Issue |
Astron. Astrophys. Suppl. Ser.
Volume 119, Number 1, October I 1996
|
|
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Page(s) | 7 - 24 | |
DOI | https://doi.org/10.1051/aas:1996224 | |
Published online | 15 October 1996 |
New weak-line T Tauri stars in Orion from the ROSAT all-sky survey *
1
Max-Planck-Institut für Extraterrestrische Physik, D-85740 Garching, Germany
2
Instituto Nacional de Astrofísica Optica y Electrónica, A.P. 51 y 216 C.P. 72000, Puebla, México
3
Osservatorio Astronomico di Capodimonte, Via Moiariello 16, I-80131 Napoli, Italy
4
Landessternwarte-Königstuhl, D-69117 Heidelberg, Germany
5
Max-Planck-Institut für Astronomie Königstuhl, D-69117 Heidelberg, Germany
6
Instituto de Astronomía, Ensenada B.C., México CP 22860
7
Lowell Observatory, 1400 West Mars Hill Road. Flagstaff, Az 86001, U.S.A.
Send offprint request to: J.M. Alcalá
Received:
20
September
1995
Accepted:
26
January
1996
We present results of the spectroscopic and photometric
follow-up observations of the ROSAT all-sky survey in the
direction of the Orion cloud complex. The main goal of these
observations is the search for X-ray emitting pre-main sequence
stars. 820 X-ray sources were detected with high confidence in
about 450 square degrees. The mean density of X-ray sources in
this region is a factor of about two higher than that of the
whole RASS. 5% of the RASS sources in this region are
identified with previously known and likely pre-main sequence
stars. We have investigated spectroscopically 181 new RASS
sources widely distributed over the entire cloud complex. On the
basis of the presence of strong Li I λ6707 absorption,
spectral type later than F0 and chromospheric emission, 112 new
weak-line T Tauri stars could be found. We present coordinates,
X-ray count-rates and finding charts of the new PMS. Optical
KC, near-infrared JHKLM and uvby-β
photometry for the new WTTS is also provided. In addition 24
dKe-dMe stars were also found on the basis of the RASS data.
Key words: X-rays: stars / stars: pre-main-sequence / ISM: Orion star forming region
© European Southern Observatory (ESO), 1996