Volume 592, August 2016
|Number of page(s)||6|
|Published online||25 July 2016|
RT Crucis: a look into the X-ray emission of a peculiar symbiotic star
1 Institut für Astronomie und Astrophysik, Kepler Center for Astro and Particle Physics, Eberhard Karls Universität, Sand 1, 72076 Tübingen, Germany
2 ISDC Data Center for Astrophysics, Université de Genève, 16 chemin d’Écogia, 1290 Versoix, Switzerland
3 Kazan Federal University, Kremlevskaja str., 18, 420008 Kazan, Russia
4 Wydział Fizyki, Uniwersytet w Białymstoku, Ciołkowskiego 1L, 15-245 Białystok, Poland
Received: 3 February 2016
Accepted: 31 May 2016
Symbiotic stars are a heterogeneous class of interacting binaries. Among them, RT Cru has been classified as prototype of a subclass that is characterised by hard X-ray spectra that extend past ~20 keV. We analyse ~8.6 Ms of archival INTEGRAL data collected during the period 2003−2014, ~ 140 ks of Swift/XRT data, and a Suzaku observation of 39 ks, to study the spectral X-ray emission and investigate the nature of the compact object. Based on the 2MASS photometry, we estimate the distance to the source of 1.2−2.4 kpc. The X-ray spectrum obtained with Swift/XRT, JEM-X, IBIS/ISGRI, and Suzaku data is well fitted by a cooling flow model modified by an absorber that fully covers the source and two partially covering absorbers. Assuming that the hard X-ray emission of RT Cru originates from an optically thin boundary layer around a non-magnetic white dwarf, we estimated a mass of the white dwarf of MWD ≈ 1.2M⊙. The mass accretion rate obtained for this source might be too high for the optically thin boundary layer scenario. Therefore we investigate other plausible scenarios to model its hard X-ray emission. We show that, alternatively, the observed X-ray spectrum can be explained with the X-ray emission from the post-shock region above the polar caps of a magnetised white dwarf with mass MWD ≈ 0.9−1.1M⊙.
Key words: X-rays: binaries / white dwarfs / stars: individual: RT Cru / stars: individual: IGR J12349-6434
© ESO, 2016
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.