Podcaster: Richard Drumm
Title: Space Scoop: The Twist Marks the Spot
Organization: 365 Days Of Astronomy
Description: Space scoop, news for children.
In the accretion disc of AB Aurigae, astronomers observed a clear overall spiral structure with a little twist or a spiral kink in one of the large spiral arms of the accretion disc that marks the spot where a planet may be forming.
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.
Today’s story is…
The Twist Marks the Spot
Thousands of exoplanets have been found so far, but we still know little about how they’re formed. What we do know is that planets are born in dusty protoplanetary discs surrounding young stars.
In 2014 I saw online the fabulous image that ALMA made of HL Tauri and was absolutely gobsmacked. Google it, click on “Images” and you, too, can have your gob smacked!
This sort of thing is what happens when cold gas and dust clump together. By closely examining this nursery and others like it, astronomers now hope to understand how they’re born.
But we’ve never observed direct evidence of a baby planet coming into existence within such a disc, until now.
Around the young star called ‘AB Aurigae’ in the wintertime constellation Auriga the Charioteer, and located 520 light-years away from Earth lies another of these dense protoplanetary discs of gas and dust.
Now, such discs have been detected around many young stars before, but a team of astronomers using the VLT, the Very Large Telescope at the Paranal Observatory found a peculiar feature that they hadn’t seen before.
In the accretion disc of AB Aurigae, they observed a clear overall spiral structure with a little twist or a spiral kink in one of the large spiral arms of the accretion disc that marks the spot where a planet may be forming.
This twist feature could be the first direct evidence of a baby planet coming into existence. This, uh, “baby” is located at about the same distance from its star as Neptune is from our Sun, so it’s not very close in by our solar system’s standards.
The obvious gaps in the HL Tauri image are indirect evidence of planets, but this AB Aurigae image is direct evidence. That’s an important distinction.
Until now, astronomers had been unable to get images of these young discs that are sharp enough to reveal structure like this.
Large scale spiral structures, like the one in the AB Aurigae disc, have been seen before in discs surrounding other young stars. Spirals of this type signal the presence of the gravity of baby planets.
The planet’s gravity pulls the gas, creating a wave in the disc. You can think of this as similar to how a boat creates waves by pushing water away while moving through it. As the planet circles around the star, the waves of gas and dust in the disc create the spiral structure.
We’ve seen something similar in Saturn’s rings where a small moonlet is interacting with the ice in the ring, making a small spiral shape in the ring particles. At Saturn the spirals are called “propellers” and are vastly smaller features than the AB Aurigae discovery.
Hey Here’s A Cool Fact:
Because of the clear skies at the Paranal Observatory in the Atacama Desert in Chile, the telescopes there can achieve stunningly clear observations of the cosmos.
The VLT is actually made up of four large individual telescopes that can operate separately or together as a team, as an interferometer. Each of these telescopes hosts a large 8.2 meter mirror that concentrates the light that is captured by the telescope. That’s 322 inches in diameter!
Each of the telescopes that make up the VLT can detect objects in space that are roughly four billion times fainter than can be detected with the naked eye!
But wait! There’s more!
In the near-infrared part of the spectrum the VLT’s adaptive optics systems can produce images that are up to 3 times as sharp as the Hubble Space Telescope!
Thank you for listening to the 365 Days of Astronomy Podcast!
End of podcast:
365 Days of Astronomy
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