Doppler tomography of XTE J1118+480 revealing chromospheric emission from the secondary star

作者：Zurita C^*; Gonzalez Hernandez J I; Escorza A; Casares J

来源：Monthly Notices of the Royal Astronomical Society, 2016, 460(4): 4289-4296.

DOI：10.1093/mnras/stw1235

• accretion
• accretion discs
• black hole physics
• stars: activity
• stars: individual: XTE J1118+480
• stars: magnetic field
• X-rays: binaries

Doppler tomography of emission lines in low-mass X-ray binaries allows us to investigate the structure and variability of the accretion discs as well as possible activity arising from the secondary stars. We present Doppler maps of the black hole binary XTE J1118+480 from spectra obtained using OSIRIS@GTC during quiescence on four different nights in 2011 and 2012. Doppler imaging of the H alpha line shows, for the first time, a narrow component from the secondary star with observed equivalent widths varying in the range 1.2-2.9 angstrom but not correlated with the veiling of the accretion disc. The H alpha flux of the secondary star is too large to be powered by X-ray irradiation, supporting chromospheric activity, possibly induced by rapid rotation, as the most likely origin of this feature in the black hole X-ray binary XTE J1118+480. In addition, we detect variations in the centroid of the H alpha line on nightly basis. These are likely caused by a precessing accretion disc, although with a much lower amplitude (similar to 50 km s(-1)) than previously observed.

• 出版日期2016-8-21