Recently, a team of astronomers from National Centre for Radio Astrophysics-Tata Institute of Fundamental Research (NCRA-TIFR), discovered eight rare radio stars with the help of the upgraded Giant Metrewave Radio Telescope (uGMRT). These rare stars belong to the Main-sequence Radio Pulse (MRP) emitters. This discovery would aid in the understanding of ‘exotic’ radio stars and stellar magnetospheres.
A research paper about the discovery was accepted for publication in The Astrophysical Journal. The lead researcher, Dr Barnali Das led the research under the supervision of Professor Chandra who have been actively involved in various projects which aim at the characterisation of this little-known class of objects MRPs. They were the ones who had initially coined the term ‘MRP’ to describe the features of these stars.
Main-Sequence Radio Pulse (MRP)
The MRPs are stars with remarkably strong magnetic fields much stronger stellar wind, and are far hotter than the sun. Stellar wind is a continuous flow of gas from a star’s uppermost atmosphere. Consequently, they generate intense radio pulses, similar to a lighthouse on a pitch-dark island.
The first MRP was discovered in 2000; and in recent years, the discovery of new stars has shot up manifold.
A total of 15 MRPs have been discovered in space so far. Out of the 15 MRPs, 11 have been discovered with the help of GHRT. Moreover, out of those 11, eight MRPs have been discovered in the year 2021 itself. The researchers believe that this discovery could counter the belief that MRPs are rare celestial bodies. On the contrary, they might be more common than initially perceived but are difficult to detect.
Giant Metrewave Radio Telescope
The GMRT is a radio telescope located at Khodad, 80 km away from Pune, and operates at over 150-1420 MHz. It is one of the largest and most sensitive fully operational low-frequency radio telescopes in the world.
The GMRT is today a frontline international facility for low-frequency radio astronomy. It has produced several exciting and important new results in the past 15 years of its operation.
It consists of 30 antennas, each of 45 m diameter and spanning over 25 km. It provides a total collecting area of about 30,000 sq m at metre wavelengths.
It was upgraded in order to add extra capability to the existing GMRT array, in terms of frequency coverage and sensitivity. The upgraded GMRT would allow to open new windows of research in astrophysics and the study of the universe. The improved frequency coverage, to be achieved by broadbanding the receiver system, would allow spectral line observations over a wider range of centimetre and metre wavelength spectrum. With increased sensitivity, the uGMRT would allow many more refined galactic and extra-galactic studies to be carried out and become a more powerful tool for detection and detailed studies of pulsars and transients.
The main targets of the uGMRT are as follows:
- Seamless frequency coverage, as far as possible, from 50 to 1500 MHz, replacing the five limited bandwidth frequency bands of the original GMRT design
- Maximum instantaneous bandwidth of 400 MHz instead of the 32 MHz bandwidth of the original GMRT design
- Improved receiver systems with higher G/Tsys and better dynamic range
- Versatile digital backend correlator and pulsar receiver catering to the 400 MHz bandwidth
- Revamped, modern servo system
- Sophisticated, next-generation monitor, and control system
- Matching improvements in mechanical systems, electrical and civil infrastructure, and computing resources
- Implementation of the upgrade with minimal disruption to the availability of the existing GMRT for scientific observations.
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