DOCSLIB.ORG

Hipparcos Observations of Pre-Main-Sequence Stars R

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Hipparcos Observations of Pre-Main-Sequence Stars R 359 HIPPARCOS OBSERVATIONS OF PRE-MAIN-SEQUENCE STARS 1 2 1 3 4 R. Wichmann , U. Bastian , J. Krautter , I. Jankovics , S.M. Rucinski 1 Landessternwarte Konigstuhl, D-69117 Heidelb erg, Germany 2 Astronomisches Rechen-Institut, D-69120 Heidelb erg, Germany 3 Gothard Astrophysical Observatory, 9707 Szombathely, Hungary 4 David Dunlap Observatory, UniversityofToronto, Canada can b e tested and re ned. Here we present rst re- ABSTRACT sults. A more complete account of this work will b e given elsewhere Wichmann et al., 1997, submitted to MNRAS. We present rst results of Hipparcos observations of nearby low-mass pre-main-sequence PMS stars T Tauri and Herbig Ae/Be stars. The data ob- tained by Hipparcos allow us to deriveweighted mean 2. NEARBY STAR-FORMING REGIONS parallaxes for three ma jor nearby star-forming re- gions SFRs, Lupus, Chamaeleon I, and Taurus- Auriga. 2.1. Taurus-Auriga Furthermore, results on the isolated ob jects AB Dor and TW Hya are presented. Finally,we discuss the For Taurus-Auriga, Elias 1978 concluded that the evolutionary status of Herbig Ae/Be HAEBE stars most likely value of the distance is ab out 140 20 p c. on the basis of Hipparcos results. In this SFR, veTTauri stars and one HAEBE star AB Aur have b een observed by Hipparcos. For the binary system RW Aur only a `sto chastic' solution in Key words: Stars: formation; Stars: late-typ e; Stars: the sense of the Hipparcos Catalogue's internal astro- pre-main-sequence. metric quality classi cation was found. We consider its parallax as dubious and do not use it further. For the remaining ve stars, we obtain a weighted 1. INTRODUCTION mean parallax of h i = 7:06 0:71 mas, or 7:14 0:70 mas if RW Aur is included 1 mas = 1 milliarcsec 3 =10 arcsec. Thus our estimate for the distance The evolutionary status of pre-main-sequence PMS is 142 14 pc, in p erfect agreement with previous stars can b e determined by placing them in the HR estimates. diagram. This allows to estimate the stellar masses and ages by comparison with theoretical evolutionary tracks. Thus, the stellar p opulations of star-forming regions SFRs can be studied, and di erent SFRs 2.2. Chamaeleon I can b e compared. Distance estimates for the Cha I SFR mainly rely on Another imp ortant scienti c goal is the determi- the two stars HD 97300 and HD 97048. A critical nation of the `birthline' Stahler 1988, Palla & discussion of distance estimates can b e found in a re- Stahler 1993, which is the lo cation in the HR di- cent review bySchwartz 1991, who concluded that agram at which PMS stars rst app ear as visible ob- the distance is most likely ab out 140 150 p c. jects. Theoretically, this dep ends on the initial mass accretion rate. There are indications that the birth- line of the Lupus SFR is anomalously low as com- Four T Tauri stars and one HAEBE star HD 97048 pared with Taurus-Auriga and Chamaeleon Hughes in Cha I were observed by Hipparcos. Again, we et al. 1994. exclude one star Sz 19 from the analysis b ecause only a `sto chastic' solution was achieved. Observations of the Hipparcos satellite for the rst The weighted mean parallax of the remaining four time allow to determine trigonometric parallaxes to- stars is h i =6:25 0:68 mas 6:16 0:67 mas if Sz 19 wards nearby SFRs, as well as yielding parallaxes for is included, equivalent to a distance of 160 17 p c, some isolated ob jects and a numb er of Herbig Ae/Be in go o d agreement with the conclusions of Schwartz HAEBE stars. Thus, previous estimates of lumi- 1991. On the other hand, it do es not supp ort nosities, and therefore lo cations in the HR diagram, 360 the large distance of 220 pc derived by Th e et al. photometry to Johnson V, and assuming negligible 1986, which is based on a multi-parameter mo del foreground extinction, we obtain an absolute magni- of HD 97300 including a seemingly implausible hot tude of M =6:07 0:02, in p erfect agreement with V 2740 K dust shell close 0.1 AU to the star. the standard value for a K1 ZAMS star. TW Hya is a K7Ve Li star that was classi ed by Rucinski & Krautter 1983 as