Friday, September 23, 2016

Hubble telescope discovers a large planet orbiting two stars                       (हबल दूरबीन ने 'दो सितारों' की परिक्रमा करने वाले ग्रह का पता लगाया )

NASA's Hubble telescope discovered planet orbiting two stars. This Planet is 8,000 light years away from Earth.

It was first spotted in 2007 by researchers with the Optical Gravitational Lensing Experiment (OHLE), which searches for and observes effects from small distortions of spacetime caused by stars and exoplanets.

It was discovered via gravitational microlensing, which relies on the concept from Einstein's Theory of Relativity that gravity can bend light waves.

When a bright, distant star is viewed from Earth, the gravity from a "lens star" between the Earth and the distant "source star" can bend light and act as a lens. The lens star bends the light from the source star into magnified images of the source star on either side of it.While the researchers knew they'd discovered a three-body system, they couldn't be sure exactly what it was made comprised of."The ground-based observations suggested two possible scenarios for the three-body system: a Saturn-mass planet orbiting a close binary star pair or a Saturn-mass and an Earth-mass planet orbiting a single star," David Bennett of the NASA Goddard Space Flight Center in Greenbelt, Md. and the paper's first author, said in a statement.

Hubble Telescope
Now, thanks to the crisp images from the Hubble spacecraft, scientists have pinpointed the twin red dwarf stars. "We were helped in the analysis by the almost perfect alignment of the foreground binary stars with the background star, which greatly magnified the light and allowed us to see the signal of the two stars," Bennett said.NASA's Kepler spacecraft has so far discovered 10 other planets orbiting binary stars — but this one stands out both for the unique way it was discovered and for its vast orbit. The planet orbits about 483 million kilometres from the stellar duo. The stars are about 11 million kilometres apart, a distance roughly 14 times the diameter of the moon's orbit around Earth."This discovery suggests we need to rethink our observing strategy when it comes to stellar binary lensing events," Yiannis Tsapras, co-author of the study from the Astronomisches Rechen-Institut (Astronomical Calculation Institute) in Heidelberg, Germany, said. "This is an exciting new discovery for microlensing." In 2014, astronomers used gravitational microlensing to discover an Earth-sized planet that shared a system with two mini-suns, but in that case it orbited just one of the twins.Thursday's news comes on the heels of a University of Edinburgh study that revealed two-star systems are more common that previously believed.

Saturday, August 20, 2016

Venus-Like Exoplanet GJ 1132b Might  have Thin Oxygen Atmosphere, But Not Life (शुक्र ग्रह की तरह दिखने वाले ग्रह  GJ 1132b  पर  ऑक्सीजन  है परन्तु जीवन नही है /)

Astronomers believe that distant exoplanet GJ 1132b, which was discovered last year, might have an atmosphere despite being an extremely hot world with a temperature of nearly 450 degrees Fahrenheit.

The study, published in the Astrophysical Journal, showed that the Venus-like planet, about 39 light years away from Earth, might have a thin and wispy atmosphere, indicating the presence of oxygen.

"On cooler planets, oxygen could be a sign of alien life and habitability," said Laura Schaefer, an astronomer at Harvard-Smithsonian Center for Astrophysics and lead author of the study, in a statement. But on a hot planet like GJ 1132b, it's a sign of the exact opposite - a planet that's being baked and sterilized."

For the study, the researchers assumed that GJ1132b began with a steamy, water-rich atmosphere. With an extremely close orbit to its host star, approximately 1.4 million miles, the planet could be bombarded with ultraviolet light. The water molecules in the atmosphere of the planet would be broken apart by the UV light into hydrogen and oxygen. Because hydrogen is lighter, it could escape into space readily, while some of the oxygen could linger behind.
Water vapor could act as a powerful greenhouse gas, trapping the intense heat of the host star inside GJ113b. Due to this, the surface of the planet could stay molten for millions of years.
Using a magma ocean-atmosphere model, the researchers believe that a magma ocean could interact with the atmosphere by absorbing about 10 percent of the oxygen, while the remaining 90 percent may stream off to space or linger around the planet.

With their findings, researchers could catch some glimpse on how the planet Venus evolved. Previous study suggests that Venus might contain Earth-like amounts of water in its early life and was broken down by the sunlight. However, Venus shows few signs of lingering oxygen.
To confirm if GJ1132b have some oxygen lingering in its atmosphere, researchers need to observe the planet using next-generation telescope like the Giant Magellan Telescope and James Webb Space Telescope to detect and analyze it.