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J/A+A/485/155    HK photometry of rho Oph PMS stars   (Alves de Oliveira+, 2008)

Deep near-IR variability survey of pre-main-sequence stars in rho Ophiuchi. Alves de Oliveira C., Casali M. <Astron. Astrophys. 485, 155 (2008)> =2008A&A...485..155A
ADC_Keywords: Molecular clouds ; Stars, pre-main sequence ; Photometry, infrared Keywords: stars: pre-main-sequence - stars: low-mass, brown dwarfs - stars: activity - stars: variables: general Abstract: Variability is a common characteristic of pre-main-sequence stars (PMS). Near-IR variability surveys of young stellar objects (YSOs) can probe stellar and circumstellar environments and provide information about the dynamics of the ongoing magnetic and accretion processes. Furthermore, variability can be used as a tool to uncover new cluster members in star formation regions. We hope to achieve the deepest near-IR variability study of YSOs targeting the rho Ophiuchi cluster. Fourteen epochs of observations were obtained with the Wide Field Camera (WFCAM) at the UKIRT telescope scheduled in a manner that allowed the study of variability on timescales of days, months, and years. Statistical tools, such as the multi-band cross correlation index and the reduced chi-square, were used to disentangle signals of variability from noise. Variability characteristics are compared to existing models of YSOs in order to relate them to physical processes, and then used to select new candidate members of this star-forming region. Variability in the near-IR is found to be present in 41% of the known population of rho Ophiuchi recovered in our sample. The behaviours shown are several and can be associated with the existence of spots on the stellar surface, variations in circumstellar extinction, or changes in the geometry of an accretion disc. Using variability, a new population of objects has been uncovered, that is believed to be part of the rho Ophiuchi cluster. Description: Near-IR photometric properties for variable stars found in rho Ophiuchi, such as the coordinates, the average H and K magnitudes, the peak-to-peak amplitude for H, K, and H-K, the slope in the variability colour-magnitude diagram, the SED class as determined from IRAC/Spitzer and WFCAM colour-colour diagrams, several variability flags, and references for the known members of rho Ophiuchi. Objects: ------------------------------------------- RA (2000) DE Designation(s) ------------------------------------------- 16 28 06 -24 32.5 rho Oph = LDN 1688 ------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table4.dat 76 137 List of variable objects (members and candidate members of rho Ophiuchi) tablea1.dat 46 39 Appendix list of variable objects with variability consistent with M dwarfs (could contain possible members of rho Ophiuchi)
See also: J/ApJ/438/813 : Stellar population in ρ Oph cloud core (Strom+, 1995) J/ApJS/112/109 : Rho Oph Near-IR Positions and Photometry (Barsony+, 1997) J/A+A/359/113 : X-ray and IR study of Rho Oph dark cloud (Grosso+, 2000) J/ApJ/613/393 : X-ray and radio sources in ρ Oph Core A (Gagne+, 2004) J/A+A/429/963 : XMM-Newton observation of the rho Oph cloud (Ozawa+, 2005) J/AJ/130/1733 : Optical spectroscopy of ρ Oph stars (Wilking+, 2005) J/ApJ/630/381 : Mid-IR imaging in ρ Oph (Barsony+, 2005) J/A+A/447/609 : 1.2mm continuum observations in rho Oph cloud (Stanke+, 2006) J/A+A/452/245 : Accretion in rho Oph pre-main sequence stars (Natta+, 2006) Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
1- 19 A19 --- AOC J2000.0 IAU designation (JHHMMSS.ss+DDMMSS.s) 21- 25 F5.2 mag Hmag Average H magnitude over all available epochs 27- 31 F5.2 mag Kmag Average K magnitude over all available epochs 33- 36 F4.2 mag Hamp Peak-to-peak H magnitude amplitude variation 38- 41 F4.2 mag Kamp Peak-to-peak K magnitude amplitude variation 43- 46 F4.2 mag (H-K)amp Peak-to-peak H-K magnitude amplitude variation 48- 50 I3 deg Slope ?=- Slope in the K vs. (H-K) diagram 52- 57 A6 --- SED SED class (1) 59- 62 A4 --- VFlag [Y0 ] Variability flags (2) 65- 69 A5 --- VCauses Variability causes (3) 72- 76 A5 --- Ref References (4)
Note (1): SED class as defined from colour-colour diagrams using IRAC/Spitzer and WFCAM/UKIRT data. Note (2): Variability flags made of 4digits as follows: first digit = star identified as variable from the CC indexes second digit = star identified as variable from the chi-square statistics third digit = star is variable in year 1 fourth digit = star is variable in year 2 (a star is a long term variable when both these digits are Y). When each of these conditions is verified it is denoted by Y (as in yes), otherwise the digits are set to 0. Note (3): Variability causes as follows: CS = cool spots HS = hot spots E = extinction AD = accretion discs EV = Extreme variability Note (4): rho Ophiuchi members, according to the following studies: 1 = Comeron et al. (1993ApJ...416..185C) 2 = Bontemps et al. (2001A&A...372..173B) 3 = Gagne et al. (2004ApJ...613..393G) 4 = Ozawa et al. (2005A&A...438..661O) 5 = Wilking et al. (2005AJ....130.1733W)
Byte-by-byte Description of file: tablea1.dat
Bytes Format Units Label Explanations
1- 19 A19 --- AOC J2000.0 IAU designation (JHHMMSS.ss+DDMMSS.s) 21- 25 F5.2 mag Hmag Average H magnitude over all available epochs 27- 31 F5.2 mag Kmag Average K magnitude over all available epochs 33- 36 F4.2 mag Hamp Peak-to-peak H magnitude amplitude variation 38- 41 F4.2 mag Kamp Peak-to-peak K magnitude amplitude variation 43- 46 F4.2 mag (H-K)amp Peak-to-peak H-K magnitude amplitude variation
Acknowledgements: Catarina Alves de Oliveira, coliveir(at)eso.org
(End) Catarina Alves de Oliveira [ESO], Patricia Vannier [CDS] 28-Apr-2008
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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