Extrasolar Planets | Universe Today

The exoplanet HAT-P-7b has been observed to have a very curious orbit. It either has a highly tilted orbit – passing almost over the poles of its parent star, HAT-P-7 -  or a retrograde orbit; that is, orbiting in the opposite direction of its parent star. Two teams of researchers, both using the Subaru Telescope in Japan, have published papers on the bizarre properties of this planet, the second exoplanet ever observed to have a retrograde orbit. Read more…

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For decades, astronomers have known our Sun contains a low amount of lithium, while other solar-like stars actually have more. But they didn't know why. By looking at stars similar to the Sun to study this anomaly, scientists have now discovered of a trend: the majority of stars hosting planets possess less than 1% of the amount of lithium shown by most of the other stars. “The explanation of this 60 year-long puzzle is for us rather simple,” said Garik Israelian, lead author on a paper appearing in this week's edition of Nature. “The Sun lacks lithium because it has planets.”

This finding sheds light not only on the lack of lithium in our star, but also provides astronomers with a very efficient way of finding stars with planetary systems.
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NASA's Spitzer Space Telescope captured this infrared image of a giant halo of very fine dust around the young star HR 8799. Image credit: NASA/JPL-Caltech/Univ. of Ariz.

Just what is going on over at the star HR 8799? The place is a mess! But we can just blame it on the kids. Young, hyperactive planets circling the star are thought to be disturbing smaller comet-like bodies, causing them to collide and kick up a huge halo of dust. HR 8799 was in the news in November 2008, for being one of the first with imaged planets. Now, NASA's Spitzer Space Telescope has taken a closer look at this planetary system and found it to be a very active, chaotic and dusty system. Ah, youth: our solar system was likely in a similar mess before our planets found their way to the stable orbits they circle in today.
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A glitch in the Kepler spacecraft's electronics means the space telescope will not have the ability to spot an Earth-sized planet until 2011, according to principal investigator William Borucki. Noisy amplifiers are creating noise that compromises Kepler's view, and the team will have to generate and upload a software fix for the spacecraft. "We're not going to be able to find Earth-size planets in the habitable zone — or it's going to be very difficult — until that work gets done," said Borucki, who revealed the problem last week to the NASA Advisory Council.
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The basic chemistry for life has been detected the atmosphere of a second hot gas planet, HD 209458b. Data from the Hubble and Spitzer Space Telescopes provided spectral observations that revealed molecules of carbon dioxide, methane and water vapor in the planet's atmosphere. The Jupiter-sized planet – which occupies a tight, 3.5-day orbit around a sun-like star — is not habitable but it has the same chemistry that, if found around a rocky planet in the future, could indicate the presence of life. Astronomers are excited about the detection, as it shows the potential of being able to characterize planets where life could exist.
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Astronomers have found 32 new planets outside our solar system with the High Accuracy Radial Velocity Planet Searcher, better known as HARPS, the spectrograph for the European Southern Observatory's (ESO) 3.6-metre telescope. The number of known exoplanets is now at 406, and HARPS itself has discovered more than 75 exoplanets in 30 different planetary systems. Included in this most recent batch are several low-mass planets – so-called "Super Earths" about the size of Neptune. The image above is an artist's impression of a planet discovered that is 6 times the mass of Earth, which circles the low-mass host star, Gliese 667 C, at a distance equal to only 1/20th of the Earth-Sun distance. Two other planets were discovered previously around this star.

"HARPS is a unique, extremely high precision instrument that is ideal for discovering alien worlds," said ESO astronomer Stéphane Udry. “We have now completed our initial five-year program, which has succeeded well beyond our expectations.”
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If any creature lives on COROT-7b, the recently confirmed rocky exoplanet, they might think the sky is falling. This planet is close enough to its star that its "day-face" is hot enough to melt rock, and according to models by scientists at Washington University in St. Louis, COROT-7b's atmosphere is made up of the ingredients of rocks and when "a front moves in," pebbles condense out of the air and rain into lakes of molten lava below. Yikes!
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More details are emerging on the extrasolar planet that was discovered by the CoRot satellite back in February. New information about this planet make it first in many respects: It is the smallest known exoplanet, it is the closest exoplanet yet to its host star, which also makes it the fastest; it orbits its star at a speed of more than 750,000 kilometers per hour. Plus, data reveal the presence of twin sister planet, another so-called super-Earth called CoRot-7c in this alien solar system. Was Obi-wan wise to conceal it?

