DOCSLIB.ORG

The Stellar Content of the Quintuplet Cluster Donald

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Stellar Content of the Quintuplet Cluster Donald THE STELLAR CONTENT OF THE QUINTUPLET CLUSTER DONALD F. FIGER, IAN S. MCLEAN AND MARK MORRIS University of California, Los Angeles Division of Astronomy, Department of Physics and Astronomy, Los Angeles, CA 90095-1562 AND FRANCISCO NAJARRO Institut für Astronomie und Astrophysik der Universität München Scheinerstr. 1, D-81679 München, Germany Abstract. The Quintuplet cluster contains over two dozen post main sequence descendants of massive O-stars, including Wolf-Rayet and OBI stars. The five Quintuplet-proper members (QPMs) may be dusty late-type Wolf-Rayet carbon stars (DWCLs), and the Pistol star may have a very high luminosity, « io6,7±0*5 L®. Coupled with its rather cool temperature, 12—23 kK, the Pistol Star is well in violation of the Humphreys—Davidson limit. We argue that the surrounding "Pistol" nebula was ejected from the star a few thousand years ago. The cluster stars imply the following approximate cluster properties: 4 7 3±α2 49 9 1 tage - 2 to 7 Myrs, M ~ 10 M®, L ~ 10 · L®, and NL2/,C > 10 · s" . The "Sickle" (GO.18-0.04) radio feature and the mid-IR ring (seen in MSX images) may naturally be explained by the presence of a young cluster and a nearby molecular cloud. 1. The Quintuplet Cluster We have used K-band spectra to identify the following cluster stars: 14 OBI, 2 Ofpe/WN9, 4 WN, 4 WC, 1 LBV candidate, 1 red supergiant (RSG), and 5 possible DWCLs (Figer, Morris, & McLean 1996). The ages are between 2 to 7 Myrs according to recent stellar evolution models (Meynet 1995); the low (high) end of the range applies to the OBI stars (RSG). The mass 61 Y. Sofue (ed.), The Central Regions of the Galaxy and Galaxies, 61-62. © 1998 IAU Printed in the Netherlands. Downloaded from https://www.cambridge.org/core. IP address: 170.106.35.234, on 30 Sep 2021 at 05:56:56, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0074180900084011 62 DONALD F. FIGER ET AL. π 1 1 r 7.0 ColoxyMog Clou is Pistol Star LBV LBVc O Mk42 0»pe/WN9 Sk-67 21 I ΟΘ 6.5 IRSI6SW CC stars τ T IRSI6NE ÛS6I OR\27 -1 6.0 HD Limit 5.5 ... J; _J I I I I I I 1 1 L_ 4.8 4.7 4.6 4.5 4.4 4.3 4.2 4.1 4.0 3.9 3.8 3.7 Log(Tei() Figure 1. HR Diagram for the Pistol Star and other luminous stars. of the cluster can be estimated by integrating a power-law IMF and as- 4±0 3 suming 30 stars having Mtm^a/ > 20 M©. We estimate ~ 10 · Μ© (a = —2.35); a similar mass is found by demanding that the cluster is stable against tidal disruption. The Lyman-continuum flux is estimated to be > 1049*9 s"1 by summing contributions from individual stars; Timmermann et al. (1996) estimate ~ 2.5 times more ionizing flux by integrating the radio emission over the region surrounding the cluster. The total luminos- ity from the cluster is estimated by adding the individual luminosities of the identified stars. We find L ~ io7,3±0,2 L©, where the uncertainty is set by assuming an error of ±0.5 in BCA' for all the stars. If we exclude the two most luminous stars, then the cluster luminosity is reduced by ~ 0.3 dex. The Pistol Star, plotted on an HR diagram in Figure 1, may be the most luminous known, and it is quite cool. The line-of-sight velocity l the cluster is ~ 130 kms"1, similar to that of the Pistol nebula. We fint 1(2.06 μτη, Hel)/\ßr^) ~ 1> suggesting that the Pistol nebula is enhanced in helium. We argue that the Pistol nebula has been ejected by the star (Figer et al. 1995; Figer et al. 1997). References Figer, D.F., McLean, LS. & Morris, M. (1995), ApJL, 447, L29 Figer, D.F., Morris, M. & McLean, LS. (1996), The Galactic Center 4th ESO/CTIO Workshop, ASP 102,263 Figer, D.F., Najarro, F., McLean, LS., Morris, M. & Geballe, T.R. (1997), in preparation. Meynet, G. (1995), AA, 298, 767. Timmermann, R., Genzel, R., Poglitsch, Α., Lutz, D., Madden, S.C., Nikola, T., Geis, Ν. & Townes, CH. (1996), ApJ, 466, 242 Downloaded from https://www.cambridge.org/core. IP address: 170.106.35.234, on 30 Sep 2021 at 05:56:56, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0074180900084011.
