Homehttps://server7.kproxy.com/servlet/redirect.srv/sruj/smyrwpoii/p2/Sciencehttps://server7.kproxy.com/servlet/redirect.srv/sruj/smyrwpoii/p2/NASA satellite notices a mysterious green light that quickly disappears
NASA satellite notices a mysterious green light that quickly disappears
NASA's NuSTAR X-ray Observatory noticed something strange. While portraying the Fireworks Galaxy, NuSTAR noticed several mysterious bright X-ray sources that looked like green and blue spots. After days, the spots disappeared.
A recent study published in the Astrophysical Journal offers potential explanations for the appearance of a green spot near the center of the galaxy that has appeared and disappeared within weeks.
The main purpose of NuSTAR observations was to investigate a supernova ̵
1; a huge explosion of stars. The green spot, known as the ultraluminous X-ray source (ULX) shown at the bottom of the galaxy in the image above, did not appear on first observation but appeared during the second 10 days later. Another space telescope, NASA's Chandra X-ray Observatory, then looked again and found that the object, the ULX-4, had quickly disappeared.
"Ten days is a really short time for such a bright object to appear," Hannah Earnshaw, a doctoral student at Caltech and lead author of the study, said in a statement. "Usually, with NuSTAR, we observe more gradual changes in time, and we do not often see a source repeatedly in rapid succession. In this case, we were fortunate to catch a source that is changing extremely fast, which is very exciting."  Now Playing: Watch this:
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The light may be from a black hole consuming another object as a star, according to the study. When objects get too close to a black hole, they can be torn apart by gravity and their debris drawn into a tight orbit around the black hole. The material in the inner edge of the disk moves so fast that it "heats up to millions of degrees and emits X-rays," NASA says. For reference, the sun's surface is about 10,000 degrees Fahrenheit.
Most ULXs last a long time because they are formed by solid objects such as black holes that "feed" a star for a long time. Short-lived X-ray sources like this ULX are not as common, so its occurrence can be explained by a scenario like a black hole that quickly destroys a small star.
There may be other possible explanations for the appearance of the green spot. The study's authors suggest that its source may be a neutron star, which is an extremely dense object created by the explosion of a star that was not large enough to create a black hole. The mass of a neutron star is similar to that of the sun, but is only about the size of a large city. Therefore, neutron stars can retrieve material and cause the debris to move very quickly into a disk.
Neutron stars can create strong magnetic fields that form "columns" and bring material to the surface. In the process, they generate strong X-rays. However, if the star is spinning too fast, the material cannot reach the surface and create these X-ray bursts. It's kind of like an invisibility cloak – astronomers can't see the X-ray signature of a neutron star. But if the material slips in some way, the invisibility cloak fails. This could explain why the ULX-4 quickly appeared and then disappeared.
"This result is a step towards understanding some of the rarer and more extreme cases in which matter accumulates on black holes or neutron stars," Earnshaw said in a statement.