Astronomers performed timing observations of an eccentric millisecond pulsar known as PSR J0955−6150. The result of the observational campaign published on the arXiv pre-print server. It delivers important insights into the nature of this object.
The most rapidly rotating pulsars are known as millisecond pulsars (MSPs). It is assumed that they are formed in binary systems. The more massive component turns into a neutron star. Then it spun-up due to accretion of matter from the secondary star.
PSR J0955−6150 is an MSP with a spin period of 1.99 ms. It was discovered in 2015 by the Parkes radio telescope. This pulsar is part of a binary system with a presumably helium white dwarf (He WD) star. The binary has an orbital period of approximately 24.58 days. It has a relatively high orbital eccentricity. PSR J0955−6150 was classified as an eccentric MSP (eMSP). It turns out to be one of the most eccentric out of the known eMSPs with the WDs.
Astronomers decided to investigate PSR J0955−6150 with Parkes and MeerKAT radio telescopes. They are hoping to get more insights into the nature of this pulsar. This will also improve our understanding of the population of eMSPs hosting helium white dwarfs.
The study revealed a strong frequency evolution of this pulsar’s intensity. It turns out that PSR J0955−6150 is located some 13,000 light years away from the Earth and its proper motion is relatively small.
Scientists found that the pulsar has a mass of approximately 1.71 solar masses. The mass of the companion star is about 0.25 solar masses. The orbital inclination of the system was measured to be 83.2 degrees. Astronomers noted the mass of the pulsar is typical for eMSPs. The mass of the companion He WD is significantly smaller than expected. They emphasized that none of the currently known hypotheses are able to explain the low mass of the companion to PSR J0955−6150 and its orbital misalignment.