Volume 384, Number 1, MarchII 2002
|Page(s)||163 - 170|
|Section||Interstellar and circumstellar matter|
|Published online||15 March 2002|
The 1998 outburst of the X–ray transient XTE J2012+381 as observed with BeppoSAX
Osservatorio Astronomico di Brera, via E. Bianchi 46, 23807 Merate (Lecco), Italy
2 Osservatorio Astronomico di Roma, via Frascati 33, 00040 Monteporzio Catone (Roma), Italy
3 Istituto di Fisica Cosmica e Applicazioni all'Informatica, C.N.R., via La Malfa 153, 90146 Palermo, Italy
4 Università di Ferrara, Dipartimento di fisica, via Paradiso 12, 44100 Ferrara, Italy
5 Istituto Tecnologie e Studio Radiazioni Extraterrestri, C.N.R., via Gobetti 101, 40129 Bologna, Italy
Corresponding author: S. Campana, campana@mera te.mi.astro.it
Accepted: 14 December 2001
We report on the results of a series of X–ray observations of the transient black hole candidate XTE J2012+381 during the 1998 outburst performed with the BeppoSAX satellite. The observed broad-band energy spectrum can be described by the superposition of an absorbed disk black body, with an iron line plus a high energy component, modelled with either a power law or a Comptonisation tail. The source showed pronounced spectral variability between our five observations. While the soft component in the spectrum remained almost unchanged throughout our campaign, we detected a hard spectral tail which extended to 200 keV in the first two observations, but became barely detectable up to 50 keV in the following two. A further re-hardening is observed in the final observation. The transition from a hard to a soft and then back to a hard state occurred around an unabsorbed 0.1–200 keV luminosity of (at 10 kpc). This indicates that state transitions in XTE 2012+281 are probably not driven only by mass accretion rate, but additional physical parameters must play a role in the evolution of the outburst.
Key words: binaries: general / black hole physics / stars: individual (XTE J2012+381) / X–rays: stars
© ESO, 2002
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.