The eight ‘Main-sequence Radio Pulse’ emitters are hotter than Sun, with unusually robust magnetic fields
In a significant discovery which is able to support within the understanding of “exotic” radio stars and stellar magnetospheres, a group of astronomers from the Pune-based National Centre for Radio Astrophysics (NCRA-TIFR) have used the upgraded Giant Metrewave Radio Telescope (uGMRT) to discover eight stars belonging to a rare class referred to as ‘Main-sequence Radio Pulse’ emitters or MRPs.
Of the entire 15 MRPs identified to this point, 11 have been found by the NCRA-TIFR group alone (with three MRPs noticed by them within the latest previous) due to the huge bandwidth and excessive sensitivity of the upgraded GMRT, which is a radio telescope situated at Khodad in Pune district and which isn’t operated by the National Radio Astronomy Observatory within the U.S.
The MRPs are stars hotter than Sun with unusually robust magnetic fields, and far stronger than stellar wind (a steady movement of fuel from a star’s higher environment). Due to this, they emit vibrant radio pulses like a lighthouse.
“The success of the GMRT programme has revolutionised our notion about this class of stars. Though the first MRP was discovered in 2000, it was only due to the high sensitivity of the uGMRT that the discovery of more such stars was possible. The success of the survey with the uGMRT suggest that the current notion of MRPs as rare objects may not be correct. Rather, they are probably more common but are difficult to detect,” says Barnali Das, a PhD pupil on the NCRA-TIFR, who has been actively finding out this phenomenon.
In truth, it was Ms. Das and her supervisor, Prof. Poonam Chandra of the NCRA who first launched the appellation ‘MRP’ final yr in an effort to grasp the properties of those stars. The duo has carried out probably the most intensive research of MRPs over an ultra-wide frequency vary, utilizing two of the world’s main radio telescopes: the uGMRT and the U.S. based mostly Karl G. Jansky Very Large Array (VLA).
Prof. Chandra says the rationale for the tough detection of MRPs was that the radio pulses are seen solely at sure occasions and the phenomenon is usually observable at low radio frequencies.
“The high sensitivity of the uGMRT and its ability to make high resolution images have been instrumental in enabling the recovery of the pulsed signal from the different types of radiation coming from the sky. This, combined with a strategic observation campaign allowed the astronomers to overcome difficulties, and reveal the true nature of these objects. We found that magnetic field and temperature are two quantities that appear to play the major role in deciding how intense the radio pulse will be,” she observes.
These findings will show essential in understanding what switches off the manufacturing of radio pulses in a sizzling magnetic star.
A analysis paper describing these new discoveries has been not too long ago accepted for publication within the prestigious Astrophysical Journal (ApJ).
The work achieved by Ms. Das, Prof. Chandra and different members of the NCRA group has proven for the primary time that the radio pulses emitted by MRPs include an unlimited quantity of data concerning the stellar magnetosphere.
“The pulsed radio emission from MRPs are the only visible signatures of the theoretical models which predicts tiny explosions in magnetic massive stars that occur at specific locations in the magnetosphere of the star. These explosions have been predicted to play an important role in regulating the transport of wind materials surrounding the star, and are likely to affect the stellar evolution as well,” Ms. Das observes.
