Category Archives: exoplanets

american astronomical society, exoplanets, Kepler mission

AAS: The Firehose of Astronomy

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https://i0.wp.com/www.cfa.harvard.edu/image_archive/2013/2/lores.jpg?resize=369%2C294
This artist’s illustration represents the variety of planets being detected by NASA’s Kepler spacecraft. A new analysis has determined the frequencies of planets of all sizes, from Earths up to gas giants. Key findings include the fact that one in six stars hosts an Earth-sized planet in an orbit of 85 days or less, and that almost all sun-like stars have a planetary system of some sort. (Hat tip to Robert Hurt for inspiring this illustration.)
Courtesy C. Pulliam & D. Aguilar (CfA)

Every January, I journey out to the American Astronomical Society for its annual Winter Meeting. And, every time, I’m amazed at new bit of information about the universe. Today’s revelation (and it’s only Day 1 of the meeting), is that the Milky Way Galaxy is populated with many planets — in fact, one team of scientists estimates that at least one out of every six stars in the galaxy has an Earth-sized planet.

That, my friends, is pretty profound.

If you postulate that the Milky Way has about a hundred billion stars, that means there are at least 17 BILLION Earth-sized planets in our galaxy. Again, that’s pretty profound. Now, the next question everybody will ask is, “How many of those are capable of supporting life?” And to answer that question requires a lot more observation. First, to support life, those planets need to be orbiting close enough to their stars that liquid water will be available to sustain life on them. Then, scientists need to look at the other conditions on the planets, and look for “bio signatures” in the planets’ atmospheres that indicate life could be there. So, even though there could be the potential for 17 billion Earth-sized worlds out there, that doesn’t say they are Earth-like… or that they have life. But, there are 17 BILLION Earth-sized worlds out there. Up until the last decade of the 20th century, we didn’t know of any.

Thanks to the Kepler Mission, which has been cranking out planetary candidate discoveries for some time now, the hunt for planets is now an understood and successful ongoing project.

Want to read more details about how the scientists came up with their numbers? Check it out here. And, stay tuned for more AAS news!

Beehive Cluster, exoplanets

Planets Just Keep Surprising Us

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They Show Up in the Darndest Places!

So, planets aren’t just for our solar system anymore. The Kepler Mission is showing us that in the field of view it’s viewing, there are probably well over a thousand worlds circling distant stars (maybe more).  Before Kepler blasted off on its planet-finding survey, ground-based astronomers were finding worlds, too.  Add to that the current crop of ground-based telescopes and the COROT mission findings and the field of planetary exploration beyond our solar system is wide open for discovery!

Every time astronomers spot more planets, the findings rewrite the rule books about planets and where they could possibly exist.  Astronomers once thought that pulsars couldn’t have planets. And, that massive, Jupiter-type planets probably formed well away from their stars. And that clusters packed with stars probably didn’t have planets.

Well, all of those rules have been broken. There WAS a pulsar with a planet spotted in 1992, and it was a great discovery.  More recently, there have been enough so-called “hot Jupiters” discovered close to their stars that astronomers have been reconsidering theories of planetary formation to account for just how those hot bad boys get up close and personal with their stellar hosts.

Astronomers have discovered two gas giant planets orbiting stars in the Beehive cluster, a collection of about 1,000 tightly packed stars. Image credit: NASA/JPL-Caltech

Now, the first time, astronomers using a ground-based instrument at the Smithsonian Astrophysical Observatory’s Fred Lawrence Whipple Observatory in Arizona found two planets as they studied the crowded inner regions of the Beehive Cluster, which is a pretty crowded place for a planet to grow up.  They found these so-called “hot Jupiters” by measuring the slight gravitational wobble that orbiting planets cause in the motions of their parent stars.

This was something of a surprise because earlier searches of other clusters had turned up two planets around massive stars but none had been found around stars like our Sun until now.

The two new Beehive planets are called Pr0201b and Pr0211b. The star’s name followed by a “b” is the standard naming convention for planets.

So, what does this discovery mean?  Identifying a couple of boiling hot planets in a crowded starfield is pretty good evidence that planets can sprout up just about anywhere. I mean, if they can exist near pulsars, which are pretty hostile environments created by the deaths of supermassive stars, then cropping up in a region where the stars are thick (but not yet dying) may not be so difficult.

If you’ve never seen the Beehive, it’s a cluster most easily visible overhead starting in early spring.  All its stars formed from the same nebular birthplace, so they have pretty much the same chemical compositions.  So, at least two of the stars have enough heavy elements surrounding them in circumstellar space to create planets.

Want to learn more about these Beehive Bad Boys?  Check out the NASA press release right here!