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 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:
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FileName Lrecl Records Explanations
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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 2000A&A...358..593S) and
Palla & Stahler (1999ApJ...525..772P 1999ApJ...525..772P)
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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
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Bytes Format Units Label Explanations
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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 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 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
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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.
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History:
From electronic version of the journal
References:
Da Rio et al. Paper I. 2009ApJS..183..261D 2009ApJS..183..261D Cat. J/ApJS/183/261
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 11-Jul-2012