Podcaster: Richard Drumm
Title: UNAWE Space Scoop – When Stars Wobble
Organization: 365 Days Of Astronomy
Description: Space scoop, news for children.
Using the VLBA, the National Science Foundation’s Very Long Baseline Array of radio telescopes, astronomers have found a Saturn-sized planet orbiting a small, cool star that’s only 35 light years away! It’s called TVLM 513–46546, it’s in the direction of the constellation Boötes and it’s right in our neighborhood! The planet has about a third of Jupiter’s mass and is closer to its star than Mercury is to our Sun and it orbits its star once every 221 days.
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…
When Stars Wobble
Using the VLBA, the National Science Foundation’s Very Long Baseline Array of radio telescopes, astronomers have found a Saturn-sized planet orbiting a small, cool star that’s only 35 light years away!
It’s called TVLM 513–46546, it’s in the direction of the constellation Boötes and it’s right in our neighborhood! The planet has about a third of Jupiter’s mass and is closer to its star than Mercury is to our Sun and it orbits its star once every 221 days.
The star is an M9 dwarf star, a red dwarf. It’s the most common type of star in the galaxy, and has about 6 to 8 percent of our Sun’s mass.
What makes this planet special is not so much what it is, but the so-called “astrometric technique” by which it was found.
Astrometry is the science of measuring star positions.
Astronomers have found more than 4,000 exoplanets beyond our solar system. In fact, we expect there are millions if not billions more!
All but a handful of these exoplanets were found without seeing them directly. Instead, astronomers have to use several special indirect techniques to find them.
This astrometric technique has long been theorized, but it’s not easy for astronomers to use. The telescope needs to take insanely precise measurements of the star’s position in the sky to pull off the detection.
Then over a period of years the telescope very carefully follows the star’s motion as it travels through space. In this case the telescope detected a teeny tiny “wobble” in the star’s movement.
Now stars don’t just wobble for the fun of it!
The wobble is caused by the gravitational pull of the planet as it orbits the star. And the planet is invisible! Only the star’s small wobble is detected.
And once this wobble is detected, the astronomers can then use mathematics to calculate where the planet is located and how massive it is and what the planet’s orbital period is or how long it’s “year” is.
Hey Here’s A Cool Fact:
This is only the second time that an exoplanet has been discovered using this technique! In 2010 another exoplanet was found using astrometry, but an optical telescope was used in that case.
This is the first time a radio telescope was used for the astrometric technique. And the VLBA array is the only radio telescope with high enough resolution to make this observation.
The right tool for the right job!
Thank you for listening to the 365 Days of Astronomy Podcast!
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365 Days of Astronomy
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