Southern Sky: Telescopic
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Stellar Variability in Open Clusters. I. a New Class of Variable Stars in NGC
Astronomy & Astrophysics manuscript no. ngc3766˙v3˙1b c ESO 2018 September 8, 2018 Stellar variability in open clusters I. A new class of variable stars in NGC 3766 N. Mowlavi1, F. Barblan1, S. Saesen1, and L. Eyer1 1Astronomy Department, Geneva Observatory, chemin des Maillettes, 1290 Versoix, Switzerland e-mail: [email protected] Accepted 16/04/2013 ABSTRACT Aims. We analyze the population of periodic variable stars in the open cluster NGC 3766 based on a 7-year multiband monitoring campaign conducted on the 1.2 m Swiss Euler telescope at La Silla, Chili. Methods. The data reduction, light curve cleaning, and period search procedures, combined with the long observation time line, allowed us to detect variability amplitudes down to the mmag level. The variability properties were complemented with the positions in the color-magnitude and color-color diagrams to classify periodic variable stars into distinct variability types. Results. We find a large population (36 stars) of new variable stars between the red edge of slowly pulsating B (SPB) stars and the blue edge of δ Sct stars, a region in the Hertzsprung-Russell (HR) diagram where no pulsation is predicted to occur based on standard stellar models. The bulk of their periods ranges from 0.1 to 0.7 d, with amplitudes between 1 and 4 mmag for the majority of them. About 20% of stars in that region of the HR diagram are found to be variable, but the number of members of this new group is expected to be higher, with amplitudes below our mmag detection limit. -
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A&A 454, 527–536 (2006) Astronomy DOI: 10.1051/0004-6361:20053468 & c ESO 2006 Astrophysics A search for photometric variability of hydrogen-deficient planetary-nebula nuclei, J. M. González Pérez1,2, J.-E. Solheim2,3, and R. Kamben2 1 Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain e-mail: [email protected] 2 Institut of Physics, University of Tromsø, 9037 Tromsø, Norway 3 Institut of Theoretical Astrophysics, University of Oslo, PO box 1029 Blindern, 0315 Oslo, Norway Received 18 May 2005 / Accepted 9 March 2006 ABSTRACT Aims. We searched for photometric variability in a sample of hot, hydrogen-deficient planetary nebula nuclei (PNNi) with “PG 1159” or “O VI” spectral type, most of them embedded in a bipolar or elliptical planetary nebula envelope (PNe). These characteristics may indicate the presence of a hidden close companion and an evolution affected by episodes of interaction between them. Methods. We obtained time-series photometry from a sample of 11 candidates using the Nordic Optical Telescope (NOT) with the Andalucía Faint Object Spectrograph and Camera (ALFOSC), modified with our own control software to be able to observe in a high- speed multi-windowing mode. The data were reduced on-line with the real time photometry (RTP) code, which allowed us to detect periodic variable stars with small amplitudes from CCD data in real time. We studied the properties of the observed modulation fre- quencies to investigate their nature. Results. We report the first detection of low-amplitude pulsations in the PNNi VV 47, NGC 6852, and Jn 1. In addition, we investi- gated the photometric variability of NGC 246. -
Isolating the Pre-Main Sequence in Collinder 34, NGC 3293, NGC 3766 and NGC 6231
MNRAS 448, 1687–1703 (2015) doi:10.1093/mnras/stv026 Isolating the pre-main sequence in Collinder 34, NGC 3293, NGC 3766 and NGC 6231 T. A. Saurin,‹ E. Bica and C. Bonatto Departamento de Astronomia, Universidade Federal do Rio Grande do Sul, CP 15051, RS, Porto Alegre 91501-970, Brazil Accepted 2015 January 6. Received 2014 December 18; in original form 2014 July 17 Downloaded from ABSTRACT We employed field star decontaminated Two Micron All Sky Survey photometry to study four nearby optical embedded clusters – Collinder 34, NGC 3293, NGC 3766 and NGC 6231 – obtaining deep colour–magnitude diagrams and stellar radial density profiles. We found what seem to be