J/AJ/113/1733       Orion Nebula Cluster population    (Hillenbrand 1997)
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On the stellar population and star-forming history of the Orion Nebula Cluster
       Hillenbrand L.A.
      <Astron. J. 113, 1733 (1997)>
      =1997AJ....113.1733H
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ADC_Keywords: Populations, stellar ; Photometry, Cousins


Abstract:
    We report on the first phase of a study of the stellar population
    comprising the Orion Nebula Cluster (ONC). Approximately 50% of the
    ~3500 stars identified to date within ~2.5pc of the namesake Trapezium
    stars are optically visible, and in this paper we focus on that sample
    with I<2.5mag. The large number and number density of stars
    (npeak>104pc-3), the wide range in the stellar mass
    (~0.1-50M{sun}), and the extreme youth (<1-2Myr) of the stellar
    population, make the ONC the best site for investigating: (1) the
    detailed shape of a truly "initial" mass spectrum; (2) the apparent
    age spread in a region thought to have undergone triggered star
    formation; (3) the time sequence of star formation as a function of
    stellar mass; and (4) trends of all of the above with cluster radius.

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
table1.dat       132     1576   Optical properties of ONC stars
table3.dat        42     1576   Derived properties of ONC stars


See also:
   II/171 : Parenago Catalog of Stars in Orion Nebula (Parenago 1954)


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

   Bytes Format Units   Label    Explanations

   1-  4  I4    ---     ID       Identification number (1)
       5  A1    ---     m_ID     Multiplicity index on ID
   7- 10  I4    ---    Parenago  ? Parenago (1954, Cat <II/171>) number (2)
  12- 13  I2    %       Mem      ?=-9 Membership probability (3)
  15- 16  I2    h       RAh      Right ascension (2000) (4)
  18- 19  I2    min     RAm      Right ascension (2000)
  21- 25  F5.2  s       RAs      Right ascension (2000)
      27  A1    ---     DE-      Declination sign
  28- 29  I2    deg     DEd      Declination (2000)
  31- 32  I2    arcmin  DEm      Declination (2000)
  34- 38  F5.2  arcsec  DEs      Declination (2000)
  40- 44  F5.2  min     Rproj    Projected radius from Theta 1C Ori
  46- 50  F5.2  mag     Imag     ?=-9.99 Adopted I magnitude (Cousins)
      52  A1    ---     l_V-I    Limit flag on V-I
                                  (from Prosser et al., 1994ApJ...421..517P)
  53- 57  F5.2  mag     V-I      ?=-9.99 Adopted V-I color index
  59- 60  I2    ---     Ref      ? Photometry reference (5)
  62- 64  A3    ---     Comm     ? Comment reference (6)
  66- 71  F6.3  [K]     logT     ?=-9.999 Effective temperature of adopted
                                  spectral type
  73-132  A60   ---     SpT      Spectral type with reference in parentheses (7)

Note (1): ID = adopted ``red'' identification number:
      1-1053 from Jones & Walker, 1988AJ.....95.1755J
   1054-2999 from Parenago, 1954, Cat II/171
   3000-3999 from this paper, 1993 January CCD data
   5000-5999 from this paper, 1995 January CCD data
   6000-6999 from this paper, 1996 January CCD data
   9000-9999 from Prosser et al., 1994ApJ...421..517P
             (number is 9000 plus original number from that paper)
Note (2): Par = Parenago or ``blue'' identification number

