188 replies to this topic

[Craven]

http://www.nasa.gov/...-20-system.html

Another batch of planets in Kepler-20 system. This time they are very close to earth size. Not in habitable zone though.



at this ocasion I wanna point out one thing - right now Kepler has been out there for just ~33 months. That's why right now we have confirmed just planets very close to their stars, because those transit their stars very often and we have clear, consistent readings. If Earth twin - in terms of distance from it's sun was there it would transit only twice so far, and given that readings tend to be very noisy, is just not enough for solid finding. We just have to wait a little longer.

Edited by Craven, 20 December 2011 - 08:16 PM.

[Raklian]

It is just a matter of time before we discover a habitable twin to Earth. The naysayers do not have the slightest idea of how massive the Universe is as well as the mind-boggling number of stars that have their own planet systems.

[Craven]

http://io9.com/58705...tarand-survived

These tiny, charred planets dove inside their dying star…and survived

(...)
The star KIC 05807616 was once much like our own Sun. Not big enough to go supernova, the star started expanding outwards once its fuel ran out, ballooning up into a red gent as much as a hundred times its original diameter. This fate awaits the Sun five billion years from now, and its final expansion will almost certainly vaporize Mercury, Venus, Earth, and possibly Mars. Nothing should be able to survive this sort of extreme stellar blast furnace.

At least, that's what astronomers always assumed. But an international team of astronomers have actually detected two planets in very close orbits around KIC 05807616. These planets, known as KOI 55.01 and KOI 55.02, are even smaller than those discovered around Kepler-20, clocking in at just 76% and 87% the size of Earth. The two planets have a couple of the closest orbits around a star we've ever seen, at just 5.76 and 8.23 hours, or 0.016 and 0.02 times the distance Mercury orbits our Sun. That makes their average temperatures around 16,000 degrees Fahrenheit.

What's remarkable is that KIC 05807616 has already shed its outer envelope of stellar material, meaning it's now much smaller than it was during its period of red giant expansion. Considering how close KOI 55.01 and KOI 55.02 are to the star, that means they must have once been inside the expanding red giant...and yet, somehow, they survived being vaporized. This is the first time we've seen any indication a planet can survive being inside a red giant.
(...)

How cool is that?!

[Craven]

Great talk about exoplanets:
Kepler, Exoplanets and SETI - Geoff Marcy





I must say that as I'm very familiar with Kepler I jumped to 27minutes. So I'm not sure about first half hour, but rest is a great content. It's not extremally scientific, but it's clearly for people who are into subject, there are very good questions toward end, not silly or naive.

[Craven]

"Mini Solar System" found

http://www.jpl.nasa....elease=2012-009



Kepler has found three smallest exoplanets to date, orbiting small red dwarf. They are 0.78, 0.73 and 0.57 times the radius of Earth. Smallest is about the size of Mars. Given their close proximity to star, they're thought to be rocky bodies, too hot to be in habitable zone or even keep atmosphere.

Once again it increases our estimate of number of exoplanets in Milky Way.

Everything in picture above is to scale: the relative size of the star, the planets, Jupiter, and its moons.

[Craven]

Exosaturn found

http://blogs.discove...#comment-466670



We have found huge planet with gargantuan, massive and complex ring system. Since star is very young (just 16 million years old) it's quite likely in process of coalescing into moons or just falling onto planet. Mass of this planet is not yet determined, but it may even turn out to be a brown dwarf. Ring system is so big that transition seen from Earth takes two months! There are gaps in rings, so it's likely that there already are massive bodies that sucked material from their orbits.

Edited by Craven, 12 January 2012 - 07:18 PM.

[Craven]

http://www.bbc.co.uk...onment-17117030

It's just conformation of what was expected, but we confirmed first exosolar waterworld: GJ 1214b - planet larger and heavier than earth, yet with way lower density, implying water composition. With conditions over there it's likely that water exists there in exotic forms like superfluid and "hot ice".

[Craven]

http://planetquest.j.../detail/2124.01

Kepler isn't making news recently, but it's still working. And among recent candidates is KOI 2124.01 - planet with estimated 1.02 Earth radius and estimated surface temperature of 300K (that is 27'C). There's also plentiful of planets no larger than 1.25 Earth radius with temperatures around 250-300 K (habitable zone).

http://planetquest.j.../detail/2650.01 - another close one.

Edited by Craven, 02 May 2012 - 02:14 PM.

[Raklian]

It's funny that everytime a news something like this is reported it is less remarkable than the last time.

It's just like in the Far Future timeline, finding the first extraterristal life form won't be so remarkable because it was already predicted with statistical certainty.

[ExplorerAtHeart]

It's funny that everytime a news something like this is reported it is less remarkable than the last time.

NOT FOR ME

[Saradus]

It's funny that everytime a news something like this is reported it is less remarkable than the last time.

It's just like in the Far Future timeline, finding the first extraterristal life form won't be so remarkable because it was already predicted with statistical certainty.

While it might be predicted with certainty, I'm sure it would still be a huge headline and people would all be very excited about find extraterrestrial life!

