Important Facts For Prelims
New Study on Spiral Galaxies
- 05 Jul 2024
- 4 min read
Why in News?
Recently, a new study has shown that there were more spiral galaxies in the early universe than astronomers had previously anticipated
What are the Key Highlights of the Research on Spiral Galaxies?
- Existing Theory: In astronomy, it's believed that as the universe cooled from a hot, dense state, it contained a lot of hot gas. This gas formed clumps that eventually came together to form galaxies.
- These early galaxies were irregular in shape and didn't have flat disks like we see in spiral galaxies today.
- Over billions of years, as these galaxies continued to cool down, they developed thick, hot disks that later flattened out into the spiral arms humans recognise now.
- Unexpected Early Formation: Contrary to the above theory, the new study suggests that spiral galaxies may have formed much earlier, around the same time as other types of galaxies were evolving.
- The study used data from NASA's James Webb Space Telescope to analyse 873 galaxies, identifying at least 216 as spiral galaxies.
- The research found that between 3 billion and 7 billion years after the Big Bang, the proportion of galaxies with spiral shapes increased significantly, from about 8% to 48%.
- Implications for Star Formation: The study's results could impact current understanding of star formation rates and the conditions necessary for earth-like planets to form within spiral galaxies.
- The presence of heavy elements in spiral arms, derived from supernovae, is crucial for planet formation.
James Webb Space Telescope (JWST)
- JWST, successor of Hubble Space Telescope is a large, infrared telescope designed to observe the most distant objects in the universe.
- It is a collaboration between NASA, the European Space Agency (ESA), and the Canadian Space Agency (CSA).
What are the Various Types of Galaxies?
| Type | Description | Examples |
| Spiral Galaxies | Flattened disk with spiral arms (regions of active star formation), central bulge. Can be barred or unbarred. | Milky Way, Andromeda Galaxy |
| Elliptical Galaxies | Smooth, oval or round shape, little gas and dust, mostly old stars. | Messier 87 |
| Lenticular Galaxies | Intermediate between spiral and elliptical, have a disk but no arms. | Sombrero Galaxy |
| Irregular Galaxies | No regular shape, can be dwarf or large. | Large Magellanic Cloud |
| Active Galaxies | Emit 100x more light from the center than stars, powered by supermassive black hole. | Various subtypes |
| Seyfert Galaxies | Most common active galaxy, emit infrared and X-rays. | Type I & II Seyfert galaxies |
| Quasars | Most luminous active galaxy, emit light across spectrum and powerful jets. | Markarian 231 |
| Blazars | Active galaxies with jets pointed at Earth, appear very bright. | TXS 0506+056 |
UPSC Civil Services Examination, Previous Year Question (PYQ)
Prelims:
Q. Consider the following phenomena: (2018)
- Light is affected by gravity.
- The Universe is constantly expanding.
- Matter warps its surrounding space-time.
Which of the above is/are the prediction/predictions of Albert Einstein’s General Theory of Relativity, often discussed in media?
(a) 1 and 2 only
(b) 3 only
(c) 1 and 3 only
(d) 1, 2 and 3
Ans: (d)
Q. Consider the following phenomena: (2013)
- Size of the sun at dusk
- Colour of the sun at dawn
- Moon being visible at dawn
- Twinkle of stars in the sky
- Polestar being visible in the sky
Which of the above are optical illusions?
(a) 1, 2 and 3
(b) 3, 4 and 5
(c) 1, 2 and 4
(d) 2, 3 and 5
Ans: (c)
