• Tag Archives exoplanets

  • Exoplanet tally soars above 1,000

    Posted on by Azrael Comment

     

    The number of observed exoplanets – worlds circling distant stars – has passed 1,000.

    Of these, 12 could be habitable – orbiting at a distance where it is neither “too hot” nor “too cold” for water to be liquid on the surface.

    The planets are given away by tiny dips in light as they pass in front of their stars or through gravitational “tugs” on the star from an orbiting world.

    These new worlds are listed in the Extrasolar Planets Encyclopaedia.

    The tally now stands at 1,010 new exoplanets, bolstered by 11 new finds from the UK’s Wide Angle Search for Planets (Wasp).

    Abel Mendez of the Planetary Habitability Laboratory at the University of Puerto Rico, said that although the number has rapidly increased in recent years, due to a lack of funding this figure is much lower than it could be.

    “We have more techniques and proven technology to detect more exoplanets, but the limit has been telescopes, especially space telescopes.

    “If we had more funding there would be more telescopes and that count would be much larger by now.”

    The Kepler space telescope, which spotted many of these worlds in recent years, broke down earlier this year. Scientists still have to trawl through more than 3,500 other candidates from this mission so the number could rapidly increase.

    In January 2013, astronomers used Kepler’s data to estimate that there could be at least 17 billion Earth-sized exoplanets in the Milky Way galaxy. They said that one in six stars could host an Earth-sized planet in close orbit.

    The number of confirmed planets frequently increases because as scientists analyse the data they are able publish their results online immediately. But as the finds are not yet peer reviewed, the total figure remains subject to change.

    “Each night we get a list of astronomy papers where there might be an exoplanet announcement. When we get that we have to review it,” explained Prof Mendez.

    This exoplanet catalogue is organised by Jean Schneider, an astronomer at the Paris Observatory. For the past 18 years he has catalogued new exoplanets on the Extrasolar Planets Encyclopaedia.

    Full article: http://www.bbc.co.uk … environment-24549384


    📂This entry was posted in Space 📎and tagged

  • NASA Hubble Finds a True Blue Planet

    Posted on by Azrael Comment

    Astronomers making visible-light observations with NASA’s Hubble Space Telescope have deduced the actual color of a planet orbiting another star 63 light-years away.

    The planet is HD 189733b, one of the closest exoplanets that can be seen crossing the face of its star.

    Hubble’s Space Telescope Imaging Spectrograph measured changes in the color of light from the planet before, during and after a pass behind its star. There was a small drop in light and a slight change in the color of the light. “We saw the light becoming less bright in the blue but not in the green or red. Light was missing in the blue but not in the red when it was hidden,” said research team member Frederic Pont of the University of Exeter in South West England. “This means that the object that disappeared was blue.”

    Earlier observations have reported evidence for scattering of blue light on the planet. The latest Hubble observation confirms the evidence.

    If seen directly, this planet would look like a deep blue dot, reminiscent of Earth’s color as seen from space. That is where the comparison ends.

    On this turbulent alien world, the daytime temperature is nearly 2,000 degrees Fahrenheit, and it possibly rains glass — sideways — in howling, 4,500-mph winds. The cobalt blue color comes not from the reflection of a tropical ocean as it does on Earth, but rather a hazy, blow-torched atmosphere containing high clouds laced with silicate particles. Silicates condensing in the heat could form very small drops of glass that scatter blue light more than red light.

    Hubble and other observatories have made intensive studies of HD 189733b and found its atmosphere to be changeable and exotic.

    HD 189733b is among a bizarre class of planets called hot Jupiters, which orbit precariously close to their parent stars. The observations yield new insights into the chemical composition and cloud structure of the entire class.

    Clouds often play key roles in planetary atmospheres. Detecting the presence and importance of clouds in hot Jupiters is crucial to astronomers’ understanding of the physics and climatology of other planets.

    HD 189733b was discovered in 2005. It is only 2.9 million miles from its parent star, so close that it is gravitationally locked. One side always faces the star and the other side is always dark.

    In 2007, NASA’s Spitzer Space Telescope measured the infrared light, or heat, from the planet, leading to one of the first temperature maps for an exoplanet. The map shows day side and night side temperatures on HD 189733b differ by about 500 degrees Fahrenheit. This should cause fierce winds to roar from the day side to the night side.

    http://www.nasa.gov/ … -a-true-blue-planet/


    📂This entry was posted in Space 📎and tagged