A few days before the end of the 2008 extreme outburst of EX Lup : accretion shocks and a smothered stellar corona unveiled by XMM-Newton - CNRS - Centre national de la recherche scientifique Accéder directement au contenu
Article Dans Une Revue Astronomy and Astrophysics - A&A Année : 2010

A few days before the end of the 2008 extreme outburst of EX Lup : accretion shocks and a smothered stellar corona unveiled by XMM-Newton

Résumé

In mid-January 2008, EX Lup, the prototype of the small class of eruptive variables called EXors, began an extreme outburst that lasted seven months. We observed EX Lup during about 21 h with XMM-Newton, simultaneously in X-rays and UV, on August 10-11, 2008 -- a few days before the end of its 2008 outburst -- when the optical flux of EX Lup remained about 4 times above its pre-outburst level. The observed spectrum of the low-level period is dominated below ~1.5 keV by emission from a relatively cool plasma (~4.7 MK) that is lightly absorbed (NH~3.6E20 cm^-2) and above ~1.5 keV by emission from a plasma that is ~ten times hotter and affected by a photoelectric absorption that is 75 times larger. During the X-ray flare, the emission measure and the intrinsic X-ray luminosity of this absorbed plasma component is five times higher than during the low-level period. The soft X-ray spectral component is most likely associated with accretion shocks, as opposed to jet activity, given the absence of forbidden emission lines of low-excitation species (e.g., [O I]) in optical spectra of EX Lup obtained during outburst. The hard X-ray spectral component, meanwhile, is most likely associated with a smothered stellar corona. The UV emission is reminiscent of accretion events, such as those already observed with the Optical/UV Monitor from other accreting pre-main sequence stars, and is evidently dominated by emission from accretion hot spots. The large photoelectric absorption of the active stellar corona is most likely due to high-density gas above the corona in accretion funnel flows (abridged).
Fichier principal
Vignette du fichier
EX_Lup_XMM_2008_final_printer.pdf (437.88 Ko) Télécharger le fichier
Origine : Fichiers produits par l'(les) auteur(s)
Loading...

Dates et versions

hal-00503211 , version 1 (16-07-2010)

Identifiants

Citer

Nicolas Grosso, Kenji Hamaguchi, Joel Kastner, Michael Richmond, David A. Weintraub. A few days before the end of the 2008 extreme outburst of EX Lup : accretion shocks and a smothered stellar corona unveiled by XMM-Newton. Astronomy and Astrophysics - A&A, 2010, 522, pp.A56. ⟨10.1051/0004-6361/200913850⟩. ⟨hal-00503211⟩
99 Consultations
148 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More