CIS: Looking for Earths by Looking for Jupiters

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CIS: Looking for Earths by Looking for Jupiters

Post by bystander » Tue May 08, 2012 12:02 am

Looking for Earths by Looking for Jupiters
Carnegie Institution for Science | 2012 May 07
In the search for Earth-like planets, it is helpful to look for clues and patterns that can help scientist narrow down the types of systems where potentially habitable planets are likely to be discovered. New research from a team including Carnegie’s Alan Boss narrows down the search for Earth-like planets near Jupiter-like planets. Their work indicates that the early post-formation movements of hot-Jupiter planets probably disrupt the formation of Earth-like planets.

Their work is published the week of May 7 by Proceedings of the National Academy of Sciences.

The team, led by Jason Steffen of the Fermilab Center for particle Astrophysics, used data from NASA’s Kepler mission to look at so-called “hot Jupiter” planets—those roughly Jupiter-sized planets with orbital periods of about three days. If a Jupiter-like planet has been discovered by a slight dimming of brightness in the star it orbits as it passes between the star and Earth, it is then possible—within certain parameters—to determine whether the hot-Jupiter has any companion planets.

Of the 63 candidate hot Jupiter systems identified by Kepler, the research team did not find any evidence for nearby companion planets. There are several possible explanations. One is that there are no companion planets for any of these hot Jupiters. Another is that the companions are too small in either size or mass to be detected using these methods. Lastly it is possible that there are companion planets, but that the configuration of their orbits makes them undetectable using these methods.

However, when expanding the search to include systems with either Neptune-like planets (known as “hot Neptunes”), or “warm Jupiters” (Jupiter-sized planets with slightly larger orbits than hot Jupiters), the team found some potential companions. Of the 222 hot Neptunes, there were two with possible companions, and of the 31 warm Jupiters, there were three with possible companions.

“The implications of these findings are that systems with Earth-like planets formed differently than systems with hot Jupiters,” Boss said. “Since we believe that hot Jupiters formed farther out, and then migrated inward toward their stars, the inward migration disrupted the formation of Earth-like planets. If our sun had a hot Jupiter, we would not be here.”

Some giant planets in other systems most likely to be alone
University of Florida | 2012 May 07

ScienceShot: Hot Jupiters Are Loners
Science NOW | Ken Croswell | 2012 May 07

Kepler constraints on planets near hot Jupiters - Jason H. Steffen et al
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— Garrison Keillor

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Astrophile: Hot Jupiters oust their siblings

Post by bystander » Wed May 09, 2012 2:02 am

Hot Jupiters oust their siblings
New Scientist | Astrophile | Maggie McKee | 2012 May 07
Object: Planets with diameters between 0.6 and 2.5 times that of Jupiter
Orbital periods: 0.8 and 6.3 days

Our solar system, 4.5 billion years ago: a giant, newly born planet senses its nest mate Jupiter nearby and nudges closer, comforted by the fact that Jupiter seems to be coming in for a cuddle too. But when the two infant worlds approach, there is no time to react when Jupiter's true intention becomes terrifyingly clear. The gargantuan planet, named after the king of the gods, flings its shell-shocked sibling into interstellar space and sets off on a rampage through the inner solar system.

One by one, Mars, Earth, Venus and Mercury are all tossed out of their orbits as Jupiter swings around our star on a path that takes it from the outer solar system to the sun's searing doorstep. Eventually, the sun tames this wild child, drawing the planet into a tight orbit around it. Sadly, that comes too late to save the rest of Jupiter's victims, which have been cast out into the cold, cruel void.


"It's fortunate for us" that scenario didn't happen, says Jason Steffen of Fermilab in Batavia, Illinois. "Had Jupiter gone through this history, it would have tossed out all the planets interior to it and possibly some exterior ones as well."

But that's exactly what seems to have transpired around other stars, according to new exoplanet observations analysed by Steffen and his colleagues. "It appears there are systems where big brother was not friendly," says Steffen.

The researchers analysed exoplanet observations from NASA's Kepler telescope, which launched in 2009 to look for the telltale dimming of stars due to planets passing in front of, or transiting, them.

They hunted for planetary siblings around 63 Jupiter-sized worlds that take less than seven days to whip around their stars. Their search was sensitive up to distances corresponding to about twice the orbital periods of these so-called hot Jupiters, or about one-tenth of the distance between Mercury and the sun. "We didn't find any," says Steffen.

He says the dearth of nearby planets suggests that the hot Jupiters formed farther out, and after a run-in with another planet or star, were pushed onto elongated orbits that ultimately led them to cross paths with any planets between their original orbits and the sun.

"It's like you have a snow plough pushing cars away, but it comes back the next day and the next day," explains Avi Mandell of NASA's Goddard Space Flight Center in Greenbelt, Maryland. "Even if you don't happen to be home one day, the next day you'll probably get hit."

However, Mandell says there may well be planetary companions around hot Jupiters at distances larger than the tight orbits probed in this earliest batch of Kepler data.

One thing, however, is clear – at least in a fair fraction of cases, "hot Jupiters are lonely," says team member Eric Ford of the University of Florida, Gainesville.

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Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
— Garrison Keillor