The disk-bearing young star IM Lupi: X-ray properties and limits on accretion

Gunther, H. M. and Matt, S. P. and Schmitt, J. H. M. M. and Gudel, M. and Li, Z. Y. and Burton, D. M. (2010) The disk-bearing young star IM Lupi: X-ray properties and limits on accretion. Astronomy and Astrophysics, 519 (10). A97. ISSN 0004-6361

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Abstract

Context. Classical T Tauri stars (CTTS) differ in their X-ray signatures from older pre-main sequence stars, e.g. weaklined TTS (WTTS). CTTS show a soft excess and deviations from the low-density coronal limit in the He-like triplets. Aims. We test whether these features correlate with accretion or the presence of a disk by observing IM Lup, a diskbearing object apparently in transition between CTTS and WTTS without obvious accretion. Methods. We analyse a Chandra grating spectrum and additional XMM-Newton data of IM Lup and accompanying optical spectra, some of them taken simultaneously to the X-ray observations. We fit the X-ray emission lines and decompose the H emission line in different components. Results. In X-rays IM Lup has a bright and hot active corona, where elements of low first-ionisation potential are depleted. The He-like Ne ix triplet is in the low-density state, but due to the small number of counts a high-density scenario cannot be excluded on the 90% confidence level. In all X-ray properties IM Lup resembles a main-sequence star, but it is also compatible with CTTS signatures on the 90% confidence level, thus we cannot decide if the soft excess and deviations from the low-density coronal limit in the He-like triplets in CTTS require accretion or only the presence of a disk. IM Lup is chromospherically active, which explains most of the emission in H. Despite its low equivalent width, the complexity of the H line profile is reminiscent of CTTS. We present an estimate for the mass accretion rate of 10−11M yr−1.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: © 2010 ESO. Deposited in accordance with the copyright policy of the publisher.
Depositing User: Ms Donna Burton
Faculty / Department / School: Historic - Faculty of Sciences - Department of Biological and Physical Sciences
Date Deposited: 17 Jul 2011 05:24
Last Modified: 21 Aug 2014 04:43
Uncontrolled Keywords: stars; formation; individual; IM Lupi; X-rays
Fields of Research (FOR2008): 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
02 Physical Sciences > 0201 Astronomical and Space Sciences > 020108 Planetary Science (excl. Extraterrestrial Geology)
02 Physical Sciences > 0204 Condensed Matter Physics > 020406 Surfaces and Structural Properties of Condensed Matter
Socio-Economic Objective (SEO2008): E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
Identification Number or DOI: doi: 10.1051/0004-6361/201014386
URI: http://eprints.usq.edu.au/id/eprint/19402

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