J/AJ/113/1733 Orion Nebula Cluster population (Hillenbrand 1997) ================================================================================ On the stellar population and star-forming history of the Orion Nebula Cluster Hillenbrand L.A. =1997AJ....113.1733H (SIMBAD/NED BibCode) ================================================================================ 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 (n_peak_>10^4^pc^-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 ) 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 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. ; 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 8000{AA} 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. 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-I_C_ 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 A_V_=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 ================================================================================ (End) Patricia Bauer [CDS] 04-Aug-1998