2005, University 2. Eva Lefa (Graduate student, University of 2. Dr Alceste Bonanos (PhD 2005, Har- of Indiana, USA) Athens) vard University, USA) 3. Dr Maria Kroustalloudi-Flerianou (PhD 3. Maria Magkanari (Graduate student, 3. Dr Dimitris Giannios (PhD 2005, Uni- 2006, Nat. Tech. Un. of Athens) University of Athens) versity of Crete) 4. Dr Athena Meli (PhD 2002, Imperial 4. Kostas Moraitis (Graduate student, Uni- 4. Dr Ioannis Gonidakis (PhD 2005, Uni- College, Univ. of London, UK) versity of Athens) versity of Manchester, UK) 5. Dr Polychronis Papaderos (PhD 1998, 5. Periklis Rammos (Graduate student, 5. Dr Paschalis Paschos (PhD 2005, Uni- University Gottingen, Germany) University of Athens) versity of Illinois Urbana-Champaign, 6. Dr Spiros Patsourakos (PhD 2000, In. USA) of Paris XI, Orsay, France) Newly elected 6. Dr Emmanouel Rovilos (PhD 2004, 7. Dr Jason Spyromilio (PhD 1989, Impe- Associate members: University of Manchester, UK) rial College, Un. of London, UK) 1. Alexandros Liakos 8. Dr Christos Tzanavaris (PhD 2003, Cam- 2. Kostantinos Markakis bridge, Institute of Astronomy, UK) 3. Kostantinos Stamou
HIPPARCHOS | Volume 2, Issue 2 5 Human Resources in Astronomy, Astrophysics & Space Physics in Greece by Vassilis Charmandaris Department of Physics, University of Crete, Greece
n this article we present a brief sta- tabase of the members of the Hellen- Inspection of Figure 2 clearly reveals I tistical analysis of the distribution of ic Astronomical Society, as well as an- that almost 30% of Greek astronomers astronomers among the various insti- cillary information collected by the au- are near or over the age of 60. tutions in Greece1. As one would ex- thor. The study was limited to individuals Furthermore, statistics over the last 10 pect, since more than half of the popu- over the age of 30, since this is typical- years indicate that on average there were lation in Greece is concentrated in the ly the age when one is competitive for less than 3 new tenure track astronomy Athens and Thessaloniki metro areas, tenure track or long term research as- position openings per year in the country, most of the astronomers in Greece are sociate positions. Some individuals over including both universities and research also associated with institutes located the retirement age of 67, who are on an institutions. The fraction of astronomers in these two cities. This is depicted in emeritus-type position and/or still ac- near the age of retirement is even larger Figure 1 where the fraction of tenured tive, were included in the analysis. The if we were to consider only the two older and tenure track astronomy faculty in error on a single 5-year bin is of the or- universities of Athens and Thessaloniki. the major AA&SP institutions in Greece der of 5% but it is very likely that the val- This implies that within the next 3 to is presented. ues of bins at ages greater than 55 are 10 years a large number of their current An additional issue, which affects the somewhat underestimated. This is due faculty members will retire and they will current state and has direct implications to the fact that there are a number of have to be replaced in a very short time to the future of Greek astronomy, is re- individuals who formally have a tenured scale. This will be an interesting challenge lated to the age distribution of Greek astronomy positions but as they are no for Greek astronomy. Will it be possible professional astronomers. In Figure 2, a longer active they were not included in for these institutions to find enough, well histogram of 135 astronomers working the database of Hel.A.S, on which analy- qualified, candidates from the available in Greece is presented, using the da- sis was based. pool of post-docs and research associates for their needs? If necessary, will changes in the legislation make it possible for the institutions to hire with a lower pace, being selective and identifying the key scientific research areas they should be investing in, without loosing any position in the process? Finally, another topic worth touching upon is the gender diversity in Greek astronomy. At the time of writing this report 14% of the permanent or ten- ure track astronomy positions in Greece were held by women. This percentage is less than in France2, which leads the way Figure 1: Distribution of tenured and tenure track astronomers in the major research institutes with ~26%, or in Italy, Russia and Spain, in Greece. The total number of astronomers included in this study is 107 and it is restricted to all above 15%, but higher than the frac- individuals on tenure or tenure track positions. tion of female astronomers in the United States which is ~10%. We should note though, that only recently one female as- tronomer in Greece reached for the first time the highest possible academic rank (Full Professor or Researcher A).
1. This article is an exerpt from a report entitled ÒAstronomy, Astrophysics & Space Phyiscs in GreeceÓ prepared by the author available at: http://arxiv.org/abs/physics/0604144 2. The percentages for the other countries mentioned are based on the 2003 report by Dr. Florence Durret (Institute d'Astrophysique Figure 2: A histogram of the age distribution of astronomers in Greece in 2006. The vertical line de Paris, France) available at: indicates the 67th year of age which is the current compulsory retirement age for civil servants. http://www2.iap.fr/sf2a/courrier.html
HIPPARCHOS | Volume 2, Issue 2 6 The prospects of employment for young astronomers in Greece by S. Kitsionas, Astrophysikalisches Institut Potsdam, An der Sternwarte 16, D-14482 Potsdam, Germany
grants usually also include contributions Abstract: Based on my recent Hipparchos article [1], I review the existing legis- towards travel and computing support. lation and employment opportunities (including PhD positions) for young astrono- mers in Greece. Several points of concern are raised, referring mainly to funding and Non-permanent employment status, that need to be addressed in order to improve the prospects of SOCIETY NEWS employment for young astronomers in Greece. personnel status We now discuss the legislation on em- The funding of temporary tions towards social security and pension ployment of non-permanent research positions in Astronomy (even at the post-doctoral level). staff. Funding for non-permanent posi- Departments in Greece 2. Astronomy groups of Research tions is channeled through each institute’s Institutes (e.g. NOA, FORTH etc.) get “special account for research’’, the oper- We first review the short-term posi- funded from the Ministry of Develop- ating mechanism of which is totally out- tions available for early stage research- ment (GSRT). dated, e.g. personnel payments can only ers (e.g. PhD students) and experienced a) The recent initiative for funding be made to external collaborators, i.e. researchers (e.g. post-docs) in Greek as- “centers of excellence’’ included gener- temporary staff status is not recognised. tronomy departments/groups (referred ous personnel expenses for both ear- Therefore, researchers can formally be to in the sequel as Greek astronomy in- ly stage and experienced researchers hired only as free-lance!!! This increases stitutes; GAIs). (through the “Competitiveness’’ pro- considerably the amount of bureaucracy 1. Astronomy Groups in Universi- gramme of the 3rd EU Support Frame- (e.g. opening of small personal business ties are funded by the Ministry of Ed- work Programme, a programme that will, for taxation purposes, subscription to the ucation. thus, also not be available indefinitely). The health-insurance fund of self-employed a) Over the last few years there have GSRT also provides funding to promote professionals (TEBE), receiving salaries been two calls for funding research collaboration with international organi- only through bank cheques –and not bank projects including personnel expenses sations (e.g. ESO, ESA etc.) that includes transfer– on irregular intervals etc.). (EPEAEK), based mostly on EU funds salaries for temporary research person- Temporary research staff are accom- for the promotion of education and ad- nel. Moreover, the GSRT announces regu- modated along the gaps of the employ- dressed mainly to early stage research- lar binational funding initiatives, but usu- ment system (e.g. they do not have to re- ers. This programme offers rather gen- ally these do not include salaries (as they ceive, and then return to the state, VAT erous financial terms to its beneficiaries mainly cover needs of permanent staff for the provided services since they are (including funding for travel and publi- in travel and infrastructure). In general employed under one contract only and/or cation expenses), but the fact that it is the GSRT is technology oriented, leaving if their programme is supported by the highly competitive and open to all disci- not too much room for pure research EU) and usually have to face ignorance of plines makes the number of fellowships funding. state agencies on their individual needs available to astronomy rather limited. A b) The PENED programmes, funded by (e.g. for researchers employed by the major problem with this sort of funding the GSRT and addressed mainly to early same programme, different bureaucratic is that it is based on funds that will not stage researchers from research groups procedures could be followed depending be available from the EU indefinitely. at the universities, mostly concentrate on the interpretation of the regulations by b) There are only a few “407’’ teach- on technological projects. They thus re- local officers of the corresponding taxa- ing positions (temporary teaching as- quire a commercial partner, making the tion/health-insurance state agencies [1]). sistantships) available to experienced selection of pure research projects rath- This should better change soon! researchers (at the postdoctoral level), er problematic. Moreover, the salary pro- The operating mechanism of the “spe- only in provincial universities. These po- vided is not really generous. cial accounts for research’’ should be re- sitions provide comfortable salaries but In summary, there are regularly a limited structured in order for research groups they last for an average of one year only. number of jobs opening in projects, which to be able to hire non-permanent em- Due to the nature of these positions, the receive funding that includes personnel ployees directly and not as free-lance researchers employed are expected to expenses, but these are not enough to external collaborators. The new Presi- spend considerable time in teaching. employ many young researchers at the dential decree for short-term positions c) The number of IKY state fellow- same time. Employment is mainly at the (the “Pavlopoulos law’’ that has been in- ships for astronomy is limited and the post-doctoral level, or at least funds are troduced to apply in the Greek legisla- postdoctoral fellowships only last for a not available for most PhD students. Most tion a long lasting corresponding EU di- maximum of 18 months. These fellow- full post-doc positions come with the rel- rective) allows for this. It also includes a ships can be awarded for research under- atively comfortable net amount of 1000 reasonable exception for the maximum taken even at non-university research in- euros. However, salaries for early stage position duration, allowing research po- stitutes. However, their financial coverage researchers can be considerably lower sitions to last for 3 years instead of the is minimal and they include no contribu- than this. Most of the above mentioned 2 years that it permits in general.
