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J/A+A/461/183       Variability of classical T Tauri        (Grankin+, 2007)

Results of the ROTOR-program. I. The long-term photometric variability of classical T Tauri stars. Grankin K.N., Melnikov S.Y., Bouvier J., Herbst W., Shevchenko V.S. <Astron. Astrophys. 461, 183 (2007)> =2007A&A...461..183G
ADC_Keywords: Stars, pre-main sequence ; Photometry, UBVRI Keywords: stars: activity - stars: pre-main sequence - stars: variables: general Abstract: We report the results of a study the long term variability of Classical T Tauri stars (CTTS) over up to 20 years, characterize it from a set of statistical parameters and discuss its origin. We characterize the long term photometric variations of 49 CTTs with sufficient data for allowing a robust statistical analysis and propose an empirical classification scheme. Several patterns of long term photometric variability are identified. The most common pattern, exhibited by a group of 15 stars which includes T Tau itself, consists of low level variability (with V-amplitude less than 0.4mag) with no significant changes occurring from season to season over many years. A related subgroup of 22 stars exhibit a similar stable long term variability pattern, though with larger amplitudes (up to 1.6mag). Besides these representative groups, we identify three smaller groups of 3-5 stars each of which have distinctive photometric properties. The long term variability of most CTTS is fairly stable and merely reflects shorter term variability due to cold and hot surface spots. Only a small fraction of CTTS undergo significant brightness changes on the long term (months, years), which probably arise from slowly varying circumstellar extinction. Description: The photometric observations of CTTS were carried out over a period extending from 1983 up to 2003. The database contains more than 21000 UBVR-observations of 72 CTTs. All the data were collected within the framework of the ROTOR-program at Mount Maidanak Observatory (Uzbekistan). File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file stars.dat 79 72 List of the stars phot/* 40 72 Individual photometry
See also: J/A+A/299/89 : COYOTES II (Bouvier+, 1995) J/A+A/310/143 : Variability of classical T Tauri stars (Fernandez+, 1996) J/A+AS/120/267 : T Tauri stars UBrHalphaz photometry (Osterloh+ 1996) J/A+AS/128/561 : UBVRI photometry of southern T Tauri stars (Batalha+ 1998) Byte-by-byte Description of file: stars.dat
Bytes Format Units Label Explanations
1- 10 A10 --- Name Simbad name 17- 18 I2 h RAh Simbad Hour of Right Ascension (J2000.0) 20- 21 I2 min RAm Simbad Minute of Right Ascension (J2000.0) 23- 26 F4.1 s RAs Simbad Second of Right Ascension (J2000.0) 28 A1 --- DE- Simbad Sign of the Declination (J2000.0) 29- 30 I2 deg DEd Simbad Degree of Declination (J2000.0) 32- 33 I2 arcmin DEm Simbad Arcminute of Declination (J2000.0) 35- 36 I2 arcsec DEs Simbad Arcsecond of Declination (J2000.0) 40- 44 F5.2 mag Bmag ? Simbad B band magnitude 46- 50 F5.2 mag Vmag ? Simbad V band magnitude 52- 62 A11 --- SpType Simbad MK spectral type 67- 79 A13 --- FileName Data file name, in "phot" subdirectory
Byte-by-byte Description of file: phot/*
Bytes Format Units Label Explanations
1- 12 F12.4 d HJD Heliocentric Julian date 14- 19 F6.3 mag Vmag ?=9.999 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
Acknowledgements: Jerome bouvier, Jerome.Bouvier(at)obs.ujf-grenoble.fr
(End) Patricia Vannier [CDS] 02-Nov-2006
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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