EDP Sciences
Free access
Issue
A&A
Volume 465, Number 1, April I 2007
Page(s) L5 - L8
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:20067016


A&A 465, L5-L8 (2007)
DOI: 10.1051/0004-6361:20067016

Letter

X-ray emission from MP Muscae: an old classical T Tauri star

C. Argiroffi1, A. Maggio2, and G. Peres1

1  Dipartimento di Scienze Fisiche ed Astronomiche, Sezione di Astronomia, Università di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy
    e-mail: [argi;peres]@astropa.unipa.it
2  INAF - Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy
    e-mail: maggio@astropa.unipa.it

(Received 22 December 2006 / Accepted 25 January 2007)

Abstract
Aims.We study the properties of X-ray emitting plasma of MP Mus , an old classical T Tauri star. We check whether an accretion process could produce the observed X-ray emission and we derive the accretion parameters and the characteristics of the shock-heated plasma. We compare the properties of MP Mus with those of younger classical T Tauri stars to test whether age is related to the properties of the X-ray emitting plasma.
Methods.XMM-Newton X-ray spectra allow us to measure plasma temperatures, abundances, and electron density. The density of cool plasma probes whether X-ray emission is produced by plasma heated in the accretion process.
Results.X-ray emission from MP Mus originates from high density cool plasma but a hot flaring component is also present, suggesting that both coronal magnetic activity and accretion contribute to the observed X-ray emission. We find a Ne/O ratio similar to that observed in the much younger classical T Tauri star BP Tau . From the soft part of the X-ray emission, mostly produced by plasma heated in the accretion shock, we derive a mass accretion rate of $5\times10^{-11}$ $M_\odot$ yr-1.


Key words: stars: abundances -- stars: circumstellar matter -- stars: coronae -- stars: individual: MP Muscae -- stars: pre-main sequence -- X-rays: stars



© ESO 2007