Astronomers discover a rare 'black widow' binary, with the shortest orbit yet

The flashing of a nearby star has drawn MIT astronomy to a new system 3,000 light years away. The star appears to be a black widow, a rapidly spinning neutron star, that is circling and slowly consuming a smaller companion star, as its arachnid namesake does to its mate.

There are about two dozen black widow binaries in the sky. The candidate named ZTF J1406+1222 has the shortest orbital period yet identified, with the companion star and pulsar circling each other every 62 minutes. The system appears to have a third star that flies around the two inner stars every 10,000 years.

The triple black widow is raising questions about how the system could have formed. The MIT team believes that the triple system likely arose from a dense constellation of old stars. The gravity of the central black hole may have pulled the cluster apart, leaving the triple black widow intact.

Kevin Burdge is a post-doctoral fellow in MIT's Department of Physics.

Burdge is the author of a study about the discovery. The triple system was detected by a new approach. The team used visible light and the flashing from the companion star to detect the black widow.

Burdge says that the system is unique because it was found with visible light, and because it came from the center of the universe. We have a new way of looking for these systems.

The co-authors of the study are from a number of institutions.

Day and night.

The black widow binaries are powered by the spinning stars of the collapsed cores of massive stars. There are flashes of high-energy gamma and X-rays in the process of spinning a Pulsar.

Normally, pulsars spin down and die as they burn off a lot of energy. A passing star can give a pulsar a new lease on life. As a star nears, the pulsar's gravity pulls material off the star, which provides new energy to spin the pulsar back up. The pulsar starts reradiating energy that strips the star and eventually destroys it.

Burdge says that black widows are called because of how the sort of pulsar consumes the thing that recycled it, just as the spider eats its mate.

The black widow has been detected by the X-ray flashes from the pulsar. Burdge was the first person to come upon ZTF J1406+1222 through the flashing of the companion star.

The day side of the companion star can be hotter than the night side due to the high-energy radiation it receives from the pulsar.

Burdge thought, instead of looking directly for the pulsar, try looking for the star that it is cooking on.

He thought that if an astronomer observed a star whose brightness was changing by a lot, it would be a strong signal that it was in a pulsar.

The star motion.

Burdge and his colleagues looked through optical data taken by the Zwicky Transient Facility, an observatory based in California that takes wide-field images of the night sky. The team studied the brightness of stars to see if any were changing dramatically by a factor of 10 or more, on a timescale of about an hour or less.

The team was able to pick out the dozen known black widow binaries. They spotted a star whose brightness had changed by a factor of 13 every 62 minutes and they thought it was part of a new black widow.

They looked up the star in observations taken by the European Space Agency's Gaia space telescope, which keeps precise measurements of the position and motion of stars in the sky. The team looked through decades old data from the Digital Sky Survey and found that the star was being followed by another star. The third star appeared to be around the innerbinary every 10,000 years.

The typical way in which black widows are confirmed is by not directly detecting the X-ray emissions from the pulsar. The team hopes to confirm that ZTF J1406+1222 is a black widow.

The one thing we know for certain is that a star with a day side that is much hotter than the night side is a black widow. There are a few weird things about it.

The optical technique will be used to illuminate more black widows and neutron stars in the sky.

More information: Kevin Burdge, A 62-minute orbital period black widow binary in a wide hierarchical triple, Nature (2022). DOI: 10.1038/s41586-022-04551-1. www.nature.com/articles/s41586-022-04551-1 Journal information: Nature Citation: Astronomers discover a rare 'black widow' binary, with the shortest orbit yet (2022, May 4) retrieved 4 May 2022 from https://phys.org/news/2022-05-astronomers-rare-black-widow-binary.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.