Issue |
A&A
Volume 370, Number 1, April IV 2001
|
|
---|---|---|
Page(s) | L22 - L25 | |
Section | Letters | |
DOI | https://doi.org/10.1051/0004-6361:20010325 | |
Published online | 15 April 2001 |
ROSAT-HRI detection of the Class I protostar YLW16A in the
Ophiuchi dark cloud
Max-Planck-Institut für extraterrestrische Physik, PO Box 1312, 85741 Garching bei München, Germany
Corresponding author: N. Grosso, ngrosso@xray.mpe.mpg.de
Received:
17
January
2001
Accepted:
2
March
2001
I analyze unpublished or partially published archival ROSAT data of the ρ Ophiuchi dark cloud.
This set of seven overlapping ROSAT HRI pointings, composed of eight ~one-hour exposures,
detects mainly the X-ray brightest T Tauri stars of this star-forming region.
Only two HRI sources are new X-ray sources, and their optical counterparts are proposed as new Weak T Tauri star candidates.
Meanwhile the ROSAT HRI caught during just one exposure a weak X-ray source (;
for Gaussian statistics) among a group of three embedded young stellar objects including two Class I protostars.
Previous ROSAT PSPC, ASCA GIS observations, and as I argue here one Einstein IPC observation,
have already detected an X-ray source in this area, but this higher angular resolution data
show clearly that X-rays are emitted by the Class I protostar YLW16A.
This is the second Class I protostar detected by the ROSAT HRI in this dark cloud.
The determination of the intrinsic X-ray luminosity of this event,
erg s-1,
critically depends on the source absorption estimate. Improvements will be obtained only by the direct determination
of this parameter from fitting of Chandra and XMM-Newton spectra.
Key words: open clusters and association: ρ Oph / stars: pre-main sequence / X-rays: stars / infrared: stars
© ESO, 2001
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