classical T Tauri star 2.3. Lupus on the basis of strong H emission as well as on the presence of ultraviolet and infrared excess, although The most recent determination of the distance to- it is lo cated far from any dark cloud. wards the Lupus SFR is from Hughes et al. 1993, who prop osed a distance of 140 20 pc, based on For this star, Hipparcos has measured a parallax of sp ectroscopic parallaxes of foreground stars. =17:72 2:21 mas 56:4 7:0 p c. Again, using Tycho photometry and assuming A = 0, we de- V Five PMS stars in Lupus including the HAEBE star rive an absolute magnitude of M =7:32 0:27 i.e. V HR5999 were observed by Hipparcos. For these 0:8 mag ab ove the main sequence, which should b e stars, we determined a weighted mean parallax of regarded as a lower limit only. Using the evolution- h i =5:26 0:75 mas, corresp onding to a distance of ary tracks from D'Antona & Mazzitelli 1994, we 7 190 27 p c. estimate the age of the star to ab out 1:5 10 yrs, and the mass to ab out 0:8M . It is noted that the lo- Murphy et al. 1986 have p ointed out that the cation in the HR diagram and the age estimate given Lupus SFR is seen pro jected onto a gap between here are somewhat in disagreement with the classical two subgroups of the Scorpius-Centaurus OB as- TTauri nature of the star. so ciation. The Hipparcos parallax indicates that the Lupus SFR is actually connected with Sco-Cen Rucinski & Krautter 1983 sp eculated that TW Hya o distance 170 pc, according to Guti errez-Moreno & mighthave escap ed from a cloud ab out 13 distant, Moreno 1968, rather than b eing lo cated in the fore- at l = 279 , b = +10 . According to Hipparcos ob- ground. servations, it has a large prop er motion: cos = 66:9 mas/yr, = 12:4 mas/yr. However, almost Hughes et al. 1994 concluded that the Lupus SFR all of this is due to solar ap ex motion. The re ex is older than Taurus-Auriga and Cha I, with the age prop er motion of TW Hya is, using the standard solar 6 distribution of its PMS stars p eaking at 3 10 yrs ap ex, cos = 67:3 mas/yr, = 18:5 mas/yr. assuming a distance of 140 p c, compared to Thus the transverse motion after correction is only 5 3 10 yrs for Taurus-Auriga and Cha I. Scaling their cos = +0:4 mas/yr, = +6:1 mas/yr, corre- 1 luminosities to a distance of 190 p c, we nd an av- sp onding to only 1.6 km s transverse velo city at erage reduction of the age by a factor of ab out 2.3. 56 p c. The solar-motion-corrected radial velo cityis 1 1 Thus, although the di erence to Taurus-Auriga and only 3:5 km s 3 km s , so that the galac- Cha I is reduced, it is still signi cant. 1 tic space motion is only of the order of 4 km s . This small motion makes it clear that TW Hya can- The larger Hipparcos distance also moves the Lupus not have escap ed from any known dark cloud within birthline up by ab out 0.25 mag. However, a distance the last few million years. Even in 15 million years it of 300 pc for the Lupus SFR would be required in would have travelled only 60 p c relative to the galac- order to match its birthline to that of the Taurus- tic standard of rest. Thus, b oth the Hipparcos par- Auriga and Cha I SFRs. Probably the birthline is allax and the Hipparcos prop er motion deep en the low b ecause there are no newly b orn stars to de ne mystery ab out the nature and lo cation of this star. it. This tentative explanation is in agreement with the observed lack of deeply emb edded near-IR ob jects in the Lupus SFR. 4. HERBIG Ae/Be STARS 3. ISOLATED STARS Most of the HAEBE observed by Hipparcos are lo- cated in distant SFRs, and thus individual parallaxes are of low precision usually. Wehave therefore calcu- Within the Hipparcos program, a small numb er of ap- lated the weighted mean o set to the ZAMS, M , v parently isolated stars have b een observed that were de ned as: susp ected to be of PMS nature. Rather accurate parallaxes were measured for AB Dor and TW Hya M = hM M i 1 V V V ;ZAMS = 66:92 0:54 mas and = 17:72 2:21 mas, resp ectively, while the observations of FK Ser and for these stars, in order to evaluate their evolutionary CoD27 11363 are inconclusive due to the large er- status and to check the calculations for the birthline rors =9:42 6:17 mas and =3:23 5:65 mas, Palla & Stahler 1993.
