Organization: 365 Days Of Astronomy
Description: Space scoop, news for children. In a recent study, a computer ran a “machine learning” software program called the Deflector Selector. It was fed millions of simulations of asteroids careening towards Earth. Each one resulted in either the asteroid hitting or missing the Earth.
Bio: Richard Drumm is President of the Charlottesville Astronomical Society and President of 3D – Drumm Digital Design, a video production company with clients such as Kodak, Xerox and GlaxoSmithKline Pharmaceuticals. He was an observer with the UVa Parallax Program at McCormick Observatory in 1981 & 1982. He has found that his greatest passion in life is public outreach astronomy and he pursues it at every opportunity.
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This is the 365 Days of Astronomy Podcast. Today we bring you a new episode in our Space Scoop series. This show is produced in collaboration with Universe Awareness, a program that strives to inspire every child with our wonderful cosmos.
Dancing With the Stars
Astronomers have spotted a new contender for Dancing with the Stars! And in an unlikely place – deep space!
Globular star clusters, called globs by us amateur astronomers and GCs by the professionals, are huge globe-like balls made up of many tens of thousands of stars. Over 150 of them swarm around our Milky Way galaxy and are among the oldest groups of stars in the Universe.
Deep inside one globular cluster of thousands of stars, one star stands out from the rest. It caught the eye of astronomers who spotted it flying backwards and forwards through space in an intricate, repeating pattern.
They used the MUSE, the Multi-Unit Spectroscopic Explorer instrument at the ESO’s VLT, the Very Large Telescope at Paranal Observatory in Chile.
The cluster is called NGC 3201 and is located in the Southern constellation Vela, the Sails. The constellation is called this because it was once part of a larger constellation Argo Navis.
That’s the mythological sailing ship that Jason and the argonauts sailed in search of the golden fleece.
This large and rather unweildy group of stars was carved into 3 constellations. The other 2 are Carina, the Keel of the ship and Puppis, which is not a puppy, but the poop deck of the Argo Navis ship.
Now stop that giggling! I’m not talking about the bathroom!
Just so you know, the planet Uranus never goes through this part of the sky.
The word poop in this case comes from the French word poupe which means the stern, the rear of the ship, so the poop deck could actually be called the stern deck.
It sits above the quarter deck where the helmsman stands with the ship’s wheel, steering the ship. Being high up it was a good place for observation. The deck forms the roof of the captain’s cabin.
Now where was I?
Oh yeah. The constellation Vela and the dancing star.
While ballroom dancers rely on a partner, this star looks like it’s floating through its graceful steps alone…
It turns out that the star does have a partner, but it’s invisible. Hidden among the many stars in this cluster is a black hole.
Black holes don’t give off any light by themselves, making them impossible to spot directly. However, we can see the effect they have on the Universe around them. The star’s dance shows us its path around the black hole.
As the MUSE instrument is a spectrometer, looking closely at the color of the light coming from the star, the doppler shift of the light was what attracted the astronomers to this one star.
It was being flung backwards and forwards at several hundred thousand kilometers an hour in a repeating 167 day pattern.
Kind of a stellar do-si-do!!!
Although they are difficult to find, black holes are fairly common in some parts of the Universe – but not in globular clusters. This is the first time a black hole this size has been seen dancing with a star in a glob.
Their impressive size and age means globular clusters should produce lots of black holes similar in size to this one, which is about 4.3 times the mass of our Sun.
That makes this black hole a so-called “stellar mass” black hole, not a supermassive one like at the center of the Milky Way. The star that’s doing the, uh, dancing has .8 solar mass.
Intermediate mass black holes of 50 solar masses have been found in globs before, but this is the first stellar mass BH that’s been found.
However, black holes have been proven so rare in globular clusters that until recently scientists assumed they must get kicked out shortly after they form. This discovery suggests that’s not necessarily the case.
Which is lucky for this star, as it would have lost its dancing partner.
Hey, Here’s A Cool Fact:
The MUSE instrument provides the astronomers with a unique capability to study the spectra of thousands of stars at the same time. It’s now being used in a large survey of 25 globs in the galaxy.
This BH is inactive, which means it’s not feeding on gas & dust and it’s not showing up in the X-ray part of the spectrum. It’s on the QT and laying low and was only detected by it’s gravitational effect on its companion.
Up till this discovery it was assumed that almost all BHs would be flung out of globs and very few would still be there in the glob after a billion years. Thus it was assumed that systems like this one shouldn’t even exist.
But clearly it does exist! Back to the drawing board, uh, blackboard! Time for a re-think!
Thank you for listening to the 365 Days of Astronomy Podcast!
End of podcast:
365 Days of Astronomy
The 365 Days of Astronomy Podcast is produced by Astronomical Society of the Pacific. Audio post-production by Richard Drumm. Bandwidth donated by libsyn.com and wizzard media. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. This year we will celebrates the Year of Everyday Astronomers as we embrace Amateur Astronomer contributions and the importance of citizen science. Join us and share your story. Until tomorrow! Goodbye!