A Planet Orbiting Two Suns

Remember Tatooine — Luke Skywalker’s home planet in the Star Wars saga, with two suns setting together on the desert horizon? Luke’s home world has always served as a good illustration of what astronomers call a circumbinary planet: a world that orbits both stars of a close binary pair.

An artist's concept of the newly discovered alien world Kepler-16b, orbiting the close binary pair — an orange and a red dwarf. NASA / JPL-Caltech / R. Hurt (SSC)

Now for the first time, NASA’s exoplanet-scouting space telescope Kepler has caught such a planet crossing the faces of both stars of the Kepler-16 binary system, a 12th-magnitude pairing 200 light-years away in Cygnus. The discovery team, led by Laurence Doyle (SETI Institute), presents its findings in this week’s issue of Science.

In most cases involving binaries, an exoplanet orbits one of two widely separated stars basically as if the star were single. Only seven exoplanets of the many discovered in binaries are thought to revolve around both stars. Kepler-16b is the first of these to be confirmed by showing itself in silhouette transiting both stars.

The two stars in the Kepler-16 system are orange and red dwarfs with 0.69 and 0.20 times the mass of the Sun. Their size ratio is also about 3 to 1. The two stars eclipse each other every 41 days as they revolve around their center of mass in a mildly eccentric orbit. When the smaller and dimmer Star B moves in front of Star A, the total light from system fades by 13%. When A blocks B, Kepler notes a 1.6% dropoff.

But in addition, Kepler’s long run of precision brightness measurements shows something extra. The system’s total light also dips by about 1.7% and 0.1% in a complex timing pattern not corresponding to these mutual stellar eclipses. So the team inferred the presence of a small third body in the system, passing across the faces of stars A and B about every 229 days.

Light curves of the four kinds of transits observed in the Kepler-16 system. The two stars eclipse each other, producing the primary and secondary eclipses. The planet crosses the face of each of the two stars, causing the tertiary and quaternary eclipses. NASA / Science / L. Doyle

From the slight gravitational tugs this object exerts on the two stars, the scientists conclude that it has only a third the mass of Jupiter. The depth of its transits show that it has about three-fourths Jupiter’s diameter. That makes it similar to Saturn but about 1.4 times denser, suggesting that the planet is richer in heavy elements.

So, how Tatooine-like is Kepler-16b? Not much, really. Tatooine, Star Wars aficionados will recall, was a terrestrial planet with mountainous landscapes, cities, and a plethora of alien species that raced pods for amusement. Kepler-16b is a gas giant with no hard surface and very cold, with an upper-atmosphere temperature probably averaging 185 K (–90°C; –130°F).

The only thing fairly Earthlike is the planet’s surface gravity, 1.5 g. So, hypothetically, you could stagger around on it but would tire out soon.

But even if it’s not lively world from Star Wars, the planet is a treasure for astronomers. The team hopes it will help unlock the mysteries of planet formation around binary stars. The three eclipsing objects orbit within 0.5° of the same plane. This indicates that they formed at the same time, from the same protoplanetary disk, and have not been much disturbed since. “I would assume everything formed at the same time,” says Doyle. “Any perturbations of the system after formation one would think would show up in non-planar orbits.”

The Kepler-16 system, showing the binary star (A and B) and their planet (b). The stars, Sun, and planets are shown in scale with each other. But the scale of their spacing (the orbits) is much greater; this is what the 0.5 a.u. scale bar refers to. On this scale, the Sun (just under 0.01 a.u. wide) would be about the size of the decimal point in "0.5". There's much more empty space in the system than the illustration and the artwork above suggest. NASA / Science / L. Doyle

“This is a milestone discovery, one we have all been waiting for,” says planetary expert Sara Seager (MIT). The timing of the discovery adds to “the coolness factor,” she notes. But this neat arrangement is changing; gravitational effects in this three-body system are warping the orbital plane around in a longer cycle (precession). So the planet will stop crossing the dim star in about 2014 and the brighter one in 2018. Not until around 2042 will the transits start up again from Earth’s point of view.

Even though the planet orbits just three times farther out than the separation of the two stars, simulations indicate that the system is stable, at least on time scales of a few million years (and probably much longer, considering that it exists for us to see). So Kepler-16 promises to be an object of curiosity for a long time to come.

October Sky..must watch..

Have you seen the movie ‘October Sky’?

No?

Then you should watch it.

Based on true story, this movie is about a boy who found his dream and tries to pursue it. Homer Hickam is a high school boy in Coalwood, West Virginia. On 4th of October Russians launches Sputnik, the first man-made satellite. He saw the Sputnik with his friends and neighbours who react with fear (those days Americans were really scared not because of satellite but because somebody else has did it before them). But Homer instantly fascinated by the object which is moving some incredible speed and orbiting around Earth. At that time he decides that he will built rocket. He started studying everything he can find on jet and rocket engine.

While many of Homer's friends are puzzled by his new obsession, several new friends share his enthusiasm, and with the encouragement of his teacher, Homer and his fellow "Rocket Boys" begin designing and launching their own homemade missiles. However, Homer's father takes a dim view of his son's interest in rockets and is convinced Homer's future should be the same as his own, working in the local coal mines.

Because, Coalwood’s main trade was coal mining and everybody have to do mining job for surviving in that small place. Only those students can escape from that small village if they can able to get football scholarship. Homer tries to get place in football team, but failed every time. Then by designing rockets and fighting against all odd condition this small village boy wins a science competition and got scholarship. For which he make everybody to proud him. This high school boy then becomes a NASA engineer Homer H. Hickam, Jr.'s.

