J/A+A/356/541 T Tauri stars in the Sco-Cen OB association (Koehler+, 2000)
Multiplicity of X-ray selected T Tauri stars in the Scorpius-Centaurus OB
association.
Koehler R., Kunkel M., Leinert C., Zinnecker H.
<Astron. Astrophys., 356, 541-558 (2000)>
=2000A&A...356..541K 2000A&A...356..541K
ADC_Keywords: Stars, pre-main sequence ; Stars, double and multiple ;
X-ray sources
Keywords: stars: pre-main sequence - stars: binaries: visual - infrared: stars -
surveys - techniques: interferometric
Abstract:
We report the results of a search for binarity among young stars,
performed in the Scorpius-Centaurus OB association on a sample of
118 X-ray selected T Tauri stars. We use speckle interferometry and
direct-imaging observations to find companions in the separation range
0.13-6". After corrections to account for confusion with background
stars and for the bias induced by the X-ray selection, we find a
multiplicity (number of binaries or multiples divided by number of
systems) of 32.6±6.1)%, and a number of companions per system of
(35.2±6.3)%. This is higher by a factor of 1.59±0.34 compared
to main-sequence stars, but slightly lower than in a sample in the
Taurus-Auriga star-forming region that was selected and studied
similary. In Scorpius-Centaurus, we find fewer binaries with nearly
equal brightness than in Taurus-Auriga. There are significant
differences between the period distributions in the two subgroups
Upper Scorpius A and B: The peak of the distribution of stars in US-A
is at about 105 days, while that of stars in US-B is around 106.5
days. We compared our results with the optical multiplicity survey of
Brandner et al. (1996A&A...307..121B 1996A&A...307..121B), whose sample contains 49 stars
that were also observed by us, and find no infrared companions. The
flux ratio distributions of close and wide binaries in our sample show
no significant difference.
Description:
Table1 contains the list of T Tau stars in the upper Scorpius region,
resulting from speckle observations carried out at the ESO New
Technology Telescope (NTT) on La Silla, Chile, in May 1994 and July
1995 with the SHARP camera (System for High Angular Resolution
Pictures) of the Max-Planck-Institut for Extraterrestrial Physics.
All observations were performed in the K-band at 2.2µm.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 80 99 T Tau stars in the upper Scorpius region
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See also:
J/AJ/124/1670 : Post-T Tauri Stars in Sco-Cen Association (Mamajek+, 2002)
J/ApJS/82/117 : UBV and H-beta in Sco-Cen association (Slawson+, 1992)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- [KKL2000b] Sequence number
4- 13 F10.6 deg RAdeg Right ascension from 2MASS (J2000)
15- 24 F10.6 deg DEdeg Declination from 2MASS (J2000)
26- 38 A13 --- RX X-ray name (1)
40 A1 --- l_Xct [<] Limit flag on Xct
41- 46 F6.1 ct Xct Counts detected by ROSAT
48- 49 A2 --- SpType Spectral classification
53- 56 A4 --- Region [US-AB] US-A or US-B Upper Scorpius region
57 A1 --- --- [_]
58- 61 A4 --- OType T Tau classification (2)
64- 80 A17 --- 2MASS Name of 2MASS counterpart (1)
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Note (1): Column added by Eric E. Mamajek
Note (2): Class (from Eric E. Mamajek) is as follows:
WTTS = Weaklined T Tauri star
PTTS = Post-T Tauri star
CTTS = Classical T Tauri star
???? = unknown
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Acknowledgements:
The data were kindly supplied by Eric E. Mamajek (CfA, Harvard)
(End) Francois Ochsenbein [CDS] 07-Dec-2004