Load more

Recommended publications
  • POSTERS SESSION I: Atmospheres of Massive Stars
    Abstracts of Posters 25 POSTERS (Grouped by sessions in alphabetical order by first author) SESSION I: Atmospheres of Massive Stars I-1. Pulsational Seeding of Structure in a Line-Driven Stellar Wind Nurdan Anilmis & Stan Owocki, University of Delaware Massive stars often exhibit signatures of radial or non-radial pulsation, and in principal these can play a key role in seeding structure in their radiatively driven stellar wind. We have been carrying out time-dependent hydrodynamical simulations of such winds with time-variable surface brightness and lower boundary condi- tions that are intended to mimic the forms expected from stellar pulsation. We present sample results for a strong radial pulsation, using also an SEI (Sobolev with Exact Integration) line-transfer code to derive characteristic line-profile signatures of the resulting wind structure. Future work will compare these with observed signatures in a variety of specific stars known to be radial and non-radial pulsators. I-2. Wind and Photospheric Variability in Late-B Supergiants Matt Austin, University College London (UCL); Nevyana Markova, National Astronomical Observatory, Bulgaria; Raman Prinja, UCL There is currently a growing realisation that the time-variable properties of massive stars can have a funda- mental influence in the determination of key parameters. Specifically, the fact that the winds may be highly clumped and structured can lead to significant downward revision in the mass-loss rates of OB stars. While wind clumping is generally well studied in O-type stars, it is by contrast poorly understood in B stars. In this study we present the analysis of optical data of the B8 Iae star HD 199478.
    [Show full text]
  • The Orbital Motion of the Quintuplet Cluster—A Common Origin for the Arches and Quintuplet Clusters?∗
    The Astrophysical Journal, 789:115 (20pp), 2014 July 10 doi:10.1088/0004-637X/789/2/115 C 2014. The American Astronomical Society. All rights reserved. Printed in the U.S.A. THE ORBITAL MOTION OF THE QUINTUPLET CLUSTER—A COMMON ORIGIN FOR THE ARCHES AND QUINTUPLET CLUSTERS?∗ A. Stolte1,B.Hußmann1, M. R. Morris2,A.M.Ghez2, W. Brandner3,J.R.Lu4, W. I. Clarkson5, M. Habibi1, and K. Matthews6 1 Argelander Institut fur¨ Astronomie, Auf dem Hugel¨ 71, D-53121 Bonn, Germany; [email protected] 2 Division of Astronomy and Astrophysics, UCLA, Los Angeles, CA 90095-1547, USA; [email protected], [email protected] 3 Max-Planck-Institut fur¨ Astronomie, Konigstuhl¨ 17, D-69117 Heidelberg, Germany; [email protected] 4 Institute for Astronomy, University of Hawai’i, 2680 Woodlawn Drive, Honolulu, HI 96822, USA; [email protected] 5 Department of Natural Sciences, University of Michigan-Dearborn, 125 Science Building, 4901 Evergreen Road, Dearborn, MI 48128, USA; [email protected] 6 Caltech Optical Observatories, California Institute of Technology, MS 320-47, Pasadena, CA 91225, USA; [email protected] Received 2014 January 16; accepted 2014 May 14; published 2014 June 20 ABSTRACT We investigate the orbital motion of the Quintuplet cluster near the Galactic center with the aim of constraining formation scenarios of young, massive star clusters in nuclear environments. Three epochs of adaptive optics high-angular resolution imaging with the Keck/NIRC2 and Very Large Telescope/NAOS-CONICA systems were obtained over a time baseline of 5.8 yr, delivering an astrometric accuracy of 0.5–1 mas yr−1.
