Weekend Update: Kepler Space Mission Locates 18 new Jupiter-sized Planets


Researchers at the California Institute of Technology (Caltech) using twin telescopes at the Keck Observatory in Hawaii, surveyed about 300 stars, and focussed on those dubbed “retired” A-type stars that are more than one and a half times more massive than the sun. The team identified 18 new Jupiter-like planets orbiting massive stars.

These stars are just past the main stage of their life hence, “retired”, and are now evolving into what’s called a subgiant star.

“It’s the largest single announcement of planets in orbit around stars more massive than the sun, aside from the discoveries made by the Kepler mission,” John Johnson, first author on the paper, said.

The astronomers searched for stars of this type that wobble, which could be caused by the gravitational tug of an orbiting planet. By searching the wobbly stars’ spectra for Doppler shifts, the lengthening and contracting of wavelengths due to motion away from and toward the observer, the team found 18 planets with masses similar to Jupiter’s.|

According to Johnson, this new bounty marks a 50 percent increase in the number of known planets orbiting massive stars and, provides an invaluable population of planetary systems for understanding how planets, and our own solar system, might form.

The researchers say that the findings also lend further support to the theory that planets grow from seed particles that accumulate gas and dust in a disk surrounding a newborn star.
According to this theory, tiny particles start to clump together, eventually snowballing into a planet. If this is the true sequence of events, the characteristics of the resulting planetary system like the number and size of the planets, or their orbital shapes will depend on the mass of the star.

In another theory, planets form when large amounts of gas and dust in the disk spontaneously collapse into big, dense clumps that then become planets. But in this picture, it turns out that the mass of the star doesn’t affect the kinds of planets that are produced.

So far, as the number of discovered planets has grown, astronomers are finding that stellar mass does seem to be important in determining the prevalence of giant planets.

The newly discovered planets further support this pattern, and are therefore consistent with the first theory, the one stating that planets are born from seed particles.

“It’s nice to see all these converging lines of evidence pointing toward one class of formation mechanisms,” Johnson added.

The Kepler space telescope has uncovered some 140 candidate planets the size of Earth circling other stars, potentially reshaping our view of the universe. Launched in March 2009, Kepler's sensitive camera stares at a field of stars in the constellations Cygnus and Lyra. The telescope looks for tiny dips in each star's brightness, a sign something is passing between the star and the Kepler spacecraft.

Harvard's Dimitar Sasselov noted the targets were just candidates, but he said the data points to an exciting possibility. "The statistical result is loud and clear," Sasselov said. "And the statistical result is that planet like our own Earth are out there. Our own Milky Way galaxy is rich in these kind of planets."

After 2013, America’s amazing career of planetary exploration, which ran from the Mariner probes in the 1960s through the great Pioneer, Viking, Voyager, Pathfinder, MarsGlobalSurveyor, MarsOdyssey, Spirit, Opportunity, MarsReconnaissanceOrbiter, Galileo and Cassini missions, will come to an end.

Additionally, the plan from the Office of Management and Budget (OMB) also leaves Hubbles successor, the Webb Telescope, the agency’s flagship, which promises fundamental breakthroughs in our understanding of the laws of the universe, not sufficiently funded to allow successful completion.

Kepler has so far found five extrasolar planets, all of which are massive "hot Jupiters" about the size of the gas giant planets in our own solar system. NASA scientists hope to announce more planets this winter, according to William Borucki, Principal Investigator at NASA Ames Research Center.

Before the mission launched, Kepler officials advertised finding at least 50 Earth-sized planets inside habitable zones, assuming such worlds are common.

Scientists released Kepler data on more than 150,000 stars in June, including about 300 stars with planetary candidates. Kepler officials retained data on approximately 400 stars to do their own follow-up observations with ground telescopes this summer.

"We found a lot of candidates," Borucki said. "Many of them are smaller than Neptune-sized, and that's wonderful."

The data only covers 43 days of observations because it takes about four months to process observations into usable formats.


The Daily Galaxy via the Astrophysical Journal Supplement Series

Image courtesy Mike Wong, Franck Marchis & W.M. Keck Observatory

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