[MarcZ]

It's funny that everytime a news something like this is reported it is less remarkable than the last time.

NOT FOR ME

Seconded.

[Craven]

I just wonder, if they confirm KOI 2124.01 and KOI 2650.01, will it make to the news. I think they were too fast with earlier news about "Earth 2.0" and this two planets may not make it to main news, while it should. This two really could be just like Earth (especially if metallicity of their stars is high enough). Sure, they could be like Venus or messed up in some other way, but right now is as close as we can get with Kepler.

[Tumaini12]

While it might be predicted with certainty, I'm sure it would still be a huge headline and people would all be very excited about find extraterrestrial life!

Damn right. But confirming that a planet could definitely support life (as we know it) is not proof that life exists there. Even a high percentage of oxygen in the atmosphere could concievably have an abiogenic origin.

The number of potential habitats for life can, of course, be vastly increased by including possible Earthlike moons of giant exoplanets (most famously, the verdant Pandora in Avatar). One thing nobody seems to consider, though: a giant planet's great gravity pulls in far more asteroids and comets than a small planet does. Its moons would be constantly in the firing line, and therefore would suffer devastating impacts many times more often than Earth does. I doubt that advanced life (such as ikrans, direhorses or Na'vi) would ever have time to evolve there.

That doesn't rule out such an exomoon for colonisation by future humanity, who could build orbital defences against dangerous impactors.

Edited by Tumaini12, 06 May 2012 - 10:55 AM.

[Craven]

Exomoons are promising because it's likely that magnetic field of gas giants would protect their atmospheres from violent red dwarfs. And red dwarfs are so common, and often have planetary systems, that it's a comforting thought. As for bombardment - I think it would be only issue for first ~1-2bn years. By now solar system i quite cleaned up. There are of course impacts all the time, but I don't think cataclysmic events are so common right now on moons of Jupiter and Saturn.

Another positivie thing about exomoons is that gravitational tug can increase chances of volcanism, that's important for soil fertility.

[Tumaini12]

magnetic field of gas giants would protect their atmospheres from violent red dwarfs. And red dwarfs are so common, and often have planetary systems, that it's a comforting thought.

Agreed. Also, planets at a habitable distance from a red dwarf would very likely be tidelocked, with all that imples for extreme temperature difference between the hemispheres and half the globe in permanent darkness. But a moon of such a planet would be tidelocked to its primary, not to the star - therefore it could still have a day and night cycle.

As for bombardment - I think it would be only issue for first ~1-2bn years. By now solar system i quite cleaned up. There are of course impacts all the time, but I don't think cataclysmic events are so common right now on moons of Jupiter and Saturn..

Astronomers do credit Jupiter & Saturn for with intercepting most of the comets which might otherwise have enterd the inner Solar System and struck Earth. If that's true, the moons of Jupiter must still be hit a lot more often than we are.

[Craven]

Agreed. Also, planets at a habitable distance from a red dwarf would very likely be tidelocked, with all that imples for extreme temperature difference between the hemispheres and half the globe in permanent darkness. But a moon of such a planet would be tidelocked to its primary, not to the star - therefore it could still have a day and night cycle.

I'm much more concerned with atmosphere issue to be hones. And I still didn't get answer anywhere. What's more important in preserving atmosphere - mass or magnetic field? If it's magnetic field, then tidally locked planets may have more important thing to worry about than extreme temperatures. Or maybe spinning metallic core is not only way to have it. Or perhaps while red dwarfs are more violent thant yellow dwarfs like our sun, they're not THAT troublesome, and wouldn't blow whole atmosphere off nearby earthlike planet (not likely, even if it's sporadic, then over millions of years it would be blown away and I don't see how planet could rebuild it's atmosphere).

[Craven]

http://www.csmonitor...-for-first-time

Light from alien 'super-earth' seen for first time



NASA's Spitzer space telescope has detected a light source coming from a large earth-like planet.

