Prelims cum Mains Science & Tech

Global team of scientists discovers one of the earliest galaxies using India’s AstroSat

In News

  • A global team led by scientists of the Inter University Centre for Astronomy and Astrophysics (IUCAA) has discovered one of the earliest galaxies in extreme ultraviolet light.
  • The team comprises scientists from India, Switzerland, France, USA, Japan and Netherlands.
  • The study was and was published on August 24 in Nature Astronomy.

About: AstroSat Mission

  • AstroSat is the first dedicated Indian astronomy mission aimed at studying celestial sources in X-ray, optical and UV spectral bands simultaneously.
  • It was launched in 2015 into a 650 km orbit.
  • AstroSat is also India’s first multi-wavelength satellite which has five unique X-ray and ultraviolet telescopes working in tandem.

Features of AstroSat:

  • AstroSat has a lift-off mass of 1515 kg.
  • The minimum useful life of the AstroSat mission is expected to be 5 years.
  • One of the unique features of AstroSat mission is that it enables the simultaneous multi-wavelength observations of various astronomical objects with a single satellite.
  • The payloads of AstroSat cover the energy bands of-
    • Ultraviolet (Near and Far)
    • Limited optical
    • X-ray regime (0.3 keV to 100keV)

Management of AstroSat

  • The spacecraft control centre at Mission Operations Complex (MOX) of ISRO Telemetry, Tracking and Command Network (ISTRAC), Bengaluru manages the satellite during its entire mission life.
  • The science data gathered by five payloads of AstroSat are telemetered to the ground station at MOX.
  • The data is then processed, archived and distributed by Indian Space Science Data Centre (ISSDC) located at Bylalu, near Bengaluru.

Mission Objectives

  • The scientific objectives of AstroSat mission are-
    • To understand high energy processes in binary star systems containing neutron stars and black holes;
    • Estimate magnetic fields of neutron stars;
    • Study star birth regions and high energy processes in star systems lying beyond our galaxy;
    • Detect new briefly bright X-ray sources in the sky;
    • Perform a limited deep field survey of the Universe in the Ultraviolet region.

Payloads of AstroSat

  • Ultra Violet Imaging Telescope (UVIT)
    • Its purpose is to image the sky simultaneously in  three wavelengths, one covering the far UV band (130 – 180 nm) and the second sensitive in near UV (200 – 300nm) and Visible (320 – 550 nm) bands.
    • The detector in each channel is a photon counting device.
  • Soft X-ray Telescope (SXT)
    • It is a focusing X-ray telescope with an X-ray CCD imaging camera.
    • This will work primarily in photon counting mode, recording the position, time and energy of every detected photon in the energy range 0.3-8 keV.
  • Large Area X-ray Proportional Counters (LAXPC)
    • Its main purpose is to record variation of total intensity of sources within its 1-degree field of view, with high time resolution and moderate spectral resolution over a large spectral band from 3 to 80 keV.
    • This payload is non-imaging.
  • Cadmium-Zinc-Telluride Imager (CZTI)
    • It is a hard X-ray coded mask camera working in the band 10-100 keV.
    • It has better spectral resolution than the LAXPC and a coarse imaging capability by the coded mask.
  • Scanning Sky Monitor (SSM):
    • It is for detection of new X-ray transients and monitoring of known X-ray sources in 2.5 – 10 keV region.

News Summary

  • AstroSat has detected extreme UV light from a galaxy called AUDFs01 which is 9.3 billion light-years away from Earth.
  • The galaxy is located in the Extreme Deep field.
    • Deep Field is the deepest view of the universe revealed with deep space imaging of NASA’s Hubble telescope.

How AstroSat was able to detect UV Radiation from distant galaxy?

  • Since UV radiation is absorbed by Earth’s atmosphere, it has to be observed from space.
  • Earlier, NASA’s Hubble Space Telescope (HST) did not detect any UV emission (with energy greater than 13.6 eV) from this galaxy because it is too faint.
  • NASA’s Hubble Space Telescope (HST) is significantly larger than the Ultra Violet Imaging Telescope (UVIT) on Astrosat.
  • AstroSat/UVIT was able to achieve this unique feat because the background noise in the UVIT detector is much less than the ones on HST.

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