HIPPARCHOS | Volume 2, Issue 2 7 Possibility for rolling grants tions should get full funding and PhD stu- cate to the rest of the astronomical com- In the previous section, I have argued dents should be primarily considered as munity in Greece in the time between the for the reform of the legislation on the early stage research employees. Howev- Hellenic Astronomical Conferences. Such employment of non-permanent research er, the Greek research employment sys- funding could be awarded by the HEL.A.S. staff in Greece. In the first section, I have tem is not probably capable of handling and would be beneficial to researchers of listed a number of funds available in re- such a big change immediately and any all employment status, as it could essen- cent years for such positions in Greece. improvement on the number of funded tially support the establishment of regular In this section, I propose altering the PhD positions should be gradual. seminar series in most GAIs. In summary, I believe that the existing mechanism with which such funding is Other means of funding awarded. In particular, I believe that for funding for computing and travel sup- the number and size of GAIs a system of The funding of positions is of course the port is more or less sufficient to pro- rolling grants would be ideal. This way, all most important issue both financially and vide a better service to the astronomi- such funds currently available for astron- in terms of the required legislation. How- cal community in Greece if it is managed omy will be put together and get distrib- ever, there is funding on other issues that centrally. is also necessary for making both perma- uted to the different departments/groups Summary and conclusions according to criteria, such as their size, nent and short-term positions in astron- their scientific impact etc. For example, omy in Greece competitive with respect Based on my previous Hipparchos arti- in the existing EPEAK scheme, the Min- to corresponding positions abroad. cle [1], I review the existing legislation istry of Education funds the different uni- The advanced needs for computing and employment opportunities (includ- versities and not directly projects. It is networks as well as computing techniques ing PhD positions) for young astrono- the universities that then distribute the and methods for both theoretical and ob- mers in Greece. Several points of con- grants to their research groups with in- servational astronomical projects makes cern are raised, referring mainly to fund- ternal evaluation procedures. What I pro- the opening of new computer manager ing and employment status, that need to pose is similar, in the sense that all fund- positions really necessary in every GAI. be addressed in order to improve the ing for astronomy will be distributed to Of particular importance in this respect is prospects of employment for young as- the different departments/groups (e.g. in the maintenance of local high-speed net- tronomers in Greece. the form of a (few?) new position(s) each works connecting departments/groups In particular, in the recent years there year, each position lasting for 2-3 years) with each other and abroad. The contin- have been a few short-term positions and then the allocation of the positions uous effort that needs to be invested for (mostly at the post-doctoral level) that to the various research teams of that the setup and maintenance of such net- definitely need to increase in numbers. department will be decided on a local works makes it impossible for the net- I argue that the establishment of rolling departmental level. The way with which work managers to be short-term or part- grants awarded to each GAI will greatly the first stage allocation to the different time employees. Moreover, their support increase the efficiency with which such departments/groups will be implemented on astronomical software will be benefi- grants are awarded within the astronomi- remains open to discussion/negotiation. cial to all members of staff (permanent or cal community. However, the existing em- A national research council is just an ex- not) of the corresponding department/ ployment legislation for non-permanent ample of a body that could be responsi- group. It would worth trying to establish staff at state run institutes is totally out- ble for the funding allocation. funding for the opening and maintenance dated and needs reform urgently. Moreo- Essentially this will provide a constant (at least for the first few years) of such ver, the employment system should soon number of post-doc and PhD positions positions through big EU IT initiatives, start moving towards providing funding per department/group and each per- such as “Information Society’’. for all research students in Greece. manent researcher of that department/ As far as travel support is concerned, Finally, I have proposed the establish- group could be assigned one such posi- I have already proposed [1] the intro- ment of centrally managed funds for the tion at relatively regular intervals. Then duction of a new student fund that will award of computing and travel support decisions will be made at a local level and award travel grants to every PhD student to young researchers in astronomy in more importantly by the real experts. in Greece (that is not funded by other Greece. This will require senior staff to get projects) to attend at least 2 internation- The new legal frameworks for re- involved in negotiations with the gov- al conferences during his/her studies. The search and higher education in Greece, ernment and/or the political parties for fund could be established at a local level which are still in their drafting stage, the implementation of the rolling grant and for students of all disciplines (e.g. for should in principle discuss such issues. It system. What would be the benefit of each university), or at a national level for is still unknown to the author to which the state out of such an exercise (since all astronomy students under the auspic- degree the proposals made in this article it will anyway allocate the same total es of the Hellenic Astronomical Society are in line with the new legislations. funds under the proposed scheme)? De- (HEL.A.S.) or the Greek National Com- creased bureaucracy is what one can mittee for Astronomy (or a National Re- References guarantee! New procedures will have search Council if/when this is introduced). to be implemented at a local level but The option of the central management of 1. Kitsionas, S., 2003, ``Important basic necessities for the development of these will be dealt with mainly by senior such a fund has the benefit of being more astrophysical research in GreeceÓ in research staff and not bureaucrats. flexible to handle a larger total sum. Hipparchos, the Hellenic Astronomical Society Ideally of course, but also according In [1] I also proposed the award of Newsletter, Plionis, M., ed., 13, pp. 10-11 to the recently voted European Charter travel support to researchers from GAIs 2. http://ec.europa.eu/eracareers/pdf/ for Researchers2, all available PhD posi- that have interesting results to communi- am509774CEE_EN_E4.pdf
HIPPARCHOS | Volume 2, Issue 2 8 velopment of Architecture. Usingaset Technology asthe Acropolis for thede- T from Pergamon). from between 86and67B.C. (coins instrument. The shipwreck wasdated suggestion thatitwasanastronomical Mechanism wasmentionedwiththe 1902)theexistenceof February tion ofthe Antikythera shipwreck (15 ous signsofbronze. Inthefirstpublica- broken, worn andcalcified, withobvi- was astrangebulkofmaterial,artifacts September 1901. Among therecovered cavations between November 1900and brought tothesurfaceduringmarineex- household goods andamphoraewere weather. A wealth ofstatues, statuettes, who were strandedthere, duetobad ponnese) in April 1900by spongedivers, Antikythera (between Crete andPelo- by chanceclosetothesmallislandof of the Ancient World can easily beranked amongthe the constructionof technological knowledge required for Taking intoaccountthetheoretical and which hasbeenfound inoneofitsscales. and theMoonfrom theSaros period, It couldalsopredict eclipsesoftheSun bit oftheMoon(firstlunaranomaly). centric gearingfor theanomalousor- with astonishingaccuracy, includingec- motion oftheseobjectswascalculated among thestars. The diurnalandannual Moon and(mostprobably) theplanets Greeks aboutthemotionofSun, the the astronomical knowledge ofancient of gears(atleast30), itputintopractice HIPPARCHOS The Antikythera Mechanismwasfound portant for thedevelopmentportant of he Antikythera Mechanism Decoding the Antikythera Mechanism . | Volume 2, Issue2 Mechanism isasim- Wonders , it , it scientific technology, today thatsurvives thera Mechanismistheoldestproof of Greeks”. Hedeclared that “the Antiky- an extensive account, “Gears from the over 30years andeventually published tre bos Karakalosfrom theResearch Cen- Solla-Price, withthehelpofCharalam- Mechanism extensively, wasDerek de Rhodes. Hediedthere in120B.C. Greek astronomer Hipparchos lived in – 150B.C.). About thistimethegreat second halfofthe2 dated, by epigraphologists, around the probably builtinRhodesandhasbeen pendent spirals(upperandlower). Itwas back oftheMechanismhadtwo inde- tate theouterannulus by oneday. The years, every 4years, theusercouldro- grees). Inorder totake intoaccountleap stellations. Ithad360divisions(360de- bore thenamesof12zodiaccon- days. The innerannulus wasfixed and months. Itwasdividedinto365(or360) fixed andbore thenamesoftwelve tric annuli. The outerannulus wasnot was abronze dialwithtwo concen- cm). The mainfeature onthefront side present-day Laptop (probably 30×20×10 table. Itssizewasnotmuch largerthana The Antikythera Mechanismwaspor- The firstscholar, whostudiedthe Demokritos in Athens. Heworked for nd century B.C. century (100 Department ofPhysics,Department of University Thessaloniki grant from theLeverhulme Foundation, Groupanism Research saloniki) created the “ and John Seiradakis(University of Thes- and Yanis Bitsakis(University of Athens) (Cardiff University), XenophonMoussas of the large stridestoward thereconstruction low theDraconiclunarmonth. Hemade and thattheupperdialwasbuilttofol- back dialsoftheMechanismwere spiral where hecorrectly postulatedthatthe cient Greek Technology” and completely changesourview ofan- ing state of the art equipmentspecially ing stateoftheart tion ofthe Antikythera Mechanism, us- amajornewthey investiga- undertook ogists. InSeptemberandOctober2005 engineers epigraphologists andpapyrol- maticians, physicists, chemists, computer of astronomers, archaeologists, mathe- by aninternationalteam soon supported of Greece) joinedtheteam, whichwas tural Foundation ofthe NationalBank Museum) and Agamemnon Tselikas (Cul- Zafeiropoulou (National Archaeological sion wasgranted, EleniMagkou andMary of Culture ofGreece. After thepermis- a new investigation from theMinistry U.K. andthepermissionto undertake bronze replicas. Wright publishedaseriesofpapers, Wright and Alan Bromley. Michael constructed by In 2001, Mike Edmunds and Tony Freeth The batonwastaken by Michael Hewlett Packar Mechanism 2006 theresults oftheinvesti- gation were announceddur- ing aninternationalconfer- by John H. Seiradakis X-Tek Systems andproduced superb d, USA. InNovember ”. They received a Antikythera Mech- , UKand 9 BRIEF SCIENCE NEWS ence in Athens and published in the in- first written evidence of the word Research Group has created a web site: ternational journal Nature. “¬™¶∞¡¬∞”, which was adopted and http://www.antikythera-mechanism.gr The results of the new investigation established by the Romans during the were surprising and stunning! New in- 1st century B.C. Before then, the name where new results are posted, includ- scriptions, that had not been read for “∂™¶∂ƒ¬∞” (Hesperia) was used, indi- ing answers to basic questions, articles, more than 2000 years were revealed cating the location of Spain toward the pictures, videos and other relevant in- with high energy X-ray tomography West, where the Sun was setting in the formation. (more than 2160 letters were unveiled) evening (∂™¶∂ƒ∞). It is evident that the Antikythera and a very careful analysis of the gears’ The new investigation of the Antiky- Mechanism is a very important record co-action unfolded their use in calcu- thera Mechanism has created word-wide of the ability of ancient Greeks to work lating (a) the 235-month Metonic lu- interest both among the scientific com- with advanced technological problems, nar cycle and (b) the lunar Saros cy- munity and the public. Responding to the offering innovative solutions that, even cle. The Metonic cycle included a pin- demand for updated and authoritative with present day standards, we cannot and-slot mechanism that reconstruct- information, the Antikythera Mechanism fail to admire and respect. ed the first anomaly of the Moon’s mo- tion (due to its elliptical orbit around the Earth). The final gear was driving a pointer that showed the position of the Moon among the constellations and its phase, with the help of a black and white coloured spherule. The 224- month Saros cycle was marked with the dates (month, day, hour) when a possible solar or lunar eclipse would occur. The markings (they were dubbed “glyphs”) were engraved with symbols (“H” –∏§¬√™– for the Sun and “™” –™∂§∏¡∏– for the Moon, etc). The fact that both letters, “H” and “™”, ap- pear simultaneously in some glyphs, means that the glyphs represent pre- dictions of future eclipses and not re- cords of past eclipses. Using a crank-driven pointer, the user of the Mechanism could manually select a date of the year in the front dial. As he was doing this, a set of other pointers were driven by the gears of the Mech- anism to show a variety of astronomi- cal phenomena. In the front dial the po- sition and the phase of the Moon was shown. In the back dials, the user could read the position of the Moon within the Metonic cycle (upper dial). The Antikythera Mechanism was a complicated instrument. Therefore it is not curious that it was accompanied by an extensive User’s Manual. As men- tioned before, at least 2160 characters have been deciphered up to now. They all fall into three broad categories: as- tronomical inscriptions, geographical inscriptions and technical inscriptions. The word “™Δ∏ƒπ°ª√™” (stationary point) is mentioned several times, obvi- ously referring to planetary stationary points. We were delighted to discover the word “¬™¶∞¡¬∞” (Spain). Accord- ing to the Spanish archaeoastronomer Juan Antonio Belmonte, it is probably the
HIPPARCHOS | Volume 2, Issue 2 10 The Astronomy top stories of 2006
mong the top physics stories se- A lected by AIP for the year 2006, five were related to astronomy. These top stories include:
1. BRIEF SCIENCE NEWS The observation of many more supernovas at redshifts of z=1. See next article by V. Charmandaris.
2.