Note (3): Adopted membership probability taken from
    Jones & Walker (1988AJ.....95.1755J) with first priority, and
    supplemented with van Altena et al. (1988AJ.....95.1744), McNamara
    (1976AJ.....81..375M and 1976AJ.....81..845M), McNamara & Huels
    (1983A&AS...54..221M), or McNamara et al. (1989AJ.....97.1427M). 
    In addition, sources showing proper motion on my CCD frames were given
    a membership probability of "0" while sources designated as "proplyds"
    were given a membership probability of 99%; see "Comm" column.
Note (4): Equinox 2000. position, referenced to the HST Guide Star Catalog
          (Cat. I/220; see text.
Note (5): Ref = photometry reference:
     (1) this paper; 1993 January CCD data
     (2) this paper; 1995 February CCD data
     (3) this paper; 1996 February CCD data
     (4) Prosser et al., 1994ApJ...421..517P
     (5) Jones & Walker, 1988AJ.....95.1755J
     (6) McCullough et al., 1995ApJ...438..394M
     (7) Breger, Gehrz, & Hackwell, 1981ApJ...248..963B
     (8) Penston, 1973ApJ...183..505P or
         Penston et al., 1975MNRAS.171..219P
     (9) Herbig & Terndrup, 1986ApJ...307..609H
    (10) Herbst, 1993, priv. comm.
    (11) Rydgren & Vrba, 1984AJ.....89..399R
Note (6): Comm = comment:
     (1) externally ionized "proplyd"
     (2) nebulous on 0.9m CCD images
     (3) unresolved double on 0.9m CCD images
     (4) >1.5 mag variability at I-band compared to Jones & Walker
         (1988AJ.....95.1755J) photographic photometry, or as designated by
         Choi & Herbst (1996AJ....111..283C) or by
         Jones & Walker (1988AJ.....95.1755J)
     (5) alternate designation from Prosser et al. (1994ApJ...421..517P):
         JW378a = 9011, JW378b = 9012, JW377a = 9013, JW377b = 9014,
         JW399a = 9034, JW399b = 9033, JW435a = 9057, JW435b = 9058,
         JW436a = 9059, JW436b = 9060, JW445b = 9067, JW445a = 9068,
         JW472a = 9099, JW472b = 9098, JW484a = 9111, JW484b = 9112,
         JW504b = 9125, JW504a = 9126, JW509a = 9129, JW509b = 9130,
         JW511b = 9134, JW511a = 9136, JW519b = 9143, JW519a = 9144,
         JW526b = 9150, JW526a = 9152, JW551b = 9172, JW551a = 9173,
         JW552a = 9183, JW552b = 9184, JW553a = 9185, JW553b = 9186,
         JW570a = 9202, JW570b = 9203, JW598b = 9234, JW598a = 9235,
         JW648b = 9262, JW648a = 9263, JW687b = 9286, JW687a = 9288,
         JW748b = 9314, JW748a = 9315, JW766b = 9321, JW766a = 9322,
         JW776a = 9323, JW776b = 9324
     (6) coordinates for JW618 given by Jones & Walker are incorrect;
         source is NE of their position
     (7) source has close companion in infrared images
     (8) large proper motion on 0.9m CCD frames; assigned zero membership
         probability
     (9) resolved double on 0.9m CCD frames
Note (7): Spectral Type = all available spectral type information with
          references in parentheses as listed below.
   B      = Blanco, 1963ApJ...137..513B
   CK     = Cohen & Kuhi, 1979ApJS...41..743C
   D      = Duncan, 1993ApJ...406..172D
   Eetal  = Edwards et al., 1993AJ....106..372E
   GS     = Greenstein & Struve, 1946PASP...58..366G
   H      = Hillenbrand, 1997 (this paper)
            "e"  indicates emission in the CaII triplet lines
            "<"  indicates spectral type is earlier than that listed
            ">"  indicates spectral type is later than that listed
             --  most spectra later than ~M3 show indications of
                 surface gravity intermediate between that of dwarfs
                 and giants, especially longward of 8000Å
   Ham    = C. Hamilton, 1994 unpublished masters thesis
   Her    = Herbig, quoted in Walker, 1969ApJ...155..447W
   HP     = Herbig, private communication, 1996
   HT     = Herbig & Terndrup, 1986ApJ...307..609H or reference therein
   J      = Johnson, 1965ApJ...142..964J
   LA     = Levato & Abt, 1976PASP...88..712L or
            Abt & Levato, 1977PASP...89..797A
   LDW    = Lallemand, Duchesne, & Walker, 1960PASP...72..268L
   M      = McNamara, 1976AJ.....81..375M and 1976AJ.....81..845M
   P      = Prosser & Stauffer, unpublished
   Par    = Parenago, 1954, Cat. II/171
   Petal  = Penston, Hunter, & O'Neill, 1975MNRAS.171..219P or
            Penston, 1973ApJ...183..505P
   S      = Strand, 1958 reference (mostly to Sharpless)
   Sam    = A.E. Samuel, 1993 unpublished PhD thesis
   SBB    = Smith, Beckers, & Barden, 1983ApJ...271..237S
   T      = Trumpler, 1931PASP...43..255T
   vA     = van Altena et al., 1988AJ.....95.1744
   W      = Walker, 1983ApJ...271..642W
   WSH    = Wolff, Strom, & Hillenbrand, 1998, in prep.


Byte-by-byte Description of file:  table3.dat

   Bytes Format Units   Label     Explanations

   1-  4  I4    ---     ID        Adopted identification number
       5  A1    ---     m_ID      Multiplicity index on ID
   7- 11  F5.2  mag     AV        ?=-9.99 Visual extinction (1)
  13- 18  F6.3  [K]    log(Teff)  ?=-9.99 Effective temperature assigned from
                                           spectral type
  20- 24  F5.2 [solLum] log(L)    ?=-9.99 Stellar luminosity (2)
  26- 30  F5.2  solRad  R         ?=-9.99 Stellar radius calculated from
                                           luminosity and effective temperature
  32- 36  F5.2  solMass M         ?=-9.99 Stellar mass (3)
  38- 42  F5.2  [yr]    log(age)  ?=-9.99 Stellar age interpolated from D'Antona
                                    & Mazitelli (1994ApJS...90..467D) isochrones

Note (1): Visual extinction calculated from optical photometry
          and spectral type; values of 0.00 indicate that the V-IC color
          is too blue for the spectral type.
Note (2): Stellar luminosity calculated from application of a bolometric
          correction to reddening-corrected photometry, assuming a distance of
          470pc; see Table 1 for applicable cluster membership information.
          luminosities are lower limits in cases where AV=0.0.
Note (3): Stellar mass interpolated from D'Antona & Mazitelli
          (1994ApJS...90..467D) tracks for stars <3M{sun}, from Swenson
          et al. (1994ApJ...425..286S) tracks for stars 3-5M{sun}, and from
          the ZAMS mass-luminosity relationship for stars >5M{sun}.


Acknowledgements: Lynne Hillenbrand 


History:
  * 04-Aug-1998: Original version
  * 17-Mar-2006: Data corrected
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(End)                                          Patricia Bauer [CDS]  04-Aug-1998