Actually why I like the movie is that because like Homer, I also wanted to build rocket and tried too. Many times. I like the way he pursue his interest in rockets did whatever he want to know about the rockets. He read books, took help of others, and always tries new things after each failure. When I compared myself with Homer I found I did not do those things which he did. After a long time, when I joined Model Rocketry Lab of Vikram A. Sarabhai Community Science Centre then I learned rocket science and aalso learned to make model rockets.

Making rockets is always a very exciting experience to me. I especially enjoyed designing part of rocketry. Trying new types of models. Not every time gives you a success, but when design works and rocket roar and jump towards sky I cannot express my feeling. I think making rockets by your own and flying them successfully, it’s like AWESOME yaar!!!! At least once in a lifetime everyone should experience it.

But before that watch October Sky. I know you will like this movie...

Earth from Space: Sacred stones of the outback

This Landsat image takes us to the Amadeus Basin in the heart of the Australian outback.

Two large rock formations are visible on the lower section of the image. Sacred to the local Aboriginal people, the Anangu, these sandstone 'bornhardts' are the main features of the Uluru-Kata Tjuta National Park, a UNESCO World Heritage site.

The group of 36 domed rock formations to the west (left) is the Kata Tjuta with the tallest dome, Mount Olga, reaching 1066 m above sea level.

Forty kilometres east of Kata Tjuta is Ayers Rock, known to the Aboriginals as Uluru. Surrounding the formation are springs, waterholes, caves and ancient paintings. Local legend claims that misfortune will fall on those who remove rocks from Uluru. It has been reported that many who had taken this risk later attempted to mail the rocks back to lift the curse.

The white area at the top of the image is the salt-crusted Lake Amadeus. Although it contains hundreds of millions of tonnes of salt, the remote location renders it nearly impossible for harvesting. This area in the southern part of the Northern Territory is home to a variety of animals, including the red kangaroo, emu, marsupial mole, various bats and over 70 species of reptiles.

The Thematic Mapper on Landsat 5, jointly managed by NASA and the US Geological Survey, acquired this image on 18 May 2011. ESA supports the Landsat series as a Third Party Mission, meaning it uses its ground infrastructure and expertise to acquire, process and distribute Landsat data to users.

Herschel paints new story of galaxy evolution

Was the universe a kinder, gentler place in the past that we have thought? The Herschel space observatory has looked back across time with its infrared eyes and has seen that galaxy collisions played only a minor role in triggering star births in the past, even though today the birth of stars always seem to be generated by galaxies crashing into each other. So what was the fuel for star formation in the past?

Simple.

Gas.

The more gas a galaxy contained, the more stars were born.

Scientists say this finding overturns a long-held assumption and paints a nobler picture of how galaxies evolve.

Astronomers have known that the rate of star formation peaked in the early Universe, about 10 billion years ago. Back then, some galaxies were forming stars ten or even a hundred times more vigorously than is happening in our Galaxy today.

In the nearby, present-day Universe, such high birth rates are very rare and always seem to be triggered by galaxies colliding with each other. So, astronomers had assumed that this was true throughout history. But Herschel’s observations of two patches of sky show a different story.

Looking at these regions of the sky, each about a third of the size of the full Moon, Herschel has seen more than a thousand galaxies at a variety of distances from the Earth, spanning 80% of the age of the cosmos.

In analyzing the Herschel data, David Elbaz, from CEA Saclay in France, and his team found that even though some galaxies in the past were creating stars at incredible rates, galaxy collisions played only a minor role in triggering star births. The astronomers were able to compare the amount of infrared light released at different wavelengths by these galaxies, the team has shown that the star birth rate depends on the quantity of gas they contain, not whether they are colliding.

They say these observations are unique because Herschel can study a wide range of infrared light and reveal a more complete picture of star birth than ever seen before. However, their work compliments other recent studies from data from the Spitzer Space Telescope and the Very Large Telescope which found ancient galaxies fed on gas,not collisions

Galaxy forming stars

“It’s only in those galaxies that do not already have a lot of gas that collisions are needed to provide the gas and trigger high rates of star formation,” said Elbaz. Today’s galaxies have used up most of their gaseous raw material after forming stars for more than 10 billion years, so they do rely on collisions to jump-start star formation, but in the past galaxies grew slowly and gently from the gas that they attracted from their surroundings.

Moon CLick

I have taken this foto on Ganesh Chaturthi from Jaipur with my simple Kodak Digital Camera by using night landscape mode..

Martian lake delta spotted by Mars Express

Formed by an asteroid strike, Eberswalde crater has nearly eroded away with time. After it formed, it was partially obliterated by another impact which shaped 140 km diameter crater Holden. Although this second strike buried Eberswalde with ejecta, 115 square kilometers of delta area and feeder channels survived. These channels once were the arteries that pumped water along the surface to pool in the crater’s interior, forming a lake. As they carried water, they also carried sediments and – just as on Earth – left their mark. With time, the water dried up and even more sediments were carried along by the wind, exposing the area in vivid relief.

NASA’s Mars Global Surveyor spacecraft spied the delta in earlier missions, giving even further solidification that Mars was once a wet world. While Eberswalde crater and Holden crater were once a part of a list of possible landing sites for the Mars Science Laboratory, Gale crater was selected as the Curiosity’s landing site, given its high mineral and structural diversity related to water. But don’t count this wonderful, wet confession of a lake out forever. Thanks to high mineral diversity and suggestive structure, we’re sure to visit the delta of Eberswalde and Holden again, from orbit or with another landing mission.