Current News Science & Technology

Type II 'Solar Radio Bursts': Early Indicators of Weather in Space

A team of scientists from the Indian Institute of Astrophysics (IIA), along with collaborators over the world, have reported that a type of solar radio bursts observed using the global network of solar radio telescopes called CALLISTO (Compound Astronomical Low-cost Low-frequency Instrument for Spectroscopy and Transportable Observatory) can be used to predict space weather hazards rapidly.

  • The scientists found that a type of solar radio slow-drifting bursts known as Type II bursts serve as early indicators of incoming space weather events that could affect the Earth.

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Currently used Methods

  • Forecasters use ground-based instruments and satellites to monitor the active regions of the Sun for any changes to predict hazardous space weather events.

Problem with Current Method

  • This takes place mainly through remote observations of the Sun's coronal mass ejections (CMEs). However, CMEs take 1-5 days to reach us, thus delaying the tracking by that period.

How the new Method Works?

  • Radio bursts at low frequencies are associated with energetic CMEs that travel far into the interplanetary (IP) medium much faster, thus speeding up the tracking process.
  • The speed of the shock due to radio bursts makes their measurements possible using ground-based radio telescopes in comparison to the detection of CMEs in-situ through space-based telescopes 1-5 days later.

Solar Radio Bursts

  • Solar radio bursts are brief periods during which the Sun's radio emission is elevated above the background level. They are signatures of the same underlying physical processes that lead to the more widely-known forms of solar activity such as sunspots, solar flares, and coronal mass ejections.

CALLISTO Spectrometer Network

  • Solar radio bursts are important phenomena for studying solar activities such as flares and coronal mass ejections (CMEs). A worldwide network of 90 stations, known as, CALLISTO (Compound Astronomical Low frequency Low cost Instrument for Spectroscopy and Transportable Observatory), has been developed such purpose.
  • Three of them in operation in India are at Gauribidanur (Karnataka), Udaipur (Rajasthan), and Ooty (Tamil Nadu).

Current News Science & Technology

b Centauri b: Contradicts our Assumption – How Planets are Formed?

A giant exoplanet, or planet located outside of our Solar System, was discovered orbiting b Centauri, a stellar pair located 325 light-years from Earth in the Centaurus constellation.

  • This is the hottest and most massive planet-hosting star system found so far.

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Why it matters? It defies our Assumption of Planet Formation

Earlier Assumption

  • What scientists know about Planet formation is – it occurs around a wide range of stellar masses and stellar system architectures.
  • The earlier studies of planets in close-in orbits around high-mass stars have revealed an increase in giant planet frequency with increasing stellar mass until a turnover point at 1.9 solar masses, above which the frequency rapidly decreases. This could potentially imply that planet formation is impeded around more massive stars, and that giant planets around stars exceeding 3 solar masses may be rare or non-existent.

The Recent Find

  • Recently scientists have found existence of a planet at 560 times the Sun-Earth distance from the 6—10 solar mass binary bCentauri through direct imaging.
  • The planet-to-star mass ratio of 0.10—0.17% is similar to the Jupiter-Sun ratio, but the orbital separation of the detected planet is approximately 100 times wider than that of Jupiter.
  • This shows that planets can reside in much more massive stellar systems than what would be expected from extrapolation of previous results for close-in planets.

b Centauri System

  • The b Centauri system is composed of two stars — b Centauri A and b Centauri B in the Centaurus constellation.
  • The giant b Centauri binary star is astronomically young at 15 million years old - our Sun is 4.6 billion years old.
  • Combined, they weigh in at about six to 10 times the mass of the Sun.
  • At this mass range, they should be too big to have a large planet.
  • The stellar pair is also more than three times as hot as our Sun, so it unleashes a tremendous amount of ultraviolet and X-ray radiation.