Watch: This binary star system has millisecond pulsar, helium-heavy companion
What's the story
A team of Chinese astronomers has discovered a unique binary star system.
The celestial pair includes a millisecond pulsar and a companion star mostly made up of helium.
The researchers observed that for one-sixth of its orbit, the radiation emissions from the pulsar were blocked, indicating an object was passing between it and Earth.
Characteristics
Pulsars are fast-spinning stars
Pulsars are a special kind of neutron star that emit beams of radiation from their poles. Because of their rapid spin, they seem to pulse when seen from Earth.
The radiation signal is only visible when one of the poles is pointed toward our planet.
In this case, the pulsar was spinning so fast that it was classified as a millisecond pulsar, rotating on its axis at least 100 times per second.
Identification
Discovery of the companion star
Using data from the 500m Aperture Spherical Radio Telescope, the research team was able to pinpoint that another star was responsible for the gaps in the pulsar's pulse.
This companion star is about one to 1.6 times the mass of our Sun and mostly made of helium.
The finding indicates that this is perhaps the first observation of a pulsar gravitationally bound to a helium-rich companion star.
Evolution
How did the helium star transform?
The researchers propose that the companion star once had a lot of hydrogen, which was stripped away by its pulsar partner.
This interaction indicates that both stars share a common envelope, which explains their close proximity to each other.
They are about 50 times closer than Mercury is to the Sun, which leads to short orbital paths and makes them circle each other every 3.6 hours.