    [Show full text]
  • 121012-AAS-221 Program-14-ALL, Page 253 @ Preflight
    221ST MEETING OF THE AMERICAN ASTRONOMICAL SOCIETY 6-10 January 2013 LONG BEACH, CALIFORNIA Scientific sessions will be held at the: Long Beach Convention Center 300 E. Ocean Blvd. COUNCIL.......................... 2 Long Beach, CA 90802 AAS Paper Sorters EXHIBITORS..................... 4 Aubra Anthony ATTENDEE Alan Boss SERVICES.......................... 9 Blaise Canzian Joanna Corby SCHEDULE.....................12 Rupert Croft Shantanu Desai SATURDAY.....................28 Rick Fienberg Bernhard Fleck SUNDAY..........................30 Erika Grundstrom Nimish P. Hathi MONDAY........................37 Ann Hornschemeier Suzanne H. Jacoby TUESDAY........................98 Bethany Johns Sebastien Lepine WEDNESDAY.............. 158 Katharina Lodders Kevin Marvel THURSDAY.................. 213 Karen Masters Bryan Miller AUTHOR INDEX ........ 245 Nancy Morrison Judit Ries Michael Rutkowski Allyn Smith Joe Tenn Session Numbering Key 100’s Monday 200’s Tuesday 300’s Wednesday 400’s Thursday Sessions are numbered in the Program Book by day and time. Changes after 27 November 2012 are included only in the online program materials. 1 AAS Officers & Councilors Officers Councilors President (2012-2014) (2009-2012) David J. Helfand Quest Univ. Canada Edward F. Guinan Villanova Univ. [email protected] [email protected] PAST President (2012-2013) Patricia Knezek NOAO/WIYN Observatory Debra Elmegreen Vassar College [email protected] [email protected] Robert Mathieu Univ. of Wisconsin Vice President (2009-2015) [email protected] Paula Szkody University of Washington [email protected] (2011-2014) Bruce Balick Univ. of Washington Vice-President (2010-2013) [email protected] Nicholas B. Suntzeff Texas A&M Univ. suntzeff@aas.org Eileen D. Friel Boston Univ. [email protected] Vice President (2011-2014) Edward B. Churchwell Univ. of Wisconsin Angela Speck Univ. of Missouri [email protected] [email protected] Treasurer (2011-2014) (2012-2015) Hervey (Peter) Stockman STScI Nancy S.
    [Show full text]
  • 2012 Annual Progress Report and 2013 Program Plan of the Gemini Observatory
    2012 Annual Progress Report and 2013 Program Plan of the Gemini Observatory Association of Universities for Research in Astronomy, Inc. Table of Contents 0 Executive Summary ....................................................................................... 1 1 Introduction and Overview .............................................................................. 5 2 Science Highlights ........................................................................................... 6 2.1 Highest Resolution Optical Images of Pluto from the Ground ...................... 6 2.2 Dynamical Measurements of Extremely Massive Black Holes ...................... 6 2.3 The Best Standard Candle for Cosmology ...................................................... 7 2.4 Beginning to Solve the Cooling Flow Problem ............................................... 8 2.5 A Disappearing Dusty Disk .............................................................................. 9 2.6 Gas Morphology and Kinematics of Sub-Millimeter Galaxies........................ 9 2.7 No Intermediate-Mass Black Hole at the Center of M71 ............................... 10 3 Operations ...................................................................................................... 11 3.1 Gemini Publications and User Relationships ............................................... 11 3.2 Science Operations ........................................................................................ 12 3.2.1 ITAC Software and Queue Filling Results ..................................................
