Paper: astro-ph/0506650
Date: Mon, 27 Jun 2005 15:53:58 GMT (332kb)

Title: X-ray Emission from Orion Nebula Cluster Stars with Circumstellar Disks
and Jets

Authors: Joel H. Kastner (Rochester Institute of Technology), Geoffrey Franz
(RIT), Nicolas Grosso (Laboratoire d'Astrophysique de Grenoble), John Bally
(University of Colorado), Mark J. McCaughrean (University of Exeter and
Astrophysikalisches Institut Potsdam), Konstantin Getman (Penn State
University), Eric D. Feigelson (Penn State University), Norbert S. Schulz
(Mass. Inst. of Technology)
Comments: 42 pages, 10 figures; accepted for publication in the Astrophysical
Journal Supplements, Special Issue on the Chandra Orion Ultradeep Project
(COUP)
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We investigate the X-ray and near-infrared emission properties of a sample of
pre-main sequence (PMS) stellar systems in the Orion Nebula Cluster (ONC) that
display evidence for circumstellar disks (``proplyds'') and optical jets in
Hubble Space Telescope (HST) imaging. Approximately 70% of ~140 proplyds were
detected as X-ray sources in the Chandra Orion Ultradeep Program observation of
the ONC, including ~25% of proplyds that do not display central stars in HST
imaging. Many proplyds display near-infrared excesses, suggesting disk
accretion is ongoing onto the central, PMS stars. Among circumstellar disks
that are detected in absorption in HST imaging, we find that X-ray absorbing
column and apparent disk inclination are well correlated, providing insight
into the disk scale heights and metal abundances of UV- and X-ray-irradiated
protoplanetary disks. Jet sources display some of the largest near-infrared
excesses among the X-ray-detected proplyds, suggesting that the origin of the
jets is closely related to ongoing, PMS stellar accretion. Some jet sources
display double-peaked X-ray spectral energy distributions, with soft components
indicative of strong shocks in the jet collimation region. These results
support models in which circumstellar disks collimate and/or launch jets from
young stellar objects and, furthermore, demonstrate that star-disk-jet
interactions may contribute to PMS X-ray emission.

\\ ( http://arXiv.org/abs/astro-ph/0506650 , 332kb)