UV Emissions from Novae in the Andromeda Galaxy

GS3 Science and Technology

Key Context:

Astronomers from the Indian Institute of Astrophysics (IIA) have detected far ultraviolet (FUV) emissions from novae in the Andromeda Galaxy, marking a first in such observations.
This achievement utilized data from AstroSat, India’s first space astronomy observatory, particularly its Ultraviolet Imaging Telescope (UVIT).

What are Novae?

• Definition:
  Novae are transient astronomical phenomena that occur when a white dwarf in a binary star system accumulates material from its companion star.
  • This accretion leads to a stellar explosion, causing a sudden increase in brightness.
  • Brightness gradually fades over weeks or months.
• Significance of UV Emissions:
  • FUV emissions provide insights into the eruption phase of novae.
  • They help monitor changes in the accretion disk’s flux and assess the stability of the accretion process.

Observations and Findings:

1. Role of UVIT on AstroSat:
   • Equipped with fine spatial resolution for observing in far UV and near UV bands.
   • Focused on novae systems 2.5 million light-years away in the Andromeda Galaxy.
2. Key Discoveries:
   • Detected stable accretion disks in some novae systems.
   • Stability over time indicates consistent material transfer and disk dynamics.
3. Accretion Disk:
   • Formed by material spiraling around a central body under gravitational forces.
   • Generates high-energy emissions, particularly in the UV spectrum, due to heating during inward motion.

About Andromeda Galaxy:

• Location: Closest spiral galaxy to the Milky Way, at a distance of 2.5 million light-years.
• Significance: Largest galaxy in the Local Group, containing over a trillion stars.

Far Ultraviolet (FUV):

• Definition: Electromagnetic spectrum region with shorter wavelengths than visible light (10–200 nm).
• Applications in Astronomy: Ideal for studying hot, energetic phenomena like novae, accretion disks, and young stars.

Significance of the Discovery:

1. Astronomical Insights:
   • Deepens understanding of the physics of novae eruptions and accretion processes.
   • Expands knowledge about phenomena in galaxies beyond the Milky Way.
2. Advancement in Space Science:
   • Demonstrates AstroSat’s capability to study distant energetic events.
   • Strengthens India’s position in global space research.
3. Future Implications:
   • Encourages further use of FUV observations for exploring cosmic phenomena.
   • Highlights potential for collaboration in international astronomical research.