Light from an alien "super-Earth" twice the size of our own Earth has been detected by a NASA space telescope for the first time in what astronomers are calling a historic achievement.
NASA's infrared Spitzer Space Telescope spotted light from the alien planet 55 Cancri e, which orbits a star 41 light-years from Earth. A year on the extrasolar planet lasts just 18 hours.
The planet 55 Cancri e was first discovered in 2004 and is not a habitable world. Instead, it is known as a super-Earth because of its size: The world is about twice the width of Earth and is super-dense, with about eight times the mass of Earth.
But until now, scientists have never managed to detect the infrared light from the super-Earth world.
"Spitzer has amazed us yet again," said Spitzer program scientist Bill Danch of NASA headquarters in Washington in a statement today (May . "The spacecraft is pioneering the study of atmospheres of distant planets and paving the way for NASA's upcoming James Webb Space Telescope to apply a similar technique on potentially habitable planets."
Spitzer first detected infrared light from an alien planet in 2005. But that world was "hot Jupiter," a gas giant planet much larger than 55 Cancri e that orbited extremely close to its parent star. While other telescopes have performed similar feats since then, Spitzer's view of the 55 Cancri e is the first time the light from a rocky super-Earth type planet has been seen, researchers said.
Since the discovery of 55 Cancri e, astronomers have pinned down increasingly strange features about the planet. The researchers already knew it was part of an alien solar system containing five exoplanets centered on the star 55 Cancri in the constellation Cancer (The Crab). [Gallery: The Oozing Planet 55 Cancri e]
But 55 Cancri e stood out because it is ultra-dense and orbits extremely close to its parent star; about 26 times closer than the distance between Mercury and our own sun.
The new Spitzer observations revealed that the star-facing side of 55 Cancri e is extremely hot, with temperatures reaching up to 3,140 degrees Fahrenheit (1,726 degrees Celsius). The planet is likely a dark world that lacks the substantial atmosphere needed to warm its nighttime side, researchers said.
And to top it all off, the planet is oozing.
Past observations of the planet by the Spitzer Space Telescope have suggested that one-fifth of 55 Cancri e is made up of lighter elements, including water. But the extreme temperatures and pressures on 55 Cancri e would create what scientists call a "supercritical fluid" state.
Supercritical fluids can be imagined as a gas in a liquid state, which can occur under extreme pressures and temperatures. On Earth, water can become a supercritical fluid inside some steam engines.
The previous studies of 55 Cancri e were performed by analyzing how the light from its parent star changed as the planet passed in front of it, a technique known as the "transit method." In the new study, astronomers used the Spitzer Space Telescope to determine the infrared light from 55 Cancri e itself.
Spitzer's new look at 55 Cancri e is consistent with supercritical-fluid waterworld theory. The planet is likely a rocky world covered with water in a supercritical fluid state and topped off with a steam blanket, researchers said.
"It could be very similar to Neptune, if you pulled Neptune in toward our sun and watched its atmosphere boil away," said the study's principal investigator Michaël Gillon of Université de Liège in Belgium. The lead author is Brice-Olivier Demory of the Massachusetts Institute of Technology in Cambridge.
The research is detailed in the Astrophysical Journal.
NASA's $770 million Spitzer Space Telescope launched in 2003 and is currently in an extended mission to study the universe in infrared light. During that extended mission, telescope engineers modified several settings on the observatory to optimize its alien planet vision, NASA officials said.
The space agency's next major infrared space observatory, the James Webb Space Telescope slated to launch in 2018, could potentially reveal even more details about 55 Cancri e and other similar super-Earth planets.
"When we conceived of Spitzer more than 40 years ago, exoplanets hadn't even been discovered," said Michael Werner, Spitzer project scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Because Spitzer was built very well, it's been able to adapt to this new field and make historic advances such as this."

[Logically Irrational]

Four White Dwarf Stars Caught in the Act of Consuming 'Earth-Like' Exoplanets

http://www.scienceda...20503104117.htm

University of Warwick astrophysicists have pinpointed four white dwarfs surrounded by dust from shattered planetary bodies which once bore striking similarities to the composition of Earth.

Using the Hubble Space Telescope for the biggest survey to date of the chemical composition of the atmospheres of white dwarf stars, the researchers found that the most frequently occurring elements in the dust around these four white dwarfs were oxygen, magnesium, iron and silicon -- the four elements that make up roughly 93 per cent of Earth.

However an even more significant observation was that this material also contained an extremely low proportion of carbon, which matched very closely that of Earth and the other rocky planets orbiting closest to our own Sun.

This is the first time that such low proportions of carbon have been measured in the atmospheres of white dwarf stars polluted by debris. Not only is this clear evidence that these stars once had at least one rocky exoplanet which they have now destroyed, the observations must also pinpoint the last phase of the death of these worlds.

The atmosphere of a white dwarf is made up of hydrogen and/or helium, so any heavy elements that come into their atmosphere are dragged downwards to their core and out of sight within a matter of days by the dwarf's high gravity. Given this, the astronomers must literally be observing the final phase of the death of these worlds as the material rains down on the stars at rates of up to 1 million kilograms every second.

Not only is this clear evidence that these stars once had rocky exoplanetary bodies which have now been destroyed, the observations of one particular white dwarf, PG0843+516, may also tell the story of the destruction of these worlds.

[eacao]

I just went through all the planets from Craven's link of Kepler findings.
This is what I got. The radius of the Earth, is of course 1Er. The mean temperature of the Earth is 287.6K (286.9 100 years ago)
Water freezes at 273K and boils at 373K. I've only taken planets with temperatures above 273 and below 300, through above 300 life could still easily exist. The closer to 287K, the better. Also remember, that if Kepler has given a planet a low average temperature, a greenhouse affect could warm the planet. The larger the planet, the larger the rise in temperature from an atmosphere.


Earth
1.0Er 287K

8758204
2.7Er 273K

8890150
1.26Er 299K

11768142
1.46Er 281K

4247991
1.47Er 310K <-- an exception, because of its size.

12121570
1.75Er 296K

9651234
2.1Er 298K

12302530
2.1Er 298K

4139816
2.0Er 293K

11177707
4.34Er 285K

11176127
2.47Er 281K

10027323
3.69Er 285K

7199906
1.85Er 273K