The first direct measurement of turbulence in space. Turbulence can be studied on Earth easily by mapping such things as the density or velocity of fluids in a tank. In space, however, where we expect turbulence to occur in such settings as solar wind, interstellar space, and the accretion disks around black holes, it’s not so easy to measure fluids in time and space. Now, a suite of four plasma-watching satellites, referred to as Cluster, has provided the first defini- tive study of turbulence in space. The satellites are positioned just outside the bow shock ahead of Earth’s magneto- sphere and measure rapid variations in sioning of uranium is exploited for mak- Grenoble, France– keeps careful account the magnetic field as solar wind parti- ing commercial electricity, or when an of both matter mass and electromagnetic cles arrive in Earth’s vicinity. The fluid in electron and positron annihilate inside energy for a process in which ions of sul- question is the wind of particles stream- a PET scanner. A new experiment –con- phur and silicon absorb neutrons, trans- ing toward the Earth from the sun, ducted by scientists from MIT, Univer- forming them into new isotopes as they while the location in question is the re- sité Laval in Quebec City, Canada, Florida emit gamma rays. In this transaction Ein- gion just upstream of Earth’s bow shock, State University, Oxford University, the stein’s equation is shown experimentally the place where the solar wind gets dis- National Institute of Standards and Tech- to be true at a level of 0.00004 percent, turbed and passes by the Earth’s mag- nology, and the Institut Laue-Langevin in a factor of 55 better than the previous netosphere. The waves in the shock-up- best test. stream plasma, pushed around by com- (http://www.aip.org/pnu/2006/split/761-1.html) plex magnetic fields, are observed to be- have a lot like fluid turbulence on Earth. The data is primarily in accord with the 4. leading theory of fluid turbulence, the so called Kolmogorov’s model. A New Triumph for Inflation New WMAP measurements of the cosmic (http://www.aip.org/pnu/2006/split/802-2.html) microwave background, including po- larization information, help to sharpen 3. cosmological numbers such as the age or the flatness of the universe. The in- The best direct test of Einstein’s flationary big bang model has passed a E=mc2 formula Albert Einstein’s for- crucial test as scientists working on the mulation of how matter and energy are Wilkinson Microwave Anisotropy Probe equivalent is an important enunciation of (WMAP) released a long-awaited second the principle of conserved energy. As far set of data at a press conference held as we know, it is at work at the moment March 17, 2006. WMAP was launched in an atom bomb explodes, when the fis- 2001 to map the anisotropies in the cos-
HIPPARCHOS | Volume 2, Issue 2 11 mic microwave background (CMB) with that is, the inhomogeneities should have made. A new computer study of how far greater precision than the Cosmic the same variation at all scales. Inflation, a pair of black holes, circling each oth- Background Explorer, the predecessor on the other hand, predicts a slight devi- er, disturbs the surrounding space and that first discovered the anisotropies ation from this flatness. The new WMAP sends huge gusts of gravitational waves in 1990s. The earlier release of WMAP data for the first time measures the outwards, should greatly benefit the data 3 years ago spectrum with experimental search for those waves with detectors such as the LIGO, Virgo, GEO600 and the planned Laser Inter- ferometer Space Antenna (LISA). The relative difficulty of computer mod- eling of complicated physical be- havior depends partly on the system in question and on the equations that describe the forces at work. To describe the complicated configura- tion of charges and currents, one uses Maxwell’s equations to determine the forces at work. In the case of black-hole binaries, the equations are those from Albert Ein- nailed stein’s theory of general relativity. Black down sever- enough holes encapsulate the ultimate in grav- al grand features of precision to itational forces, and this presents dif- the universe that had previously show a preference for inflation rather ficulties for computations attempting been known only very roughly, includ- than the Harrison-Zeldovic spectrum –a to model behavior nearby. Neverthe- ing: the time of recombination (380,000 test that was long-awaited as inflation’s less, physicists from various groups (Al- years after the big bang, when the first smoking gun. bert Einstein Institute, University of Je- atoms were formed); the age of the uni- na, Penn-State University, University of verse; and the makeup of the universe. (http://www.aip.org/pnu/2006/split/769-1.html) Texas at Brownsville, Goddard Space Since that 2003 announcement, WMAP Flight Center, Caltech) have now de- researchers have painstakingly worked rived algorithms that not only produce to reduce the uncertainties in their re- 5. accurate estimates of the gravitational sults. The big new thing in this announce- waves of the inspiraling black holes, even Modeling gravity wave emissions ment, based on three years of data, was over the short time intervals leading up from black hole mergers, the kinds the release of a map of the sky contain- to the final merger, but also is easily im- of events that LIGO or LISA would pos- ing information about the microwaves’ plemented on computers. sibly detect. Accurate calculations of the polarization. The microwaves are partly (http://www.aip.org/pnu/2006/split/771-1.html) polarized, or oriented, from the time of gravitational waveforms emitted during K.K. their origin (emerging from the so called the collision of black holes can now be sphere of last scattering) and partly po- larized by scattering, on their journey to Earth, from the pervasive plasma of mostly ionized hydrogen created when ultraviolet radiation from the first gener- ation of stars struck surrounding inter- stellar gas. WMAP now estimates that this reionization, effectively denoting the era of the first stars, occurred 400 million years after the big bang, instead of 200 million years as had been previ- ously thought. The main step forward is that smaller error bars, courtesy of the polarization map and the much better temperature map across the sky –with an uncertainty of only 200 billionth of a degree Kelvin– provide a new estimate for the inhomogeneities in the CMB’s temperature. The simplest model, called Harrison-Zeldovich, posits that the spec- trum of inhomogeneities should be flat;
HIPPARCHOS | Volume 2, Issue 2 12 Dark Energy at Redshift z=11
ark energy, the unidentified force Using the Hubble, a team led by Ad- constrain the variation enough to con- D that’s pushing the universe to ex- am Riess, an astrophysicist at the Space vince scientists that dark energy is con- pand at ever faster rates, was already Telescope Science Institute and at Johns stant. Perlmutter says his team is also at work as early as z=1, nine billion Hopkins University has now observed looking at supernovae from the distant years ago, scientists reported during a 23 new supernovae dating back to 8 past, focusing on ones from dust-free re- NASA press conference on November to 10 billion years ago. That was an era gions of the universe, in order to esti- 16, 2006. New Hubble Space Telescope of intense star formation, when galax- mate the statistical and systematic un- BRIEF SCIENCE NEWS sightings of distant supernova explo- ies were three times as bright as they certainties of the measurements. sions support the explanation of dark are today. Until now, astronomers had The new data also confirm the reli- energy as energy of the vacuum whose only seen seven supernovae from that ability of supernovae as signposts of the density has stayed constant through- period, Riess said, too few to measure universe’s expansion. The particular kind out the universe’s history. This cosmic the properties of dark energy. The da- of supernova used for this kind of meas- acceleration was first revealed in 1998 ta, which will be publisned in the Astro- urement, called type Ia, takes place when by two separate teams of astrophysi- physical Journal on February 2007) show a white dwarf star becomes heavier by cists. By measuring the brightness of that the repulsive action of dark energy accreting matter from a companion star, supernova explosions from up to sev- was already active at that time, and are until –at a critical mass of about 1.4 en billion light years ago, the scientists consistent with a constant energy den- times the mass of our sun– it undergoes discovered an unexpected discrepan- sity –in other words, with an energy of a thermonuclear explosion. Virtually all cy. The supernovae appeared dimmer, the vacuum that does not dilute itself as type Ia supernovae have very standard and thus farther, than expected from the universe expands, eventually fueling characteristics –they all follow the same their measured redshifts, that is super- an exponential growth of the universe. cycle, have roughly the same brightness novae at a given distance were less red More complicated models with non-con- and relative abundances of elements, as shifted than expected. Because red shift stant energy density –including a class seen from their spectra. This makes as- measures how much light waves stretch known as quintessence models– are not trophysicists believe that type Ia’s have a as the universe expands, the lower red completely ruled out, Riess said during predictable intrinsic brightness, making shift meant that, early on, the light from the press conference: the new data still their distances easy to estimate. It now these distant supernovae had traveled allows for variations of up to 45 per- appears that the same is true for the in a universe that was expanding at a cent from constant density. “It’s still pret- oldest supernovae, even though the el- slower rate than the current universe ty crude,” Riess said. For more recent emental composition of the universe as (whose rate of expansion is known by ages, dark energy is known to have been a whole was different back then. other means). The then-widely accepted constant up to a 10 percent variation. model of cosmology required instead Lawrence Berkeley Lab astrophysicists V.Ch. that the universe be slowing down in its Saul Perlmutter, who leads another su- expansion, owing to the mutual gravita- pernova search, says that this is a step in 1. Reprinted from the NASA HQ Press office tional tug of all of the matter and en- the right direction, but that only a new, (http://www.nasa.gov/hubble) and the Phys- ergy contained in it. dedicated space telescope will be able to ics News Update.
HIPPARCHOS | Volume 2, Issue 2 13 Skinakas observatory – Crete, Greece A General Description of Infrastructure and Activities by Yiannis Papamastorakis, Department of Physics, University of Crete, Greece www.skinakas.org.gr
1. Location 2. Founding Institutions 3. Seeing Characteristics 4. Telescopes and Instruments 5. Research Activities 6. Educational & Training Activities
1. Location Skinakas Observatory (Longitude 24o 53' 57'' East, Latitude 35o 12' 43'' North) is located on the Ida mountain in Central Crete at an altitude of 1750 m, 25 km line-of-sight distance and 60 km by road from the city of Heraklion. On the road, 20 km before Skinakas, one finds the tra- ditional town of Anoghia, which is well known for its significant role in the recent Cretan history. About 6 km line-of-sight west of the Observatory, lies Ideon An- dron, the famous cave where, according to Myth, the infant Zeus was raised. At the western outskirts of Heraklion, on the way to Skinakas Observatory, are located Fig.1: Aerial photograph of Skinakas Observatory the Physics Department of the University of Crete (UoC), with the Astronomy Lab- oratory, and the Foundation for Research and Technology – Hellas (FORTH). From there the driving time to Skinakas Ob- servatory is about 1.5 hours.