pre-main sequences detached in different amounts from main sequences in these http://mnras.oxfordjournals.org/ diagrams. The structural analysis of each cluster revealed different radial distributions for these two sequences. We argued that the detached evolutionary sequences in our sample may be evidence of sequential star formation. Finally, we compared the sample cluster parameters with those of other young clusters in the literature and point out evidence that NGC 3766 and NGC 6231 might be evolving to OB associations. Key words: open clusters and associations: individual: Collinder 34 – open clusters and asso- ciations: individual: NGC 3293 – open clusters and associations: individual: NGC 3766 – open clusters and associations: individual: NGC 6231. at Universidade Federal do Rio Grande Sul on April 6, 2015 that may be interpreted as mass and age segregation (e.g. Hillen- 1 INTRODUCTION brand 1997). Youngstar clusters remain embedded in molecular clouds during the Using Two Micron All Sky Survey (2MASS;1 Skrutskie et al. -
Constraints on Common Envelope Magnetic Fields from Observations Of
MNRAS 439, 2014–2024 (2014) doi:10.1093/mnras/stu079 Advance Access publication 2014 February 10 Constraints on common envelope magnetic fields from observations of jets in planetary nebulae James Tocknell,1,2‹ OrsolaDeMarco1,2 and Mark Wardle1,2 1Department of Physics and Astronomy, Macquarie University, Sydney, NSW 2109, Australia 2Astronomy, Astrophysics and Astrophotonics Research Centre, Macquarie University, Sydney, NSW 2109, Australia Accepted 2014 January 13. Received 2014 January 13; in original form 2013 August 22 ABSTRACT The common envelope (CE) interaction describes the swallowing of a nearby companion by Downloaded from a growing, evolving star. CEs that take place during the asymptotic giant branch phase of the primary may lead to the formation of a planetary nebula (PN) with a post-CE close binary in the middle. We have used published observations of masses and kinematics of jets in four post-CE PN to infer physical characteristics of the CE interaction. In three of the four systems http://mnras.oxfordjournals.org/ studied, Abell 63, ETHOS 1 and the Necklace PN, the kinematics indicate that the jets were launched a few thousand years before the CE and we favour a scenario where this happened before Roche lobe overflow, although better models of wind accretion and wind Roche lobe overflow are needed. The magnetic fields inferred to launch pre-CE jets are of the order of a few gauss. In the fourth case, NGC 6778, the kinematics indicate that the jets were launched about 3000 yr after the CE interaction. Magnetic fields of the order of a few hundreds to a few thousands gauss are inferred in this case, approximately in line with predictions of post-CE magnetic fields. -
Density Profiles of Populous Star Clusters in the Magellanic Clouds
Density profiles of populous star clusters in the Magellanic Clouds Grigor Nikolov,1,2 Anastasos Dapergolas,3 Mary Kontizas,2 Valeri Golev,1 Maya Belcheva2 1 Department of Astronomy, Faculty of Physics, Sofia University, BG-1164 Sofia, Bulgaria 2 Department of Astrophysics, Astronomy & Mechanics, Faculty of Physics, University of Athens, GR-15783 Athens, Greece 3 IAA, National Observatory of Athens, GR-11810 Athens, Greece [email protected] (Conference poster) Abstract. The Large Magellanic Cloud (LMC) and the Small Magellanic Cloud (SMC) provide the unique opportunity to study young and populous star clusters. Some of them are elliptical in shape, or are members of a multiple systems, which are almost absent in the Milky Way. We have selected a sample of Magellanic Clouds’ star clusters, some of them candidates of a multiple system components, to investigate them by means of their number density profiles. This approach allows us to determine the radial distribution of the stars of different magnitude. Since the brighter stars have larger masses than the fainter stars, the profiles can be used to trace mass-segregation in the clusters. We have fitted a theoretical model by Elson, Fall & Freeman [1987] to determine the core radius and the concentration of the stars for each magnitude range. Key words: star clusters Профили на плътността на населени звездни купове в Магелановите облаци Григор Николов, Анастасос Даперголас, Мери Контизас, Валери Голев, Мая Белчева Големият и Малкият Магеланови облаци предлагат уникалната възможност за изуча- ване на млади богато населени звездни купове. Някои от тях имат елиптична форма или са членове на двойни системи, каквито се срещат много рядко в Млечния път. -
