Thursday, January 26, 2012

NASA's Kepler Misson Reveals New Planetary Systems


NASA's Kepler mission has continued to advance our knowledge of planetary systems with the recent discovery of 11 new systems hosting 26 confirmed planets. With the latest data now released by NASA the total number of planets revealed by Kepler has nearly doubled, and the number of stars known to have more than one planet that passes before their host star has tripled.

These discoveries are expected to help astronomers better develop our understanding of how planets are formed. The planets recently discovered range in size from 1.5 times to radius of Earth to larger than Jupiter. Fifteen of the planets range in size between that of Earth and Neptune, and further observations will be made to determine which worlds are rocky like Earth, and which have thick gaseous atmospheres more like Neptune. The planets found by Kepler orbit their host star between every six to 143 days, and all are closer to their host star than Venus is to our sun.

According to a NASA press release:

"Prior to the Kepler mission, we knew of perhaps 500 exoplanets across the whole sky," said Doug Hudgins, Kepler program scientist at NASA Headquarters in Washington. "Now, in just two years staring at a patch of sky not much bigger than your fist, Kepler has discovered more than 60 planets and more than 2,300 planet candidates. This tells us that our galaxy is positively loaded with planets of all sizes and orbits."

Kepler identifies planet candidates by repeatedly measuring the change in brightness of more than 150,000 stars to detect when a planet passes in front of the star. That passage casts a small shadow toward Earth and the Kepler spacecraft.

“Confirming that the small decrease in the star's brightness is due to a planet requires additional observations and time-consuming analysis," said Eric Ford, associate professor of astronomy at the University of Florida and lead author of the paper confirming Kepler-23 and Kepler-24. “We verified these planets using new techniques that dramatically accelerated their discovery.”

Each of the new confirmed planetary systems contains two to five closely spaced transiting planets. In tightly packed planetary systems, the gravitational pull of the planets among themselves causes one planet to accelerate and another planet to decelerate along its orbit. The acceleration causes the orbital period of each planet to change. Kepler detects this effect by measuring the changes, or so-called Transit Timing Variations (TTVs).

“By precisely timing when each planet transits its star, Kepler detected the gravitational tug of the planets on each other, clinching the case for ten of the newly announced planetary systems,” said Dan Fabrycky, Hubble Fellow at the University of California, Santa Cruz and lead author for a paper confirming Kepler-29, 30, 31 and 32."

No comments: