2019A&A...626A..64H


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.13CEST06:50:56

2019A&A...626A..64H - Astronomy and Astrophysics, volume 626A, 64-64 (2019/6-1)

Chandra X-ray spectroscopy of the focused wind in the Cygnus X-1 system. III. Dipping in the low/hard state.

HIRSCH M., HELL N., GRINBERG V., BALLHAUSEN R., NOWAK M.A., POTTSCHMIDT K., SCHULZ N.S., DAUSER T., HANKE M., KALLMAN T.R., BROWN G.V. and WILMS J.

Abstract (from CDS):

We present an analysis of three Chandra High Energy Transmission Gratings observations of the black hole binary Cyg X-1/HDE 226868 at different orbital phases. The stellar wind that is powering the accretion in this system is characterized by temperature and density inhomogeneities including structures, or "clumps", of colder, more dense material embedded in the photoionized gas. As these clumps pass our line of sight, absorption dips appear in the light curve. We characterize the properties of the clumps through spectral changes during various dip stages. Comparing the silicon and sulfur absorption line regions (1.6-2.7keV∼7.7-4.6Å) in four levels of varying column depth reveals the presence of lower ionization stages, i.e., colder or denser material, in the deeper dip phases. The Doppler velocities of the lines are roughly consistent within each observation, varying with the respective orbital phase. This is consistent with the picture of a structure that consists of differently ionized material, in which shells of material facing the black hole shield the inner and back shells from the ionizing radiation. The variation of the Doppler velocities compared to a toy model of the stellar wind, however, does not allow us to pin down an exact location of the clump region in the system. This result, as well as the asymmetric shape of the observed lines, point at a picture of a complex wind structure.

Abstract Copyright: © ESO 2019

Journal keyword(s): accretion, accretion disks - stars: individual: HDE 226868 - stars: individual: Cyg X-1 - stars: winds, outflows - techniques: spectroscopic - X-rays: binaries

Simbad objects: 3

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Number of rows : 3

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 V* GP Vel HXB 09 02 06.8610736194 -40 33 16.896402010 6.85 7.37 6.87 6.31 6.05 B0.5Ia 1373 0
2 V* V779 Cen HXB 11 21 15.0920367078 -60 37 25.627505233   14.4       O9III/Veq 994 0
3 HD 226868 HXB 19 58 21.6758193269 +35 12 05.782512305 9.38 9.72 8.91 8.42   O9.7Iabpvar 3925 0

    Equat.    Gal    SGal    Ecl

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2020.07.13-06:50:56

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