Luminosities and Mass-Loss Rates of SMC and LMC AGB Stars and Red Supergiants Dependence of Mass Loss on Metallicity, the Amount of Dust Pro- PAH Emission1
Astronomy & Astrophysics manuscript no. art63 c ESO 2018 November 10, 2018 Luminosities and mass-loss rates of SMC and LMC AGB stars and Red Supergiants ⋆ M. A. T. Groenewegen1, G. C. Sloan2, I. Soszy´nski3, and E. A. Petersen4,5 1 Koninklijke Sterrenwacht van Belgi¨e, Ringlaan 3, B–1180 Brussels, Belgium e-mail: [email protected] 2 Cornell University, Astronomy Department, Ithaca, NY 14853-6801, USA 3 Warsaw University Observatory, Al. Ujazdowskie 4, 00-478 Warszawa, Poland 4 University of Nebraska, Department of Physics and Astronomy, Lincoln, NE 68588, USA 5 NSF REU Research Assistant, Cornell University, Astronomy Department, Ithaca, NY 14853-6801, USA received: 2009, accepted: 20-08-2009 ABSTRACT Context Mass loss is one of the fundamental properties of Asymptotic Giant Branch (AGB) stars, and through the enrichment of the interstellar medium, AGB stars are key players in the life cycle of dust and gas in the universe. However, a quantitative understanding of the mass-loss process is still largely lacking, particularly its dependence on metallicity. Aims To investigate the relation between mass loss, luminosity and pulsation period for a large sample of evolved stars in the Small and Large Magellanic Cloud. Results Dust radiative transfer models are presented for 101 carbon stars and 86 oxygen-rich evolved stars in the Magellanic Clouds for which 5–35 µm Spitzer IRS spectra are available. The spectra are complemented with available optical and infrared photometry to construct the spectral energy distribution. A minimisation procedure is used to fit luminosity, mass-loss rate and dust temperature at the inner radius. -
XMM-Newton Observations of the Galactic Globular Clusters NGC 2808 and NGC 4372
A&A 480, 397–407 (2008) Astronomy DOI: 10.1051/0004-6361:20078327 & c ESO 2008 Astrophysics XMM-Newton observations of the Galactic globular clusters NGC 2808 and NGC 4372 M. Servillat, N. A. Webb, and D. Barret CESR, Université Paul Sabatier, CNRS, 9 avenue du Colonel Roche, 31400 Toulouse, France e-mail: [email protected] Received 20 July 2007 / Accepted 28 November 2007 ABSTRACT Aims. Galactic globular clusters harbour binary systems that are detected as faint X-ray sources. These close binaries are thought to play an important role in the stability of the clusters by liberating energy and delaying the inevitable core collapse of globular clusters. The inventory of close binaries and their identification is therefore essential. Methods. We present XMM-Newton observations of two Galactic globular clusters: NGC 2808 and NGC 4372. We use X-ray spectral and variability analysis combined with ultra-violet observations made with the XMM-Newton optical monitor and published data from the Hubble Space Telescope to identify sources associated with the clusters. We compare the results of our observations with estimates from population synthesis models. Results. Five sources out of 96 are likely to be related to NGC 2808. Nine sources are found in the field of view of NGC 4372, none being located inside its half-mass radius. We find one quiescent neutron star low mass X-ray binary candidate in the core of NGC 2808, and propose that the majority of the central sources in NGC 2808 are cataclysmic variables. An estimation leads to 20±10 cataclysmic variables with luminosity above 4.25 × 1031 erg s−1. -
Abstracts Connecting to the Boston University Network
