Exactly how you put things together really matters. It turns out that dense neutron stars next to tiny dwarf stars can lead to the neutron star just plain destroying the tiny star. These systems are called spider pulsars, and individual systems are given names like “black widows”, “redbacks” and so on after spider species where the female devours her mate.

Finding these systems is a challenge. They generally make themselves known through periodic gamma-ray flickering, but flickering alone could be many different things. The latest to be identified required the use of many telescopes and the computing power of thousands of volunteers.

The Fermi space telescope had previously spotted a source, inelegantly named 3FGL J2039-5617, that had associated optical and X-ray variations that seemed to indicate that there was a binary star system at the center of all these strange signals. The orbital period appeared to be about 5.5 hours. Remarkably, the changes in optical light the team observed showed changing colors and brightnesses that seemed to indicate that a tiny star about one-sixth the size of the Sun was being distorted into something like a teardrop shape and heated up on the distorted side.

That something was too tiny to be accurately identified using optical telescopes.

And the Fermi Telescope data, which was perfect to solve this mystery, was too big for any one telescope to sort through in less than 500 years. And let’s face it, no one has time for that.

This is where citizen science comes in. The Einstein@home project acts as a screen saver, and while you aren’t using your computer, it will use your computer to process data for research teams like this one. That 500-year processing time got reduced to just two months thanks to the myriad volunteers who donated their processors to this task. In the data, they found gamma-ray flickering consistent with that tiny but massive unseen companion being a neutron star that rotates 377 times per second. It is so energetic that it is evaporating away that one-sixth solar mass companion the researchers can see.

This work is described in a new paper in the Monthly Notices of the Royal Astronomical Society, and according to lead author Colin Clark: For J2039-5617, there are two main processes at work. The pulsar heats up one side of the light-weight companion, which appears brighter and more bluish. Additionally, the companion is distorted by the pulsar’s gravitational pull causing the apparent size of the star to vary over the orbit.

To add some context, that one-sixth solar mass star is several times bigger than Jupiter in size but packs more mass than the Sun has into a volume you could roughly rest on Manhattan if you felt like destroying the planet because that is exactly what this star would do. This neutron star is smaller than your average moon and smaller than a big asteroid, and it is a destroyer of stars.

This is your friendly reminder, the universe is trying to kill us. 

More Information

The University of Manchester press release

“Einstein@Home discovery of the gamma-ray millisecond pulsar PSR J2039–5617 confirms its predicted redback nature,” C J Clark et al., 2020 November 23, Monthly Notices of the Royal Astronomical Society