There was a lot of activity in the skies this past week, including some which directly affected our own planet, so let’s check things out and see if we need to open a metal umbrella.
“Empirical evidence indicates that at least one supernova has rained heavy elements on Earth in the past. Supernovae are known to release significant quantities of dust at sub-relativistic speeds. We also see evidence of clumpiness or ‘bullets’ in supernova ejecta.”
That astronomer-speak comes from astronomer Amir Sira, co-author of the paper (submitted to the submitted to the Astrophysical Journal) “Observational Signatures of Sub-Relativistic Meteors” with Abraham Loeb, who’s made a name for himself recently with his theories on extraterrestrial life forms, alien space ships and more. Sira and Loeb’s latest theory is that Earth’s atmosphere is being bombarded by large meteors – 1 mm to 10 cm (0.04 to 4 inches) – that are traveling at a tremendous speed – up to 1% of the speed of light or 100 times faster than most meteors.
Sira and Loeb refer to clumps of them with a scary “bullets” description and proposed a way to detect them with a global network of 600 infrasound microphones and optical-infrared instruments to detect the acoustic signature and optical flashes and physical explosions created by these “bullets” as they enter our atmosphere. Are we in any danger? Only of learning more about our solar system and universe. Kudos to Sira and Loeb for promoting more ways to entice kids to become astronomers and create jobs for them.
Moving on to the colliding black holes …
Astronomers who study colliding galaxies refer to something known as the “final parsec problem.” While they can see the massive physical destruction of the merger, they are unclear about what happens when the central black holes of each galaxy are within one parsec (3.26 light-years) of each other. The good news (maybe) is, they may find out in April. Scientific American interviews astrophysicists Daniel D’Orazio and Rosanne Di Stefano who in 2017 predicted that the black holes entering the area of the final parsec would produce a flare that could be detected by gravitational lensing if the black holes line up with earth as one passes in front of the other, thus distorting and magnifying the light of the black hole in the rear. A 2018 study of Kepler space telescope data found an active galactic nuclei (AGN) called KIC 11606854 that appears to be a pair of merging black holes. The astronomers were so excited, they called it “Spikey.”
It gets better. According to their preprint paper, “Spikey” may flare again in April 2020, so the astronomers have reserved NASA’s Chandra X-ray Observatory to watch it. Are we in any danger? Only of disappointment should Spikey not live up to its name. On the other hand, a flare will push the theory closer to fact and give future space telescope missions better data to work with and more likely locations to point to.
Then there’s the mysterious Milky Way gas …
“The absence of stellar counterparts indicates that the point-like object may be a quiescent black hole. This discovery adds another intermediate-mass black hole candidate in the central region of our Galaxy.”
Astrophysicist Shunya Takekawa of the National Astronomical Observatory of Japan and colleagues were studying the motion of a high-velocity gas cloud in the center of the Milky Way called HCN-0.085-0.094 when they noticed that one of the three clumps that made up the cloud appeared to be swirling around a black hole. Its actions suggested this is an unusual quiet black hole, but its size is what got them excited — 100 to 100,000 solar masses. That would make it an intermediate-mass black hole, something that has been theorized but never actually proven or seen. In this case, that’s because it’s quiescent – giving off no detectable radiation because it’s not feeding. As they write in their preprint paper, this is the closest potential intermediate black hole ever found and that discovery itself is amazing, considering the possible event horizon (outer boundary) of this black hole is only the size of Neptune or Uranus.
Yes indeed, it was a busy week for black holes, supernovas and astronomers.