Load more

Recommended publications
  • Publication List – Beate Stelzer
    PUBLICATION LIST – BEATE STELZER Refereed publications 87. Pizzocaro D., Stelzer B., Paladini R., Tiengo A., Lisini G., Novara G., Vianello G., Belfiore A, Marelli M., Salvetti D., Pillitteri I., Sciortino S., D’Agostino D., Haberl F., Watson M., Wilms J., Salvaterra R., De Luca A. Results from DROXO IV. EXTraS discovery of an X-ray flare from the Class I protostar candidate ISO-Oph 85 2016, A&A 587, A36 86. Antoniucci S., Nucita A.A., Giannini T., Lorenzetti D., Stelzer B., Gerardi D., Delle Rose S., Di Paola A., Giordano M., Manni L., Strafella F. 2015, A&A 584, A21 First X-ray dectection of the young variable V1180 Cas 85. Stelzer B. 2015, AN 336, 493 Variability of young stellar objects: Accretion, disks, outflows, and magnetic activity 84. Osten R., Melis C., Stelzer B., Bannister K.W., Radigan J., Burgasser A.J., Wolszczan A. & Luhman K.L. 2015, ApJ 805, L3 The Deepest Constraints on Radio and X-ray Magnetic Activity in Ultracool Dwarfs from WISE J104915.57-531906.1 83. Borsa F., Scandariato G., Rainer M., ... Stelzer B. 2015, A&A 578A, 64 The GAPS Programme with HARPS-N at TNG. VII. Putting exoplanets in the stellar context: magnetic activity and asteroseismology of τ Bootis A 82. Maldonado J., Affer L., Micela G., Scandariato G., Damasso M., Stelzer B., et al. 2015, A&A 557A, 132 Stellar parameters of early M dwarfs from ratios of spectral features at optical wavelengths 81. Frasca A., Biazzo K., Lanzafame A.C., Alcal´aJ.M., Brugaletta E., Klutsch A., Stelzer B., et al.
    [Show full text]
  • Probing Protoplanetary Disk Upper Atmospheres for Heating and Dust Settling Using Synthetic CO Spectra Josiah Lewis Covenant College
    Clemson University TigerPrints Publications Physics and Astronomy 7-1-2010 Probing Protoplanetary Disk Upper Atmospheres for Heating and Dust Settling using Synthetic CO Spectra Josiah Lewis Covenant College Martin Kronberg University of Washington Sean D. Brittain Clemson University, [email protected] Follow this and additional works at: https://tigerprints.clemson.edu/physastro_pubs Part of the Astrophysics and Astronomy Commons Recommended Citation Please use publisher's recommended citation. This Article is brought to you for free and open access by the Physics and Astronomy at TigerPrints. It has been accepted for inclusion in Publications by an authorized administrator of TigerPrints. For more information, please contact [email protected]. Journal of the Southeastern Association for Research in Astronomy, 4, 20-25, 2010 July 1 °c 2010. Southeastern Association for Research in Astronomy. All rights reserved. PROBING PROTOPLANETARY DISK UPPER ATMOSPHERES FOR HEATING AND DUST SETTLING USING SYNTHETIC CO SPECTRA Josiah Lewis1 Covenant College, Box 625, 14049 Scenic Highway, GA 30790 Martin Kronberg1 University of Washington, Seattle, C319 Physics/Astronomy Building, Seattle, WA 98195 and Sean Brittain Department of Physics and Astronomy, Clemson University, Clemson, SC 29634-0978 ABSTRACT CO emission is a useful probe of the warm gas distribution in the planet forming regions of disks around Herbig Ae/Be (HAeBe) stars. We model UV fluoresced and thermally excited CO in the circumstellar disks of several HAeBes. We find indications of dust settling in the upper atmospheres of HD 141569 and HD 97048 and a correlation between PAH luminosity and gas heating in these two systems. Subject headings: circumstellar matter—line: profiles—planetary systems: protoplanetary disks— stars: individual (HD 100546, HD 1415469, HD 97048) 1.