2. Founding Institutions Skinakas Observatory was jointly found- ed by the UoC, FORTH and the Max- Planck Institut für Extraterrestrische Physik (MPE, Garching) in 1984 as a re- search and educational facility.
3. Seeing Characteristics Fig.2: Seeing measurement using DIMM method Using a two-aperture Differential Im- age Motion Monitor (DIMM), the see- 4. Telescopes 0.02 arcsec/m in normal mode. With ing over Skinakas was measured during and Instruments the use of a Focal Reducer, the scale is two campaigns in 2000 and 2001. For multiplied by a factor of 1.87. The tele- a total of 45 nights the median seeing On the summit of Skinakas mountain scope works together with an off-axis was found to be less than 0.7 arcsec. there are three telescopes: guiding unit, which provides tracking Seeing values as low as 0.25 arcsec have • A 1.3 m modified Ritchey-Chret- with an accuracy of 0.2 arcsec. been observed, indicating that Skinakas ien telescope, which has been in work- • A wide field Schmidt-Cassegrain is an excellent site for astronomical ob- ing order since 1995. It has an f/8 fo- 30 cm telescope, which was installed servations. cal ratio with a corresponding scale of on Skinakas in 1986 as the first tel-
HIPPARCHOS | Volume 2, Issue 2 14 REVIEWS
Fig.3: 1.3m Ritchey-Chretien telescope (left), 30cm Scmidt-Cassegrain telescope (top right), 60cm Cassegrain telescope (lower right)
escope there. It is of f/3.2 focal ratio, sion lines in the optical region. Several was commissioned in the Summer of 2006 computer controlled with an autogu- of these filters can also be used with the as an instrument of the 1.3 m telescope. It iding unit. 30 cm telescope for wide field imaging. is a bench mounted spectrograph in white • In the summer of 2006, a 60 cm Cas- For spectroscopic observations, the pupil arrangement using an Echelle R2.14, segrain telescope was installed in col- Focal Reducer installed on the 1.3 m tel- 31.6 grooves/mm grating with two prisms laboration with Tübingen University. It is escope is used as a slit spectrograph as cross dispersion elements. The spec- with slit widths 80, 160, 320 and 640 m. trograph is currently working with a 100 of f/8.2 focal ratio and will operate in ro- Using one of the 10 blazed gratings re- m diameter fiber achieving a resolution botic mode with a Peltier cooled, 4006 sults in dispersions ranging from 530 of R~19000. With a microlens coupled x 2672, 9 m pixel, CCD camera. Å/mm down to 25 Å/mm. 50 m fiber –to be installed in the Spring Several CCD cameras are used for im- A high resolution fiber-fed Echelle of 2007– it is expected to achieve a res- aging or spectroscopy. These are three Spectrograph with dispersion 3 Å/mm olution of up to 38,000. LN2 cooled cameras, a Photometrics front illuminated Thomson chip 1024 x 1024, with 19 m pixel size, a Photomet- rics back illuminated SITe chip 1024 x 1024, with 24 m pixel size, an ISA back illuminated SITe chip 2000 x 800, with 15 m pixel size, and a newly gained deep Peltier cooled Andor camera back illumi- nated E2V chip 2048 x 2048, with 13.5 m pixel size. For photometric observations with the 1.3 m telescope (in normal mode or with the Focal Reducer) the standard U, B, V, R, I broadband filters are avail- able together with a set of Strömgren filters (u, v, b, y, H‚). Also, 16 narrow- band interference filters are availa- ble covering the most important emis- Fig.4: The Echelle Spectrograph
HIPPARCHOS | Volume 2, Issue 2 15 Another significant addition to the infrastructure at Skinakas is a Near-In- frared camera (NIR), manufactured by Fraunhofer IOF, Jena and commissioned in the Summer of 2006 on the 1.3 m tel- escope. It is a f/7.7 Offner design with a Rockwell Hawaii Array of 1024 x 1024, with 18.5 m pixel size. It covers the spectral range between 1 and 2.4 m and includes two sets of filters, 5 nar- rowband (FeII/1644 nm, H2/2122 nm, H2/2144 nm, BrG/2166 nm, CO/2295 nm) and the broadband J, H, and K. Another instrument provided and op- erated by the researchers of the MPE (G. Kanbach’s group) on the 1.3 m Ski- nakas telescope is OPTIMA (Opti- cal Pulsar TIMing Analyzer), a fib- er-fed high speed photo-counter. It uti- lizes sensitive avalanche photo-diodes detecting the fast intensity variability of objects with time resolution of sec. The improved version of the instru- ment, OPTIMA-Burst, run on a three month campaign in the Summer of 2006 on the 1.3 m telescope, to observe gam- ma-ray bursts immediately after detec- tion by the SWIFT satellite. There is a Microwave link connect- ing Skinakas Observatory with the UoC S Fig.5: Near Infrared Camera mounted on the 1.3m Skinakas telescope and FORTH with a 2 Mbit/sec line. T Fig. 6: OPTIMA-Burst mounted on the 1.3m telescope The telescopes and the basic instru- ments (Autoguiders, Filter-wheel, CCD cameras) can be controlled remote- ly or run in robotic mode. Live dem- onstrations of the remotely controlled use of the 1.3 m telescope were car- ried out from Bulgaria, CERN-Geneva, FORTH-Heraklion and Bremen-Germa- ny in 2006.
5. Research Activities The current research projects, conduct- ed by the members of the Astrophysics Group in Crete, that involve the acqui- sition and use of optical data from Ski- nakas Observatory include: XDeep narrow band observations (performed with both the 0.3 m and 1.3 m telescopes at Skinakas) com- plemented by deep long slit spectra at selected positions of the target objects, are used to study the mor- phology and the energy distribution of Planetary Nebulae and Supernova Remnants. XPhotometry and spectroscopy of Be/ X-ray binaries with a compact star companion, using data from the 1.3 m telescope. The main objective is
HIPPARCHOS | Volume 2, Issue 2 16 to characterize the optical/IR varia- bility time scales of these objects by monitoring the evolution of the disc over many years. XPhotometry and spectroscopy of field stars in order to optically iden- tify newly discovered X-ray sources by satellites like SWIFT and INTE- GRAL. XFast photometry of BL Lac objects, on time scales of ~minutes, with the use of different optical band filters. The main aim is to characterize the intra-night flux and spectral varia- tions of these objects. Members of the group also participate in many of the World Earth Blazar Telescope campaigns. XPhotometry of time-scales of min- utes/days is also performed to ra- · dio-quiet AGN, with central engines Fig. 7: Supernova Remnant CTB1 (H +N[II] filter) of small black-hole mass. The total number of refereed publica- est. There are currently 3 undergradu- XPhotometry and spectroscopy of tions based (partly or solely) on Skinakas ate, 2 master’s-level and 1 PhD students, X-ray sources in the Local Group Observations exceeds 80. working on an Astrophysics related The- Galaxies M33 and M31 is being per- sis project in the Physics Department of formed with the aim of identifying the UoC. them. Furthermore, R-band and H· 6. Educational On a European level, undergraduate stu- nightly monitoring of the central part & Training Activities dents from the International University of of M31 is also conducted for the de- A large number of Astrophysics courses Bremen come for regular summer visits to tection of new novae. are offered to under- and post-graduate Skinakas Observatory in order to be intro- students in the Physics Department as duced in Observational Astronomy. Previous research programs included part of the teaching responsibilities of In the framework of two recent re- among others: the faculty members. At Skinakas Ob- search projects (one sponsored by the XStructure of Spiral Galaxies servatory, students have the possibili- Greek Ministry of Transport & Commu- XPhotometry of Star Clusters ty to do their Diploma Thesis on Ob- nication and the other by the EU as part servational Astrophysics participating in of the eTEN programme), the 1.3 m Ski- XRR Lyrae Variables the research projects highlighted above. nakas telescope has been remotely op- XInteraction of Cometary Tails with This involves analysis and interpretation erated from Secondary School classes as the Solar Wind of data in the various fields of inter- part of their Astronomy education.