    [Show full text]
  • The Circumnuclear Ring (CNR) (11 Slides) – Quintuplet Proper Members (Qpms) (6 Slides) – Pistol Nebula (10 Slides)
    SOFIA/FORCAST Observations of the Galactic Center Ryan M. Lau SOFIA Community Collaborators: T. L. Herter, M. R. Morris, E. E. Becklin, M. J. Hankins, Task Force Teletalks, J. D. Adams, G. E. Gull, C. P. Henderson, J. Schoenwald February 6, 2013 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau Talk Outline • Background – The Galactic Center – Observations • Results and Science – The Circumnuclear Ring (CNR) (11 slides) – Quintuplet Proper Members (QPMs) (6 slides) – Pistol Nebula (10 slides) • Further Work 2 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau The Galactic Center • ~500 pc unique region containing a 4,000,000 solar mass black hole, massive stars, supernovae, and star formation regions QC & Pistol • 10% of present SF activity in Galaxy occurs in GC yet only tiny fraction of a percent of volume in Galactic disk CNR 10 pc • Contains ~4/12 of the LBVs and ~90/240 of Wolf-Rayet stars in galaxy 3 SOFIA/FORCAST Observations of the Galactic Center R. M. Lau The Galactic Center: Inner 50 Pc • Circumnuclear Ring (CNR) – Dense ring of gas and dust surrounding Sgr A* by 1.4 pc • Quintuplet Cluster (QC) QC & Pistol – ~4 Myr cluster of hot, massive stars – Named after 5 bright IR sources within cluster (we observe 4 of them) • Pistol Nebula CNR – Asymmetric shell of dust and 10 pc gas surrounding the Pistol star – Appears to be shaped by 8 μm Spitzer/IRAC image of the inner interaction with QC winds 50 pc of the Galactic Center 4 SOFIA/FORCAST Observations of the Galactic Center R.
    [Show full text]
  • Massive Stars in the Galactic Center Quintuplet Cluster
    Institut für Physik und Astronomie Astrophysik Massive stars in the Galactic Center Quintuplet cluster Dissertation zur Erlangung des akademischen Grades Doktor der Naturwissenschaften (Dr. rer. nat.) eingereicht an der Mathematisch-Naturwissenschaftlichen Fakultät der Universität Potsdam von Adriane Liermann Potsdam, Juni 2009 This work is licensed under a Creative Commons License: Attribution - Noncommercial - No Derivative Works 3.0 Germany To view a copy of this license visit http://creativecommons.org/licenses/by-nc-nd/3.0/de/deed.en Published online at the Institutional Repository of the University of Potsdam: URL http://opus.kobv.de/ubp/volltexte/2009/3722/ URN urn:nbn:de:kobv:517-opus-37223 [http://nbn-resolving.org/urn:nbn:de:kobv:517-opus-37223] Summary The presented thesis describes the observations of the Galactic center Quintuplet cluster, the spectral analysis of the cluster Wolf-Rayet stars of the nitrogen sequence to determine their fundamental stellar parameters, and discusses the obtained results in a general context. The Quintuplet cluster was discovered in one of the first infrared surveys of the Galactic center region (Okuda et al. 1987, 1989) and was observed for this project with the ESO-VLT near-infrared integral field instrument SINFONI-SPIFFI. The subsequent data reduction was performed in parts with a self-written pipeline to obtain flux-calibrated spectra of all objects detected in the imaged field of view. First results of the observation were compiled and published in a spectral catalog of 160 flux-calibrated K-band spectra in the range of 1.95 to 2.45 µm, containing 85 early-type (OB) stars, 62 late-type (KM) stars, and 13 Wolf-Rayet stars.
    [Show full text]
  • FY13 High-Level Deliverables
    National Optical Astronomy Observatory Fiscal Year Annual Report for FY 2013 (1 October 2012 – 30 September 2013) Submitted to the National Science Foundation Pursuant to Cooperative Support Agreement No. AST-0950945 13 December 2013 Revised 18 September 2014 Contents NOAO MISSION PROFILE .................................................................................................... 1 1 EXECUTIVE SUMMARY ................................................................................................ 2 2 NOAO ACCOMPLISHMENTS ....................................................................................... 4 2.1 Achievements ..................................................................................................... 4 2.2 Status of Vision and Goals ................................................................................. 5 2.2.1 Status of FY13 High-Level Deliverables ............................................ 5 2.2.2 FY13 Planned vs. Actual Spending and Revenues .............................. 8 2.3 Challenges and Their Impacts ............................................................................ 9 3 SCIENTIFIC ACTIVITIES AND FINDINGS .............................................................. 11 3.1 Cerro Tololo Inter-American Observatory ....................................................... 11 3.2 Kitt Peak National Observatory ....................................................................... 14 3.3 Gemini Observatory ........................................................................................