    [Show full text]
  • Arxiv:0808.3207V1 [Astro-Ph] 23 Aug 2008 Nfgr .Nwonsaswr Rtdrcl Icvrdi C in Discovered Directly H first Were and Surroun Stars Variability Area Newborn the of 4
    Handbook of Star Forming Regions Vol. II Astronomical Society of the Pacific, 2008 Bo Reipurth, ed. Chamaeleon Kevin L. Luhman Department of Astronomy and Astrophysics The Pennsylvania State University University Park, PA 16802, USA Abstract. The dark clouds in the constellation of Chamaeleon have distances of 160-180pc from the Sun and a total mass of ∼5000 M⊙. The three main clouds, Cha I, II, and III, have angular sizes of a few square degrees and maximum extinctions of AV ∼ 5-10. Most of the star formation in these clouds is occurring in Cha I, with the remainder in Cha II. The current census of Cha I contains 237 known members, 33 of which have spectral types indicative of brown dwarfs (>M6). Approximately 50 members of Cha II have been identified, including a few brown dwarfs. When interpreted with the evolutionary models of Chabrier and Baraffe, the H-R diagram for Cha I exhibits a median age of ∼2 Myr, making it coeval with IC 348 and slightly older than Taurus (∼1 Myr). TheIMF ofChaI reachesa maximumat a massof0.1-0.15 M⊙, and thus closely resembles the IMFs in IC 348 and the Orion Nebula Cluster. The disk fraction in Cha I is roughly constant at ∼ 50% from 0.01 to 0.3 M⊙ and increases to ∼ 65% at higher masses. In comparison, IC 348 has a similar disk fraction at low masses but a much lower disk fraction at M ∼> 1 M⊙, indicating that solar-type stars have longer disk lifetimes in Cha I. 1. Introduction The southern constellation of Chamaeleon contains one of the nearest groups of dark clouds to the Sun (d ∼ 160-180 pc).
    [Show full text]
  • Tetrahedral Hydrocarbon Nanoparticles in Space: X-Ray Spectra
    Mon. Not. R. Astron. Soc. 000, 1–7 (2018) Printed 15 October 2018 (MN LATEX style file v2.2) Tetrahedral hydrocarbon nanoparticles in space: X-ray spectra G. Bilalbegovic´1, A. Maksimovic´2, L. A. Valencic3;4 1Department of Physics, Faculty of Science, University of Zagreb, Bijenickaˇ cesta 32, 10000 Zagreb, Croatia 2Center of Excellence for Advanced Materials and Sensing Devices, Rudjer Boskoviˇ c´ Institute, Bijenickaˇ cesta 54, 10000 Zagreb, Croatia 3NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA 4The Johns Hopkins University, Department of Physics & Astronomy, 366 Bloomberg Center, 3400 N. Charles St., Baltimore, MD 21218, USA 15 October 2018 ABSTRACT It has been proposed, or confirmed, that diamond nanoparticles exist in various environ- ments in space: close to active galactic nuclei, in the vicinity of supernovae and pulsars, in the interior of several planets in the Solar system, in carbon planets and other exoplanets, carbon- rich stars, meteorites, in X-ray active Herbig Ae/Be stars, and in the interstellar medium. Using density functional theory methods we calculate the carbon K-edge X-ray absorption spectrum of two large tetrahedral nanodiamonds: C26H32 and C51H52. We also study and test our methods on the astrophysical molecule CH4, the smallest C-H tetrahedral structure. A possible detection of nanodiamonds from X-ray spectra by future telescopes, such as the project Arcus, is proposed. Simulated spectra of the diffuse interstellar medium using Cyg X-2 as a source show that nanodiamonds studied in this work can be detected by Arcus, a high resolution X-ray spectrometer mission selected by NASA for a Phase A concept study.
