Multiwavelength Observations of Multiple Eruptions of the Recurrent Nova M31N 2008-12a

Journal article

We report the optical, UV, and soft X-ray observations of the 2017–2022 eruptions of the recurrent nova M31N 2008-12a. We find a cusp feature in the r′ - and i′ -band light curves close to the peak, which could be related to jets. The geometry of the nova ejecta based on morpho-kinematic modeling of the Hα emission line indicates an extended jet-like bipolar structure. Spectral modeling indicates an ejecta mass of 10−7–10−8 M ⊙ during each eruption and an enhanced helium abundance. The supersoft source phase shows significant variability, which is anticorrelated to the UV emission, indicating a common origin. The variability could be due to the reformation of the accretion disk. We infer a steady decrease in the accretion rate over the years based on the intereruption recurrence period. A comparison of the accretion rate with different models on the MWD–Ṁ plane yields the mass of a CO white dwarf, powering the H-shell flashes every ∼1 yr, to be >1.36 M ⊙ and growing with time, making M31N 2008-12a a strong candidate for the single degenerate scenario of the Type Ia supernovae progenitor.

Authors: Basu, J; Pavana, M; Anupama, GC; Barway, S; Singh, KP

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Astronomical Society
• Journal: The Astrophysical Journal
• Volume: 966
• Issue: 1
• Article number: 44
• Publication date: 2024-04-24
• Acceptance date: 2024-02-19
• DOI: 10.3847/1538-4357/ad2c8e
• EISSN: 1538-4357
• ISSN: 0004-637X
• Language: English
• Keywords: Cataclysmic variable stars; Andromeda Galaxy; X-ray astronomy; Ultraviolet astronomy; Photometry; Transient sources; Recurrent novae; Spectroscopy