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J/ApJS/107/281       Atlas of hot, luminous stars at 2 microns (Hanson+ 1996)
A spectral atlas of hot, luminous stars at 2 microns
     Hanson M.M., Conti P.S., Rieke M.J.
    <Astrophys. J. Suppl. Ser. 107, 281 (1996)>
    =1996ApJS..107..281H
ADC_Keywords: Stars, luminous ; Spectra, infrared

Keywords: atlases - infrared: stars - stars: early-type -
          stars: fundamental parameters

Abstract:
    We present 2um (K band) spectra of 180 well-studied, optically
    visible, luminous stars. Most of the stars are of OB spectral type,
    but we have also included a number of Oe and Be stars, OBN and OBC
    stars, cool hypergiant stars, and high-mass X-ray binary stars. Our
    aim in studying normal OB stars is to develop an empirical
    relationship between 2um spectral features of these massive stars and
    their stellar temperature and luminosity. We find the system of lines
    between 2.0 and 2.2um is particulary good for differentiating the
    early- and mid-O type stars. In the late-O and early-B stars,
    differentiation becomes more difficult, as the features show only
    moderate changes. We have developed a spectral classification system
    for the K band to be used to estimate effective temperatures of O and
    early-B stars. We demonstrate that K-band spectroscopy is superior in
    estimating the temperature of hot, luminous stars than the traditional
    methods of using infrared or even optical photometric colors alone.
    The only requirements are that adequate resolution (R>1000) and
    signal-to-noise (S/N∼70) be achieved. With our classification system,
    stars behind large amounts of visible extinction, such as young,
    heavily reddened H II regions throughout our Galaxy, may be identified
    and studied for the first time through 2um spectroscopy. Emission
    lines are commonly seen in the K-band spectra of supergiant stars,
    however, the OBN supergiants, which have a higher ratio of some
    processed materials at their surface, may be more likely to show line
    emission, especially the He I singlet transition at 2.058um. This has
    led us to propose an evolutionary scenario for some of the Galactic
    center He I emission-line stars, which evokes rotational mixing
    (Maeder 1987A&A...178..159M; Langer 1992A&A...265L..17L) to explain
    both the strong line emission and high luminosity of these mysterious
    sources. We have compared our spectroscopic database with the most
    recent stellar atmosphere models. We are encouraged by the good match
    between the model line profiles at 2um of Schaerer et al.
    (1996A&A...312..475S) and those observed in OB stars. Finally, we
    include a thorough discussion of the observational and reduction
    methods employed to obtain the spectra shown in this atlas for the
    benefit of those wishing to obtain similar, classification-quality,
    near-infrared spectra.

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
table1.dat        95      187   Stars in 2 micron spectral atlas
table1.tex        97      216   AASTeX version of table1.dat
fits/*             0        .   Directory of FITS spectra


Byte-by-byte Description of file: table1.dat

   Bytes Format  Units  Label       Explanations

   1- 11  A11    ---    Star       *Star number
  14- 21  A8     ---    FITSfile   *Eight-character name for data files
  24- 39  A16    ---    Sp          Optical spectral type
      40  A1     ---    u_Sp        A colon indicates Sp is uncertain
  42- 44  A3     ---    r_Sp       *Reference to optical spectral type
  47- 52  A6     ---    Detector   *Detector used for the observation
  55- 58  I4     ---    SpRes       Spectral resolution, Lambda / dLambda
  60- 64  A5    "MM/YY" DateObs     Date of observation (MM/YY)
  66- 78  A13    ---    SpK         K-band spectral type
  81- 95  A15    ---    Notes       Notes, mostly alternate identifications

Note on Star:
  Note that HD 47129 is also known as Plaskett's Star. Bagnuolo, Gies &
  Wiggs (1992ApJ...385..708B) show it to be a pair of supergiants.
Note on FITSfile:
  The spectrum is stored in FITS format as file:
   fits/FITSfile.fit
Note on r_Sp:
  Reference to the optical spectral type.
        W72   Walborn (1972AJ.....77..312W)
        W73   Walborn (1973AJ.....78.1067W)
        MT    Massey & Thompson (1991AJ....101.1408M)
        C74   Conti (1974ApJ...187..539C)
        Mth   Mathys (1988A&AS...76..427M)
        C71   Conti & Alschuler (1971ApJ...170..325C)
        W76   Walborn (1976ApJ...205..419W)
        M55   Morgan, Code, & Whitford (1955ApJS....2...41M)
        WF    Walborn & Fitzpatrick (1990PASP..102..379W)
        L     Lennon, Dufton, & Fitzsimmons (1992A&AS...94..569L)
        BS    Bright Star Catalogue, Hoffleit (1982, See Cat. V/50)
        S     SIMBAD database
        J93   Jones et al. (1993ApJ...411..323J)
        GS    Garmany & Stencil (1992A&AS...94..211G)
        vP    van Paradijs (1994, in X-ray Binaries, ed. Lewin,
               van Paradijs & van den Heuvel, p. 536)
        HP    Howarth & Prinja (1989ApJS...69..527)
        G77   Garrison, Hiltner, & Schild (1977ApJS...35..111G)
Note on Detector:
  CRSP   KPNO Cryogenic Infrared Spectrometer
  FSPEC  Steward Observatory Infrared Spectrometer
  IRS    CTIO Infrared Spectrometer
  OSIRIS Ohio State Infrared Imaging Spectrometer


Origin: AAS CD-ROM series, Volume 7, 1996           Lee Brotzman [ADS] 09-Oct-96

(End)                                          Patricia Bauer [CDS]  03-Feb-1997