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J/ApJ/722/1092         Optical photometry of the ONC. II.        (Da Rio+, 2010)

A multi-color optical survey of the Orion Nebula Cluster. II. The H-R diagram. Da Rio N., Robberto M., Soderblom D.R., Panagia N., Hillenbrand L.A., Palla F., Stassun K.G. <Astrophys. J., 722, 1092-1114 (2010)> =2010ApJ...722.1092D
ADC_Keywords: HR diagrams ; Extinction ; Stars, masses ; Stars, ages ; Clusters, open ; Stars, pre-main sequence ; Spectral types Keywords: open clusters and associations: individual (Orion Nebula Cluster) - stars: formation - stars: luminosity function, mass function - stars: pre-main sequence Abstract: We present a new analysis of the stellar population of the Orion Nebula Cluster (ONC) based on multi-band optical photometry and spectroscopy. We study the color-color diagrams in BVI, plus a narrowband filter centered at 6200Å, finding evidence that intrinsic color scales valid for main-sequence dwarfs are incompatible with the ONC in the M spectral-type range, while a better agreement is found employing intrinsic colors derived from synthetic photometry, constraining the surface gravity value as predicted by a pre-main-sequence isochrone. We refine these model colors even further, empirically, by comparison with a selected sample of ONC stars with no accretion and no extinction. We consider the stars with known spectral types from the literature, and extend this sample with the addition of 65 newly classified stars from slit spectroscopy and 182 M-type from narrowband photometry; in this way, we isolate a sample of about 1000 stars with known spectral type. We introduce a new method to self-consistently derive the stellar reddening and the optical excess due to accretion from the location of each star in the BVI color-color diagram. This enables us to accurately determine the extinction of the ONC members, together with an estimate of their accretion luminosities. We adopt a lower distance for the Orion Nebula than previously assumed, based on recent parallax measurements. With a careful choice of also the spectral-type-temperature transformation, we produce the new Hertzsprung-Russell diagram of the ONC population, more populated than previous works. Description: We utilize our multi-band optical catalog presented in Paper I (Cat. J/ApJS/183/261) to construct the HR diagram of the ONC. The catalog consists of a nearly simultaneous photometry over a field of view (FOV) of ∼34'x34' which comprises most of the ONC. Photometry of the ONC was obtained in UBVI, Hα and in the 6200Å medium-band filters using the Wide Field Imager (WFI) at the 2.2m MPG/ESO telescope on La Silla. We complement the optical photometry with spectroscopy, extending the spectral catalog of that work with new spectral types from slit spectroscopy. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table3.dat 150 1002 Positions in the H-R diagram and values of mass and age from Siess (2000A&A...358..593S) and Palla & Stahler (1999ApJ...525..772P)
See also: J/A+A/534/A10 : HST/NICMOS III imaging in ONC (Andersen+, 2011) J/A+A/515/A13 : Very low mass objects in ONC (Rodriguez-Ledesma+, 2010) J/ApJS/183/261 : Optical photometry of the ONC (Da Rio+, 2009) J/AJ/113/1733 : Orion Nebula Cluster population (Hillenbrand 1997) Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 4 I4 --- ID [1/1753] Index number (<[DRS2009] NNNN> in Simbad) 6 I1 h RAh [5] Hour of Right Ascension (J2000) 8- 9 I2 min RAm [33/36] Minute of Right Ascension (J2000) 11- 15 F5.2 s RAs Second of Right Ascension (J2000) 17 A1 --- DE- [-] Sign of the Declination (J2000) 18 I1 deg DEd [5] Degree of Declination (J2000) 20- 21 I2 arcmin DEm [10/43] Arcminute of Declination (J2000) 23- 27 F5.2 arcsec DEs Arcsecond of Declination (J2000) 29- 33 F5.3 [K] logT Log of the effective temperature 35- 40 F6.3 [Lsun] logL ? Log of the luminosity 42- 47 F6.3 mag AV [0/12.15] V band extinction 49 A1 --- l_logAc Limit flag on logR 50- 54 F5.2 [-] logAc [-5/0] Log of the accretion to total luminosities 56- 60 F5.3 Msun M.S0 ? Siess (S0; 2000A&A...358..593S) derived mass 62- 66 F5.3 [yr] logA0 ? Log of the S0 derived age 68- 72 F5.3 Msun M.P9 ? Palla & Stahler (P9; 1999ApJ...525..772P) derived mass 74- 78 F5.3 [yr] logA9 ? Log of the P9 derived age 80- 82 A3 --- r_SpT Spectral type reference (1) 84- 87 I4 --- H97 [1-9280]? Hillenbrand 1997 (Cat. J/AJ/113/1733) number (<[H97b] NNNN> in Simbad) 89- 90 I2 % Mm [0/99]? H97 membership probability 92-150 A59 --- SpT MK spectral type information
Note (1): Reference as follows: H97 = Hillenbrand 1997, Cat. J/AJ/113/1733; NEW = classified from our spectroscopy; TiO = M-type star classified from the [TiO] photometric index.
History: From electronic version of the journal References: Da Rio et al. Paper I. 2009ApJS..183..261D Cat. J/ApJS/183/261
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 11-Jul-2012
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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