    [Show full text]
  • HD 97048: a Closer Look at the Disk
    A&A 470, 625–631 (2007) Astronomy DOI: 10.1051/0004-6361:20066610 & c ESO 2007 Astrophysics HD 97048: a closer look at the disk C. Doucet1,2, E. Habart3, E. Pantin1,2,C.Dullemond4,P.O.Lagage1,2,C.Pinte5, G.Duchêne5, and F. Ménard5 1 AIM, Unité Mixte de Recherche CEA – CNRS – Université Paris VII – UMR 7158, France e-mail: [email protected] 2 DSM/DAPNIA/service d’Astrophysique, CEA/Saclay, 91191 Gif-sur-Yvette, France 3 Institut d’Astrophysique Spatiale (IAS), 91405 Orsay Cedex, France 4 Max-Planck-Institut fur Astronomie Heidelberg, Konigstuhl 17, Heidelberg, Germany 5 Laboratoire d’Astrophysique de Grenoble, CNRS/UJF UMR 5571, Grenoble, France Received 20 October 2006 / Accepted 30 April 2007 ABSTRACT Aims. Large ground-based instruments, like VISIR on the VLT, providing diffraction-limited (∼0.3 arcsec) images in the mid-infrared where strong PAH features appear, enable us to see the flaring structure of the disks around Herbig Ae stars. Although progress has been made in modelling the disk with radiative transfer models able to reproduce the spectral energy distribution (SED) of Herbig Ae stars, the constraints brought by images have not been yet fully exploited. We investigate whether these new observational imaging constraints can be accounted for by predictions based on existing models of passive, centrally irradiated hydrostatic disks made to fit the SEDs of the Herbig Ae stars. Methods. The images taken by VISIR in the 8.6 and 11.3 µm aromatic features reveal a large flaring disk around HD 97048 inclined to the line of sight.
    [Show full text]
  • Arxiv:0708.0266V1 [Astro-Ph] 2 Aug 2007 5 H,Cnd;[email protected]
    submitted to ApJ A Comprehensive View of Circumstellar Disks in Chamaeleon I: Infrared Excess, Accretion Signatures and Binarity Ivana Damjanov1, Ray Jayawardhana1, Alexander Scholz2, Mirza Ahmic1, Duy C. Nguyen1, Alexis Brandeker3, Marten H. van Kerkwijk1 ABSTRACT We present a comprehensive study of disks around 81 young low-mass stars and brown dwarfs in the nearby ∼2 Myr-old Chamaeleon I star-forming region. We use mid-infrared photometry from the Spitzer Space Telescope, supplemented by findings from ground-based high-resolution optical spectroscopy and adaptive +6 optics imaging. We derive disk fractions of 52% ± 6% and 58−7% based on 8 µm and 24 µm colour excesses, respectively, consistent with those reported for other clusters of similar age. Within the uncertainties, the disk frequency in our sample of K3–M8 objects in Cha I does not depend on stellar mass. Diskless and disk-bearing objects have similar spatial distributions. There are no obvious transition disks in our sample, implying a rapid timescale for the inner disk clearing process; however, we find two objects with weak excess at 3–8 µm and substantial excess at 24 µm, which may indicate grain growth and dust settling in the inner disk. For a sub-sample of 35 objects with high-resolution spectra, we investigate the connection between accretion signatures and dusty disks: in the arXiv:0708.0266v1 [astro-ph] 2 Aug 2007 vast majority of cases (29/35) the two are well correlated, suggesting that, on average, the timescale for gas dissipation is similar to that for clearing the inner dust disk. The exceptions are six objects for which dust disks appear to persist even though accretion has ceased or dropped below measurable levels.
    [Show full text]
  • HD 97048'S CIRCUMSTELLAR ENVIRONMENT AS REVEALED BY
    The Astronomical Journal, 133:2122 Y2131, 2007 May A # 2007. The American Astronomical Society. All rights reserved. Printed in U.S.A. HD 97048’s CIRCUMSTELLAR ENVIRONMENT AS REVEALED BY A HUBBLE SPACE TELESCOPE ACS CORONAGRAPHIC STUDY OF DISK CANDIDATE STARS R. L. Doering,1, 2 M. Meixner,2 S. T. Holfeltz,2 J. E. Krist,3 D. R. Ardila,4 I. Kamp,5 M. C. Clampin,6 and S. H. Lubow2 Received 2006 July 14; accepted 2007 January 6 ABSTRACT We present the results of a coronagraphic scattered-light imaging survey of six young disk candidate stars using the Hubble Space Telescope Advanced Camera for Surveys. The observations made use of the 1.800 occulting spot through the F606W (broad V ) filter. Circumstellar material was imaged around HD 97048, a Herbig Ae/Be star located in the Chamaeleon I dark cloud at a distance of 180 pc. The material is seen between 200 (360 AU) and 400 (720 AU) from the star in all directions. A V-band azimuthally averaged radial surface brightness profile peaks at r ¼ 200 with a value of 19:6 Æ 0:2 mag arcsecÀ2 and smoothly decreases with projected distance from the star as I / rÀ3:3Æ0:5. An inte- grated flux of 16:8 Æ 0:1 mag is measured between 200 and 400, corresponding to a scattered-light fractional luminosity À4 lower limit of Lsca /LÃ > 8:4 ; 10 . Filamentary structure resembling spiral arms similar to that seen in Herbig Ae/Be disks is observed. Such structure has been attributed to the influence of orbiting planets or stellar encounters.
