Talk:Hubble discovers 16 new planets

Notes from presentation given by Dr. Sahu September 21, 5pm
Project: SWEEP – Sagittarius Eclipsing Extra solar Planet Search Sag – Crowded field, in galactic center, northern sky Searching for planets coming in front of star The entire time, for seven days Doubles the amount of known transiting planets (previously 10, 200 by rad. Vel., 2 by microlensing) Ultra short period planets as well (periods around half a day) 5 less than any other period Many large gassy ones found close to star with short periods All found in galactic disk 2 kpc away, relatively massive stars First attempt, none found, expected 17 – Ron Gilliland, globular cluster, very little heavy elements Monitored star’s light curve – must be consistent with that of a planet 1/10000 would be candidates looked at 180,000 stars, so expect to find 18 other phenomena can mimic, but can be accurately predicted. At least 50% must be planets (conservative estimate) two of the stars bright enough for rad. Vel, in order to verify (Chili scope) most of the candidates are like our sun (high element abundance), proving what kind of stars planets form around on average, higher mass star means more heavy elements Hubble instrument just recently installed (2002) Before couldn’t see to galactic bulge Farther and fainter than ever before Planets equally abundant in area Expect Jupiter sized planets, a couple smaller than Saturn Took full year to process data Most amount of data HST has collected in a single week Can use data for other searches 100 billion stars out there, 6% have planets, with confidence can say 6 billion jovian planets “The biggest surprise would be if there are no more surprises.” – Sahu “We could answer the questions we started out with.” – Sahu The planets are too big to form with star Has to get trapped in the orbit “The most complex project I have worked on.” – Sahu

Phone interview with Dr. Sahu – September 27
ME: How do you know it’s not a dwarf? SAHU: cannot rule out everything. But at least 50% have to be planets. We know how many eclipsing stars there are, estimate how many dwarfs, extrapolate from that. A majority must be planets. Found way more eclipsing objects than number of red dwarfs that were expected.

ME: What is the shortest distance of planet from the star? SAHU: Shortest distance from star: 4.1 stellar radii, same as the ones with even larger periods, but in absolute units, .008 AU is the shortest. 740,000 miles

ME: Can you expect to confirm the rest? SAHU: James web space telescope 2013 best chance of confirming the rest

ME: how can you be sure they are all planets? SAHU: lots of statistical analysis. “It gives us confidence that at least a majority of them have to be planets,” would be surprised of all of them turned out to be.

Notes from Phone interview with Sara Seager September 28
Radial velocity only tells us the minimum mass Transit tells us the size and the mass, and from that we can determine the density, which is an important tool in discovering what kind of planet it is. Three of the new planets are unusual, and we can’t fit them into the standard model. One is like Saturn. “We know it’s a planet, but it’s a crazy planet” 2/3 of it is rock. More rock and ice than our whole solar system. Some are so big, that we can’t explain them. There has to be some sort of extra energy in its core. It’s also easier to detect a small planet by transit than by radial velocity There are two paths you can take to learn about a planet. You can image, but the star is so bright, you can’t usually see anything. Then there is transiting. Using this, you can learn all about the planet. "This is tremendously exciting. It doubles the amount of transiting planets found." "There are lots of nasty tricks nature can pull on us." and because we can't be 100% sure of all of them "I think people will take issue with that."

The above notes were compiled and originally posted by Mputney.

Good Job
Good work...Sorry I could not reply earlier. Jason Safoutin 20:53, 5 October 2006 (UTC)

Image tagged
The image on this article has been tagged on Commons, it'll need uploaded locally if that can't be quickly resolved. --Brian McNeil / talk 21:02, 5 October 2006 (UTC)


 * Commons always deletes images, even if they are sourced. Trust me because I've experienced darn image problems at that site :(