Top Astronomy & Astrophysics research from the week of 8/23/2020

Next week’s night sky

The moon reaches its full stage, halfway through its rotation around Earth, on Tuesday. This is a great time to look more closely at the moon! With a good set of binoculars, you should be able to make out the detail of the craters and planes of the lunar surface. On Saturday, the moon and Jupiter will be only around 1 degree apart. Just wait about half an hour after sunset, and then look for a reddish brown-object shining right near the moon.

NEOWISE rotating

Researchers at the Gemini North telescope in Hawaii were able to catch a mesmerizing video of comet NEOWISE rotation. A 15-hour exposure was enough to confirm that the comet had a rotation period of 7.5 hours. 

Comets start to rotate when gas jets of the comet. This makes the comet act somewhat like an out of control hose. Comet rotation can be more complicated because they can spin in 3D, but this doesn’t seem to be the case for NEOWISE.

Supernovae could have caused a mass extinction.

Cosmic rays from nearby supernova may have begun one of Earth’s mass extinctions, researchers say, destroying Earth’s ozone layer around 359 million years ago. 

Researchers considered a variety of explanations, ranging from large asteroid impacts to solar flares and gamma-ray bursts. Out of all these, a supernova seemed the most likely cause. A supernova would have delivered a one-two punch, first bathing Earth in high energy ultraviolet radiation, X-rays and gamma rays, slamming debris into the solar system. This would compress the heliosphere and subject Earth to cosmic rays. Damage to the planet’s ozone layer could have remained for up to 100,000 years. One way to prove a nearby supernova occurred is to look for radioactive isotopes of plutonium-244 and samarium-146 in rocks. This knowledge would massively impact our understanding of Earth’s history. To learn more, go here: Nearby supernova blasts may be culprits in at least one mass extinction. 

A strange black hole

For the first time, research watched the destruction of a supermassive black hole’s destruction. The corona is a ring of high-energy particles that encircles a black hole’s event horizon.

The cause of this transformation is unclear. Researchers guess that the source of the may have been a star caught in the black hole’s gravitational pull. The star may have ricocheted through the black hole’s disk of swirling material. This caused caused everything in the vicinity to suddenly plummet into the black hole.

The result, as the astronomers observed, was a surprising drop in the black hole’s brightness, by a factor of 10,000, in under just one year. In fact, the corona even changed by a factor of 100 in eight hours!

After the corona’s disappearance, researchers watched as the black hole began to slowly pull together material from its outer edges to reform its accretion disk. Then, the black hole began to create X-rays close to its event horizon. In just a few months, the black hole was able to generate a new corona, almost back to its original form. Understanding this event will be extremely important to understand how a black hole’s corona is heated and powered in the first place. To learn more, go here: https://iopscience.iop.org/article/10.3847/2041-8213/ab91a1/meta. 

Do you have any cool astronomy research news from this week? Share it in the comments below!