The binary system is 5,000 light years from Earth. Credits: NASA's Goddard Space Flight Center
Astronomers are preparing to watch some high-energy fireworks when a pulsar the size of a city meets one of the brightest stars in our galaxy in 2018.
Already plans are being made across the globe to make sure that the rare event is captured in every wavelength from radio to the highest energy gamma rays.
The pulsar, known as J2032+4127, is the remnant of a massive star, a magnetised ball 19km across with a mass twice that of the Sun.
It’s strong magnetic field causes it to emit a beam of photons, which then sweep across the Galaxy, as the pulsar spins seven times every second.
The pulsar’s gamma rays were picked up by the Large Area Telescope (LAT) and then followed up by observations at other wavelengths throughout 2011 to 2014.
It was then that the team realised something odd was going on.
"We detected strange variations in the rotation and the rate at which the rotation slows down, behaviour we have not seen in any other isolated pulsar," says Andrew Lyne, professor of physics at the University of Manchester.
"Ultimately, we realized these peculiarities were caused by motion around another star, making this the longest-period binary system containing a radio pulsar."
The pulsar is in a binary system with nearby MT91 213, a massive star in the constellation of Cygnus, 15 times the mass of the Sun and 10,000 times brighter.
Every 25 years the pulsar completes an elongated orbit around the partner star, much longer than any previously known pulsar-massive star binary.
Credits: NASA's Goddard Space Flight Center
The star is embedded in a large disk of dust and gas, caused by the Sun’s intense stellar winds.
When the pulsar passes closest to MT91 213 it travels through the star’s dust disk and this is next due to happen in 2018 and scientists are expecting to see fireworks.
"This forewarning of the energetic fireworks expected at closest approach in three years' time allows us to prepare to study the system across the entire electromagnetic spectrum with the largest telescopes," says Ben Stappers, a professor of astrophysics at the University of Manchester.