    [Show full text]
  • Resolving the Inner Regions of the HD 97048 Circumstellar Disk with VLT/NACO Polarimetric Differential Imaging
    A&A 538, A92 (2012) Astronomy DOI: 10.1051/0004-6361/201118246 & c ESO 2012 Astrophysics Resolving the inner regions of the HD 97048 circumstellar disk with VLT/NACO polarimetric differential imaging S. P. Quanz1,S.M.Birkmann2,D.Apai3,S.Wolf4, and T. Henning5 1 Institute for Astronomy, ETH Zurich, Wolfgang-Pauli-Strasse 27, 8093 Zurich, Switzerland e-mail: [email protected] 2 ESA/ESTEC, Keplerlaan 1, Postbus 299, 2200 AG Noordwijk, The Netherlands 3 Department of Astronomy/Department of Planetary Sciences, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721, USA 4 University of Kiel, Institute of Theoretical Physics and Astrophysics, Leibnizstrasse 15, 24098 Kiel, Germany 5 Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany Received 11 October 2011 / Accepted 7 December 2011 ABSTRACT Context. Circumstellar disks are the cradles of planetary systems and their physical and chemical properties directly influence the planet formation process. Because most planets supposedly form in the inner disk regions, i.e., within a few tens of AU, it is crucial to study circumstellar disks on these scales to constrain the conditions for planet formation. Aims. Our aims are to characterize the inner regions of the circumstellar disk around the young Herbig Ae/Be star HD 97048 in polarized light. Methods. We used VLT/NACO to observe HD 97048 in polarimetric differential imaging (PDI) mode in the H and Ks band. This technique offers high-contrast capabilities at very small inner working angles and probes the dust grains on the surface layer of the disk that act as the scattering surface.
    [Show full text]
  • THE STAR FORMATION NEWSLETTER an Electronic Publication Dedicated to Early Stellar Evolution and Molecular Clouds
    THE STAR FORMATION NEWSLETTER An electronic publication dedicated to early stellar evolution and molecular clouds No. 177 — 22 July 2007 Editor: Bo Reipurth ([email protected]) Abstracts of recently accepted papers Statistics of superimposed flares in the Taurus molecular cloud K. Arzner1, M. G¨udel1, K. Briggs1, A. Telleschi1 and M. Audard2 1 Paul Scherrer Institut, CH 5232 Villigen, Switzerland 2 Columbia Astrophysics Laboratory, 550 West 120th St., MC 5247, New York, NY 10027, USA E-mail contact: arzner at astro.phys.ethz.ch Context. Stochastically occurring flares provide a possible mechanism of coronal heating in magnetically active stars such as T Tauri objects in star-forming regions. Aims.We investigate the statistics of stellar X-ray light curves from the XMM-Newton Extended Survey of the Taurus Molecular Cloud (XEST). Methods. To this end, the light curve is modeled as superimposed flares occurring at random times and with random amplitudes. The flare shape is estimated non-parametrically from the observations, while the flare amplitude distri- bution is modeled as a truncated power law, and the flare times are assumed as uniformly distributed. From these model assumptions, predictions on the binned counts are derived and compared with the observations. Results. From a sample of 22 XEST observations matching the above model assumptions we find that the majority of cases have flare amplitude distributions with slopes steeper than two. This favours the role of small flares in coronal heating for 5 targets, of which, however, 4 are foreground or background main-sequence stars. Published by Astronomy & Astrophysics (Vol. 468, p.
