Related papers: On an apparent dearth of recurrent nova super-remn…

M31N 2017-01e is the second-fastest recurrent nova known, with a recurrence period of 2.5 years in the Andromeda Galaxy (M31). This system exhibits a unique combination of properties: a low outburst amplitude ($\sim3$ magnitude), starkly…

Another outburst of the recurrent M31 nova M31N 2008-12a was announced in late November 2013. Optical data suggest an unprecedentedly short recurrence time of approximately one year. In this Letter we address the X-ray properties of M31N…

We present the discovery of a supernova remnant (SNR) in M31 which is unlike any other remnant known in that galaxy. An optical MMT spectrum of WB92-26 sampling most of this marginally resolved object reveals strong lines of [O II], [Ne…

The 2008 discovery of an eruption of M31N 2008-12a began a journey on which the true nature of this remarkable recurrent nova continues to be revealed. M31N 2008-12a contains a white dwarf close to the Chandrasekhar limit, accreting at a…

We report combined optical and X-ray observations of nova M31N 2007-12b. Optical spectroscopy obtained 5 days after the 2007 December outburst shows evidence of very high ejection velocities (FWHM H$\alpha \simeq 4500$ km s$^{-1}$). In…

Some extragalactic SNRs are more than two orders of magnitude more luminous than the young Galactic SNR Cas A. These SNRs are called super-luminous or ultra-luminous SNRs. Their high luminosities can be caused by chance superpositions of…

We have detected a spatially resolved supernova remnant (SNR) in the center of the Andromeda Galaxy, in radio, X-ray, and optical wavelengths. These observations provide the highest spatial resolution imaging of a radio/X-ray/optical SNR in…

The nova M31N 2023-11f (2023yoa) has been recently identified as the second eruption of a previously recognized nova, M31N 2013-10c, establishing the latter object as the 21st recurrent nova system thus far identified in M31. Here we…

Supernova remnants (SNRs) are diffuse extended sources characterized by a complex morphology and a non-uniform distribution of ejecta. Such a morphology reflects pristine structures and features of the progenitor supernova (SN) and the…

M31 is an ideal laboratory for observing and studying recurrent novae. To date, there have been 18 recurrent nova discovered in M31, six of which have recurrence periods less than nine years. M31N 2017-12a (AT2017jdm) is a transient that…

We report the optical, UV, and soft X-ray observations of the $2017-2022$ eruptions of the recurrent nova M31N 2008-12a. We infer a steady decrease in the accretion rate over the years based on the inter-eruption recurrence period. We find…

In our preceding paper, Liverpool Telescope data of M31 novae in eruption were used to facilitate a search for their progenitor systems within archival Hubble Space Telescope (HST) data, with the aim of detecting systems with red giant…

M31-2015-LRN is a likely stellar merger discovered in the Andromeda Galaxy in 2015. We present new optical to mid-infrared photometry and optical spectroscopy for this event. Archival data shows that the source started to brighten $\sim$2…

Recent discoveries of recombining plasmas (RPs) in supernova remnants (SNRs) have dramatically changed our understanding of SNR evolution. To date, a dozen of RP SNRs have been identified in the Galaxy. Here we present Suzaku deep…

Recurrent novae (RNe) play an important role as one of the suspected progenitor systems of Type Ia supernovae (SNe) which are used as primary distance indicators in cosmology. Thus, it is important to investigate the nature of their central…

A long-term (1995-2016) survey for novae in the nearby Andromeda galaxy (M31) was conducted as part of the Research-Based Science Education initiative. During the course of the survey 180 nights of observation were completed at Kitt Peak,…

The extensive grid of numerical simulations of nova eruptions of Yaron et al.(2005) first predicted that some classical novae might deviate significantly from the Maximum Magnitude - Rate of Decline (MMRD) relation, which purports to…

We report the discovery of a previously unknown eruption of the recurrent nova M31N 2017-01e that took place on 11 January 2012. The earlier eruption was detected by Pan-STARRS and occurred 1847 days (5.06 yr) prior to the eruption on 31…

Chandra observations of M31 allow the first spatially resolved X-ray image of a supernova remnant (SNR) in an external spiral galaxy. CXOM31 J004327.7+411829 is a slightly elongated ring-shaped object with a diameter of ~11'' (42 pc). In…

Recurrent novae undergo thermonuclear-powered eruptions separated by less than 100 years, enabled by subgiant or red giant donors transferring hydrogen-rich matter at very high rates onto their massive white dwarf companions. The…