The search for life around other stars is essentially a search for a habitable zone – the area around a star where the distance is warm enough to sustain liquid water on the surface, but cold enough such that the water does not boil away or escape.
This definition of habitable zone now has to change to take into account the star itself. New research shows that winds coming off Red Giant stars can strip the planet of Oxygen. No Oxygen, no life. This means that our nearest confirmed Earth-sized exoplanet, around Proxima Centauri and only 4 light-years away, is not a good spot to go look for neighbors.
“If we want to find an exoplanet that can develop and sustain life, we must figure out which stars make the best parents,” said Vladimir Airapetian, lead author of the paper and a solar scientist at NASA’s Goddard Space Flight Center. “We’re coming closer to understanding what kind of parent stars we need.”
The Kepler mission continues to explore and discover, and among the most recent discoveries lie a potential Earth twin.
As discussed on
“Kepler has identified many exoplanets but few are within their star’s Goldilocks zone. Among eight new planets they have spied in distant solar systems, astronomers say one in particular has usurped the title of most Earth-like alien world. All eight were picked out by Nasa’s Kepler space telescope, taking its tally of such exoplanets past 1,000.But only three sit safely within the “habitable zone” of their host star – and one in particular is rocky, like Earth, as well as only slightly warmer.
The find was revealed at a meeting of the American Astronomical Society.
The three potentially habitable planets join Kepler’s “hall of fame”, which now boasts eight fascinating planetary prospects. And researchers say the most Earth-like of the new arrivals, known as Kepler 438b, is probably even more similar to our home than Kepler 186f – which previously looked to be our most likely twin. At 12% larger than Earth, the new claimant is bigger than 186f but it is closer to our temperature, probably receiving just 40% more heat from its sun than we do from ours. So if we could stand on the surface of 438b it may well be warmer than here, according to Dr Doug Caldwell from the Seti (Search for Extra-Terrestrial Intelligence) Institute in California.”
It used to be simple. We had 9 planets. 4 were small and rocky and close to the Sun. 4 were big and gassy and far from the Sun. The we had Pluto. The first disruption of this pretty picture was when we found of other bodies like a Pluto and so decided Pluto could not be a planet. Then we found other planetary systems in which the large planets were close to the star. Now the latest discovery might mean a complete rethink of our whole notion of planets. Now we have discovered a planet the same size as Earth, but gassy and not rocky.
Earth’s gassy ‘twin’ has been discovered in another solar system 200 light years away and is known as KOI-314c. It weighs the same as Earth but is 60% larger, leading scientists to suspect it has a thick gaseous atmosphere. It orbits a dim red dwarf star at such a close distance that temperatures on its surface could be as high as 104C – too hot for most forms of life on Earth.
Lead astronomer Dr David Kipping, from the Harvard-Smithsonian Centre for Astrophysics in the US, said: “This planet might have the same mass as Earth, but it is certainly not Earth-like. It proves that there is no clear dividing line between rocky worlds like Earth and fluffier planets like water worlds or gas giants.”
They’re also showcasing yet again that a major assumption astronomers were making as recently as 1995—that other solar systems would more or less resemble ours—was completely misguided. “Nature,” says Kipping, “continues to surprise us.” By now, that should hardly be a surprise.
It used to be simple. Star were the objects that shined. Planets go around stars. But the hunt for ever-colder star-like bodies two years ago led to a a new class of such objects. However, until now no one has known exactly how cool their surfaces really are – some evidence suggested they could be room temperature.
A new study shows that while these brown dwarfs, sometimes called failed stars, are indeed the coldest known free-floating celestial bodies, they are warmer than previously thought with temperatures about 250-350 degrees Fahrenheit. To reach such low surface temperatures after cooling for billions of years means that these objects can only have about 5 to 20 times the mass of Jupiter. Unlike the Sun, these objects’ only source of energy is from their gravitational contraction, which depends directly on their mass.
“If one of these objects was found orbiting a star, there is a good chance that it would be called a planet,” says Trent Dupuy, a Hubble Fellow at the Harvard-Smithsonian Center for Astrophysics. But because they probably formed on their own and not in a proto-planetary disk, astronomers still call these objects brown dwarfs even if they are “planetary mass.”
The new data also present new puzzles to astronomers that study cool, planet-like atmospheres.
