J/ApJS/183/261 Optical photometry of the ONC (Da Rio+, 2009)
A multi-color optical survey of the Orion nebula cluster.
I. The catalog.
Da Rio N., Robberto M., Soderblom D.R., Panagia N., Hillenbrand L.A.,
Palla F., Stassun K.
<Astrophys. J. Suppl. Ser., 183, 261-277 (2009)>
=2009ApJS..183..261D 2009ApJS..183..261D
ADC_Keywords: Photometry, H-alpha ; Photometry, UBVRI ; Equivalent widths ;
Stars, M-type ; Surveys ; Spectral types
Keywords: catalogs - stars: formation - stars: pre-main sequence -
open clusters and associations: individual (Orion Nebula Cluster) -
stars: luminosity function, mass function
Abstract:
We present U, B, V, I broadband, 6200Å TiO medium band, and
Hα narrow band photometry of the Orion Nebula Cluster (ONC)
obtained with the WFI imager at the ESO/MPI 2.2 telescope at La Silla
Observatory. The nearly simultaneous observations cover the entire ONC
in a field of about 34x34arcmin2. They enable us to determine
stellar colors avoiding the additional scatter in the photometry
induced by stellar variability typical of pre-main-sequence stars. We
identify 2612 point-like sources in the I band; 58%, 43%, and 17% of
them are also detected in V, B, and U, respectively. 1040 sources are
identified in the Hα band. In this paper we present the
observations, the calibration techniques adopted, and the resulting
catalog. We show the derived color-magnitude diagram of the population
and discuss the completeness of our photometry. We define a
spectrophotometric TiO index that takes into account the fluxes in the
V, I, and TiO bands. Comparing it with spectral types of ONC members
in the literature, we find a correlation between the index and the
spectral type valid for M-type stars, which is accurate to better than
1 spectral subclass for M3-M6 types and better than 2 spectral
subclasses for M0-M2 types. This allows us to newly classify 217
stars.
Description:
The Wide Field Imager (WFI) is a focal reducer-type camera mounted at
the Cassegrain focus of the 2.2-m MPG/ESO telescope at La Silla. Our
target field was observed in service observing mode on the nights of
2005 January 1 and 2 (hereafter indicated as Night A and Night B,
respectively).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 110 2621 WFI photometric catalog relative to Night A
observations
table4.dat 48 217 New M-type stars classified from the [TiO] index
table5.dat 94 1040 Hα excess
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See also:
J/AJ/113/1733 : Orion Nebula Cluster population (Hillenbrand 1997)
J/AJ/121/1676 : ONC low-mass stars photometry (Rebull+, 2001)
J/ApJ/574/258 : Orion nebula X-ray-emitting young stars (Feigelson+, 2002)
J/ApJS/160/353 : Membership of the Orion nebula population (Getman+, 2005)
J/ApJ/660/704 : Optical and X-ray variability of ONC PMS (Stassun+, 2007)
J/ApJ/660/1462 : Abundances of ONC X-ray PMS stars (Maggio+, 2007)
J/A+A/502/883 : I phot. of very low mass ONC stars (Rodriguez-Ledesma+, 2009)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- [DRS2009] Identification number
6- 7 I2 h RAh Hour of Right Ascension (J2000)
9- 10 I2 min RAm Minute of Right Ascension (J2000)
12- 16 F5.2 s RAs Second of Right Ascension (J2000)
18 A1 --- DE- Sign of the Declination (J2000)
19- 20 I2 deg DEd Degree of Declination (J2000)
22- 23 I2 arcmin DEm Arcminute of Declination (J2000)
25- 28 F4.1 arcsec DEs Arcsecond of Declination (J2000)
30- 37 F8.5 mag Umag ? U band Vega magnitude (1)
39- 44 F6.4 mag e_Umag ? Error in Umag
46- 53 F8.5 mag Bmag ? B band Vega magnitude (1)
55- 60 F6.4 mag e_Bmag ? Error in Bmag
62- 69 F8.5 mag Vmag ? V band Vega magnitude (1)
71- 76 F6.4 mag e_Vmag ? Error in Vmag
78- 85 F8.5 mag TiO ? TiO band Vega magnitude (1)
87- 92 F6.4 mag e_TiO ? Error in TiO
94- 99 F6.3 mag Imag I band Vega magnitude (1)
101-105 F5.3 mag e_Imag Error in Imag
107-110 I4 --- [H97b] ? Hillenbrand 1997 (Cat. J/AJ/113/1733)
catalog identification
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Note (1): the filters have central wavelength and width (Å):
-------------------
Name lamc FWHM
-------------------
U 3404 732
B 4511 1335
V 5395 893
I 8269 2030
TiO 6208 194
Ha 6588 74
-------------------
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq Running number
5- 8 I4 --- [DRS2009] Identification number from table2.dat
10- 11 I2 h RAh hour of right ascension (J2000)
13- 14 I2 min RAm Minute of right ascension (J2000)
16- 20 F5.2 s RAs Second of right ascension (J2000)
22 A1 --- DE- Sign of declination (J2000)
23- 24 I2 deg DEd Degree of declination (J2000)
26- 27 I2 arcmin DEm Arcminute of declination (J2000)
29- 32 F4.1 arcsec DEs Arcsecond of declination (J2000)
34- 39 F6.3 mag [TiO] Index of [TiO] (2)
41- 44 A4 --- SpT Spectral type
46- 48 F3.1 --- e_SpT Uncertainty of spectral type
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Note (2): the [TiO] index is defined as the difference between the linear
interpolation at 620nm of the V and I magnitudes and the apparent
magnitude in the TiO band:
[TiO] = (V - (V-I).f) - m(TiO)
where f = 813/2874 = 0.283 is the ratio
(λTiO-λV)/(λI-λV)
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Seq Running identification number
6- 9 I4 --- [DRS2009] Identification number from table2.dat
11- 12 I2 h RAh Hour of Right Ascension (J2000)
14- 15 I2 min RAm Minute of Right Ascension (J2000)
17- 21 F5.2 s RAs Second of Right Ascension (J2000)
23 A1 --- DE- Sign of the Declination (J2000)
24- 25 I2 deg DEd Degree of Declination (J2000)
27- 28 I2 arcmin DEm Arcminute of Declination (J2000)
30- 33 F4.1 arcsec DEs Arcsecond of Declination (J2000)
35- 43 E9.2 0.1nm EWA Hα equivalent width in Angstroms (1)
45- 54 E10.2 Hz EWHz Hα equivalent width in Hertz (1)
56- 65 E10.2 mW/m2 Ex.erg Hα excess in erg/s/cm2
67- 75 E9.2 mJy Ex.mJy Hα excess in mJy
77- 85 E9.2 mW/m2 Cont.erg Hα continuum in erg/s/cm2
87- 94 F8.4 mJy Cont.mJy Hα continuum in mJy
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Note (1): We follow the standard convention, i.e. positive E.W. is
associated with an absorption, negative E.W. with an emission.
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History:
From electronic version of the journal
References:
Da Rio et al. Paper II. 2010ApJ...722.1092D 2010ApJ...722.1092D Cat. J/ApJ/722/1092
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 19-Jan-2010