    [Show full text]
  • Consistent Dust and Gas Models for Protoplanetary Disks III. Models for Selected Objects from the FP7 DIANA? Project
    Consistent dust and gas models for protoplanetary disks III. Models for selected objects from the FP7 DIANA? project P. WOITKE,1 I. KAMP,2 S. ANTONELLINI,3 F. ANTHONIOZ,4 C. BALDOVIN-SAVEEDRA,5 A. CARMONA,6 O. DIONATOS,5 C. DOMINIK,7 J. GREAVES,8 M. GUDEL¨ ,5 J. D. ILEE,9 A. LIEBHARDT,5 F. MENARD,4 M. MIN,10 C. PINTE,11 C. RAB,2 L. RIGON,12 W.F. THI,13 N. THUREAU,12 AND L. B. F. M. WATERS10 1SUPA, School of Physics & Astronomy, University of St Andrews, North Haugh, KY16 9SS, UK, and Centre for Exoplanet Science, University of St Andrews, St Andrews, UK 2Kapteyn Astronomical Institute, University of Groningen, The Netherlands 3Kapteyn Astronomical Institute, University of Groningen, The Netherlands, and Astrophysics Research Centre, School of Mathematics and Physics, Queens University Belfast, University Road, Belfast BT7 1NN, UK 4Universite´ Grenoble-Alpes, CNRS Institut de Planetologie´ et dAstrophyisque (IPAG) F-38000 Grenoble, France 5University of Vienna, Department of Astrophysics, Turkenschanzstrasse¨ 17, A-1180, Vienna, Austria 6IRAP, Universite´ de Toulouse, CNRS, UPS, Toulouse, France 7Astronomical institute Anton Pannekoek, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands 8School of Physics and Astronomy, Cardiff University, 4 The Parade, Cardiff CF24 3AA, UK 9Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK 10SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, and Astronomical institute Anton Pannekoek, University of Amsterdam,
    [Show full text]
  • Astronomy Astrophysics
    A&A 390, 1089–1113 (2002) Astronomy DOI: 10.1051/0004-6361:20020773 & c ESO 2002 Astrophysics The rich 6 to 9 µm spectrum of interstellar PAHs? E. Peeters1;2,S.Hony3,C.VanKerckhoven4,A.G.G.M.Tielens2;1, L. J. Allamandola5, D. M. Hudgins5, and C. W. Bauschlicher5 1 SRON National Institute for Space Research, PO Box 800, 9700 AV Groningen, The Netherlands 2 Kapteyn Institute, PO Box 800, 9700 AV Groningen, The Netherlands 3 Astronomical Institute “Anton Pannekoek”, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands 4 Instituut voor Sterrenkunde, K.U.Leuven, Celestijnenlaan 200B, 3100 Heverlee, Belgium 5 NASA-Ames Research Center, Space Science Division, MS: 245-6, Moffett Field, CA 94035-1000, USA Received 4 December 2001 / Accepted 16 May 2002 Abstract. IR spectroscopy provides a valuable tool for the characterisation and identification of interstellar molecular species. Here, we present 6–9 µm spectra of a sample of reflection nebulae, HII regions, YSOs, evolved stars and galaxies that show strong unidentified infrared bands, obtained with the SWS spectrograph on board ISO. The IR emission features in this wave- length region show pronounced variations. 1) The 6.2 µmfeatureshiftsfrom6.22to6.3µm and clearly shows profile variations. 2) The 7.7 µm complex is comprised of at least two subpeaks peaking at 7.6 and one longwards of 7.7 µm. In some cases the main peak can apparently shift up to 8 µm. Two sources do not exhibit a 7.7 µm complex but instead show a broad emission feature at 8.22 µm. 3) The 8.6 µm feature has a symmetric profile in all sources and some sources exhibit this band at slightly longer wavelengths.
    [Show full text]
  • A CRIRES Search for Near-IR H2 Emission from Herbig Ae/Be Stars
    UvA-DARE (Digital Academic Repository) Warm gas in protoplanetary disks van der Plas, G. Publication date 2010 Link to publication Citation for published version (APA): van der Plas, G. (2010). Warm gas in protoplanetary disks. General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. UvA-DARE is a service provided by the library of the University of Amsterdam (https://dare.uva.nl) Download date:29 Sep 2021 A CRIRES search for near-IR H2 5 emission from Herbig Ae/Be stars A. Carmona, G. van der Plas, M.E. van den Ancker, M. Audard, L.B.F.M Waters, B. Acke, D. Fedele, E. Pantin To be submitted. Abstract We report on a sensitive search for H2 1-0 S(1), 1-0 S(0) and 2-1 S(1) ro-vibrational emission at 2.12, 2.22 and 2.25 μm in a sample of 14 Herbig Ae/Be stars, employing CRIRES, the ESO-VLT near-infrared high-resolution spectrograph, at R∼90,000.
    [Show full text]