Fig. 8: Comet Hale-Bopp Fig. 9: Globular star cluster NGC 6426
HIPPARCHOS | Volume 2, Issue 2 17 Eclipsing Binaries: Tools for Calibrating the Extragalactic Distance Scale by Alceste Bonanos Department of Terrestial Magnetism, Carnegie Institute of Washington, USA
Abstract 1. Introduction and 1350 in the SMC (Wyrzykowski et The last decade has seen a dramatic in- al. 2004). A catalog of the eclipsing bina- In the last decade, over 7000 eclips- ries found by the MACHO project with ing binaries have been discovered in crease in the number of extragalactic eclipsing binaries discovered. Most of ~4500 binaries in the LMC and 1500 in the Local Group through various vari- the SMC is underway. Note that some ability surveys. Measuring fundamental these have been found as a side product of the microlensing surveys towards the of these binaries are foreground or ga- parameters of these eclipsing binaries lactic. The SuperMACHO project, using has become feasible with 8 m class Large and Small Magellanic Clouds (LMC and SMC). Starting in the early 1990s the the CTIO Blanco 4 meter telescope, has telescopes, making it possible to use surveyed the Magellanic Clouds down to eclipsing binaries as distance indica- EROS Experiment, the MACHO Project, the Microlensing Observations in Astro- VR~23 mag (Huber et al. 2005), extend- tors. Distances obtained using eclips- ing the sample to include solar type stars, ing binaries provide an independent physics (MOA) and the OGLE Project began monitoring the Magellanic Clouds some of which will be W UMa variables. method for calibrating the extragalac- The first detection of an extragalactic W tic distance scale and thus determining with 1 meter telescopes in a search for dark matter in the form of massive com- UMa was recently made by (Kaluzny et the Hubble constant. This method has al. 2006), with photometry from the 6.5 been used for determining distances pact halo objects. As a side product they have discovered thousands of variable meter Magellan telescopes at Las Cam- to eclipsing binaries in the Magellan- panas, Chile. ic Clouds and the Andromeda Gal- stars, including many eclipsing binaries. The 75 EROS binaries in the LMC pub- Fewer eclipsing binaries are known axy and most recently to a detached in more distant galaxies, partly due to eclipsing binary in the Triangulum Gal- lished by Grison et al. (1995) doubled the known binaries in the galaxy at the time. their faintness and the necessity of large axy by the DIRECT Project. The in- amounts of time on medium size tele- creasing number of eclipsing binaries Soon after, the MOA group released a catalog of 167 eclipsing binaries in the scopes (2-4 meters) to obtain good qual- found by microlensing and variability ity light curves. Two microlensing surveys surveys also provide a rich database SMC (Bayne et al. 2002), followed by the extensive catalogs of the OGLE-II Project are underway for M31. The Wendelstein for advancing our understanding of Calar Alto Pixellensing Project (Fliri et star formation and evolution. which comprise of 2580 eclipsing binaries in the LMC (Wyrzykowski et al. 2003) al. 2006) discovered 31 eclipsing bina- ries in the bulge of M31. The variable star catalog released by the POINT-AGAPE Survey (An et al. 2004) has not been searched systematically for eclipsing bi- naries, but is bound to contain some among the 35000 variables. The DIRECT Project (see Stanek et al. 1998; Bonanos et al. 2003) began moni- toring M31 and M33 in 1996, specifically for Cepheids and detached eclipsing bi- naries (DEBs) with the 1.2 m telescope on Mount Hopkins, Arizona. In M31, a total of 89 eclipsing binaries were found in the 6 fields surveyed. A variability sur- vey using the 2.5 m Isaac Newton tele- scope by Vilardell et al. 2006 has found 437 eclipsing binaries in M31, bringing the total to over 550 eclipsing binaries. In M33, the DIRECT Project has found 148 eclipsing binaries (see Mochejska et al. 2001, and references therein). Eclips- ing binaries have also been discovered by the Araucaria Project in NGC 6822, a dwarf irregular galaxy in the Local Group Figure 1: Primary eclipses of SC16 in V with curve of best fit. Upper panels show residuals in (Mennickent et al. 2006). magnitudes. Filled boxes indicate observations from the MACHO project, open boxes observa- It is worth mentioning the eclipsing tions from the OGLE project (from Alcock et al. 2002). binaries discovered beyond the Local
HIPPARCHOS | Volume 2, Issue 2 18 Group. The first such discovery was to yield the physical radii and effective ing binary systems. Their sample was made back in 1968 by Tammann & Sand- temperatures. The velocity semi-ampli- selected from the OGLE-II database of age, who presented the light curve of a tudes determine both the mass ratio and SMC eclipsing binaries as the brightest 6 day period binary in NGC 2403 (M81 the sum of the masses, thus the individ- systems (B<16 mag) with short periods group) with B~22 mag. More recently, ual masses can be solved for. Further- (Porb<5 days) to increase the efficiency the Araucaria Project has discovered a more, by fitting synthetic spectra to the of multi-fiber spectroscopy over a typi- binary in NGC 300 (Sculptor group). observed ones, one can infer the effec- cal observing run. The mean true dis- Mennickent et al. (2004) present the tive temperature, surface gravity and lu- tance modulus from the whole sample light curve of the B~21.5 mag detached minosity. Comparison of the luminosity is 18.91±0.03 (random) ±0.1 (system- eclipsing binary in this galaxy. of the stars and their observed bright- atic) and the implied LMC distance is Finally, the discovery of 3 Cepheid bi- ness yields the reddening of the system 18.41±0.04 (random) ±0.1 (systemat- naries in the LMC by Udalski et al. (1999) and distance. ic), again in support of the “short” dis- and Alcock et al. (2002) provides a new Measuring distances with eclipsing bi- tance scale. REVIEWS way of calibrating the Cepheid period- naries is an essentially geometric meth- M31 and M33, being the nearest spi- luminosity relation and the extragalactic od and thus accurate and independent ral galaxies, are crucial stepping-stones distance scale. The light curve of one of of any intermediate calibration steps. in the extragalactic distance ladder. Ri- these (SC16) is shown in Figure 1. With the advent of 8 m class telescopes, bas et al. (2005) have determined the eclipsing binaries have been used to ob- first distance to a spiral galaxy, specifi- cally to a semi-detached system (V=19.3 2. Eclipsing Binaries tain accurate distance estimates to the LMC, SMC, M31 and M33; these results mag) in M31. Note that, at such distanc- as Distance Indicators are presented below. es, the location of the binary within the Eclipsing binaries provide an accurate galaxy has an insignificant effect on the method of measuring distances to near- distance (<1%). Light curves for the sys- by galaxies with an unprecedented ac- 3. Eclipsing Binary Distances tem in M31 were obtained from the sur- curacy of 5% —a major step towards a to the Magellanic Clouds vey of Vilardell et al. (2006) with the 2.5 very accurate and independent determi- and M31 m Isaac Newton telescope and spectros- nation of the Hubble constant. Reviews copy with the 8 m Gemini telescope us- The first extragalactic distance measure- and history of the method are present- ing GMOS. Such stars are at the limit of ment using a detached eclipsing binary ed by Andersen (1991) and Paczynski current spectroscopic capabilities. The system was published by Guinan et al. (1997). The method requires both pho- resulting distance is 772±44 kpc and (1998) and demonstrated the great po- tometry and spectroscopy of an eclips- distance modulus is 24.44±0.12 mag, in tential and usefulness of EBs as distance ing binary. From the light and radial ve- agreement with previous distance deter- indicators. The detached 14th mag sys- locity curve the fundamental parameters minations to M31. tem HV 2274 was observed with the of the stars can be determined accu- Faint Object Spectrograph (FOS) on- rately. The light curve yields the frac- board the Hubble Space Telescope. The 4. DIRECT Distance tional radii of the stars, which are then UV/optical spectrophotometry was used to a Detached Eclipsing combined with the radial velocity curves to derive the radial velocity curve and Binary in M33 reddening. The distance to HV 2274 was (a) Motivation determined to be 47.0±2.2 kpc (Guinan et al. 1998, Fitzpatrick et al. 2002). Dis- The DIRECT Project (see Stanek et al. tances to 3 more systems in the LMC 1998; Bonanos et al. 2003) aims to meas- have been determined: the detached 15th ure distances to the nearby Androme- magnitude system HV 982 (Fitzpatrick da (M31) and Triangulum (M33) galaxies et al. 2002) at a distance of 50.2±1.2 with eclipsing binaries and the Baade- kpc, the 15th magnitude detached EROS Wesselink method for Cepheids. It be- 1044 (Ribas et al. 2002) at 47.5±1.8 kpc gan surveying these galaxies in 1996 with and the 14th magnitude semi-detached 1 m class telescopes. The goal of the DI- system HV 5936 at 43.2±1.8 kpc (Fit- RECT Project is to replace the current zpatrick et al. 2003). These support a anchor galaxy of the extragalactic dis- “short” distance scale to the LMC, in tance scale, the LMC, with the more suit- contrast to the LMC distance of 50 kpc able spiral galaxies in the Local Group, adopted by the Key Project (Freedman M31 and M33. These are the nearest spi- Figure 2: Photo of the LMC (from Fitzpatrick ral galaxies to ours, yet more than ten et al. 2003), indicating the locations of eclips- et al. 2001). The spread in the distances ing binaries with distance determinations and is most likely an indication of the intrin- times more distant than the LMC and of two future targets, EROS 1066 and MA- sic extent of the LMC along the line of therefore more difficult to observe stars CHO 0537. The optical center of the LMC’s sight. in them. The Cepheid period-luminosity bar is indicated by the open box, and the Harries et al. (2003) and Hilditch et relation is used to measure distances to LMC’s line of nodes is shown by the line. al. (2005) have conducted a systematic a few tens of Mpc, while Type Ia super- The “near side” of the LMC is to the east of spectroscopic survey of eclipsing bina- novae are used to probe distances out the line of nodes. The location of SN 1987A is also indicated. ries in the SMC, obtaining fundamental to a few hundred Mpc. Galaxies hosting parameters and distances to 50 eclips- both Cepheids and Type Ia supernovae
HIPPARCHOS | Volume 2, Issue 2 19 become calibrators of the luminosities LMC when measuring distances, which (b) DIRECT Observations of supernovae, which are used to deter- introduces systematic errors. Finally, The DIRECT project involves three stag- mine the Hubble constant, H . the reddening across the LMC has been 0 es: surveying M31 and M33 in order to How is the Cepheid period-luminos- shown to be variable (Nikolaev et al. find detached eclipsing binaries and Cep- ity calibrated? Figure 3 shows 84 recent 2004), which has to be carefully account- heids; once discovered selecting and fol- measurements of the distance modulus ed for. These effects add up to a 10-15% lowing up the best targets with medium of the LMC using 21 methods (Figure error in the distance to the LMC, which size telescopes (2-4 m class) to obtain is taken from Benedict et al. 2002). The in the era of precision cosmology is un- more accurate light curves and lastly, ob- large spread in the different measure- acceptable. The replacement of the cur- taining spectroscopy which requires 8-10 ments is quite disturbing. There are sev- rent anchor galaxy of the distance scale m class telescopes. DIRECT completed eral problems with using the LMC as the with a more suitable galaxy or galaxies is the survey stage in 1996-1999 with 200 anchor of the distance scale, which de- long overdue. Furthermore, the Hubble full/partial nights on 1 m class telescopes mand its replacement. The zero point of Space Telescope Key Project (Freedman in Arizona. Follow up observations of the period-luminosity relation is not well et al. 2001) has measured the value of the 2 best eclipsing binaries were ob- determined and the dependence on me- H by calibrating Cepheids measured in 0 tained in 1999 and 2001 using the Kitt tallicity remains controversial. There is spiral galaxies and calibrating secondary Peak 2.1 m telescope in Arizona. The to- increasing evidence for elongation of the indicators and found H =72±8 km s–1 0 tal number of eclipsing binaries found LMC along the line of sight that compli- Mpc–1. This result is heavily dependent in M33 were 237, however only 4 are cates a distance measurement. One has on the distance modulus to the LMC bright enough (V <20 mag) for dis- to additionally include a model of the they adopt (18.50 mag or 50 kpc). max tance determination with currently avail- able telescopes. The criteria for selection include a detached configuration (stars are well within their Roche lobes) and deep eclipses, which remove degenera- cies in the modeling and a short period (<10 days) that makes follow up obser- vations feasible. Bonanos et al. (2006) presented the first distance determination to a de- tached eclipsing binary (DEB) in M33 that was found by Macri et al. (2001). D33J013346.2+304439.9 is located in the OB 66 association shown in Figure 4. Follow up optical data were obtained in order to improve the quality of the light curve and additional infrared obser- vations were made using the 8 m Gemini telescope in order to better constrain the extinction to the system. Spectra of the DEB were obtained in 2002-2004 with the 10-meter Keck-II telescope and 8 m Gemini telescope on Mauna Kea. Note that ~4 hours of observations per epoch were required for radial velocity measurements, a large investment of 8- 10 m class telescope time. Absorption lines from both stars are clearly resolved in the spectrum, making it a double lined spectroscopic binary. Careful modeling with non-lo- cal thermodynamic equilibrium mod- el spectra yielded effective tem- peratures Teff1=37000±1500K and Teff2=35600±1500K. The primary star is defined as the hotter star eclipsed at phase zero. We measured radial veloci- ties from the spectra and from the light Figure 3: Recent determinations of the distance modulus of the LMC. Colors represent the vari- and radial velocity curves derived the ous methods, while the numbers refer to the individual investigations (from Benedict et al. 2002, parameters of the DEB components. The see paper for details). The thick vertical line denotes the distance modulus adopted by the HST V-band light curve model fit for the DEB Distance Scale Key Project (Freedman et al. 2001). is shown in Figure 5. Note that the de-
HIPPARCHOS | Volume 2, Issue 2 20 viation of the secondary eclipse from ing eclipsing binaries. Wyithe & Wilson phase 0.5 is due to the eccentricity of (2002) propose the use of semi-detached the system. The radial velocity curve is eclipsing binaries to be just as good or presented in Figure 6. The rms residuals better distance indicators as detached are 26.0 km s-1 for the primary and 28.0 eclipsing binaries, which have been tra- km s-1 for the secondary star. We find ditionally considered to be ideal. Semi- the DEB components to be O7 type detached binaries provide other benefits: stars with masses: M1=33.4±3.5 Mo, their orbits are tidally circularized and M2=30.0±3.3 Mo and radii R1=12.3±0.4 their Roche lobe filling configurations Ro, R2=8.8±0.3 Ro. provide an extra constraint in the pa- rameter space, especially for complete (c) Distance Determination eclipses. Bright semi-detached binaries in Having measured the temperatures of M33 or M31 are not as rare as DEBs, and the stars from the spectra, we comput- are easier to follow-up spectroscopically, Figure 5: V-band phased light curve of the ed fluxes and simultaneously fit the op- as demonstrated by Ribas et al. (2005) in DEB with model fit from the Wilson-Devin- M31. Thus, for the determination of the tical and near-infrared BVRJHKs pho- ney program. The blue circles correspond to tometry. The best fit that minimized the distances to M33 and M31 to better than the 278 V-band observations and the solid photometric error over the 6 photo- 5% we suggest both determining distanc- line to the model; the rms is 0.01 mag (from metric bands yielded a distance modulus es to other bright DEBs and to semi-de- Bonanos et al. 2006). to the DEB and thus M33 of 24.92±0.12 tached systems found by DIRECT and mag (964±54 kpc). The fit of the red- other variability surveys. Additional spec- dened model spectrum to the photom- troscopy of the DEB would also improve etry is shown in Figure 7. Thus the first the current distance determination to DIRECT result is a 6% distance to M33, M33, since the errors are dominated by which is very accurate considering the the uncertainty in the radius or velocity faintness of the system and limited spec- semi-amplitude. troscopy. How does the M33 DIRECT distance There are several avenues for improv- compare to previous determinations? Ta- ing the distance to M33 and M31 us- ble 1 presents a compilation of 13 re-
Figure 6: Radial velocities for the DEB meas- ured by two-dimensional cross correlation with synthetic spectra. Model fit is from Wil- son-Devinney program. Error bars corre- spond to the rms of the fit: 26.0 km s-1 for the primary (filled circles) and 28.0 km s-1 for the secondary (open circles) (from Bo- nanos et al. 2006).
