ü Indian astronomers from the National Centre for Radio Astrophysics (NCRA), Pune, have discovered a rare spiral galaxy in the early universe using data from the James Webb Space Telescope (JWST).
ü It is the second farthest spiral galaxy ever discovered
ü The galaxy was named Alaknanda after the river in Uttarakhand.
ü The name was chosen to align with the Indian tradition of using female names for galaxies, similar to Mandakini which is the Hindi name for the Milky Way.
Key Findings:
ü The galaxy was identified by analyzing data from the UNCOVER survey which is a public JWST dataset.
o It possesses a prominent disk with two perfectly symmetrical spiral arms and a small central bulge.
ü It is formed approximately 1.5 billion years after the Big Bang, making it an implausibly old structure for that epoch
ü It is a fully developed galaxy with a high star-formation rate, producing the equivalent of 60 solar masses per year along its spiral arms
● Why is it Significant?
ü Standard galaxy formation models suggest it takes billions of years for stable, rotating disks to form spiral arms.
ü Alaknanda’s mature structure in such a young universe poses a significant puzzle to astronomers
● Theories of Formation:
ü Scientists propose two possibilities:
o Cold Gas Accretion:
▪ The galaxy grew steadily by drawing in cold gas to form a stable disk
o Merger Event:
▪ It may have interacted or merged with a smaller companion galaxy, triggering arm formation