(Sorry, couldn't resist the twin sister/Star Wars reference….)
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If you've ever wanted to communicate with aliens, here's your chance. Cosmos Magazine is offering the chance to send a message to another planet, Gliese 581 d. This exoplanet is about 20.3 light-years from Earth, in the constellation Libra, and some have said if life is elsewhere in the Universe, this is the mostly likely place that we currently know about. It was first discovered in 2007, and astronomers say this planet is well within the habitable zone around its star, where liquid water oceans could exist. Cosmos is collecting short, 160 character messages to be transmitted out to the vicinity of Gliese 581 d with the Canberra Deep Space Communication Complex in Tidbinbilla, Australia. Cosmos says it will take about 20 years for the message to reach its destination, and admits there is no guarantee of a response. If interested, check out Cosmos' "Hello From Earth" webpage. Hurry, as the deadline is 5pm Monday August 24, 2009 Sydney time (07:00 GMT Monday 24 August 2009).

This is Cosmos' way of celebrating the IYA and National Science Week in Australia. However, we've had lively discussions here on before UT about if we are sending too much information out into the cosmos. What do you think?

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Planet hunters from the UK have discovered the largest exoplanet yet, and its uniqueness doesn't end there. Dubbed WASP-17, this extra large world is twice the size of Jupiter but is super-lightweight, "as dense as expanded polystyrene" one astronomer said. Plus it is going the wrong way around its home sun, making it the first exoplanet known to have a retrograde orbit. As a likely a victim of planetary billiards, astronomers say this unusual planet casts new light on how planetary systems form and evolve.
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First results from the Kepler mission. Credit: NASA

NASA researchers have published confirmation this week that the Kepler mission will be able to reveal the presence of Earth-sized planets around Sun-like stars. The mission's first scientific results appear today in the journal Science.

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In what might be a evidence of planetary billiards, astronomers have found an exoplanet with an extremely odd orbit. The question is, was this planet the cue ball or the object ball? While most planets orbit around a star's mid-section, this one – called XO-3b — is tilted about 37 degrees from the star's equator. It's also a massive planet, about 10 times the size of Jupiter. Such a misalignment must have occurred as a result of a disturbance, such as a collision with another object, sometime after the planet's formation. But astronomers say they don't yet know what caused the unusual orbit of XO-3b.
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Most scientists predict that in about a billion years, the sun's ever-increasing radiation will have scorched the Earth beyond habitability. The breathable air will be toast, the carbon dioxide that serves as food for plant life will disappear, the oceans will evaporate; and all living things will disappear. Or maybe not. A group of researchers from Caltech have studied a mechanism which would cause any planet with living organisms to remain habitable longer than originally thought, perhaps doubling the lifespan. This sounds like good news for future inhabitants of Earth, but also, this mechanism could increase the chance that life elsewhere in the Universe might have the time to progress to advanced levels.
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In order to support life, an exoplanet should simply hang out where heat from its star is just right for liquid water. Right?

Not necessarily. New research is suggesting that in order to support life, such a planet might also need plate tectonics, and those are triggered in a narrower band of distance from the parent star.

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Science fiction is lousy with examples of planets that orbit a system of two suns. Tatooine, in the Star Wars saga, is endowed with a pair of suns to light up the sky, as is the planet Magrathea in The Hitchhiker's Guide to the Galaxy. It would indeed be quite a spectacle to wake up to more than one Sun every day for us who have only one. This sight may entirely be possible to view around the young binary star system V4046 Sagittarii, as new images from the Smithsonian's Submillimeter Array (SMA) have confirmed the existence of a molecular cloud – which could harbor, or later produce planets -  orbiting the twin stars. This is the first time that evidence of planetary formation around a binary system of stars has been uncovered.

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