Figure 7: Fit of the reddened DEB model spectrum to the BVRJHKs ground-based photometry. Overplotted is the U and I pho- tometry from Massey et al. (2006). The dis- Figure 4: Color image of M33 (B, V, I and H·) indicating the location of the OB 66 association tance modulus to the DEB and thus M33 is that hosts the DEB. Credit: T.A.Rector (NRAO/AUI/NSF and NOAO/AURA/NSF) and M.Hanna found to be 24.92±0.12 mag (964±54 kpc) (NOAO/AURA/NSF). (from Bonanos et al. 2006).
HIPPARCHOS | Volume 2, Issue 2 21 cent distance determinations to M33 ranging from 24.32 to 24.92 mag, in- cluding the reddening values used. Our measurement although completely inde- pendent yields the largest distance with a small 6% error, thus is not consistent with some of the previous determina- tions. This possibly indicates unaccount- ed sources of systematic error in the calibration of certain distance indicators. Note the Freedman et al. (2001) distance to M33 is not consistent with the DIRECT measurement. This could be due to their ground based photometry which is likely affected by blending, but highlights the importance of securing the anchor of the Table 1: Recent Distance Determinations to M33 (from Bonanos et al. 2006). extragalactic distance scale. The eclipsing binary distances to the LMC presented above indicate a shorter distance to the pheids, which most methods rely on. An means of measuring masses, radii and LMC. Combined with eclipsing binary independent calibration of the extraga- luminosities of stars. For example, appli- distances to M31 and M33, we should lactic distance scale has become possi- cations to the extremes of stellar mass soon be able to reduce the errors in the ble. The recent distance determinations ranges are underway in order to provide distance scale and thus the Hubble con- to the LMC, SMC, M31 and M33 are pro- constraints to theoretical models of stel- stant to 5% or better. viding 6% distances to these galaxies that lar atmospheres and evolution, such as will improve over the next few years. for M-dwarfs and at the other extreme Combined with geometric distances to for very massive (>50 Mo) O-stars and 5. Epilogue the maser galaxy NGC 4258, the extra- Wolf-Rayet stars. Future projects such The accelerating rate of discovery of galactic distance scale will soon be an- as the wide field imaging surveys Pan- eclipsing binaries provides immense op- chored to several spiral galaxies (M31, STARRS and the Large Synoptic Sur- portunities. With current spectroscop- M33, NGC 4258). vey Telescope (LSST) will survey the sky ic capabilities it has become possible to In addition to their use as distance in- down to 24th mag and yield thousands of measure distances to Local Group gal- dicators, eclipsing binaries provide many binaries in the Galaxy, the Local Group axies out to 1 Mpc, thus providing dis- more opportunities to advance our un- and beyond. tances independent of the controversial derstanding of star formation and evo- LMC distance and the calibration of Ce- lution. In particular, they provide direct
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HIPPARCHOS | Volume 2, Issue 2 22 Mid-Infrared Spectroscopic Diagnostics of Galactic Nuclei by Vassilis Charmandaris Department of Physics, University of Crete & IESL/Foundation for Research & Technology - Greece
Abstract dust and subsequently re-emitted at long- According to the so-called “Unified er wavelengths. So the original question Model” for AGN (see Figure 1) the pu- In this paper I summarize the science naturally translates to what fraction of tative accretion disk near the event ho- motivations, as well as a few mid-in- REVIEWS the bolometric energy observed from a rizon of the SMBH is surrounded by a frared spectroscopic methods used to galaxy originates from an accretion disk torus that blocks the light to the observ- identify the principal mechanisms of (AGN) compared to usual star formation er if he/she happens to be close to the energy production in dust enshroud- activity. This issue is of particular interest plane of the torus. Only for inclinations ed galactic nuclei. The development of in cases where most of the energy of a sufficiently high above this plane the ob- the various techniques is briefly dis- galaxy originates from the nuclear regions server has a direct view to the broad cussed. Emphasis is given to the use rather than the outer regions/disk. line region, to observe it either directly of the data that are becoming avail- Historically, our knowledge on the or via its polarized light emission. This able with the infrared spectrograph physics of the nuclear activity of galaxies model, with various corrections related (IRS) on Spitzer as well as some of is mostly based on optical and near-IR to the structure of the obscuring me- the results which have been obtained spectroscopy, obtained in major ground dium (whether it consists of are clumpy by over the past three years. based telescope facilities. A wealth of di- optically thick clouds or a rather uniform agnostic methods to classify and quanti- distribution of molecular gas and dust), 1. Introduction fy the AGN activity has been developed has been tested extensively in the optical One of the open issues in extragalactic over the years (ie Veilleux & Osterbroc and the near-IR. Recently the last puzzle astronomy is how to quantify the physical 1987; Armus et al. 1989; Kennicutt 1998; of this unification was resolved with the mechanisms that contribute to the ener- Kewley et al. 2001). A presentation of observation of silicate in emission from gy production in galactic nuclei. The most these methods is well beyond the scope the inner torus of quasars, has recently luminous galaxies often display strong of this review but it is only fair to state been verified in the mid-IR (Siebenmor- evidence of massive star formation tak- that they have been extremely successful gen et al. 2005, Hao et al. 2005) ing place in their nucleus. This is typical- in providing insight into the properties The effects of this dust absorption are ly due to the large quantities of atomic of galactic nuclei, in particular in cases very strong, vary substantially as a func- and molecular gas driven in their center where a direct line of sight to the nu- tion of wavelength, and historically are as a result of instabilities on their disk cleus is available. Polarization measure- the principal reasons complicating the such as bars, which often form during tid- ments have also been very useful in iden- interpretation of the optical data. It is al interactions. It is also widely accept- tifying evidence of AGN activity, in cases useful to be reminded that a 10eV op- ed that most galactic nuclei likely harbor where the nucleus is indirectly probed tical photon can penetrate ¾0.5mag of a super-massive black hole (SMBH) (see via scattered light (Heisler et al. 1997). dust, while a 1keV X-ray photon can review of Ferrarese & Ford 2005). Due pass through a hydrogen column of to the high densities found in the nuclei ¾1022 cm–2. If we were to consider the the SMBH may accrete matter at a vari- case of our Galactic Center where the 12 able rate, even though this accretion does AV ¾30mag, only ¾1 in 10 optical pho- not always result in emission of radiation tons emitted in the nucleus of the Milky (Narayan et al. 1998) which would char- Way can reach our Sun. However, if we acterize the galaxy as harboring an active were to observe in K-band (2.2m) the nucleus (AGN). A prime example of such A2.2m ¾2.5mag, and one can detect 10% “non-AGN” is our own Galactic Cent- of the near-IR photons emitted from the 6 er, which does contain a ¾10 MҺ SMBH source. Based on the arguments above, and accretes material, but does not display X-rays are clearly the best diagnostic of any visible AGN activity (Genzel & Townes an AGN especially for higher redshift 1987; Ghez et al. 1998). However, in the systems, as the slope of the X-ray spec- cases where AGN activity is present, hard trum and the sensitivity of the detectors result in relatively flat sensitivity out to electromagnetic radiation, mostly in form Figure 1. An artist conception (not in scale) of UV and X-rays, is emitted from the of the “Unified Model” (Urry & Padovani z¾4–5 (Brandt & Hasinger 2005). How- nucleus. This is typically observed either 1995, Antonucci 1993) according to which ever, the energy emitted in X-rays from directly, in the form of X-rays and radio the obscuring torus which, depending on its the majority of luminous extragalactic emission, which are less affected by ob- orientation, may block the line of sight of the sources is ¾ 1042ergs–1, several orders scuration, and/or indirectly as high ener- observer to the central engine, determines of magnitude bellow their bolometric the observational characteristics of an AGN. gy photons are absorbed by the gas and luminosity. This, in addition to the fact
HIPPARCHOS | Volume 2, Issue 2 23 that X-ray observations need to be molecules (Lutz et al. 1998). The im- In addition to the mid-IR high-ioniza- performed from space, and most ex- proved sensitivity of the infrared spec- tion lines and the 6–18m PAH emis- tragalactic sources are intrinsically faint trograph (IRS) on Spitzer (Houck et al. sion features, the strength of the 3.3m in X-rays, makes estimates of the con- 2004; Werner et al. 2004), a factor of PAH has also been proven a useful AGN tribution of an AGN to their bolomet- ¾100 compared to ISO, enables us to tracer. This feature, which can be probed ric luminosity rather challenging (see extend these diagnostics. More detec- from the ground for relatively bright Mushotzky 2004). Radio waves are an tions based on the [NeV] lines were se- sources, has an EW of ¾0.1m in star- appealing alternative, in particular given cured for a large sample of galaxies and burst systems but is also suppressed in the latest improvements in VLBA (Lons- an in depth study of PAH emission has AGN (see Imanishi 2006). dale et al. 1993, 2003). Even in this case become possible (see Figure 2). Moreo- though, there are difficulties in detect- ver, techniques employing correlations 3. Mid-IR Continuum ing higher redshift systems, as well as based on the strength of other lines such Diagnostics in disentangling issues related to non- as [SIV]Ï10.5m and [SIII]Ï18.7/33.5m thermal emission and self-absorption or principal component analysis are al- Even though high ionization line emis- from embedded nuclei (see Condon so being explored (see Weedman et al. sion is the ideal probe of an active nu- 1992). The use of the infrared part of 2005; Armus et al. 2006; Brandl et al. cleus, despite the IRS sensitivity, the lines the spectrum 3m<Ï<1000m in or- 2006; Dale et al. 2006; Buchanan et al. are often difficult to detect in highly ex- der to develop AGN diagnostics is an 2006, for details). More specifically the tinct and faint/distant sources. The pres- avenue which has been explored for the use of the 6.2m PAH is now readily ence of an AGN though can also be in- past twenty years for two main reasons: used instead of the 7.7m PAH which ferred by detecting the thermal emission a) most luminous galaxies, QSOs being a is more affected by uncertainties in the from dust surrounding the putative torus “bright” exception, emit a sizeable frac- extinction due to the absorption by the heated by the accretion disk to nearly tion their energy (>30% in the infra- 9.7m silicate feature. sublimation temperatures (¾1000K) and red and b) the infrared is considerably less affected by dust absorption than the optical. The all sky survey by IRAS provided the first opportunity to clas- sify a large number of galaxies based on the shape of their global spectral energy distribution (SED), de Grijp et al. (1987) showed that a ratio of S60/ S25>0.26 2 could result in a 70% suc- cess rate in identifying previously un- known Seyferts.
