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Mapping the shape of the accretion disk of Hercules X‐1
Author(s) -
Leahy D.A.
Publication year - 2004
Publication title -
astronomische nachrichten
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.394
H-Index - 63
eISSN - 1521-3994
pISSN - 0004-6337
DOI - 10.1002/asna.200310210
Subject(s) - physics , astrophysics , accretion disc , accretion (finance) , modulation (music) , orbit (dynamics) , phase (matter) , intermediate polar , turn (biochemistry) , binary number , orbital inclination , astronomy , stars , nuclear magnetic resonance , arithmetic , mathematics , quantum mechanics , acoustics , engineering , white dwarf , aerospace engineering
Abstract Hercules X‐1 is an x‐ray binary with a 1.7 day orbit and which exhibits a regular 35‐day intensity cycle, which comes in two types: 0.2 orbital phase turn‐on and 0.7 phase turn‐on. The cycle is well measured by the RXTE/ASM and is caused by a sequence of occultations by the inner and outer edges of the accretion disk. In addition to the 35‐day x‐ray cycle, the accretion disk shadows the companion star HZ Her to give the regular and well known optical modulation, and gives a modulation of the EUV emission from the system. The x‐ray modulation is most precisely measured and best for determination of the disk shape. Here disk and emission region models are used to derived the disk shape from the 0.2 turn‐on cycles and compared to a previous derivation based on 0.7 turn‐on cycles. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)