Planets, stars, orin between? Additional objects discovered in the past two years remain to be studied and will hopefully shed light on some of these outstanding issues.
For decades, the names given to newly discovered planets have almost always failed to live up to the excitement these celestial finds represent. (Take for example forgettable monikers such as CFBDSIR2149, HD 189733b, 55 Cancri e, and Kepler-69c.) The organization that oversee’s the naming of new planets, the International Astronomical Union (IAU), knows that these titles are the opposite of cool and catchy. And thankfully, something is being done about it — the IAU is moving away from leaving selective working groups to name planets and opening up the process to the public.
Unsurprisingly, there are a few rules that the IAU imposed on the new process. Proposed names must be 16 characters or less, and preferably one word. The Paris-based group asks that names are pronounceable in as many languages as possible, and not offensive in any language or culture. The group also says that submissions should be “not too similar to an existing name of an astronomical object,” such as another planet, or named dwarf planets, stars, and solar systems. Using a pet name or a name that is “purely or principally commercial in nature” is also forbidden, the IAU says.
So how do you actually suggest a name? The IAU has set up an email address for that: firstname.lastname@example.org. Submissions will “be handled on a case-by-case basis, with advice given on the best way to proceed,” the organization says. And, in case you’re wondering, it’s the IAU who will be sifting through public input and selecting the best names. The group also reserves the right to open things up to a public vote, as it did in July in the christening of Pluto’s fourth and fifth moons, Kerberos and Styx. Among the names the IAU shot down: Vulcan.
63 light-years: the distance from Earth to the blue exoplanet HD 189773b, which looks like a cozy place to live—except its surface temperature is 1,000 degrees Celsius and it rains glass. Sideways..
HD 189773b looks like Earth because it’s blue. Astronomers have determined its true color, a first for an exoplanet, or a planet orbiting a star other than Earth’s own sun.
The blue color is thought to come from silicate particles in the planet’s atmosphere, which scatter blue light. Because of the planet’s surface temperature, the particles could condense to form glass. These glass grains would then fly around in the planet’s 4,000 mph (7,000 kilometers per hour) wind. Ouch.
Astronomers have confirmed the existence of almost 1000 planets orbiting distant stars (as of May 31, 2013). And we have several thousand more candidate planets. But how many have we seen directly? Answer: almost none.
And it isn’t because they are too small- we can small objects, or because they are too dim- we can see dim objects. The problem is that they are too close to bright objects, their parent star. It’s like looking for a match, beside a lighthouse lamp. Turn the lighthouse off and you can see it. A new tweak on an old method in optical physics, an adaptive optics, can be used to blank out the star.
So far, astronomers have directly observed only a dozen exoplanets. The image below shows the lightest one imaged so far, announced by the European Southern Observatory (ESO) on June 3, 2013. The blue circle in the image below is the size of the orbit of Neptune – 8th planet from the sun in our solar system. The star in the center is HD 95086, located about 300 light-years away. The likely planet appears as a faint but clear dot close to the star.
With 2013 now here, how about we move house? This infographic from last year summarizes where we might go to. It looks at the potential of many of factors required for each planet and moon to support life. And who comes out on top, but Titan. It is mostly of water ice and rocky material. Much as with Venus prior to the Space Age, the dense, opaque atmosphere prevented understanding of Titan’s surface until new information accumulated with the arrival of the Cassini–Huygens mission in 2004, including the discovery of liquid hydrocarbon lakes in the satellite’s polar regions. The surface is geologically young; although mountains and several possible volcanoes have been discovered, it is smooth and few impact craters have been found. Best of all it is not that far away, so we could always pop home to visit our Earthly relatives for the holidays.
The nearest single Sun-like star to the Earth might hosts five planets – one of which is in the “habitable zone” where liquid water can exist. Tau Ceti’s planetary quintet – reported in an online paper that will appear in Astronomy and Astrophysics – was found in existing planet-hunting data.
The study’s refined methods of sifting through data should help find even more far-flung worlds. The star now joins Alpha Centauri as a nearby star known to host planets.
The cool part about this story is that tau ceti is a naked eye star, in the constellation of cetis, near Pisces in the sky.
Go out and have a look. Someone on one of those planets looking at you would see you in constellation Bootes. At only 12 light years it about as close a neighbor as we could get.