J/A+A/319/184 New WTTS in the Chamaeleon complex (Alcala+ 1997)
A study of the Chamaeleon star forming region from the ROSAT all-sky survey:
II. The pre-main sequence population.
Alcala J.M., Krautter J., Covino E., Neuhaeuser R., Schmitt J.H.M.M.,
Wichmann R.
<Astron. Astrophys. 319, 184 (1997)>
=1997A&A...319..184A 1997A&A...319..184A (SIMBAD/NED BibCode)
ADC_Keywords: Stars, pre-main sequence
Mission_Name: ROSAT
Keywords: X-ray: stars - stars: pre-main-sequence; activity -
ISM: Chamaeleon clouds - surveys
Abstract:
We analyse the nature of the optical counterparts of the ROSAT all-sky
survey (RASS) X-ray sources identified with new weak-line T Tauri
(WTTS) stars in the Chamaeleon star forming region (SFR). The new WTTS
are distributed throughout the whole SFR, while the classical T Tauri
stars (CTTS) are found only in the cloud cores. Adopting a distance of
150pc we derive the stellar parameters and place the new WTTS in the
HR diagram. By comparison with theoretical pre-main sequence (PMS)
evolutionary tracks, we find masses in the range of 0.2-2.5M☉
and ages from a few 105yr to 5x107yr. Many of the youngest WTTS
are located far away from the main Chamaeleon dark clouds.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1 104 82 Stellar parameters of the new weak-line T Tauri
stars (WTTS) in the Chamaeleon complex.
table2 101 82 X-ray data of the new WTTS in the Chamaeleon
complex.
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Byte-by-byte Description of file: table1
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Bytes Format Units Label Explanations
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1- 14 A14 --- RXJ ROSAT all-sky survey source designation
Alcala' et al. (1995A&AS..114..109A 1995A&AS..114..109A)
16- 20 A5 --- SpT Spectral type
23- 27 F5.3 [K] logTeff Logarithm of effective temperature
29- 33 F5.2 mag Av ? Visual stellar extinction
36- 40 F5.2 solLum Lbol ? Bolometric luminosity
42- 46 F5.2 solRad Rad ? Stellar radius
48- 52 F5.2 solRad RadBE ? Stellar radius derived from the
Barnes-Evans relation Barnes & Evans
(1976MNRAS.174..489B 1976MNRAS.174..489B)
55- 58 F4.2 solMass Mass ? Stellar mass (1)
61- 64 F4.2 solMass e_Mass ? Error on the stellar mass.
67- 71 F5.2 Myr t ? Stellar age (1)
74- 77 F4.2 Myr e_t ? Error on the stellar age.
80- 83 F4.2 mW/m2 FHa ? H-alpha surface flux
88-100 A13 --- notes Notes to table (2)
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Note (1): Data derived using the pre-main sequence evolutionary tracks by
D'Antona & Mazzitelli (1994ApJS...90..467D 1994ApJS...90..467D).
Note (2): a) stars lacking RI and JHKLM magnitudes. The luminosity for these
stars was derived using UBV photometry and adopting a bolometric
correction.
b) visual binaries found by Brandner et al. (1996A&A...307..121B 1996A&A...307..121B).
c) designation by Walter (1992AJ....104..758W 1992AJ....104..758W).
d) designation by Lawson, et al. (1996MNRAS.280.1071L 1996MNRAS.280.1071L).
e) probable spectroscopic binary (Covino et al. 1997).
f) stars falling below the main sequence when adopting
a distance of 150pc.
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Byte-by-byte Description of file: table2
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Bytes Format Units Label Explanations
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1- 16 A16 --- RXJ ROSAT all-sky survey source designation
Alcala' et al. (1995A&AS..114..109A 1995A&AS..114..109A) (1)
17- 21 F5.2 --- HR1 Hardness ratio 1
23- 26 F4.2 --- e_HR1 Error on hardness ratio 1
30- 34 F5.2 --- HR2 Hardness ratio 2
36- 39 F4.2 --- e_HR2 Error on hardness ratio 2
42- 46 F5.2 [cm-2] logNH Logarithm of Hydrogen column density
49- 52 F4.2 keV kTx X-ray emission energy
54- 57 F4.2 keV e_kTx Error on X-ray emission energy
60- 63 F4.2 10-18J/ct ECF Energy conversion factor
65- 68 F4.2 10-18J/ct e_ECF Error on the energy conversion factor
72 A1 --- l_ECF Limit flag on ECF
73- 77 F5.2 [10-7J] logLx Logarithm of the X-ray luminosity
79- 82 F4.2 [10-7J] e_logLx Error on logarithm of the X-ray luminosity
86 A1 --- l_logFx Limit flag on logFx
87- 90 F4.2 [mW/m2] logFx ? Logarithm of the X-ray surface flux
92- 95 F4.2 [mW/m2] e_logFx ? Error on log. of the X-ray surface flux
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Note (1): °: X-ray fits with both NH and Tx as free parameters
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Acknowledgements: Juan M. Alcala
References:
Alcala et al., 1995, A&AS 114, 109 (Paper I) =1995A&AS..114..109A 1995A&AS..114..109A
Barnes & Evans, 1976, MNRAS 174, 489 =1976MNRAS.174..489B 1976MNRAS.174..489B
Brandner et al., 1996, A&A 307, 121 =1996A&A...307..121B 1996A&A...307..121B
Covino et al., 1997, in prep.
D'Antona & Mazzitelli, 1994, ApJS 90, 467 =1994ApJS...90..467D 1994ApJS...90..467D
Lawson, et al., 1996, MNRAS 280, 1071 =1996MNRAS.280.1071L 1996MNRAS.280.1071L
Walter, 1992, AJ 104, 758 =1992AJ....104..758W 1992AJ....104..758W
(End) Patricia Bauer [CDS] 12-Aug-1996