20th Cambridge Workshop: Cool Stars, Stellar Systems, and the Sun July 29 - Aug 3, 2018 Boston / Cambridge, USA Abstracts Connecting to the Boston University Network 1. Select network ”BU Guest (unencrypted)” 2. Once connected, open a web browser and try to navigate to a website. You should be redirected to https://safeconnect.bu.edu:9443 for registration. If the page does not automatically redirect, go to bu.edu to be brought to the login page. 3. Enter the login information: Guest Username: CoolStars20 Password: CoolStars20 Click to accept the conditions then log in. ii Foreword Our story starts on January 31, 1980 when a small group of about 50 astronomers came to- gether, organized by Andrea Dupree, to discuss the results from the new high-energy satel- lites IUE and Einstein. Called “Cool Stars, Stellar Systems, and the Sun,” the meeting empha- sized the solar stellar connection and focused discussion on “several topics … in which the similarity is manifest: the structures of chromospheres and coronae, stellar activity, and the phenomena of mass loss,” according to the preface of the resulting, “Special Report of the Smithsonian Astrophysical Observatory.” We could easily have chosen the same topics for this meeting. Over the summer of 1980, the group met again in Bonas, France and then back in Cambridge in 1981. Nearly 40 years on, I am comfortable saying these workshops have evolved to be the premier conference series for cool star research. Cool Stars has been held largely biennially, alternating between North America and Europe. Over that time, the field of stellar astro- physics has been upended several times, first by results from Hubble, then ROSAT, then Keck and other large aperture ground-based adaptive optics telescopes. -
A Basic Requirement for Studying the Heavens Is Determining Where In
Abasic requirement for studying the heavens is determining where in the sky things are. To specify sky positions, astronomers have developed several coordinate systems. Each uses a coordinate grid projected on to the celestial sphere, in analogy to the geographic coordinate system used on the surface of the Earth. The coordinate systems differ only in their choice of the fundamental plane, which divides the sky into two equal hemispheres along a great circle (the fundamental plane of the geographic system is the Earth's equator) . Each coordinate system is named for its choice of fundamental plane. The equatorial coordinate system is probably the most widely used celestial coordinate system. It is also the one most closely related to the geographic coordinate system, because they use the same fun damental plane and the same poles. The projection of the Earth's equator onto the celestial sphere is called the celestial equator. Similarly, projecting the geographic poles on to the celest ial sphere defines the north and south celestial poles. However, there is an important difference between the equatorial and geographic coordinate systems: the geographic system is fixed to the Earth; it rotates as the Earth does . The equatorial system is fixed to the stars, so it appears to rotate across the sky with the stars, but of course it's really the Earth rotating under the fixed sky. The latitudinal (latitude-like) angle of the equatorial system is called declination (Dec for short) . It measures the angle of an object above or below the celestial equator. The longitud inal angle is called the right ascension (RA for short). -
Planetary Nebulae
Southern Planetaries 6/27/04 9:20 PM Observatory Tents Nebula Filters by Andover Ngc 60 Meade NGC60 Premier online astronomy For viewing emission and Find, compare and buy Refractor Telescope $181 shop has a selection of planetary nebulae. Telescopes! Simply Fast Free Shipping. Affiliate. observatory dome tents Narrowband and O-III types Savings www.amazon.com www.telescopes.net www.andcorp.com www.Shopping.com Observing Down Under: Part II - Planetary Nebulae by Steve Gottlieb Shapley 1 - AAO This is the second part in a series based on my trip to Australia last summer, covering observations of a few southern showpiece objects. The other parts in the series are: Southern Globular Clusters Southern Galaxies Two Southern Galaxy Groups During the stay