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New Complexities in the Low-State Line Profiles of AM Herculis

Kafka, S. and Ribeiro, T. and Baptista, R. and Honeycutt, R. K. and Robertson, J. W. (2008) New Complexities in the Low-State Line Profiles of AM Herculis. Astrophysical Journal, 688 (2). pp. 1302-1314. ISSN 0004-637X. http://resolver.caltech.edu/CaltechAUTHORS:KAFapj08

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Abstract

When accretion temporarily ceases in the polar AM Her, the emission-line profiles are known to develop several distinct components, whose origin remains poorly understood. The new low-state spectra reported here have a more favorable combination of spectral resolution (R ~4500), time resolution (~3 minute exposures), and S/N than earlier work, revealing additional details of the orbital dependence of the line profiles. The central strong feature of Hα is found to be composed of two components of similar strength, one having K ~ 100 km s^−1 and phased with the motion of the secondary star, the other having little or no detectable radial velocity variations. We attribute the central line component to gas near the coupling region, perhaps with a contribution from irradiation of the secondary star. The two satellite components have radial velocity offsets of ~±250 km s^−1 on either side of the central strong Hα peak. These satellites most likely arise in large loops of magnetically confined gas near the secondary star due to magnetic activity on the donor star and/or interactions of the magnetic fields of the two stars. Doppler maps show that these two satellite features have concentrations at velocities that match the velocity locations of L4 and L5 in the system.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1086/592186DOIUNSPECIFIED
Additional Information:© 2008. The American Astronomical Society. We would like to thank our anonymous referee for a careful review of the manuscript. We acknowledge with thanks the variable star observations from the AAVSO International Database contributed by observers worldwide and used in this research.
Subject Keywords:novae, cataclysmic variables; stars: activity; stars: individual (AM Herculis); stars: magnetic fields
Issue or Number:2
Record Number:CaltechAUTHORS:KAFapj08
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:KAFapj08
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:12560
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:12 Dec 2008 23:45
Last Modified:26 Dec 2012 10:35

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