In an article published on February 21, 2024, in the journal Monthly Notices of the Royal Astronomical Society, an international team reports the serendipitous discovery of a pulsar with an unusual behavior, which has not been cataloged before, naming it PARROT.
In December 2020, the "great conjunction" between Saturn and Jupiter occurred, a rare phenomenon where the planets could be observed, in the same field of the sky, in close proximity. This astronomical event sparked the interest of astronomers worldwide and led to multiple observation campaigns.
In this context, an international scientific team, led by Oleg Smirnov, a professor at the
Rhodes Centre for Radio Astronomy Techniques & Technologies (RATT) in South Africa, and including notably an astronomer from the Paris Observatory - PSL, was prompted to point the MeerKAT radio telescope of the South African Radio Astronomy Observatory (SARAO) towards the concerned area of the sky.
And then, surprise: in the field of view, in the vicinity of Saturn, a completely unexpected radio source suddenly activated, for about 45 minutes, before turning off again. Such "transient" sources are very rare and therefore scientifically interesting.
Over the following months, intrigued scientists used MeerKAT several times, thereby managing to characterize the radio emission as being the signature of a variable pulsar.
Initially planned for radio observation of the great conjunction between Saturn and Jupiter, this film captures, against all odds, a transient source of unknown origin.
© Smirnov, O.M.et al / RATT An Object Not Catalogued Until Now
While pulsars are well-known objects and numbered in the thousands, this one stands out because of its exceptional radio behavior, showing signal amplifiers reaching, in a few minutes, up to 100 times the brightness usually recorded for this type of object.
This factor, equal to or greater than 10, has indeed earned it a new designation in the pulsar nomenclature. The scientific team has named it "PARROT", an acronym for "pulsar with anomalous refraction recurring on odd timescales".
Pulsars, and other very compact radio objects, often exhibit variations due to scintillation in the solar wind and the interstellar medium. This radio scintillation is not very different from the "twinkling" of stars when observed in optics through the atmosphere.
But no scintillation effect can make a star more than ten times brighter! This phenomenon of extreme radio amplification, known as "lensing", over such short periods, is unprecedented.
The underlying mechanisms remain unknown to this day. They could be explained by unusual structures in the solar wind or by dense plasma in the pulsar's environment. Research avenues are being explored.
Indeed, the discovery of the PARROT pulsar demonstrates MeerKAT's potential to make more such discoveries of transient phenomena and other cosmic variables in the future. The scientific community has high hopes and expectations for its upcoming revelations.
Reference:
This discovery is detailed in an article titled "The RATT PARROT: Serendipitous Discovery of a Peculiarly Scintillating Pulsar in MeerKAT Imaging Observations of the Great Saturn-Jupiter Conjunction of 2020", published in the MNRAS journal on February 21, 2024.
https://doi.org/10.48550/arXiv.2312.12165