Hi My Friends: A VUELO DE UN QUINDE EL BLOG., An international team of astronomers using data from NASA's Hubble
Space Telescope has made an unparalleled observation, detecting
significant changes in the atmosphere of a planet located beyond our
solar system.
This artist's rendering illustrates the
evaporation of HD 189733b's atmosphere in response to a powerful
eruption from its host star. NASA's Hubble Space Telescope detected the
escaping gases and NASA's Swift satellite caught the stellar flare.
(Credit: NASA's Goddard Space Flight Center)
› Larger image (JPG)
› Larger image (80 MB TIF)
Hubble, Swift Detect First-Ever Changes in an Exoplanet Atmosphere
An international team of astronomers using data from NASA's Hubble Space
Telescope has made an unparalleled observation, detecting significant
changes in the atmosphere of a planet located beyond our solar system.
The scientists conclude the atmospheric variations occurred in response
to a powerful eruption on the planet's host star, an event observed by
NASA's Swift satellite.
"The multiwavelength coverage by Hubble and Swift has given us an
unprecedented view of the interaction between a flare on an active star
and the atmosphere of a giant planet," said lead researcher Alain
Lecavelier des Etangs at the Paris Institute of Astrophysics (IAP), part
of the French National Scientific Research Center located at Pierre and
Marie Curie University in Paris.
The exoplanet is HD 189733b, a gas giant similar to Jupiter, but about
14 percent larger and more massive. The planet circles its star at a
distance of only 3 million miles, or about 30 times closer than Earth's
distance from the sun, and completes an orbit every 2.2 days. Its star,
named HD 189733A, is about 80 percent the size and mass of our sun.
Astronomers classify the planet as a "hot Jupiter." Previous Hubble
observations show that the planet's deep atmosphere reaches a
temperature of about 1,900 degrees Fahrenheit (1,030 C).
HD 189733b periodically passes across, or transits, its parent star, and
these events give astronomers an opportunity to probe its atmosphere
and environment. In a previous study, a group led by Lecavelier des
Etangs used Hubble to show that hydrogen gas was escaping from the
planet's upper atmosphere. The finding made HD 189733b only the
second-known "evaporating" exoplanet at the time.
The system is just 63 light-years away, so close that its star can be
seen with binoculars near the famous Dumbbell Nebula. This makes HD
189733b an ideal target for studying the processes that drive
atmospheric escape.
"Astronomers have been debating the details of atmospheric evaporation
for years, and studying HD 189733b is our best opportunity for
understanding the process," said Vincent Bourrier, a doctoral student at
IAP and a team member on the new study.
Swift's Ultraviolet/Optical Telescope captured this view of HD
189733b's star on Sept. 14, 2011. The image is 6 arcminutes across.
Credit: NASA/Swift/Stefan Immler
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Strong X-ray emission makes the host star of HD 189733b stand out
in this view from Swift's X-Ray Telescope. The image combines data from
Sept. 13 and 14, 2011, and is 6 arcminutes across.
Credit: NASA/Swift/Stefan Immler
› Larger image
When HD 189733b transits its star, some of the star's light passes
through the planet's atmosphere. This interaction imprints information
on the composition and motion of the planet's atmosphere into the star's
light.
In April 2010, the researchers observed a single transit using Hubble's
Space Telescope Imaging Spectrograph (STIS), but they detected no trace
of the planet's atmosphere. Follow-up STIS observations in September
2011 showed a surprising reversal, with striking evidence that a plume
of gas was streaming away from the exoplanet.
The researchers determined that at least 1,000 tons of gas was leaving
the planet's atmosphere every second. The hydrogen atoms were racing
away at speeds greater than 300,000 mph. The findings will appear in an
upcoming issue of the journal Astronomy & Astrophysics.
Because X-rays and extreme ultraviolet starlight heat the planet's
atmosphere and likely drive its escape, the team also monitored the star
with Swift's X-ray Telescope (XRT). On Sept. 7, 2011, just eight hours
before Hubble was scheduled to observe the transit, Swift was monitoring
the star when it unleashed a powerful flare. It brightened by 3.6 times
in X-rays, a spike occurring atop emission levels that already were
greater than the sun's.
"The planet's close proximity to the star means it was struck by a blast
of X-rays tens of thousands of times stronger than the Earth suffers
even during an X-class solar flare, the strongest category," said
co-author Peter Wheatley, a physicist at the University of Warwick in
England.
After accounting for the planet's enormous size, the team notes that HD
189733b encountered about 3 million times as many X-rays as Earth
receives from a solar flare at the threshold of the X class.
Hubble is a project of international cooperation between NASA and the
European Space Agency. Swift is operated in collaboration with several
U.S. institutions and partners in the United Kingdom, Italy, Germany and
Japan. NASA's Goddard Space Flight Center in Greenbelt, Md., manages
both missions.
For more information about Swift, visit:
http://www.nasa.gov/swift
For more information about Hubble, visit:
http://www.nasa.gov/hubble
For images and video related to this finding, visit:
For more information about Swift, visit:
For more information about Hubble, visit:
NASA
Guillermo Gonzalo Sánchez Achutegui
ayabaca@gmail.com
ayabaca@hotmail.com
ayabaca@yahoo.com
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