Mon. Not. R. Astron. Soc., 501, 596-605 (2021/February-2)
New radial velocity observations of AH Her: evidence for material outside the tidal radius.
ECHEVARRIA J., HERNANDEZ SANTISTEBAN J.V., SEGURA MONTERO O., RAMIREZ S.H., RUELAS-MAYORGA A., SANCHEZ L.J., MICHEL R., COSTERO R., GONZALEZ-BUITRAGO D.H. and OLIVARES J.
Abstract (from CDS):
Spectroscopic observations of AH Herculis during a deep quiescent state are put forward. We found the object in a rare long minima, allowing us to derive accurately the semi-amplitudes: K1=121±_4 km s–1 and K2 = 152 ± 2 km s–1 and its mass functions MWsin 3i = 0.30 ± 0.01 M☉ and MRsin 3i = 0.24 ± 0.02 M☉, while its binary separation is given by asin i = 1.39 ± 0.02 R☉. The orbital period Porb = 0.25812 ± 0.00032 d was found from a power spectrum analysis of the radial velocities of the secondary star. These values are consistent with those determined by Horne, Wade & Szkody. Our observations indicate that K5 is the most likely spectral type of the secondary. We discuss why we favour the assumption that the donor in AH Her is a slightly evolved star, in which case we find that the best solution for the inclination yields i = 48° ± 2°. None the less, should the donor be a ZAMS star, we obtain that the inclination is between i = 43° and i = 44°. We also present Doppler tomography of H α and H β, and found that the emission in both lines is concentrated in a large asymmetric region at low velocities, but at an opposite position to the secondary star, outside the tidal radius and therefore at an unstable position. We also analyse the H α and H β line profiles, which show a single broad peak and compare it with the previous quiescent state study that shows a double-peaked profile, providing evidence for its transient nature.
© 2020 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society
techniques: radial velocities - techniques: spectroscopic - stars: individual: AH Her - novae, cataclysmic variables
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