National Radio Astronomy Observatory | 2020 Sep 18
Astronomers using the National Science Foundation’s Very Long Baseline Array (VLBA) have made the first direct geometric measurement of the distance to a magnetar within our Milky Way Galaxy — a measurement that could help determine if magnetars are the sources of the long-mysterious Fast Radio Bursts (FRBs).Magnetar Parallax Illustration ~ Credit: Sophia Dagnello, NRAO/AUI/NSF
Magnetars are a variety of neutron stars — the superdense remains of massive stars that exploded as supernovae — with extremely strong magnetic fields. A typical magnetar magnetic field is a trillion times stronger than the Earth’s magnetic field, making magnetars the most magnetic objects in the Universe. They can emit strong bursts of X-rays and gamma rays, and recently have become a leading candidate for the sources of FRBs.
A magnetar called XTE J1810-197, discovered in 2003, was the first of only six such objects found to emit radio pulses. It did so from 2003 to 2008, then ceased for a decade. In December of 2018, it resumed emitting bright radio pulses.
A team of astronomers used the VLBA to regularly observe XTE J1810-197 from January to November of 2019, then again during March and April of 2020. By viewing the magnetar from opposite sides of the Earth’s orbit around the Sun, they were able to detect a slight shift in its apparent position with respect to background objects much more distant. This effect, called parallax, allows astronomers to use geometry to directly calculate the object’s distance. ...
A Magnetar Parallax ~ H. Ding et al
- Monthly Notices of the RAS (online 21 Aug 2020) DOI: 10.1093/mnras/staa2531
- arXiv.org > astro-ph > arXiv:2008.06438 > 14 Aug 2020
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