2025/03/10 by M. Veresvarska, M Veresvarska, S. Scaringi +25 · 1 voice · 10 citations
Physics and Astronomy · #Astronomy #Astrophysics #Computer graphics (images) #Flicker #Gamma-ray bursts and supernovae #Physics #Spin (aerodynamics) #astro-ph.HE #astro-ph.SR
paper · pdf · doi:10.1093/mnras/staf412
published in Monthly Notices of the Royal Astronomical Society 539(3), 2424-2434 (Oxford University Press)
arxiv published 2025/03/10 · openalex publication_date 2025/03/12 · arxiv updated 2025/04/10 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
ABSTRACT Magnetic accreting white dwarfs in cataclysmic variables have been known to show bursts driven by different physical mechanisms; however, the burst occurrence is much rarer than in their non-magnetic counterparts. DW Cnc is a well-studied intermediate polar that showed a burst with a 4-mag amplitude in 2007. Here we report on a recent burst in DW Cnc observed by All-Sky Automated Survey for Supernovae that reached a peak luminosity of 6.6 × 1033 erg s-1, another 4 mag increase from its quiescent high state level. The released energy of the burst suggests that these are micronovae, a distinctive type of burst seen in magnetic systems that may be caused by a thermonuclear runaway in the confined accretion flow. Only a handful of systems, most of them intermediate polars, have a reported micronova bursts. We also report on the reappearance of the negative superhump of DW Cnc as shown by Transiting Exoplanet Satellite Survey and OPTICAM data after the system emerges from its low state and immediately before the burst. We further report on a new phenomenon, where the spin signal turns ‘on’ and ‘off’ on the precession period associated with the negative superhump, which may indicate pole flipping. The new classification of DW Cnc as a micronova as well as the spin variability show the importance of both monitoring known micronova systems and systematic searches for more similar bursts, to limit reliance on serendipitous discoveries.