A black widow binary it’s a rare oddity: a dead star that spins rapidly and slowly devours a smaller companion star, much like its namesake spider does with its mate. In a new study published Wednesday in the journal Naturescientists may have found the most closely coupled black widow binary yet, one whose partners are so close the duo could fit inside our Sun. Much of it remains a mystery, suggesting this discovery may be a case of mistaken identity and that the researchers could have found something completely new to science.
HERE IS THE BACKGROUND – Black Widow binaries are powered by pulsars, rapidly spinning neutron stars, which are extraordinarily dense cores of dead stars that contain up to 2.17 times the mass of the Sun in the size of a city. Pulsars can spin at breakneck speeds, spinning hundreds of times a second, emitting flashes of gamma rays and X-rays like high-powered headlights.
Normally, pulsars spin down and come to life like ordinary neutron stars while burning off an enormous amount of energy. However, in a black widow binary, the pulsar’s companion breathes new life into the dead star. The pulsar’s gravity, strong enough to squash protons together with electrons to form neutrons, rips material from its companion, a flood of plasma whose force helps the pulsar spin again. Afterwards, the pulsar emits energy that further depowers its partner, eventually destroying it.
Astronomers discovered the first black widow binary in the 1980s. Since then, astronomers have found roughly two dozen black widow binaries in the Milky Way, along with another type of spider star called a redback, which also consists of a pulsar and your doomed partner. (Black widows have companions less than a tenth the mass of our Sun, while redbacks have larger companions.)
WHAT DID THE SCIENTISTS DO? — Every black widow binary that astronomers have detected to date appeared through X-ray and gamma-ray flares from its pulsar. In the new study, the researchers sought to see black widow binaries from visible flashes of light from the pulsar’s companions.
The day side of a black widow pulsar’s companion, the side that perpetually faces its vampire captor, can be many times hotter than its night side due to the constant torrent of radiation it receives from the pulsar. The astronomers sought to find a star whose brightness regularly changed by a considerable amount, suggesting that it might orbit closely around a pulsar.
In the new study, scientists investigated data from the Zwicky Transient Facility (ZTF) instrument at the California Institute of Technology’s Palomar Observatory near San Diego. They examined images of the entire night sky, analyzing 20 million stars to see if the brightness of any star changed dramatically by a factor of 10 or more on a time scale of about an hour or less.
WHAT DID YOU FIND? — This new technique identified known black widow binaries, validating their accuracy. He also detected what appeared to be a star whose brightness changed by a factor of 13 every 62 minutes. This suggests that it was probably part of a new black widow binary about 3,700 light-years from Earth, which scientists named ZTF J1406+1222.
“All known black widow pulsars have been found because they emit X-rays, gamma rays or radio waves, but this is the first time we’ve used visible light, the kind our eyes can see, to find something like this.” The lead author of the study, Kevin Burdge, an astrophysicist at the Massachusetts Institute of Technology (MIT), says Reverse.
ZTF J1406+1222 probably consists of a pulsar and a cool failed star known as a brown dwarf. These objects are between 13 and 90 times the mass of Jupiter, too big to be planets, but not big enough to be true stars.
Telescopes cannot distinguish between the ZTF J1406+1222 pulsar and the brown dwarf, but the pulsar is likely to be between 1.4 and twice the mass of the Sun, while the brown dwarf is likely to be several dozen times the mass of the Sun. of Jupiter, says Burdge. Scientists estimated that they are separated by less than about 450,000 kilometers. Given this short distance and the relatively small sizes of each object, “it could all fit inside the Sun,” says Burdge.
ZTF’s pulsar J1406+1222 and its companion orbit each other every 62 minutes, the shortest orbit yet observed for a black widow binary. The previous record holder, PSR J1653-0158, had stars orbiting each other every 75 minutes.
Interestingly, this black widow binary is unique in that it has a third companion about 10 to 20 percent the mass of the Sun that orbits much farther out, at a distance of about 600 times the average distance between Earth and the Sun. Sun. This distant companion orbits the close pair every 10,000 years.
It remains uncertain how ZTF’s pulsar J1406+1222 and its companion could have gotten into such a tight orbit, since the way a pulsar erodes its companion should drive them apart.
“The third partner may have helped them get there,” suggests Burdge. “Basically, any time you have two things orbiting each other, and you also have a third wider thing orbiting each other, that third wider thing can gravitationally interact with the inner binary and actually change the inner binary’s orbit to push things around.” a little bit closer”.
More technically, the third partner can make the orbit of its two partners more elongated or eccentric. As the brown dwarf approaches the pulsar in the eccentric orbit, it feels a powerful gravitational pull, “and that dissipates energy, which quickly causes the orbit to settle into a very tight circular orbit,” says Burdge.
WHATS NEXT? — Interestingly, astronomers have so far detected no gamma rays or X-rays from ZTF J1406+1222. Although many details about it so far suggest that it is a black widow binary, until future observations from, say, NASA’s Chandra X-ray Observatory confirm the presence of a pulsar, “it is entirely possible that this object could also be something we’ve “never seen before and even more exotic,” says Burdge. “The only thing I know for sure is that we’ve never seen anything like this object, and that there’s probably a lot more to learn from it and other similar objects than I’m aware of.” finding right now, and that’s what makes me so excited about these.”
Burdge points out that the Vera Rubin Observatory in Chile can find many more of these objects, since “it will be about 40 times more powerful than ZTF in terms of how far it can see.”