The star 1RXS J165424.6-433758 has been identified as a polar star, a rare kind of catastrophic variable that appears in binary systems where a white dwarf with a powerful magnetic field interacts with a regular companion star. A recent preprint published on arXiv describes these findings in depth.
Astronomers describe poles like these as a special class of variable events. In these systems, light changes dramatically when material from the companion star is captured by the white dwarf, guided by a strong magnetic field. The result is periodic brightening that marks the poles as magnetic cataclysmic variables.
1RXS J165424.6-433758, also listed as AX J165420-4337, first surfaced in ROSAT data as an X-ray source during the 1990s. At that time researchers faced questions about the nature of the object. A team led by Brendan O’Connor from George Washington University combined observations across multiple wavelengths and instruments to unlock the mystery.
New analyses summarize the DGPS (Galactic Deep Survey) observations with Swift, NuSTAR, the South African Large Telescope, and the South African Astronomical Observatory’s meter telescope, complemented by archival XMM-Newton data and follow up from the same source. The synthesis indicates that J1654 is a classic polar magnetic catastrophe variable located roughly 460 parsecs away from Earth.
Data point to a 10.1 keV temperature and an energy output near 65 nonillion ergs per second, reinforcing the classification as a polar system. Further scrutiny reveals a rotation period around 2.87 hours and a surface magnetic field strength near 3.5 megagauss, signatures that align with known polar characteristics.
The white dwarf in the system is paired with a late-type main sequence star, possessing a radius around 0.38 solar radii and an effective temperature near 4300 kelvin. The white dwarf’s estimated mass sits near 0.58 solar masses, placing it within the typical range for such compact binary configurations.
Cited: DGPS team. The research adds a clear datapoint to the census of magnetic cataclysmic variables and helps refine models of how strong magnetic fields shape accretion in binary systems.
Given these findings, the discovery reinforces the view that magnetic fields play a pivotal role in driving the dramatic, periodic energy releases seen in these systems. The study highlights how multiwavelength campaigns, combining spaceborne observatories with ground-based facilities, are essential to painting a complete picture of such stellar pairs.