'Ultraviolet Emissions': ISRO’s AstroSat detects nuclear explosion in Andromeda Galaxy

Produced by: Tarun Mishra

First UV Detection of  Novae in Andromeda

Astronomers, led by a team from the Indian Institute of Astrophysics (IIA), Bengaluru, have for the first time detected far-ultraviolet emissions from novae during outbursts in the Andromeda galaxy. These findings, made using ISRO’s AstroSat satellite, provide new insights into stellar explosions and galactic enrichment.

Understanding Novae in Binary Star Systems

Novae are sudden explosions occurring in binary star systems, where a dense white dwarf star accumulates material from its companion Sun-like star. This buildup triggers thermonuclear reactions, resulting in a bright outburst.

AstroSat’s Ultraviolet  Imaging Telescope (UVIT)

Researchers used UVIT, which observes far and near ultraviolet wavelengths, to study 42 novae in Andromeda. Among these, four novae were observed in the act of erupting, showcasing the telescope’s precision.

Accretion Disks as Precursors

The study focused on accretion disks formed by material pulled from the companion star to the white dwarf. These disks, visible in ultraviolet light, provide critical insights into the conditions leading to nova eruptions.

The “Calm Before the  Storm” Observed

Periods of dimming were noted, where accumulated material acted as a shell blocking radiation. This phase precedes the thermonuclear explosion, which ejects matter into space and increases system brightness dramatically.

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Challenges of Detecting  Novae in Andromeda

Identifying novae in Andromeda's bright central region required advanced image processing techniques. These efforts confirmed the presence of the explosions and showcased the potential of UVIT for such studies.

Published Findings in  Leading Journal

The research, published in the Astrophysical Journal, highlights how novae contribute to enriching galaxies with new elements, advancing the understanding of galactic chemical processes.

Future Missions to  Explore Novae

The study underlines the need for upcoming ultraviolet and X-ray missions to further investigate the mechanisms of novae. These findings are expected to enhance knowledge of stellar evolution and the role of such explosions in shaping galactic composition.