Infrared spectroscopy of the Be/X-ray transient A0535+26 |
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Authors: | J S Clark I A Steele M J Coe & P Roche |
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Institution: | Physics Department, University of Southampton, Southampton SO17 1BJ,;Astrophysics Research Institute, Liverpool John Moores University, Liverpool L3 3AF,;Astronomy Centre, MAPS, University of Sussex, Brighton BN1 9QH |
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Abstract: | We present infrared spectroscopy of the Be/X-ray binary HDE 245770/A0535+26 obtained over the period 1992–1995. The spectra show significant variability, reflecting changes in the circumstellar environment during this time. A reduction in the flux observed in the Paschen series lines between 1993 December and 1994 September correlates with a similar reduction in both the strength of Hα and the optical continuum emission, which can be attributed to a reduction in the emission measure of the disc. A turnover between optically thin and thick emission is seen for both Paschen and Brackett series lines, and allows an estimate of the disc density as ~1012 cm?3. Echelle spectroscopy reveals strong similarities between the He I 1.008, 2.058 μm, Hα and Paschen series line profiles, suggesting their formation in a similar (and asymmetric) region of the disc. In contrast, the line profile of He I 6678 Å indicates that it is formed at smaller radii than the other transitions. |
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Keywords: | binaries: close stars: emission-line Be stars: individual: A0535+26 stars: neutron infrared: stars X-rays: stars |
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