2. Mid-IR Emission Line Diagnostics The advent of mid-IR spectroscopy with the Infrared Space Observatory (ISO) opened a new window in the study of active and starburst galaxies (see Ver- ma et al. 2005, for a review). Emission lines from relatively high excitation ions which are not produced by O stars can be used as a direct probe of AGN ac- tivity. In the infrared such lines are the [NeV]Ï14.3m and [NeV]Ï24.3m with an ionization potential of 97.1eV, and the [OIV] Ï25.9m with 54.9eV. The ne- on lines were detected by ISO in Sey- ferts, though their detection in ULIRGs was challenging due to the limitations in the sensitivity of the ISO spectrographs (Genzel et al. 1998; Sturm et al. 2000). Another indicator is the strength of the emission bands from polycyclic aromatic Figure 2. Mid-infrared excitation diagrams for [NeV]Ï14.3m (top) and [OIV]Ï25.9m (bot- hydrocarbons (PAH) at 3.3, 6.2, 7.7, 8.6, tom) as a function of the 6.2mPAHEW, for starbursts (green circles – Brandl et al. 2006), AGN 11.3, 12.7, 16.3 and 17.1m, which are (red squares, Weedman et al. 2006) and ULIRGs (in blue diamonds), adapted from Armus et al. suppressed in AGN since the hard ra- (2006). The vertical (red) and horizontal (green) lines in dictate the fraction of AGN and star- diation field photo-dissociates the PAH burst contribution.
HIPPARCHOS | Volume 2, Issue 2 24 radiating in near equilibrium. This emis- agnostic method –the so called “Lau- tion of a number of galaxies based on it. sion had been detected in Seyfert galax- rent Diagram”– which takes advantage Even though we suggest the reader to ies and is now evident in IRS spectra of of this difference, as well as the destruc- review the original paper for a detailed distant sources (see Alonso-Herrero et tion of PAHs in both AGN and extreme discussion of the method, a few points al. 2003, and Figure 3). starbursts. Using three template mid-IR are worth mentioning here. Unlike extreme starbursts or HII re- spectra for a “pure” AGN, an HI I re- gions which also display a rising slope gion, and a photodissociation region XThe predictive power of the method at Ï>10m, due to the heating of the (PDR) they defined an AGN dominated depends strongly on the selection of the grains to T¾300K by the embedded O/ locus in a two parameter phase-space template spectra used as the three cor- B stars, the presence of this hot con- (see Figure 4). The proximity of a gal- nerstones. In the original paper of Lau- tinuum at Ͼ5m is only seen in AGN. axy to one of the three corners, i.e. the rent et al. (2000) Centaurus A was se- This is due to the fact the very close to AGN corner, would suggest the extent lected as the AGN template, while now an AGN the hard radiation field from by which the mid-IR spectrum displays the wealth of high quality IRS spectra the accretion disk can heat the dust to AGN characteristics. A first application enabled us to fine tune the selection. nearly sublimation temperature (either of this method to Spitzer/IRS spectros- ~1500K for silicate or ~1000 for graph- copy has been presented in Armus et al. XThe actual coordinates of the three ite) which would have a black body peak (2007). In Figure 4 we display the princi- templates depend on the corresponding according to Wien’s law at ~3-5m. Lau- ple of the method with the three tem- PAH to 5.5m continuum and 14.5 to rent et al. (2000) proposed an AGN di- plate spectra used, as well the classifica- 5.5m continuum ratios. Since the con-
Figure 3. The SED of the nucleus of NGC1068, our nearest Sy-2 at D=14.4Mpc (left), adapted from Alonso-Herrero et al. (2003) compared to the IRS spectrum of FSC15307+3252, a quasar at z=0.92, D=5.8Gpc (see Teplitz et al. 2006). Note the similarity in the thermal emission from the dust near the AGN torus heated to near sublimation temperatures.
Figure 4. An application of the “Laurent Diagram” based on Spitzer/IRS spectra. On the left we display the three template spectra: M17 (scaled by 10-3) as the HII/extreme starburst, 3C273 as the pure AGN template, and NGC7023 as the pure PDR template. On the right we show the location of a number of starbursts, AGNs and ULIRGs on the diagram. The dotted and solid lines indicate the 50 and 75% contribution of the corresponding template to the integrated spectrum of a source (see also Armus et al. 2007)
HIPPARCHOS | Volume 2, Issue 2 25 tinuum fluxes are calculated by integrat- lying continuum in the calculation of the the diagram. Note that the nucleus of a ing under the spectrum, the wavelength 6.2m PAH, also affects the value of the galaxy, which may contain a strong AGN range used for the integration directly abscissa. and/or HI I region component, is often affects the value of the ordinate for all XNone of the templates have been more enshrouded than the PDR regions points in the diagram. It is not obvious corrected for extinction, so the intrinsic in its disk. As a result of this variable ex- that a flat ÓfÓ spectrum will result in an extinction in the observed integrated tinction, there is no one-to-one transla- ordinate equal to unity. In addition, the spectrum of a source may result in plac- tion of an extinction vector for all points exact selection of the limits and under- ing it outside the parameter space of placed in the Laurent diagram.
Figure 5. Model fitst to the IRS spectrum and SED of NGC7714, NGC6240, and PG0804+761. The contribution of the various temperature compo- nents is indicated by the dotted and dashed lines. Note how well the model fit trace, PAH emission features, as well as the silicate absorption and –in the case of PG0804+76– emission features. The presence of an AGN in PG0804+761 is also revealed by the hot dust component peaking at ¾4m. For more details on the luminosity contribution of eachcomponent see Marshall etal. (2006)
HIPPARCHOS | Volume 2, Issue 2 26 The method provides quantitative erties and match the observed spectro- and hot (>300K). The results of the fits means for estimating the AGN contribu- photometry. A large set of theoretical are used to calculate the relative bolo- tion to the “integrated mid-IR spectrum” SEDs are now available for compari- metric contributions from the different of a galaxy. Even though the ¾25–35m son with the observations (i.e. Elitzur & components, providing a method to com- flux traces luminosity it has not yet been Shlosman 2006; Siebenmorgen & Kruegel pare the infrared properties of starburst demonstrated that the this method can 2007, and references therein.). However, galaxies and quasars. Sample results of be used to estimate the contribution of limited knowledge of the details in the the fitting method on NGC7714 –a star- an AGN to the infrared luminosity (LIR) spatial distribution and geometry of the burst galaxy–a ULIRG such as NGC6240 of a system. sources, in particular for systems such and the quasar PG0804+761 are pre- The “Laurent Diagram” appears to as starburst and ULIRGs, which are in- sented in Figure 5. be the most powerful method for AGN herently disturbed, often make this ap- classification in the mid-IR for galaxies proach rather challenging. where no detections or strong limits on Recently, a new fitting approach rely- 5. Conclusions high ionization lines are available. More ing on the Spitzer/IRS 5–38m spectra, It has become evident from the numer- analysis based on Spitzer/IRS spectra will using constrains from near- and far-IR ous contributions presented during this be need to extend its predictive power observations has been developed (Mar- meeting that the high quality of Spitzer/ to the whole IR. Ongoing work indicates shall et al. 2006). The method assumes IRS spectroscopy is opening new hori- that the method can also be applied in that the SED of a galaxy can be decom- zons in the use of the infrared as a tracer Spitzer/IRS low resolution spectroscopic posed into dust components at differ- of the properties of nearby and high-red- studies of extended star forming regions ent characteristic temperatures, source shift galaxies. With another 2.5 years of where variations in the slope of the mid- emission components, embedded phot- mission to go, we have just glimpsed on IR spectrum and the strength of PAHs ospheric emission from starburst cores the possibilities that lie ahead. can be used to quantify the intensity of or an active nucleus as well as PAH fea- star formation of the regions (Leboutel- ture emission. The emission from each Acknowledgments. I would like to thank lier priv. comm.). component is calculated using a realis- Jim Houck for giving me the opportuni- tic dust model consisting of a distribu- ty to spend 5.5 formative years in Ithaca tion of thermally emitting carbonaceous 4. Theoretical Modeling and participate in the Spitzer/IRS “ven- and silicate grains. The model accounts ture”. I would also like to acknowledge Another approach to quantitatively as- for stochastic emission from very small all members of the IRS instrument team sess the contribution of the various grains by fitting model PAH templates to at Cornell and Caltech for many en- components in the observed IR emis- the spectra. This method has been ap- lightening and stimulating discussions on sion from a source is to fit the IR spec- plied in a variety of Spitzer/IRS data and spectroscopy and the infrared. I also ap- trum using theoretical models. Ideally most sources are well fit by a maximum preciate the help of Lee Armus and Jas- one could use a full 3D radiative trans- of four components referred as cold on Marshall who provided data and plots fer calculation to model the dust prop- (¾30K), tepid (¾100K), warm (¾200K), for this paper prior to publication.
