The Zwicky Transient Facility (ZTF) telescope located near San Diego, California (USA), scans millions of stars every two nights in search of celestial objects that show unusual behavior . Now, a team of researchers claims to have found what appears to be a pulsar and a small star orbiting each other faster than we’ve ever seen. The scientists designed an algorithm that finds objects that get much brighter or much dimmer over the course of 80 minutes. This is where our protagonist comes in: her brightness varies by a factor of 13 every 62 minutes. Something was happening here.
a deadly dance
The pulsar, known as a ‘black widow’ in astronomy , is slowly cannibalizing its companion and consuming its matter and energy . Thus, a flash from a nearby star led MIT astronomers to a mysterious new system 3,000 light-years from Earth. This new “black widow binary” is thus starring a rapidly spinning pulsar that is spinning around slowly slowly consuming a smaller companion star, just as some spiders would in the natural world.
“Lower-mass stars donate material to their companion stars but suffer the consequences ,” the authors explain in their study published in the journal Nature.
Although we already know of quite a few black widow binaries in our galaxy, this “black widow binary” candidate, called ZTF J1406+1222, has the shortest orbital period identified so far: every 62 minutes. The system is unique in that it appears to host a distant third star that orbits the two inner stars every 10,000 years.
“This 62-minute orbit is remarkable because we don’t understand how stars can get into such a tight orbit. The process of the pulsar ablating its partner should actually separate them. This is pushing the limits of what we thought possible”, explains Kevin Burdge, co-author of the work.
A triple black widow?
Could be. According to the MIT scientists, as with most black widow binaries, the triple system probably arose from a dense constellation of old stars known as a globular cluster. This cluster could have drifted toward the center of the Milky Way, where the gravity of the central black hole was enough to pull the cluster apart and leave this triplet intact.
The scientists also note that this is the first black widow system discovered using optical light. “The black widow population we’ve been finding so far with other wavelengths of light, like X-rays, gamma rays and radio waves, is probably biased because we haven’t caught all of them. We now have a new lens through which we can identify these systems,” says Burdge.
Follow-up observations with NASA’s Chandra X-ray Observatory will provide new insights and hopefully confirm the nature of this unusual system. The system orbits in the galactic halo and astronomers believe it is close to the galactic center, so further study could provide insights beyond the physics of the black widow pulsar.
“Our data indicates that we are seeing a black widow binary, but it could be something completely new,” says the expert Data from NASA’s Chandra X-ray Observatory, a space telescope that orbits in a large ellipse around Earth, will confirm the finding.
The goal is to continue observing the new system, as well as apply the optical technique to illuminate more neutron stars and black widows in the sky.
Referencia: Burdge, K.B., Marsh, T.R., Fuller, J. et al. A 62-minute orbital period black widow binary in a wide hierarchical triple. Nature 605, 41–45 (2022). https://doi.org/10.1038/s41586-022-04551-1
