A survey for Fe 6.4 keV emission in young stellar objects in rho Oph: the strong fluorescence from Elias 29

Abstract

We report the results of a search for 6.4 keV Fe fluorescent emission in Young Stellar Objects (YSOs) with measured accretion luminosities in the rho Oph cloud, using all existing chandra and XMM-Newton observations of the region. A total of nine such YSOs have X-ray data with sufficiently high S/N for the 6.4 keV line to be potentially detected if present. A positive detection of the Fe 6.4 keV line is reported for one object, Elias 29, in both the XMM-Newton and the chandra data. The 6.4 keV line is detected in Elias 29 both during quiescent and flaring emission, unlikely all previously reported detections of 6.4 keV Fe fluorescence in YSOs which were made during intense flaring. The observed equivalent width of the fluorescent line is large, at W_alpha approx 140 eV, ruling out fluorescence from diffuse circumstellar material. It is also larger than expected for simple reflection from a solar-composition photosphere or circumstellar disk, but it is compatible with being due to fluorescence from a centrally illuminated circumstellar disk. The X-ray spectrum of Elias 29 is also peculiar in terms of its high (ionized) Fe abundance, as evident from the very intense Fe xxv 6.7 keV line emission; we speculate on the possible mechanism leading to the observed high abundance.

arXiv commentAccepted by A&A

References in corpus (7)

• ISOCAM observations of the rho Ophiuchi cloud: Luminosity and mass functions of the pre-main sequence embedded cluster
• A Systematic Study of X-Ray Flares from Low-Mass Young Stellar Objects in the Rho Ophiuchi Star-Forming Region with Chandra
• The Environment and Nature of the Class I Protostar Elias 29: Molecular Gas Observations and the Location of Ices
• Stellar Properties of Pre-Main Sequence Stars from High Resolution Near-IR Spectra
• An XMM-Newton-based X-ray survey of pre-main sequence stellar emission in the L1551 star-forming complex
• Coronal structure geometries on pre-main sequence stars
• Chandra and ASCA Observations of the X-ray-brightest T-Tauri Stars in the Rho Ophiuchi Cloud

Cited by in corpus (19)

• Bright X-ray flares in Orion young stars from COUP: evidence for star-disk magnetic fields?
• X-Ray Spectroscopy of Stars
• The Sun in Time: Activity and Environment
• On the origin of [NeII] 12.81 micron emission from pre-main sequence stars: Disks, jets, and accretion
• X-rays from RU Lupi - Accretion and winds in CTTS
• Energetic Protons, Radionuclides and Magnetic Activity in Protostellar Disks
• The onset of X-ray emission in young stellar objects: a Chandra observation of the Serpens star-forming region
• Coronae in the Coronet: A very deep X-ray look into a stellar nursery
• Sulfur-Bearing Species Tracing the Disk/Envelope System in the Class I Protostellar Source Elias 29
• X-ray Fluorescent Fe Kalpha Lines from Stellar Photospheres
• Results from Droxo. I. The variability of fluorescent Fe 6.4 keV emission in the young star Elias 29: High-energy electrons in the star's accretion tubes?
• Results from DROXO. III. Observation, source list and X-ray properties of sources detected in the "Deep Rho Ophiuchi XMM-Newton Observation"
• Geometry Diagnostics of a Stellar Flare from Fluorescent X-rays
• Fe K alpha and hydrodynamic loop model diagnostics for a large flare on II Peg
• The nature of the fluorescent iron line in V 1486 Ori
• The gas disk: Evolution and chemistry
• The complex phenomena of YSOs revealed by their X-ray variability
• Results and Perspectives of Young Stellar Object long look programs
• Star Forming Regions