22nd April 2025 (9 Topics)

Copy

1 Apr

2 Apr

3 Apr

4 Apr

5 Apr

7 Apr

8 Apr

9 Apr

10 Apr

11 Apr

12 Apr

14 Apr

15 Apr

16 Apr

17 Apr

18 Apr

19 Apr

21 Apr

22 Apr

23 Apr

24 Apr

Bullseye Galaxy Discovery

Context

Astronomers have discovered a unique galaxy, named the Bullseye Galaxy (LEDA 1313424), that contains nine concentric rings — more than any previously known ring galaxy. This rare celestial structure was observed using the Hubble Space Telescope and the W.M. Keck Observatory in Hawaii. Researchers believe this galaxy may also offer valuable insights into the formation of giant low surface brightness (GLSB) galaxies, which are crucial to understanding dark matter in the universe.

What is the Bullseye Galaxy?

LEDA 1313424, or the Bullseye Galaxy, is an unusually large galaxy around 250,000 light-years in diameter — about 5 times the size of the Milky Way.
It contains nine ring-like structures — an exceptional feature, since most known ring galaxies have only two or three rings.
This makes it a rare cosmic object, captured during a brief stage of its evolution.
How Did the Rings Form: A Galactic Collision
- About 50 million years ago, a blue dwarf galaxy passed directly through the centre of the Bullseye Galaxy.
- This rare head-on collision triggered gravitational ripples in the gas of the Bullseye Galaxy.
- These ripples caused gas compression and new star formation, which created the distinct concentric rings seen today.
Ring Formation Mechanism: Although the stars' orbits remained unaffected, the gas and star clusters realigned, forming wave-like patterns that resulted in ring formation. The presence of a gas trail between the two galaxies, even though they are 130,000 light-years apart, supports the collision theory.

Fact-Box (LSB and GLSB Galaxies)

Low Surface Brightness (LSB) Galaxies:

These galaxies have very faint disks, with low surface brightness and little visible star formation.
Despite containing large amounts of hydrogen gas (required for star formation), they form very few stars.
They are rich in dark matter, which makes them critical to studying the dark matter distribution in the universe.

Giant Low Surface Brightness (GLSB) galaxy

A subclass of LSBs, Giant LSBs are massive spiral galaxies with very diffuse stellar disks.
Example: Malin 1, the largest known spiral galaxy — about 6.5 times wider than the Milky Way.
These galaxies often appear in isolation, far from other galaxies.
Their central black holes are smaller than those in other massive galaxies, suggesting they are less evolved.

India, China at 75 — a time for strategy, not sentiment

International Relations India and its Neighbourhood

A reminder to the President and Governors

Polity & Governance Union Legislature

New Pathways for India’s Creative Economy

Economy Economic Sectors

India’s Temporary Tariff on Steel Imports

Economy Trade and Commerce

Hindu Kush-Himalayan Region Snowfall at 23-Year Low

Ecology and Environment Climate Change

Article 142

Polity & Governance Constitutional Provisions

Mumbai International Cruise Terminal

Economy Infrastructure

Successful docking of SpaDeX Satellites (for second time)

Science & Technology Satellites and Launch Vehicles

GS Analyst: Daily Current Affairs

Bullseye Galaxy Discovery

What is the Bullseye Galaxy?

Fact-Box (LSB and GLSB Galaxies)