J/AJ/128/2316 BVRIJHKs photometry in sigma Ori cluster (Sherry+, 2004)
Photometric identification of the low-mass population of Orion OB1b. I. The σ Orionis cluster. Sherry W.H., Walter F.M., Wolk S.J. <Astron. J., 128, 2316-2330 (2004)> =2004AJ....128.2316S
ADC_Keywords: Clusters, open ; Stars, pre-main sequence ; Photometry, UBVRIJKLMNH Keywords: open clusters and associations: individual (sigma Orionis) - stars: formation - stars: imaging - stars: low-mass, brown dwarfs - stars: pre-main-sequence Abstract: We report an optical photometric survey of 0.89deg2 of the Orion OB1b association centered on sigma Ori. This region includes most of the sigma Ori cluster, the highest-density region within Orion OB1b. We have developed a statistical procedure to identify the young, low-mass, pre-main-sequence population of the association. We estimate that the cluster has 160 members in the mass range (0.2M☉≤M≤1.0M☉). The cluster has a radius of 35pc and an estimated age of 2.5±0.3Myr. We estimate that the total mass of the cluster is 225±30M☉. This mass is similar to the estimated mass of the ∼5x105yr old cluster NGC 2024. NGC 2024 and sigma Ori appear to be a well-matched pair of clusters, except for the ∼2Myr difference in their ages. Description: In this paper we analyze data from observations made with the 0.9 and 1.5m telescopes at the Cerro Tololo Inter-American Observatory (CTIO) between 1996 and 2002 as part of a B, V, RC, and IC survey of the belt of Orion (Orion OB1b) File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table3.dat 63 58 Adopted Color-Temperature Relation for ∼3Myr Old Stars table4.dat 111 234 Photometry of Likely Cluster Members
See also: J/A+A/429/1007 : RIJHK photometry of VLM objects near eps Ori (Scholz+, 2005) J/A+A/419/249 : RJHKs photometry of sigma Ori low-mass stars (Scholz+, 2004) J/AN/325/705 : RIJHKs of low-mass stars in sigma Ori (Bejar+, 2004) Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 2 A2 --- SpType MK spectral type (1) 4- 8 I5 K Teff Effective temperature (2) 10- 14 F5.2 mag BC Bolometric correction 16- 20 F5.2 mag U-V ? The (U-V) color index 22- 26 F5.2 mag B-V ? The (B-V) color index 28- 32 F5.2 mag V-Rc ? The (V-RC) color index 34- 38 F5.2 mag V-Ic The (V-IC) color index 40- 44 F5.2 mag V-J The (V-J) color index 46- 50 F5.2 mag V-H The (V-H) color index 52- 56 F5.2 mag V-K The (V-K) color index 58- 62 F5.2 mag V-L The (V-L) color index
Note (1): Colors and bolometric correction for stars earlier than M7 were taken from Kenyon & Hartmann (1995, Cat. J/ApJS/101/117>). For stars later than M7 we used U-V, B-V, and V-Rc from Berriman et al. (1992ApJ...392L..31B) and V-Ic, V-J, V-H, V-K, V-L and bolometric corrections from Leggett et al. (2001ApJ...548..908L). Note (2): Teff for M stars are from Luhman (1999ApJ...525..466L).
Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
1- 2 I2 h RAh Hour of right ascension (J2000) (1) 4- 5 I2 min RAm Minute of right ascension (J2000) (1) 7- 12 F6.3 s RAs Second of right ascension (J2000) (1) 14 A1 --- DE- Sign of the declination (J2000) (1) 15- 16 I2 deg DEd Degree of declination (J2000) (1) (1) 18- 19 I2 arcmin DEm Arcminute of declination (J2000) 21- 25 F5.2 arcsec DEs Arcsecond of declination (J2000) (1) 27- 31 F5.2 mag Bmag ? The B-band magnitude 33- 36 F4.2 mag e_Bmag ? Error in Bmag 38- 42 F5.2 mag Vmag The V-band magnitude 44- 47 F4.2 mag e_Vmag Error in Vmag 49- 53 F5.2 mag Rcmag The RC band magnitude 55- 58 F4.2 mag e_Rcmag Error in Rmag 60- 64 F5.2 mag Icmag The IC band magnitude 66- 69 F4.2 mag e_Icmag Error in Imag 71- 75 F5.2 mag Jmag ? 2MASS J-band magnitude (2) 77- 80 F4.2 mag e_Jmag ? Error in Jmag 82- 86 F5.2 mag Hmag ? 2MASS H-band magnitude (2) 88- 91 F4.2 mag e_Hmag ? Error in Hmag 93- 97 F5.2 mag Ksmag ? 2MASS Ks-band magnitude (2) 99-102 F4.2 mag e_Ksmag ? Error in Ksmag 104-105 I2 % Prob Membership probability 107-110 F4.2 solMass Mass Estimated mass (3)
Note (1): Objects are identified as [SWW2004] JHHMMSS.sss+DDMMSS.ss in Simbad Note (2): Available at http://iras.ipac.caltech.edu/ Note (3): Masses were estimated from the observed V-IC using a 2.5Myr isochrone.
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 23-Aug-2005
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