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HIPPARCHOS | Volume 2, Issue 2 27 The Athens Solar Orbiter Workshop
he Sun has many satellites, the larg- The Workshop was attended by more with ESA’s science programme funding. T est of which are the planets and than 200 scientists and agency members It is now hoped to obtain final approval our Earth. Solar Orbiter, an ESA satellite from Europe, the USA, Russia and China. to start Solar Orbiter at the end of 2007 planned to be launched in 2015, will be Among the participants were the ESA with the goal to launch in 2015, before the closest satellite to orbit the Sun: its director of Science, prof. D. Southwood the period covered by the new science shortest solar distance will be around along with many other ESA and NASA programme Cosmic Vision 2015-2025. A CONFERENCES 45 solar radii, one fifth of the distance executives. The participants were wel- Call for Letters of Intent to propose for Sun-Earth, where solar radiation is 25 come by academician, prof. G. Conto- the payload of Solar Orbiter was re- times stronger. Evidently, the technical poulos and the vice-rector of the Un. of cently issued by ESA, and was answered challenges are immense for a man made Athens prof. D. Asimakopoulos. The 22- by many groups in Europe (including object to reach these extreme and hos- member scientific organizing commit- several Greek groups) and America, an tile conditions. Equally challenging are tee (SOC) which was co-chaired by E. impressive response that again clearly the unique scientific goals of Solar Or- Marsch (Germany), R. Marsden (ESA) and shows the wide and strong interest of biter which will: K. Tsinganos (Greece), consisted of sci- the solar and heliospheric science com- • Determine the properties, dynamics entists from 10 countries, ESA and the munity in this unique mission. In fact, in and interactions of plasma, fields and USA while the local organizing com- the recent Nov. 2006 ESA/SPC, the ESA particles in the near-Sun heliosphere; mittee (LOC) consisted of K. Tsinganos executives called the Athens meeting • Investigate the links between the so- (Chair), I. Daglis, E. Dara, C. Gontikakis, X. the “break-through” towards the pro- lar surface, corona and inner helio- Moussas, S. Patsourakos, and M. Zoulias. cess of materialization of the Solar Or- sphere; The Solar Orbiter satellite was originally biter mission. • Explore, at all latitudes, the energet- selected in October 2000 as an ESA F- Given that it is the task of this com- ics, dynamics and fine-scale structure mission, with a launch foreseen in the munity in Europe and worldwide to ex- of the Sun’s magnetized atmosphere; time frame 2008-2013. Six years later, ploit the research opportunities offered • Probe the solar dynamo by observing however –despite continued strong sup- by Solar Orbiter and to define its scien- the Sun’s high-latitude field, flows and port from the international solar and tific goals in more depth and detail, the seismic waves. heliospheric science community and a prime motivation for the second Solar The second Workshop devoted to ESA’s number of industrial feasibility studies– Orbiter Workshop was to prepare for, Solar Orbiter mission was held in Ath- the mission has yet to enter its imple- and make the best possible use of, So- ens, Greece, on 16-20 October 2006. mentation phase. No technical show- lar Orbiter within the context of the net- stoppers have been identified; rather work of international solar/heliospheric the mission has suffered, and continues missions. The top-level objectives of the to suffer, from workshop were to: problems • Inform the wider community of the Solar Orbiter opportunity and to in- vestigate synergies to enhance this opportunity, including ground- based support and mod- elling; • Discuss Solar Orbiter operations strat- ence to be conducted with Solar Orbiter tatives to be crucial for the health and egies and scenarios, and outline how in the context of past, present and future survival of the mission in the ESA pro- the goals of Orbiter will be achieved; solar and heliospheric physics missions. gramme. The planned joint ESA/NASA • Strengthen the political and scientific Together with the contributed oral pa- effort promises great enhancements of support for the mission, demonstrat- pers and posters, the invited talks ad- the science possible and offers novel and ing the wide international interest in dressed the specific science targets and unique perspectives for this new multi- the mission. goals for Solar Orbiter. Models and theo- spacecraft approach to solar and helio- • Improve the definition of the payload retical aspects were discussed in special spheric physics. scientifically and technologically; theory presentations. There was also a The venue and conference hotel was session devoted to mission aspects and the Divani Palace Acropolis in Athens, • Identify ways of mission optimization instrumental and technological issues. just a couple of blocks away from Acrop- and international cooperation. In parallel with the planned scientific olis. The attendees enjoyed the hospital- The workshop was organized around program, a good part of the discussion ity of the Greek hosts and their many these goals in several sessions address- time of the Workshop was spent in nu- helpers. The presentations (invited, oral ing the science objectives and the in- merous community, committee and bi- and posters) which will be published by strumental approaches and observation- lateral meetings. Special attention was ESA proceedings, were all of very high al strategies to achieve them. A specific given to the synergies of Solar Orbiter quality and made the Workshop a great focus of the meeting was the exploi- with contemporary space missions and success. Sincere thanks go to all whose tation of the unique orbit and vantage existing ground-based observatories. In contributions and active engagement point of Solar Orbiter that are ideal to particular, the envisioned collaboration were essential for the workshop achiev- link remote-sensing with in-situ obser- with the NASA Sentinels was strongly ing its goals. vations. Invited reviews defined the gen- supported by the workshop attendees eral state of the field and placed the sci- and concluded by the agency represen- Kanaris Tsinganos
X-ray summer school, September 18-20, 2006
he Institute of Astronomy & As- the following: All lectures can be downloaded from T trophysics of the National Ob- • I. Georgantopoulos (National Observa- the school’s web page: servatory of Athens organised the first tory): Overview of X-ray Astronomy www.astro.noa.gr/~ig/xrayschool/ X-ray Astronomy school. This was • A. Mastichiadis (University of Athens): index.htm held between September 18-20 at Pen- Radiation Processes teli. The school was addressed at post- • K. Nandra (Imperial College London): The meeting was very timely given that graduate and young postdoctoral scien- Active Galactic Nuclei X-ray Spectros- in recent years we have seen a golden age tists. The meeting was a success. Over copy in X-ray Astronomy with a wealth of da- ta coming from NASA’s Chandra, ESA’s 20 young astrophysicists from all over • A. Akylas (National Observatory): In- XMM and Japan’s Suzaku X-ray missions. Greece but with the majority of them troduction to XMM Data Analysis coming from the University of Athens The meeting was particularly interesting • K. Tsinganos (University of Athens): and the National Observatory of Ath- for Greek scientists since Greece joined Jets I ens. The talks covered both theoreti- ESA last year and a large fraction of ESA’s • N. Vlahakis (University of Athens): cal issues (e.g. radiation mechanisms activities are devoted on X-ray Astrono- Jets II in X-ray Astronomy) as well as obser- my and Space Sciences in general. ESA is vational topics. More emphasis was giv- • M. Plionis (National Observatory): planning to launch within the next decade en on the extragalactic Universe. Apart X-ray surveys of clusters the XEUS mission as a replacement to from the lectures there was a ‘hands- • S. Vasilakos (Academy of Athens): Large its current XMM mission. XEUS is ex- on’ session dedicated on the analysis of Scale Structure in the X-ray Universe pected to revolutionise X-ray Astronomy data from the XMM X-ray mission in • G. Chartas (Penn State University): having a telescope with an area at least 10 front of a computer. The lecturers came CCDs in X-ray Astronomy times larger than XMM reaching an angu- from both Greek and International In- • A. Georgakakis (Imperial College Lon- lar resolution of 2 arcsec. stitutes. In particular the program was don): Galaxies at X-ray Wavelengths I. Georgantopoulos
29 Recent Developments in Gravity, NEB XII Nafplion 29/6 - 2/7/2006
ontinuing the 24 year old tradition, one of the Greek rela- C tivistic groups, this time the Relativity Group of the Phys- ics Department of the University of Athens, organized the 12th
CONFERENCES Conference of the series “Recent Developments in Gravity” (NEB XII). This time NEB took place at Nafplio, Greece, from Thursday 29th of June to Sunday 2nd of July, 2006. The Confer- ence was attended by more than 100 participants, more than 50% of whom were relativists from abroad (Greek and foreign nationals). This signals a tendency of the last few Conferences to open up the Greek Relativity Conference to the interna- tional scientific community. Actually, many notable members of the relativistic community from all over the globe showed particular interest to come to Nafplio, and spend four relaxed days in a nice sunny and historical place, presenting the results of their more recent work and discussing with colleagues and students from Greece. The NEB XII Conference covered various aspects of gravita- the hospitable environment, but with respect to the high level tional physics: Relativistic Astrophysics, Mathematical Relativ- of talks as well. We hope the next Conference that will be or- ity, Quantum Gravity, and Cosmology. Although the program ganized by the Relativity Group of the Aristotle University of was rather heavy and for the first time we had parallel sessions Thessaloniki, in the summer of 2008, will raise the standards of running in the afternoons, the wonderful weather (apart from the Conference even higher, thus further establishing our Con- the heavy rain during the last afternoon) and the beauty of Naf- ference as a notable Conference in the Relativistic community plion helped the organizers offer the participants a warm, pleas- all over the world. ant, and creative time. According to most attendees’ response, Theocharis Apostolatos their impression was more than good, not only with respect to
The Schutz Symposium on Gravitational Waves and Relativistic Astrophysics 24 - 26 August 2006, Santorini, Greece
n the occasion of the 60th birthday of Bernard Schutz O (Director of the Albert-Einstein-Institute, Max-Planck- Institute for Gravitational Physics, Golm) a very special sym- posium was organized by his students and collaborators on the island of Santorini. The symposium was attended by more than 50 participants, whose scientific careers were initiated or influenced by Bernard Schutz. At the Bellonio Cultural Center in Fira, where the symposium took place on three consecutive days, several speakers presented the impact that Bernard Schutz had as an advisor, collaborator or student (in the case of his own advisor, Kip Thorne) on their research in a wide range of topics that included Stellar Oscillations and Instabilities, Gravi- tational Wave Theory, Detection and Data Analysis, Relativistic Astrophysics, Numerical Relativity, Computing and Science Out- reach. A memorable highlight of the social programme was the birthday party which was organized with the help of Bernard by Bernard Schutz of his path in science, from the days he was Schutz’s close family and which all participants particularly en- a student to the present. joyed. The symposium ended with a very inspiring presentation Nikolaos Stergioulas
HIPPARCHOS | Volume 2, Issue 2 30 !!!
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