Activity of the Polar AM Her (RX J1816.2+4952): A Short Review

We show that AM Her displays the transitions between the high and low states with an intermittently existing dominant cycle with length between 400 and 800 days. Moreover, these transitions accumulate in clusters, which produces an additional long cycle after smoothing; a single isolated short episo...

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Main Authors: V. Šimon, A. Henden
Format: Article
Language:English
Published: Czech Technical University in Prague 2015-02-01
Series:Acta Polytechnica CTU Proceedings
Online Access:https://ojs.cvut.cz/ojs/index.php/APP/article/view/2838
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author V. Šimon
A. Henden
author_facet V. Šimon
A. Henden
author_sort V. Šimon
collection DOAJ
description We show that AM Her displays the transitions between the high and low states with an intermittently existing dominant cycle with length between 400 and 800 days. Moreover, these transitions accumulate in clusters, which produces an additional long cycle after smoothing; a single isolated short episode of the low state does not suggest a break of this cycle. The seasons of existence of the cycle can be controlled by the lifetime of the active regions (e.g. prominences, spots) on the donor. In some high-state episodes, a higher luminosity of the bremsstrahlung emission is not accompanied by a higher optical (cyclotron+stream) emission. Part of the bremsstrahlung emission can be buried in some episodes. Changes of the structure of the accretion region(s) are necessary to explain the variations of the optical and X-ray activity in the high-state episodes of AM Her.
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spelling doaj-art-fd59d416e29e4193bcc696bfcd7c560e2025-08-20T03:22:23ZengCzech Technical University in PragueActa Polytechnica CTU Proceedings2336-53822015-02-0121818510.14311/APP.2015.02.00812606Activity of the Polar AM Her (RX J1816.2+4952): A Short ReviewV. Šimon0A. Henden1Astronomical Institute, Academy of Sciences of the Czech Republic, 25165 Ondˇrejov, Czech Republic Czech Technical University in Prague, FEL, Prague, Czech RepublicAAVSO, 49 Bay State Road, Cambridge, MA 02138, USAWe show that AM Her displays the transitions between the high and low states with an intermittently existing dominant cycle with length between 400 and 800 days. Moreover, these transitions accumulate in clusters, which produces an additional long cycle after smoothing; a single isolated short episode of the low state does not suggest a break of this cycle. The seasons of existence of the cycle can be controlled by the lifetime of the active regions (e.g. prominences, spots) on the donor. In some high-state episodes, a higher luminosity of the bremsstrahlung emission is not accompanied by a higher optical (cyclotron+stream) emission. Part of the bremsstrahlung emission can be buried in some episodes. Changes of the structure of the accretion region(s) are necessary to explain the variations of the optical and X-ray activity in the high-state episodes of AM Her.https://ojs.cvut.cz/ojs/index.php/APP/article/view/2838
spellingShingle V. Šimon
A. Henden
Activity of the Polar AM Her (RX J1816.2+4952): A Short Review
Acta Polytechnica CTU Proceedings
title Activity of the Polar AM Her (RX J1816.2+4952): A Short Review
title_full Activity of the Polar AM Her (RX J1816.2+4952): A Short Review
title_fullStr Activity of the Polar AM Her (RX J1816.2+4952): A Short Review
title_full_unstemmed Activity of the Polar AM Her (RX J1816.2+4952): A Short Review
title_short Activity of the Polar AM Her (RX J1816.2+4952): A Short Review
title_sort activity of the polar am her rx j1816 2 4952 a short review
url https://ojs.cvut.cz/ojs/index.php/APP/article/view/2838
work_keys_str_mv AT vsimon activityofthepolaramherrxj181624952ashortreview
AT ahenden activityofthepolaramherrxj181624952ashortreview