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 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)
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16 28 06 -24 32.5 rho Oph = LDN 1688
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File Summary:
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FileName Lrecl Records Explanations
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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)
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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
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Bytes Format Units Label Explanations
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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)
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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 1993ApJ...416..185C)
2 = Bontemps et al. (2001A&A...372..173B 2001A&A...372..173B)
3 = Gagne et al. (2004ApJ...613..393G 2004ApJ...613..393G)
4 = Ozawa et al. (2005A&A...438..661O 2005A&A...438..661O)
5 = Wilking et al. (2005AJ....130.1733W 2005AJ....130.1733W)
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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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
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Acknowledgements:
Catarina Alves de Oliveira, coliveir(at)eso.org
(End) Catarina Alves de Oliveira [ESO], Patricia Vannier [CDS] 28-Apr-2008