Unfolding mysteries of the night sky
- July 14, 2022
- Posted by: OptimizeIAS Team
- Category: DPN Topics
Unfolding mysteries of the night sky
Subject :Science and Technology
- With the release of its first five stunning images, the James Webb Space Telescope has demonstrated an acute observational capacity and revealed aspects of the cosmos hitherto hidden from other telescopes.
- The deep field image of the SMACS 0723 cluster of galaxies has images that date back to times when the first stars were born.
- In contrast, the Southern Ring Nebula image details a dying star. The Eight-Burst Nebula, also known as the Southern Ring Nebula or NGC 3132, is a well-known planetary nebula in the constellation Vela, located approximately 2,500 light-years from Earth.
- In Stephan’s quintet, the JWST has captured the cataclysmic cosmic collision of galaxies.
- By analyzing the spectrum of the radiation from WASP-96 b, an exoplanet (a planet orbiting a distant star), the telescope has shown conclusively the presence of water vapour in the atmosphere of this hot, puffy gas giant planet orbiting a distant Sun-like Star.
Peering back in time
- About 13.8 billion years ago, through the Big Bang, our Universe
- The first stars and galaxies were born around 300 million years after the Big Bang.
- As light travels with a velocity of about 3,00,000 km per second, light from a distant object will take time to reach us on Earth.
- Hence, when we see a distant stellar object, we see it as if it were far back in time.
- Further, light from distant objects is stretched out by the expansion of our Universe, driving the radiation from the visible range into the infrared.
- Therefore, to look deep back into the early phases of the Universe, we need a giant infrared telescope. JWST is the biggest infrared telescope ever built.
- To observe the massive SMACS 0723 cluster of galaxies, which, as Einstein’s general relativity theory predicts, distorts the fabric of spacetime.
- As a result of this ”gravitational lensing” effect, some galaxies appear distorted in an arc shape, some are split into multiple images, and some are magnified.
- The kaleidoscope of colours in the image captured by the JWST’s Mid-Infrared Instrument (MIRI) are false colours, corresponding to a radiation wavelength.
Where stars are born
- Stars and star clusters are formed inside giant gas clouds.
- The visible light is obscured by the thick dust that goes into the making of these stars and renders it opaque.
- Shrouded in thick dust clouds, these star forming regions remained hidden to even powerful telescopes, until now.
- Other phenomena that one sees include ionized gas and hot dust wafting away due to radiation from young stars, causing turbulence and eddies and dust swirling in the surrounding gas.
A star on its deathbed
- Planetary nebulae have nothing to do with planets. They are gas shells formed from the cast-off outer layers of a dying star.
- Intermediate mass stars with a mass of 0.8 to eight times the mass of the Sun end their lives with drama.
- They do not die in one big explosion but go through a cycle of fits and starts.
- The dying star will expel its outer layer and expand, while simultaneously, its core will contract.
- The contracting centre will once again start to emit energy, and the star will have a lease of life.
- The expelled shell is pushed by this radiation and expands in space like a ring around the central star.
- After some time, the central star again sheds its outer layer while the remaining core contracts.
- Over time successive waves of expelled outer shells surround the central star-like concentric rings.
- The remaining core of the star ultimately becomes a faint glowing white dwarf.
- After trillions of years, they cool down and no longer shine, ultimately becoming black dwarfs.