‘Star With 3 Super-Earth Exoplanets Just 21 Light Years Away’


exoplanet-destruction_01

Astronomers said Thursday they had found a planetary system with three super-Earths orbiting a bright, dwarf star one of them likely a volcanic world of molten rock.
The four-planet system had been hiding out in the M-shaped, northern hemisphere constellation Cassiopeia, “just” 21 light years from Earth, a team reported in the journal Astronomy & Astrophysics.

It comprises four planets one giant and three super-Earths orbiting a star dubbed HD219134.

Super-Earths have a mass higher than Earth’s but are lighter than gas giants like Neptune, Saturn or Jupiter. They can be made of gas, rock, or both.

The planet with the shortest orbit, HD219134b, zips around every three days, and has now been observed transiting across the face of its star as seen from the vantage point of Earth.

three_earths_nasa_official

Measurements from the ground and with Nasa’s Spitzer space telescope showed its mass was 4.5 times higher than Earth’s, and that it was 1.6 times larger.

“Its mean density is close to the density of Earth, suggesting a possibly similar composition as well,” said a press statement from the University of Geneva, whose astronomers took part in the research.

“It’s very close to the star. The temperature is about 700 degrees” Kelvin (427 Celsius, 800 Fahrenheit), study co-author Stephane Udry told AFP.

“Probably the surface is melting… kind of a melted lava world with volcanoes… not good for life.”

It was not in the so-called “habitable zone” of its star, and would not have liquid water necessary for life.

But HD219134b is exciting for another reason: it is the closest transiting planet known to scientists, and thus offers a rare opportunity for further study of its composition and atmosphere against the backdrop of its star.

“These transiting systems are especially interesting in that they allow characterisation of the atmosphere of the planet (by studying) the light of the star going through the atmosphere,” Udry said.

And the system is relatively near at a distance of 21 light years from Earth. By comparison, the closest star to our Sun is three light years away, and the second six light years.

Among HD219134b’s fellow planets, the second furthest from the star weighs 2.7 times as much as Earth and orbits in 6.8 days, the next is 8.7 times more massive than Earth with a 47-day orbit.

A giant planet further out orbits once every three years, the team said.

Source : NDTV

Advertisements

Planets orbiting Kepler 444 suggest there’s ancient life in the Milky Way


red_star_by_enricoagostoni

NASA’s exoplanet hunting Kepler space telescope has encountered a few problems as of late, but there’s still a mountain of data for astronomers to dig through from the last four years. Astronomers analyzing Kepler data recently uncovered something unusual — a solar system about 117 light years away in the direction of Lyra called Kepler-444 with at least five Earth-sized planets. That would be unusual enough, but this planetary system is also extraordinarily ancient at roughly 11.2 billion years.

Astronomers are intrigued by this discovery for several reasons. First, that’s a lot of small rocky planets. Kepler detects alien worlds by the transit method. It watches distant suns for slight dips in brightness that indicate a planet has passed between it and the telescope. These events can be used to calculate the characteristics of the planet, but it works best for larger worlds (super Earths and gas giants). Spotting five planets between the size of Mercury and Venus (basically a little smaller than Earth) is unusual.

Kepler-444

Artistic Depiction of Kepler 444 with its Star

The age of Kepler-444 is also something to note. At 11.2 billion years old, the planets orbiting this star were already older than Earth is now when our sun ignited 4.5 billion years ago. The universe itself is only 13.8 billion or so years old, making Kepler-444 one of the oldest stars in the Milky Way. It would have been from the first generation of stars that dotted the sky. Kepler-444 is still very sun-like because it’s 25% smaller and cooler. That means it burns through its nuclear fuel more slowly.

Finding small rocky planets that are billions of years older than Earth suggests that advanced life may have existed in the universe for a very long time. Life on Earth might be very new by comparison. Just think, planets similar to Earth were forming more than 7 billion years before Earth formed, and some of them could have supported life. If other first-generation stars like Kepler-444 have planets, uncountable civilizations could have come into being eons before the first single-cell life appeared on Earth.

The planets orbiting Kepler-444 themselves are not able to support life as we know it. All five planets are packed very close to the parent star with orbits closer than that of Mercury in our solar system. With solar years less than 10 Earth days, they definitely stood out in the Kepler data. The surfaces of these worlds have been baked by the intense heat, reducing any organic material to cinders.

Kepler-444 isn’t a bastion of alien life, but it improves our understanding of planetary formation and points us in a new direction. Astronomers are anxious to find other ancient stars with rocky planets in hopes they might prove more hospitable to life. What if there was still something alive on one of these ancient worlds? That might sound like science fiction right now, but maybe it won’t always be — there’s still a lot of data from Kepler, and future telescopes will improve our ability to spy distant exoplanets.

Source: Geek.com

Ground-Based Telescope Observes Exoplanet Transiting Bright Star


Follow us on Google+ , Twitter and Facebook

HD_85512_b_planet

 Graphical representation of an Exoplanet (Click Image to Download)

For the first time, an international team of astronomers has used a ground-based telescope to detect and observe the transit of a planet in front of a Sun-like star outside of our own solar system.

Until now, only space-based telescopes were capable of detecting the transits of exoplanets as they passed by bright stars.

Distortions caused by the atmosphere , the same phenomenon that makes stars look like they’re twinkling, makes it difficult for astronomers to observe transiting planets around bright stars from telescopes based on Earth.

In September, 2013, Japanese astronomers, using the ground-based Subaru telescope were able to observe the transit of super-Earth, GJ 1214b , but this exoplanet orbits a much dimmer star, known as a red dwarf.

According to team leader, Dr. Ernst de Mooij  of Queen’s University Belfast  in Northern Ireland, 55 Cancri e, was measured to have a diameter of about 26,000 km, which is twice that of Earth, but with eight times its mass.

hires

This artist’s conception shows the super-Earth 55 Cancri e (right) compared to the Earth (left). (NASA/JPL) (Click Image to Download)

The most recent achievement involves a super-sized Earth-like planet in a binary star system more than 40-light years away. Called 55 Cancri e , the planet orbits its primary star 55 Cancri A , in the constellation Cancer. The solar system’s secondary star, 55 Cancri B, is a red dwarf star which is located about 159,321,732,615 km from the primary star.

Scientists say that while the primary star can be seen with the naked eye, it takes ideal conditions such as a clear and moonless night.

646920main_pia15622-43_946-710

An artist’s concept of exoplanet 55 Cancri e as it closely orbits its star 55 Cancri A (NASA/JPL-Caltech) (Click Image to Download)

Previous studies have found that the planet makes one complete orbit around its sun in about 18 hours and that since its daytime temperature can reach nearly 1,700° Celsius, 55 Cancri e is not at all hospitable to life.

A number of small, extra-solar planets are expected to be discovered in the next ten years as new observational space missions — including NASA’s Transiting Exoplanet Survey Satellite (TESS) , and the European Space Agency’s Planetary Transits and Oscillations of Stars (PLATO)  –are launched.

Both PLATO – set to go in 2014 and TESS, scheduled for a 2017 launch – will look for transiting Earth-like planets circling nearby bright stars.

Source : blogs.voanews.com