Energetic Outburst Observed in Dwarf Nova MASTER OT J030227.28+191754.5
A recent study has documented an exceptionally energetic outburst from the dwarf nova MASTER OT J030227.28+191754.5, which occurred between 2021 and 2022. This outburst reached an amplitude of 10.2 magnitudes and lasted for 60 days. The research, led by Yusuke Tampo and a team of 62 authors, identified key characteristics of this event that classify it as a WZ Sge-type dwarf nova.
The study highlighted two significant observations: the presence of double-peaked optical emission lines and the detection of early and ordinary superhumps. These findings allowed the researchers to determine the orbital period and mass ratio of the system, recorded at approximately 0.05986 days and 0.063, respectively. These values fall within the expected range for low-mass-ratio dwarf novae.
According to the authors, the standard disk model requires an accretion rate of about 1020 grams per second to account for the peak optical luminosity observed during the outburst. They noted that a substantial mass was likely stored in the disk at the onset of the outburst, which could not be solely attributed to the influence of the primary white dwarf, estimated to be over 1.15 solar masses.
The researchers proposed that the origin of this unusually energetic outburst may be linked to lower quiescent viscosity compared to other WZ Sge-type dwarf novae. This conclusion is considered valid across a wide range of binary parameter spaces, unless the inclination is low enough to allow for a bright disk that could explain the outburst amplitude.
The optical spectra observed at the peak of the outburst revealed strong emission lines from the Balmer, He I, and He II series, with a core width narrower than approximately 800 km/s. The authors suggested that this narrow component could not be explained by a Keplerian disk, indicating the potential influence of disk winds.
This research contributes to the understanding of dwarf novae and their outbursts, providing insights into the mechanisms behind such energetic events. The full study can be accessed at arXiv:2408.13783.