    [Show full text]
  • Metallicity in the GC Roberta M
    Journal of Physics: Conference Series OPEN ACCESS Related content - Massive stars in galaxies. Metallicity in the GC Roberta M. Humphreys - Do Voids Cluster? To cite this article: Francisco Najarro 2006 J. Phys.: Conf. Ser. 54 036 S. Haque-Copilah and D. Basu - Near-Infrared Spectra of Galactic Stellar Clusters Detected on Spitzer/GLIMPSE Images Maria Messineo, Ben Davies, Valentin D. View the article online for updates and enhancements. Ivanov et al. Recent citations - Atmospheric NLTE models for the spectroscopic analysis of blue stars with winds J. Puls et al - Mass loss from hot massive stars Joachim Puls et al - Two extremely luminous WN stars in the Galactic center with circumstellar emission from dust and gas A. Barniske et al This content was downloaded from IP address 161.111.20.207 on 22/07/2021 at 11:58 Institute of Physics Publishing Journal of Physics: Conference Series 54 (2006) 224–232 doi:10.1088/1742-6596/54/1/036 Galaxy Center Workshop 2006 Metallicity in the GC Francisco Najarro1 1 Instituto de Estructura de la Materia, CSIC, Serrano 121, 29006 Madrid, Spain E-mail: [email protected] Abstract. We review quantitative spectroscopic studies of massive stars in the three Galactic Center clusters: Quintuplet, Arches and Central cluster. Thanks to the impressive evolution of IR detectors and the new generation of line blanketed models for the extended atmospheres of hot stars we are able to accurately derive the physical properties and metallicity estimates of the massive stars in these clusters. For the Quintuplet cluster our analysis of the LBVs provides a direct estimate of α-elements and Fe chemical abundances in these objects.
    [Show full text]
  • On the Fine Structure of the Cepheid Metallicity Gradient
    A&A 566, A37 (2014) Astronomy DOI: 10.1051/0004-6361/201323198 & c ESO 2014 Astrophysics On the fine structure of the Cepheid metallicity gradient in the Galactic thin disk, K. Genovali1, B. Lemasle2,G.Bono1,3, M. Romaniello4, M. Fabrizio5, I. Ferraro3,G.Iannicola3,C.D.Laney6,7, M. Nonino8, M. Bergemann9,10, R. Buonanno1,5, P. François11,12, L. Inno1,4, R.-P. Kudritzki13,14,9, N. Matsunaga15, S. Pedicelli1, F. Primas4, and F. Thévenin16 1 Dipartimento di Fisica, Università di Roma Tor Vergata, via della Ricerca Scientifica 1, 00133 Rome, Italy e-mail: [email protected] 2 Astronomical Institute Anton Pannekoek, Science Park 904, PO Box 94249, 1090 GE Amsterdam, The Netherlands 3 INAF – Osservatorio Astronomico di Roma, via Frascati 33, Monte Porzio Catone, Rome, Italy 4 European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching bei Munchen, Germany 5 INAF – Osservatorio Astronomico di Collurania, via M. Maggini, 64100 Teramo, Italy 6 Department of Physics and Astronomy, N283 ESC, Brigham Young University, Provo, UT 84601, USA 7 South African Astronomical Observatory, PO Box 9, Observatory 7935, South Africa 8 INAF – Osservatorio Astronomico di Trieste, via G.B. Tiepolo 11, 40131 Trieste, Italy 9 Max-Planck-Institut fur Astrophysik, Karl-Schwarzschild-Str. 1, 85741 Garching, Germany 10 Institute of Astronomy, University of Cambridge, Madingley Road, CB3 0HA, Cambridge, UK 11 GEPI – Observatoire de Paris, 64 avenue de l’Observatoire, 75014 Paris, France 12 UPJV – Université de Picardie Jules Verne, 80000 Amiens, France 13 Institute for Astronomy, University of Hawai’i, 2680 Woodlawn Dr, Honolulu, HI 96822, USA 14 University Observatory Munich, Scheinerstr.
