Ibadan, 20 July 2023. – An international team of astronomers, including the South African Astronomical Observatory (SAAO), the University of Cape Town (UCT), and the South African Radio Astronomy Observatory (SARAO), have discovered a rare type of white dwarf pulsar. This rare type of spinning white dwarf star provides a new understanding of the role of magnetic fields in stellar evolution.
The research team described the newly detected white dwarf pulsar, J191213.72-441045.1 (J1912-4410 for short), which is in a binary system with an orbital period of just over 4 hours. However, the white dwarf’s rotation period is just a little over 5 minutes long, meaning it’s spinning about 270 times faster than the Earth does.
Dr. Ingrid Pelisoli, Research Fellow at the University of Warwick’s Department of Physics and lead author, said: “We used data from a few different survey telescopes to find potential white dwarf pulsar candidates, focusing on those that had similar characteristics to AR Sco. After observing a couple of dozen candidates, we found one that showed very similar light variations to AR Sco. We then followed these up with a number of other telescopes, both from the ground and space.”
The research telescopes included the optical telescopes at the Sutherland site of the SAAO, including the 10-m diameter Southern African Large Telescope and the MeerKAT radio telescope array. Professor David Buckley of the SAAO, UCT, and the University of the Free State, together with his SAAO and University of Johannesburg colleague, Professor Stephen Potter, initiated the South African optical observations. He stated: “Like for the case of AR Sco, we were able to show that J1912-4410 also shows pulsed polarization and pulsed spectral lines, confirming its white dwarf pulsar nature.”