EDP Sciences
Free access
Volume 405, Number 1, July I 2003
Page(s) 285 - 290
Section Stellar atmospheres
DOI http://dx.doi.org/10.1051/0004-6361:20030674

A&A 405, 285-290 (2003)
DOI: 10.1051/0004-6361:20030674

Long-term X-ray variability of the microquasar system LS 5039/RX J1826.2-1450

P. Reig1, M. Ribó2, J. M. Paredes2 and J. Martí3

1  G.A.C.E., Institut de Ciències dels Materials, Universitat de Valencia, 46071 Paterna-Valencia, Spain
    e-mail: pablo.reig@uv.es
2  Departament d'Astronomia i Meteorologia, Universitat de Barcelona, Av. Diagonal 647, 08028 Barcelona, Spain
    e-mail: mribo@am.ub.es; josep@am.ub.es
3  Departamento de Física, Escuela Politécnica Superior, Universidad de Jaén, Virgen de la Cabeza 2, 23071 Jaén, Spain
    e-mail: jmarti@ujaen.es

(Received 14 February 2003 / Accepted 16 April 2003)

We report on the results of the spectral and timing analysis of a BeppoSAX observation of the microquasar system LS 5039 / RX J1826.2-1450 . The source was found in a low-flux state with $F_{\rm X}$(1-10 keV) = $4.7 \times 10^{-12}$ erg cm -2 s -1, which represents almost one order of magnitude lower than a previous RXTE observation 2.5 years before. The 0.1-10 keV spectrum is described by an absorbed power-law continuum with photon-number spectral index $\Gamma=1.8\pm0.2$ and hydrogen column density of $N_{\rm H}=1.0^{+0.4}_{-0.3} \times 10^{22}$ cm -2. According to the orbital parameters of the system, the BeppoSAX observation covers the time of an X-ray eclipse should one occur. However, the 1.6-10 keV light curve does not show evidence of such an event, which allows us to give an upper limit to the inclination of the system. The low X-ray flux detected during this observation is interpreted as a decrease in the mass accretion rate onto the compact object due to a decrease in the mass-loss rate from the primary.

Key words: stars: individual: LS 5039 , RX J1826.2-1450 , 3EG J1824-1514 -- X-rays: stars -- stars: variables: general -- radio continuum: stars

Offprint request: P. Reig, pablo.reig@uv.es

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