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.
Triplet Planets Found Around Newborn Star
There have been over 3,700 exoplanets discovered so far. The smallest exoplanet we’ve found is about the size of our Moon, while the largest is 28 times the diameter of Earth!
Some seriously clever techniques have been used to hunt down these alien worlds. One way is watching for the slight wobble of a star as a planet gently tugs it this way and that with its gravity.
The wobble is detected by looking at the spectrum of the star and spotting the doppler shift of the light as the star comes slowly closer and then farther away from us.
Another way is to look for the extremely slight dimming of a star when a planet passes in front of it as seen from here on Earth.
And a very few exoplanets have been found by direct imaging, or simply taking a photo of them with a big honking telescope.
But to find the youngest planets astronomers have had to go back to the drawing board and find another way altogether. The exoplanet hunting strategies that have been used so far don’t work for protoplanets, or planets that are still in the process of forming.
Young stars are surrounded by thick discs of gas and dust, making them ideal planet-forming factories. After all, planets are made when small bits of gas and dust clump together, growing larger and larger until a planet is born.
But that disk of gas and dust around young stars also tends to hide any newly-made planets that are in there. The dust is especially bothersome.
To uncover these planets a brand new technique was needed, one that allows us to ignore the dust altogether and just look at the motion of the gas that’s there.
With the ALMA radiotelescope array in the Atacama Desert of Chile we have just the tool we need to find these elusive planets.
Two teams of astronomers have used ALMA to study the young star HD 163296. It’s a star in the constellation Sagittarius, which has 1.9 times the mass of the Sun and is only 4.4 million years old.
The gas around stars moves in a very simple and predictable way… unless there’s a planet involved, mucking things up.
Planets cause unusual movements in the gas, a bit like the whirlpools you see in a river as water moves around a rock.
One team, led by a Dr. Teague with astronomers from Michigan, Carnegie & Munich found 2 planets. A 1 Jupiter-mass planet at 83 AU and a 1.3 Jupiter-mass planet 137 AU away from the star.
The other team, using a technique that favored finding protoplanets that are farther out, and led by one Dr. Pinte with astronomers from Monash, Grenoble and Berkley, found 1 planet at 260 AU from the star.
By carefully studying the movement or kinematics of the CO, or carbon monoxide, gas in the dusty shell surrounding the star, the two teams of astronomers were able to tease out the locations of the 3 protoplanets.
We’ve found gaps in protoplanetary disks before that were suggestive of planets forming there, but this is the very first time we can say with certainty that we’ve found planets around such a young star!
Hey, Here’s A Cool Fact:
This new technique is similar to the way the planet Neptune was discovered. The planet Uranus was spotted moving in an unusual way. It was being pulled out of its normal orbit by the gravity of an unknown object.
By taking very careful measurements of Uranus and using some complex math, Neptune’s location was discovered.
French mathematician Urbain Le Verrier published his calculations on August 31st of 1846. He made them available to astronomer Johann Galle of the Berlin Observatory the following month.
Galle received the letter from Le Verrier on September 23rd, 1846. That very night, after less than an hour of observing and just after midnight into September 24th, Galle and his student d’Arrest found Neptune. It was less than 1° from where Le Verrier had predicted it would be.
The first test of Newton’s law of universal gravitation was Henry Cavendish’s 1798 torsion balance experiment. With the Neptune discovery Le Verrier had also verified Newton’s law!
Mathematics had found a planet!
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!