Jul 20th: Is it a Star, is it a Planet? No! It’s a Brown Dwarf!


Podcaster: Richard Drumm
Space Scoop: Is it a Star, is it a Planet? No! It’s a Brown Dwarf!

Organization:365 Days Of Astronomy

Link : astrosphere.org ; http://unawe.org/kids/unawe1718/

Description: Space scoop, news for children.

When the Solar System was formed, there were lots of spare pieces left over. These spare pieces are called asteroids and comets.

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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.

Is it a Star, is it a Planet? No! It’s a Brown Dwarf!
As clouds of cosmic gas shrink, they grow denser and hotter. When the temperature at the core reaches a scorching 10 million degrees Centigrade, the clump officially flares into life as a bright new star.

But not all collapsed clouds are massive enough to manage to reach the extreme temperatures needed to be born as a star. Those that don’t are known as failed stars, or ‘Brown Dwarfs’.

Brown dwarves are half way between gas giant planets, like Jupiter and Saturn, and stars. They have from 13 to 75 times the mass of Jupiter.

Stars like our Sun fuse hydrogen into helium in their cores and generate a good amount of heat and light. Brown dwarves, on the other hand, are thought to possibly fuse deuterium and lithium, generating only a little energy.

They shine dimly, and can have planets around them like stars, but they have atmospheres, clouds and storms, like planets have.

Like stars, brown dwarfs create their own light, because they are hot. They glow a dim red in visible light and shine much more brightly in invisible infrared light, like the light used in TV remote controls.

Overall, brown dwarfs are smaller, dimmer and cooler than main sequence stars.

This makes them remarkably difficult to spot. So far, we’ve found approximately 3,000 in our galaxy. But astronomers think that many more are lurking in the dark, behind dust lanes and invisible to our telescopes.

In fact, a team of astronomers searching for these failed stars, expected that they’d find few brown dwarves in small star clusters, and more in large, dense clusters.

To test this theory they looked in the nearby, small star cluster NGC 1333 in the constellation Perseus. They were surprised when they found found one brown dwarf for every two stars!

Then they looked in the constellation Vela in the southern skies, at the more distant and much denser star cluster RCW 38.

Though they expected to find that the higher star density of the Vela cluster would produce more brown dwarves, they found the same large numbers of them as they had in the smaller cluster.

So there’s no evidence that the density of the star cluster has much effect on the rate of brown dwarf production.

In the areas they’ve studied so far they found from 2 to 5 brown dwarves for every 10 regular, main sequence stars. So brown dwarf formation appears to be a universal process.

The Milky Way forms about 4 main sequence stars a year, and 1 or 2 brown dwarves a year as well.

If this is what we can expect across our entire galaxy, it could be that the total number of brown dwarfs in the Milky Way are between 25 to 100 billion!

And this estimate doesn’t include the smallest and faintest brown dwarfs, so that number could actually be much higher! The new generation of super telescopes like the EELT will provide us with more data and answer many of our questions.

Hey, Here’s A Cool Fact:
Though brown dwarves can have many times Jupiter’s mass, their size is about the same as Jupiter. The gasses are more dense, but occupy approximately the same volume.

So if you were to take 50 more Jupiters and pile them all on top of our Jupiter, the resulting planet would basically be the same size. Just more massive is all.

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 Astrosphere New Media. 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 celebrate more discoveries and stories from the universe. Join us and share your story. Until tomorrow! Goodbye!

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