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dc.contributor.authorRosen, S.R.
dc.contributor.authorPrinja, R.K.
dc.contributor.authorDrew, J.E.
dc.contributor.authorMason, K.O.
dc.contributor.authorHowell, S.B.
dc.identifier.citationRosen , S R , Prinja , R K , Drew , J E , Mason , K O & Howell , S B 1998 , ' Phase-resolved Hubble Space Telescope ultraviolet spectroscopy of V795 Her ' , Monthly Notices of the Royal Astronomical Society , vol. 299 , no. 2 , pp. 305-318 .
dc.identifier.otherPURE: 155922
dc.identifier.otherPURE UUID: 3f6ab8d3-ece8-4ac0-af1a-4d5689ce0d0b
dc.identifier.otherdspace: 2299/3297
dc.identifier.otherScopus: 0043237021
dc.description‘The definitive version is available at’ Copyright Blackwell Publishing. DOI: 10.1046/j.1365-8711.1998.01844.x [Full text of this article is not available in the UHRA]
dc.description.abstractWe present highly time-resolved HST FOS UV spectroscopy of the nova-like binary V795 Her. Several key results emerge. For the first time we find a strong 2.6-h signature in the variability of the UV lines. The HST data reveal no evidence of a 4.8-h ‘period’, in contrast to our previous IUE observations. This, and differences in the spectral line characteristics, suggests that HST found the system in a different state from earlier IUE observations. The C IV line alone contains a fairly stable, asymmetric, extended blueward absorption trough which we associate with a wind outflow. The 2.6-h variations of the line profiles are largely confined to an interval of about 0.4 in phase and to the velocity regime −1500 < v < 0 km s−1, the changes being dominated by the apparent decline and re-emergence of a blueshifted emission peak. The complex profiles permit many empirical interpretations, but the simplest attributes the variability to a narrow (FWHM∼1000 km s−1) emission component which is always blueshifted with a mean velocity of around –600 km s−1. This interpretation, however, is not readily related to any obvious source within the binary. An alternative picture, which attempts to relate the UV and (simultaneously observed) optical line behaviour, invokes a more stable, broad (FWHM∼2000 km s−1) emission feature, the intrinsic morphology of which is disguised by superposed constant and variable absorption components. One tentative physical explanation of such a decomposition involves an accretion stream that overflows the accretion disc. However, several problems with this model remain to be resolved. We also draw attention to similarities between the velocity-restricted behaviour in the UV lines of V795 Her and that in the optical lines of T Tauri stars. This might indicate a connection between V795 Her and the magnetically influenced inflow/outflow characteristics associated with the central star in T Tauri systems. If such a connection were eventually demonstrated, it would reopen the question of whether the 2.6-h period in V795 Her is really the binary period and whether the system is in fact related to the intermediate polars.en
dc.relation.ispartofMonthly Notices of the Royal Astronomical Society
dc.subjectaccretion discs
dc.subjectcataclysmic variables
dc.titlePhase-resolved Hubble Space Telescope ultraviolet spectroscopy of V795 Heren
dc.contributor.institutionSchool of Physics, Astronomy and Mathematics
dc.description.statusPeer reviewed
rioxxterms.typeJournal Article/Review

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