A team of astronomers has identified a new class of cosmic X-ray sources, termed "millinovae," based on their surprising behavior observed in the Magellanic Clouds, satellite galaxies of the Milky Way. This discovery, led by researchers from the Astronomical Observatory of the University of Warsaw and published in Astrophysical Journal Letters, showcases 29 unusual objects that experience brightness outbursts 10 to 20 times their normal levels over a few months. One specific object, OGLE-mNOVA-11, was closely studied beginning in November 2023, revealing ionized helium, carbon, and nitrogen along with X-ray emissions at a staggering 600,000 degrees Celsius.
These millinovae appear to be binary systems with a white dwarf and a subgiant star, allowing material to flow from the subgiant to the white dwarf, potentially causing X-ray emissions through energy release or thermonuclear explosions. The research emphasizes the significance of millinovae in astrophysics, as they may contribute to the understanding of Type Ia supernovae, critical for cosmic distance measurements and the discovery of the Universe’s accelerating expansion. This study represents a collaborative effort among various international institutions, shedding light on previously mysterious celestial phenomena.
