Year: 2002
Type: article
Abstract: 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.
Source: Astronomy and Astrophysics
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Funders: National Geographic Society, California Institute of Technology, Space Telescope Science Institute, Bundesministerium für Bildung und Forschung, Consejo Nacional de Ciencia y Tecnología, Bundesministerium für Bildung, Wissenschaft, Forschung und Technologie, Dirección General de Asuntos del Personal Académico, Universidad Nacional Autónoma de México
Awards: G6693794689, G7550253023
OpenAlex ID: W2030458732