June 6, 2014
So, there have been two exciting planetary discoveries last week:
a) Two planets have been discovered around Kapteyn star, which is around 13 light years away. Since planets form with the star at around the same time, and the star is around 11.5 billion years old, the planets are the oldest known. Kapteyn star itself is likely to be a star of another tiny galaxy absorbed into the Milky Way, the remnant of that galaxy being the globular cluster Omega Centauri. Both planets are super Earth, with Kapteyn b having the possibility of liquid water to exist. Link here and here.
b) The most massive terrestrial planet yet has been discovered, and it is dubbed a mega Earth. Kepler 10c is 17 times the mass of the Earth, which is basically around Neptune’s mass. The size, though, is 2.3 times the Earth. This means the object has the density of a rock, so we know it can’t be a gas giant planet like Neptune. It is indeed a new type of planet, since a rocky planet is not expected to be this massive. I love surprises like this! More here and here.
January 24, 2014
First of all, yes, 3 planets doesn’t count as a “planet”, singular, I know, but it sounds better this way… Whatever, on to the topic.
While this is not the first time, it is pretty cool that three planets have been found in an open cluster. This one is called the Messier 67. Open clusters are group of stars numbering in the thousands that are born from the same gas cloud. So for example, Orion Nebula may one day be an open cluster! Anyways, these open clusters eventually dissipate and the stars go on on their own. As for why this is important is the fact that crowded open clusters are believed to be planet unfriendly. That doesn’t mean it is impossible, but it does mean that finding some make them quiet special and fascinating to study at.
All three planets are gas giants. They were found by measuring the wobble of the parent star with the Doppler Shift. While we may not exactly know their size, we know their mass. They are 0.34, 0.40, and 1.54 times the mass of Jupiter. Let me remind you, of course, that all scientific measurements have uncertainties, and the one for the third one is particularly large, plus/minus 0.24. Interestingly, two of them orbit around sun like stars, although slightly less luminous than the sun (sun has luminosity 2, these two stars have luminosity 5). The planets themselves, though, orbit too close. They are the hot Jupiter varieties, and there is nothing like them in the Solar System. That similarity and contrast is what makes those planets very interesting. The planet more massive than Jupiter, on the other hand, orbit a giant star, but farther away. This one has what one might say a more reasonable orbit.
Other than that, there is not much more to say. They happen to be pretty cool because they were found in tight open clusters. You can look at the study, if you want all the nitty gritty details. You can also get a good summary from Universe Today here.
January 16, 2014
KOI-314c is a recently discovered Earth massed planet. Its density is also quiet low considering that the planet’s diameter is 1.6 times the Earth. It was discovered using the Kepler telescope, which detects the dimming of a star as the planet orbits in front of it. The press release I linked above has tons of information about it. Badastronomy also has a great general summary here.
Speaking of planets larger than the Earth, but smaller than Neptune, the most common types of planets to be discovered seems to be those. Thanks to Kepler, we are getting a better idea of the size distribution of planets, at least those that orbit close to the star. Of course, the planets are not going all going to be of the same density. Some might be rocky, others could be icy, and it could also be gassy like Neptune. Based on the measurements of the densities, most of them seem to be the gaseous kind. Another noteworthy point about this discovery is that the Solar System has no planet of this kind even though it is extremely common in the universe. Of course, this doesn’t make the Solar System special, it just got the way it is by the laws of physics and chance. Still, it is a cool fact, and it shows how diverse star systems and planets are.
October 31, 2013
This Earth sized planet is really close to its star, completing an orbit in 8.5 hours. It is so hot that its surface is probably melted. Its density shows it is similar in composition to planet Earth, so it probably has an iron core wrapped with rock. How it got so close, scientists are trying to figure out, since the various scenarios they have in mind doesn’t seem to be adequate. More details here. If only I could get behind the paywall for the studies. *sigh*
January 9, 2011
This is so last year, but I want to post this for the interest of general education. The reason I am posting it this late is because I forgot, but now that I remembered, here it is. The reason I am posting this is that in astronomy, the search for extrasolar planet is more relevant than ever. Better and better technologies like the Kepler space telescope are being used to probe the vast expanses of our galaxy in search of habitable planets. The e-mail interview below is one I did for my English research report for college, but I believe you may find it of benefit too. The topic is on the method of searching extrasolar planets and some of the discoveries astronomers have made. The one being interviewed is Christine Pulliam, public affairs specialist from the Harvard-Smithsonian Center for Astrophysics, to whom I am very thankful for spending some of her probably precious time answering my request and allowing me to post this. I hope you enjoy it: Read the rest of this entry »