J1152 Is an Unusual Long-Period Dwarf Nova with Recurring Eclipses, Observations Find

Why It Matters

J1152 provides a unique laboratory for studying disk‑wind interactions in long‑period dwarf novae, refining accretion‑disk instability models that underpin predictions of outburst behavior across the cataclysmic‑variable population.

Key Takeaways

• J1152 has 10.46‑hour orbital period with deep eclipses
• Outbursts recur every 40–60 days, amplitude ~1.6 mag
• Disk‑wind signatures indicate optically thick gas during outburst
• Donor star likely K3 type, moderately inflated, mildly evolved
• First detailed optical study combines SALT, TESS, and ground photometry

Pulse Analysis

Dwarf novae are a subclass of cataclysmic variables where a white dwarf accretes material from a companion star via an accretion disk. While short‑period systems dominate surveys, long‑period dwarf novae like SRGA J115215.0−510656 are scarce, offering insight into how orbital separation influences disk stability and outburst mechanics. The 10.46‑hour orbit places J1152 among the longest‑period U Gem‑type systems, where the donor star’s evolutionary state can significantly affect mass‑transfer rates and outburst amplitudes.

The research team led by Nikita Rawat leveraged the South African Large Telescope’s spectroscopic power alongside high‑cadence TESS photometry to capture both quiescent and eruptive phases. Deep, recurring eclipses confirm a high‑inclination geometry, while the 40‑60‑day outburst cadence and modest 1.6‑mag brightening contrast with the larger swings seen in shorter‑period dwarf novae. Crucially, spectral analysis uncovered dense, optically thick gas flowing as a disk wind during outburst, a phenomenon increasingly recognized as a driver of angular‑momentum loss and outburst shaping in accretion disks.

These findings have broader implications for theoretical models of disk‑instability and wind‑driven mass loss. By documenting a clear inside‑out outburst profile and linking it to wind signatures, J1152 challenges existing simulations that often neglect wind feedback in long‑period binaries. Future monitoring, especially with next‑generation X‑ray and UV observatories, could quantify wind energetics and refine predictions of outburst recurrence. As more long‑period dwarf novae are identified, J1152 will serve as a benchmark for calibrating the role of donor evolution and disk winds in shaping the diverse phenomenology of cataclysmic variables.