Volume 392, Number 2, September III 2002
|Page(s)||505 - 514|
|Section||Interstellar and circumstellar matter|
|Published online||30 August 2002|
A new two-pole accretion polar: RX J1846.9+5538*
Astrophysical Institute Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany
2 Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstraße, 85740 Garching, Germany
3 Instituto de Astronomía, UNAM, Apdo.Post. 877, 22860 Ensenada, B.C., México
4 Sonneberg Observatory, 96515 Sonneberg, Germany
Corresponding author: R. Schwarz, email@example.com
Accepted: 29 May 2002
We report the discovery of a new, bright () AM Her system as the optical counterpart of the soft ROSAT All-Sky-Survey source RX J1846.9+5538 (=1RXS J184659.4+553834). Optical photometric and spectroscopic follow-up observations reveal a single period of 128.7 min, consistent with a high degree of spin-orbit synchronization, and a low polar field strength ( MG) of the primary accretion region. The system was observed in optical intermediate and high states that differ by about 1 mag. These brightness variations were accompanied by a correlated change of the optical light curve, which we interpret as a switch between one- and two-pole accretion. This explanation is also supported by the X-ray light curves, which at two different epochs display emission from two equally bright accretion regions separated by ~. Both spots possess distinct spectral X-ray properties as seen from the X-ray hardness ratio, where the secondary accretion region appears significantly softer, thus probably indicating a higher field strength compared to the primary region. In all ROSAT pointings a deep dip is present during the primary flux maxima, very likely caused by absorption in one of the accretion streams.
Key words: X-rays: stars / cataclysmic variables / accretion / stars: magnetic fields / stars: individual: RX J1846.9+5538
© ESO, 2002
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.