ROSAT-HRI detection of the Class I protostar YLW16A in the rho Ophiuchi dark cloud

Authors
Citation
N. Grosso, ROSAT-HRI detection of the Class I protostar YLW16A in the rho Ophiuchi dark cloud, ASTRON ASTR, 370(1), 2001, pp. L22-L25
Citations number
27
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Space Sciences
Journal title
ASTRONOMY AND ASTROPHYSICS
ISSN journal
0004-6361 → ACNP
Volume
370
Issue
1
Year of publication
2001
Pages
L22 - L25
Database
ISI
SICI code
0004-6361(200104)370:1<L22:RDOTCI>2.0.ZU;2-R
Abstract
I analyze unpublished or partially published archival ROSAT data of the rho Ophiuchi dark cloud. This set of seven overlapping ROSAT HRI pointings, co mposed of Eight similar to one-hour exposures, detects mainly the X-ray bri ghtest 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 RI caught during just one expo sure a weak X-ray source (L = 10; SNR = 4.1 sigma 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 her e one Einstein IPC observation, have already detected an X-ray source in th is area, but this higher angular resolution data show clearly that X-rays a re emitted by the Class I protostar YLW16A. This is the second Class I prot ostar detected by the ROSAT HRI in this dark cloud. The determination of th e intrinsic X-ray luminosity of this event, L-X[0.1-2.4 keV] = (9.4-450) 10 (30) ergs(-1), critically depends on the source absorption estimate. Improv ements will be obtained only by the direct determination of this parameter from fitting of Chandra and XMM-Newton spectre.