Twin of Solar system Discovered

VIa OWH, astronomers have found evidence of a solar system much like our own, and it is relatively close in galactic terms. The system Epsilon Eridani, just 10.5 light years from Earth and the eighth closest to our sun has been observed to have two rings of rocky asteroids in oribit around it, somewhat like the geography of our solar system, and an icy outer ring consistent with our Kyper Belt. The gaps in the rings are likely spots for planets to lurk, and the inner ring is 3 astronomical units from the star, just as in our solar system.

"Epsilon Eridani is much younger than the sun — about 850 million years old, compared with 4.5 billion years for our system.

"This really is a system like our solar system was when it was five times younger than it is now," said one of the discoverers, Massimo Marengo, an astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. "It's like a time machine for our solar system."

"This system probably looks a lot like ours did when life first took root on Earth," said Dana Backman of the SETI Institute in Mountain View, Calif., the lead author of a report to be published Jan. 10 in the Astrophysical Journal.

SETI chose Epsilon Eridani as one of the first targets in its long — but so far fruitless — search for signs of extraterrestrial intelligence in 1960. The suspected planets are too far away to be detected directly, so their presence has to be inferred by indirect measurements."

At least one and perhaps three or more planets may be in orbit around the star, which is in the constellation Eridanus near Orion. The star is a bit smaller and cooler than our Sun, bringing the star's habitable zone closer to it than our own system. More on the discovery at Livescience here.

Large Cache of Exoplanet Discoveries Announced

Great note from Astrobiology last Sunday on the recent spate of "superEarth" discoveries, including the find of a single system that includes at least three near Earth mass planets. The system is located 42 light-years away near the constellations Doradus and Pictor. While the planets have short orbital periods, all less than 20 days, they weigh in at only 4-9 Earth masses.

"Using the HARPS instrument at the ESO La Silla Observatory, they have found a triple system of super- Earths around the star HD 40307. Moreover, looking at their entire sample studied with HARPS, the astronomers count a total of 45 candidate planets with a mass below 30 Earth masses and an orbital period shorter than 50 days. This implies that one solar-like star out of three harbors such planets - a finding may help astrobiologists understand the potential for habitable environments in the Universe."

These discoveries make it near certain that the holy grail of planet hunting, a near Earth mass planet in the habital zone of its star, will be found in relatively short order if the implications of these observations bear out as expected.

Smallest Planet Discovered

via National Geographic, the smallest exoplanet yet found orbitting a star has been discovered by a team using the relatively novel gravitational lensing technique. Gravitational lensing utilzies the bending of light around large gravitational objects to focus on distant objects. The planet, called MOA-2007-BLG-192Lb, is only three earth masses and orbits what is thought to be a brown dwarf.

"The planet is 3,000 light-years from Earth and has a close-in orbit similar to Venus's. But because the newfound body's parent is so much cooler than our sun, MOA-2007-BLG-192Lb is most likely to be even colder than Pluto. Even so—and despite almost no solar heating—there's a slim chance that the planet could maintain a habitable temperature if the atmosphere is as thick with molecular hydrogen as researchers think it could be, according to study leader David Bennett."

The fact we've discovered such a small mass planet orbiting a rather small failed star leads researchers to believe there are many more such objects in the cosmos. The new planet is only the seventh such exoplanet discovered by the gravitational lensing technique.

Distant Stellar Collision?

From ScienceDaily, astronomers have discovered a very odd object orbiting a brown dwarf known as 2M1207A. The object, known as 2M1207B (those astronomers are awfully clever with those names, aren't they?) is about the size of Saturn, but many of its charateristics do not match up. The system itself is very young, around 8 million years old, but the planet is far too warm, at 2400 degrees F, than it should be.
Conversely, given that temperature, it should be up to 10 times more bright than observations show it to be. The only hypothesis that answers the contradiction is that the object has suffered a cosmic collision in the recent past. If true, it would be the first such recently collided object we have ever observed.

"The planets in our solar system assembled from dust, rock, and gas, gradually growing larger over millions of years. But sometimes, two planet-sized objects collided catastrophically. For example, the Moon formed when an object about half the size of Mars hit the proto-Earth. If planet formation works the same way in other star systems, then 2M1207B might be the product of a collision between a Saturn-sized gas giant and a planet about three times the size of Earth. The two smacked into each other and stuck, forming one larger world still boiling from the heat generated in the collision."

Observations on the object will continue which could confirm the theory, including a surface gravity calculation from a spectrum analysis, which could give us the answer within a year or so. Even if 2M1207B's odd characteristics are not the result of a collision, astronomers believe we will discover many such objects with the next generation of space and Earth based telescopes being planned or built.

Largest Exoplanet Discovered

The largest planet ever discovered has been found orbiting a star 1400 light years from Earth, but also has some additional unusual features along with its size. It is 1.7 times Jupiter's diameter, but has an extremely low density of .2 gram per cubic centimeter. A handful of similar "puffy" planets have been found, which has astronomers scratching their collective heads - this class of planet is not easily explained by current planet formation theories. The planet's has a quick orbital period of 3 1/2 days and was discovered by the transit technique.

ScienceDaily has some more details here.