    [Show full text]
  • Astrophysics New Galactic Wolf-Rayet Stars, and Candidates
    UvA-DARE (Digital Academic Repository) New Galactic Wolf-Rayet stars, and candidates (Research note) An annex to The VIIth Catalogue of Galactic Wolf-Rayet Stars van der Hucht, K.A. DOI 10.1051/0004-6361:20065819 Publication date 2006 Document Version Final published version Published in Astronomy & Astrophysics Link to publication Citation for published version (APA): van der Hucht, K. A. (2006). New Galactic Wolf-Rayet stars, and candidates (Research note): An annex to The VIIth Catalogue of Galactic Wolf-Rayet Stars. Astronomy & Astrophysics, 458(2), 453-459. https://doi.org/10.1051/0004-6361:20065819 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:03 Oct 2021 A&A 458, 453–459 (2006) Astronomy DOI: 10.1051/0004-6361:20065819 & c ESO 2006 Astrophysics New Galactic Wolf-Rayet stars, and candidates (Research Note) An annex to The VIIth Catalogue of Galactic Wolf-Rayet Stars K.
    [Show full text]
  • The Messenger
    Czech Republic joins ESO The Messenger Progress on ALMA CRIRES Science Verification Gender balance among ESO staff No. 128 – JuneNo. 2007 The Organisation The Czech Republic Joins ESO Catherine Cesarsky The XXVIth IAU General Assembly, held This Agreement was formally confirmed (ESO Director General) in Prague in 2006, clearly provided a by the ESO Council at its meeting on boost for the Czech efforts to join ESO, 6 December and a few days thereafter by not the least in securing the necessary the Czech government, enabling a sign- I am delighted to welcome the Czech public and political support. Thus our ing ceremony in Prague on 22 December Republic as our 13th member state. From Czech colleagues used the opportunity (see photograph below). This was impor- its size, the Czech Republic may not be- to publish a fine and very interesting pop- tant because the Agreement foresaw long to the ‘big’ member states, but the ular book about Czech astronomy and accession by 1 January 2007. With the accession nonetheless marks an impor- ESO, which, together with the General signatures in place, the agreement could tant point in ESO’s history and, I believe, Assembly, created considerable media be submitted to the Czech Parliament in the history of Czech astronomy as well. interest. for ratification within an agreed ‘grace pe- The Czech Republic is the first of the riod’. This formal procedure was con- Central and East European countries to On 20 September 2006, at a meeting at cluded on 30 April 2007, when I was noti- join ESO. The membership underlines ESO Headquarters, the negotiating teams fied of the deposition of the instrument of ESO’s continuing evolution as the prime from ESO and the Czech Republic arrived ratification at the French Ministry of European organisation for astronomy, at an agreement in principle, which was Foreign Affairs.
    [Show full text]
  • The Quintuplet Cluster III
    A&A 540, A14 (2012) Astronomy DOI: 10.1051/0004-6361/201117534 & c ESO 2012 Astrophysics The Quintuplet cluster III. Hertzsprung-Russell diagram and cluster age A. Liermann1, W.-R. Hamann2, and L. M. Oskinova2 1 Max-Planck Institut für Radioastronomie, 53121 Bonn, Germany e-mail: [email protected] 2 Universität Potsdam, Institut für Physik und Astronomie, 14476 Potsdam, Germany Received 21 June 2011 / Accepted 2 February 2012 ABSTRACT The Quintuplet, one of three massive stellar clusters in the Galactic center (GC), is located about 30 pc in projection from Sagittarius A∗. We aim at the construction of the Hertzsprung-Russell diagram (HRD) of the cluster to study its evolution and to constrain its star-formation history. For this purpose we use the most complete spectral catalog of the Quintuplet stars. Based on the K-band spectra we determine stellar temperatures and luminosities for all stars in the catalog under the assumption of a uniform reddening towards the cluster. We find two groups in the resulting HRD: early-type OB stars and late-type KM stars, well separated from each other. By comparison with Geneva stellar evolution models we derive initial masses exceeding 8 M for the OB stars. In the HRD these stars are located along an isochrone corresponding to an age of about 4 Myr. This confirms previous considerations, where a similar age estimate was based on the presence of evolved Wolf-Rayet stars in the cluster. We derive number ratios for the various spectral subtype groups (e.g. NWR/NO, NWC/NWN) and compare them with predictions of population synthesis models.
    [Show full text]