at the Magellan Observatory I had full access to an 18" f/4.5 JMI NGT-18, an innovative split-ring truss- tube equatorial with a rotating upper cage assembly. The scope was housed in a 4.5 meter dome (which came in very handy on windy nights) and outfitted with DSC's and it could be converted to use with a bino-viewer. Because I was trying to survey the full gamut of DSO's mostly below -50° (I easily could have spent the entire time just on the Large Magellanic Cloud!), I generally stuck to eye-candy -- and there was plenty to feast on! - and was really loafing it with an 18" on these brighter planetaries (everything below was immediately visible once in the field). Some of these were reobservations for me but from northern California I never had a really good look. -
Observing List Evening of 2011 Dec 25 at Boyden Observatory
Southern Skies Binocular list Observing List Evening of 2011 Dec 25 at Boyden Observatory Sunset 19:20, Twilight ends 20:49, Twilight begins 03:40, Sunrise 05:09, Moon rise 06:47, Moon set 20:00 Completely dark from 20:49 to 03:40. New Moon. All times local (GMT+2). Listing All Classes visible above 2 air mass and in complete darkness after 20:49 and before 03:40. Cls Primary ID Alternate ID Con Mag Size Distance RA 2000 Dec 2000 Begin Optimum End S.A. Ur. 2 PSA Difficulty Optimum EP Open Collinder 227 Melotte 101 Car 8.4 15.0' 6500 ly 10h42m12.0s -65°06'00" 01:32 03:31 03:54 25 210 40 challenging Glob NGC 2808 Car 6.2 14.0' 26000 ly 09h12m03.0s -64°51'48" 21:57 03:08 04:05 25 210 40 detectable Open IC 2602 Collinder 229 Car 1.6 100.0' 520 ly 10h42m58.0s -64°24'00" 23:20 03:31 04:07 25 210 40 obvious Open Collinder 246 Melotte 105 Car 9.4 5.0' 7200 ly 11h19m42.0s -63°29'00" 01:44 03:33 03:57 25 209 40 challenging Open IC 2714 Collinder 245 Car 8.2 14.0' 4000 ly 11h17m27.0s -62°44'00" 01:32 03:33 03:57 25 209 40 challenging Open NGC 2516 Collinder 172 Car 3.3 30.0' 1300 ly 07h58m04.0s -60°45'12" 20:38 01:56 04:10 24 200 30 obvious Open NGC 3114 Collinder 215 Car 4.5 35.0' 3000 ly 10h02m36.0s -60°07'12" 22:43 03:27 04:07 25 199 40 easy Neb NGC 3372 Eta Carinae Nebula Car 3.0 120.0' 10h45m06.0s -59°52'00" 23:26 03:32 04:07 25 199 38 easy Open NGC 3532 Collinder 238 Car 3.4 50.0' 1600 ly 11h05m39.0s -58°45'12" 23:47 03:33 04:08 25 198 38 easy Open NGC 3293 Collinder 224 Car 6.2 6.0' 7600 ly 10h35m51.0s -58°13'48" 23:18 03:32 04:08 25 199 -
Stats2010 E Final.Pdf
Imprint Publisher: Max-Planck-Institut für extraterrestrische Physik Editors and Layout: W. Collmar und J. Zanker-Smith Personnel 1 PERSONNEL 2010 Directors Min. Dir. J. Meyer, Section Head, Federal Ministry of Prof. Dr. R. Bender, Optical and Interpretative Astronomy, Economics and Technology also Professorship for Astronomy/Astrophysics at the Prof. Dr. E. Rohkamm, Thyssen Krupp AG, Düsseldorf Ludwig-Maximilians-University Munich Prof. Dr. R. Genzel, Infrared- and Submillimeter- Scientifi c Advisory Board Astronomy, also Prof. of Physics, University of California, Prof. Dr. R. Davies, Oxford University (UK) Berkeley (USA) (Managing Director) Prof. Dr. R. Ellis, CALTECH (USA) Prof. Dr. Kirpal Nandra, High-Energy Astrophysics Dr. N. Gehrels, NASA/GSFC (USA) Prof. Dr. G. Morfi ll, Theory, Non-linear Dynamics, Complex Prof. Dr. F. Harrison, CALTECH (USA) Plasmas Prof. Dr. O. Havnes, University of Tromsø (Norway) Prof. Dr. G. Haerendel (emeritus) Prof. Dr. P. Léna, Université Paris VII (France) Prof. Dr. R. Lüst (emeritus) Prof. Dr. R. McCray, University of Colorado (USA), Prof. Dr. K. Pinkau (emeritus) Chair of Board Prof. Dr. J. Trümper (emeritus) Prof. Dr. M. Salvati, Osservatorio Astrofi sico di Arcetri (Italy) Junior Research Groups and Minerva Fellows Dr. N.M. Förster Schreiber Humboldt Awardee Dr. S. Khochfar Prof. Dr. P. Henry, University of Hawaii (USA) Prof. Dr. H. Netzer, Tel Aviv University (Israel) MPG Fellow Prof. Dr. V. Tsytovich, Russian Academy of Sciences, Prof. Dr. A. Burkert (LMU) Moscow (Russia) Manager’s Assistant Prof. S. Veilleux, University of Maryland (USA) Dr. H. Scheingraber A. v. Humboldt Fellows Scientifi c Secretary Prof. Dr. D. Jaffe, University of Texas (USA) Dr.