J/A+A/479/827 UBVR light curves of weak-line T Tauri stars (Grankin+, 2008)
Results of the ROTOR-program.
II. The long-term photometric variability of weak-line T Tauri stars.
Grankin K.N., Bouvier J., Herbst W., Melnikov S.Yu.
<Astron. Astrophys. 479, 827 (2008)>
=2008A&A...479..827G 2008A&A...479..827G
ADC_Keywords: Stars, pre-main sequence ; Photometry, UBVRI
Keywords: stars: rotation - stars: fundamental parameters - stars: starspots -
stars: variables: general - stars: pre-main sequence
Abstract:
T Tauri stars exhibit variability on all timescales, whose origin is
still debated. On WTTS the variability is fairly simple and attributed
to long-lived, ubiquitous cool spots. We investigate the long term
variability of WTTS, extending up to 20 years in some cases,
characterize it statistically and discuss its implications for our
understanding of these stars. We have obtained a unique, homogeneous
database of photometric measurements for WTTS extending up to
20-years. It contains more than 9000 UBVR observations of 48 WTTS. All
the data were collected at Mount Maidanak Observatory (Uzbekistan) and
they constitute the longest homogeneous record of accurate WTTS
photometry ever assembled. Definitive rotation periods for 35 of the
48 stars are obtained. Phased light curves over 5 to 20 seasons are
now available for analysis. Light curve shapes, amplitudes and colour
variations are obtained for this sample and various behaviors
exhibited, discussed and interpreted. Our main conclusion is that most
WTTS have very stable long term variability with relatively small
changes of amplitude or mean light level. The long term variability
seen reflects modulation in the cold spot distributions. Photometric
periods are stable over many years, and the phase of minimum light can
be stable as well for several years. On the long term, spot properties
do change in subtle ways, leading to secular variations in the shape
and amplitudes of the light curves.
Description:
We report the results of a study the long term variability of
Weak-Line T Tauri stars (WTTS) over up to 18 years. The photometric
observations of WTTS were carried out over period extending from 1986
up to 2004. The database contains more than 9000 UBVR-observations of
48 WTTs. All the data were collected within the framework of the
ROTOR-program at Mount Maidanak Observatory (Uzbekistan).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 76 48 List of the stars
phot/* . 48 Individual photometry
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J/A+A/299/89 : COYOTES II (Bouvier+, 1995)
J/A+AS/145/187 : Photometric observations of WTTS (Chavarria+ 2000)
Byte-by-byte Description of file: stars.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Simbad name
13- 14 I2 h RAh Simbad Hour of Right Ascension (J2000.0)
16- 17 I2 min RAm Simbad Minute of Right Ascension (J2000.0)
19- 22 F4.1 s RAs Simbad Second of Right Ascension (J2000.0)
24 A1 --- DE- Simbad Sign of the Declination (J2000.0)
25- 26 I2 deg DEd Simbad Degree of Declination (J2000.0)
28- 29 I2 arcmin DEm Simbad Arcminute of Declination (J2000.0)
31- 32 I2 arcsec DEs Simbad Arcsecond of Declination (J2000.0)
35- 39 F5.2 mag Bmag ? Simbad B band magnitude
42- 46 F5.2 mag Vmag ? Simbad V band magnitude
49- 53 A5 --- SpType Simbad MK spectral type
56- 63 F8.5 d Per ? Known period (from table3 of paper)
65- 76 A12 --- FileName Data file name, in "phot" subdirectory
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Byte-by-byte Description of file: phot/*
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Bytes Format Units Label Explanations
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1- 12 F12.4 d HJD Heliocentric Julian date
14- 19 F6.3 mag Vmag Johnson V magnitude
21- 26 F6.3 mag U-B ?=9.999 Johnson (U-B) color index
28- 33 F6.3 mag B-V ?=9.999 Johnson (B-V) color index
35- 40 F6.3 mag V-R ?=9.999 Johnson (V-R) color index
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Acknowledgements:
Konstantin Grankin, kgrankin(at)crao.crimea.ua
(End) Patricia Vannier [CDS] 04-Jan-2008