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J/ApJ/664/481  Optical/IR photometry of Collinder 69 (Barrado y Navascues+ 2007)

Spitzer: accretion in low-mass stars and brown dwarfs in the λ Orionis cluster. Barrado y Navascues D, Stauffer J.R., Morales-Calderon M., Bayo A., Fazzio G., Megeath T., Allen L., Hartmann L.W., Calvet N. <Astrophys. J., 664, 481-500 (2007)> =2007ApJ...664..481B
ADC_Keywords: Photometry ; Magnitudes ; Stars, pre-main sequence ; YSOs ; Clusters, open Keywords: open clusters and associations: individual (lambda Orionis) - stars: low-mass, brown dwarfs - stars: pre-main sequence Abstract: We present multiwavelength optical and IR photometry of 170 previously known low-mass stars and brown dwarfs of the 5Myr Collinder 69 cluster (λ Orionis). The new photometry supports cluster membership for most of them, with less than 15% of the previous candidates identified as probable nonmembers. The near-IR photometry allows us to identify stars with IR excesses, and we find that the Class II population is very large, around 25% for stars (in the spectral range M0-M6.5) and 40% for brown dwarfs, down to 0.04M, despite the fact that the Hα equivalent width is low for a significant fraction of them. In addition, there are a number of substellar objects, classified as Class III, that have optically thin disks. The Class II members are distributed in an inhomogeneous way, lying preferentially in a filament running toward the southeast. The IR excesses for the Collinder 69 members range from pure Class II (flat or nearly flat spectra longward of 1um), to transition disks with no near-IR excess but excesses beginning within the IRAC wavelength range, to two stars with excess only detected at 24um. Collinder 69 thus appears to be at an age where it provides a natural laboratory for the study of primordial disks and their dissipation. Description: The optical and the near-IR (NIR) data for the bright candidate members come from Barrado y Navascues et al. (2004, Paper I, Cat. J/ApJ/610/1064). The RI (Cousins system) data were collected with the Canada-France-Hawaii Telescope (CFHT) in 1999, whereas the JHKs data come from the Two Micron All Sky Survey (2MASS; Cutri et al. 2003, Cat. II/246). For the objects with large Error in 2MASS JHKs, we have obtained additional measurements with the WHT (La Palma Observatory, Spain) and INGRID (4.1'x4.1' FOV) in 2002 November and 2003 February and with the Calar Alto 3.5m telescope (Almeria, Spain) and Omega2000 in 2005 October. Our Spitzer data were collected during 2004 March 15 (MIPS) and October 11 (IRAC). Objects: ----------------------------------------------------------------- RA (2000) DE Designation(s) ----------------------------------------------------------------- 05 35.2 +09 42 λ Ori cluster = Cl Collinder 69 ----------------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 48 61 *Additional Near-IR Photometry for the Candidate Members of the λ Orionis Cluster (WHT/INGRID, La Palma, 2002Nov and 2003Feb) table3.dat 136 167 *Photometry for Candidate Members of the λ Orionis Cluster (CAHA/Omega2000)
Note on table1.dat and table3.dat: LOri 097 and LOri 145 are artifacts. LOri 123 is a non-member and has uncertainties in its photometry.
See also: J/AJ/118/2409 : VRI photometry of λ Ori PMS stars (Dolan+, 1999) J/AJ/121/2124 : λ Ori pre-main-sequence stars photometry (Dolan+, 2001) J/AJ/123/387 : VRI phot. of λ Ori star-forming region (Dolan+, 2002) J/ApJ/610/1064 : lambda Ori substellar population (Barrado y Navascues+, 2004) J/A+A/488/167 : Low-mass stars in σ Ori and λ Ori (Sacco+, 2008) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 4 A4 --- --- [LOri] 6- 8 I3 --- LOri Sequence number (lOri-CFHT NNN in Simbad) 10- 15 F6.3 mag Imag I band magnitude 17- 21 F5.2 mag Jmag WHT/INGRID J band magnitude 23- 26 F4.2 mag e_Jmag Error in J band magnitude 28- 32 F5.2 mag Hmag ?=- WHT/INGRID H band magnitude 34- 37 F4.2 mag e_Hmag ? Error in H band magnitude 39- 43 F5.2 mag Ksmag ?=- WHT/INGRID Ks band magnitude 45- 48 F4.2 mag e_Ksmag ? Error in Ks band magnitude
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 4 A4 --- --- [LOri] 6- 8 I3 --- LOri Sequence number (lOri-CFHT NNN in Simbad) 10- 14 F5.2 mag Rcmag CFHT Cousins R band magnitude 16- 19 F4.2 mag e_Rcmag Error in Rc band magnitude 21- 25 F5.2 mag Icmag CFHT Cousins I band magnitude 27- 30 F4.2 mag e_Icmag Error in Ic band magnitude 32- 37 F6.3 mag Jmag ?=- 2MASS J band magnitude 39- 43 F5.3 mag e_Jmag ? Error in J band magnitude 45- 50 F6.3 mag Hmag ?=- 2MASS H band magnitude 52- 56 F5.3 mag e_Hmag ? Error on H band magnitude 58- 63 F6.3 mag Ksmag ?=- 2MASS Ks band magnitude 65- 69 F5.3 mag e_Ksmag ? Error on Ks band magnitude 71- 76 F6.3 mag 3.6mag ?=- Spitzer/IRAC 3.6micron band magnitude 78- 82 F5.3 mag e_3.6mag ? Error on 3.6micron band magnitude 84- 89 F6.3 mag 4.5mag ?=- Spitzer/IRAC 4.5micron band magnitude 91- 95 F5.3 mag e_4.5mag ? Error on 4.5micron band magnitude 97-102 F6.3 mag 5.8mag ?=- Spitzer/IRAC 5.8micron band magnitude 104-108 F5.3 mag e_5.8mag ? Error on 5.8micron band magnitude 110-115 F6.3 mag 8.0mag ?=- Spitzer/IRAC 8.0micron band magnitude 117-121 F5.3 mag e_8.0mag ? Error on 8.0micron band magnitude 123-127 F5.3 mag 24mag ?=- Spitzer/IRAC 24micron band magnitude 129-133 F5.3 mag e_24mag ? Error on 24micron band magnitude 135-136 A2 --- Mm [YN?] Final membership
History: From electronic version of the journal
(End) Emmanuelle Perret [CDS] 27-May-2009
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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