OPTICAM reveals hints of cyclotron emission from the intermediate polar V709 Cas
ABSTRACT Magnetic cataclysmic variables of the intermediate polar (IP) subclass display a wide range of variability across different wavelengths. In late 2024 October/early November, the IP V709 Cas was observed over 10 nights by the OPtical TIming CAMera at the San Pedro Mártir Observatory in simultaneous three-colour (g, r, and i, or z band) photometry. On two of these nights, V709 Cas was simultaneously observed by the Neutron star Interior Composition ExploreR X-ray telescope. A periodogram analysis of the optical g- and r-band light curves reveals no prominent features at the white dwarf (WD) spin, but prominent features at the spin-orbit beat. In contrast, the X-ray and near-infrared (near-IR) i- and z-band periodograms show prominent features at the spin, but not the spin-orbit beat. Optical beat and near-IR spin pulsations have been seen in the IP PQ Gem, with simultaneous circular polarization detected in the near-IR, indicating cyclotron origin. We therefore speculate that we are seeing cyclotron radiation from V709 Cas, possibly adding it to the small group of cyclotron-emitting IPs. Combining analytical approximations with our expectation for cyclotron harmonics in the near-IR, we suggest a WD magnetic field strength of $10~{\rm MG} < B < 40$ MG.
Authors
- F. Vincentelli (ORCID: https://orcid.org/0000-0002-1481-1870)
- R. Michel (ORCID: https://orcid.org/0000-0003-1263-808X)
- Noel Castro Segura (ORCID: https://orcid.org/0000-0002-5870-0443)
- A. Castro (ORCID: https://orcid.org/0000-0002-7832-5337)
- Domitilla de Martino (ORCID: https://orcid.org/0000-0002-5069-4202)
- Z A Irving (ORCID: https://orcid.org/0009-0006-0951-3429)
- Simone Scaringi (ORCID: https://orcid.org/0000-0001-5387-7189)
- D. A. H. Buckley (ORCID: https://orcid.org/0000-0002-7004-9956)
- D. Altamirano (ORCID: https://orcid.org/0000-0002-3422-0074)
- M Veresvarska (ORCID: https://orcid.org/0000-0002-0146-3096)
Institutions
- University of Cape Town (ZA)
- Universidad Autónoma de Baja California (MX)
- Durham University (GB)
- Astronomical Observatory of Capodimonte (IT)
- Ensenada Institute of Technology (MX)
- University of Warwick (GB)
- Institute for Space Astrophysics and Planetology (IT)
- South African Radio Astronomy Observatory (ZA)
- Astronomical Observatory (RS)
- University of Southampton (GB)
Publication Details
- Journal
- Monthly Notices of the Royal Astronomical Society
- Published
- 2025-12-08
- DOI
- https://doi.org/10.1093/mnras/staf2177
- Primary Topic
- Astrophysical Phenomena and Observations
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- Smithsonian Institution
- National Aeronautics and Space Administration
- UK Research and Innovation
- Ministerio de Ciencia, Innovación y Universidades
- European Commission
- Goddard Space Flight Center
- Smithsonian Astrophysical Observatory
- HORIZON EUROPE Framework Programme
- Science and Technology Facilities Council
- Agencia Estatal de Investigación
- Astrophysics Science Division
- Astrophysics Division