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First detection of light from extrasolar planets HARVARD-SMITHSONIAN CENTER FOR ASTROPHYSICS NEWS RELEASE Posted: March 22, 2005 Two teams of astronomers announced at a press conference today that they have directly detected light from two known planets orbiting distant stars. This discovery opens a new frontier in the study of extrasolar planets. Researchers now can directly measure and compare such planetary characteristics as color, reflectivity, and temperature.
"It's an awesome experience to realize we are seeing the glow of distant worlds," said Charbonneau. "When I first saw the data, I was ecstatic." Each of the two target planets periodically crosses in front of and behind its star. When in front, the planet partially eclipses the star and blocks a small portion of the star's light. Similarly, the system dims slightly when the planet disappears behind its star since the star blocks the planet's light. By observing this "secondary eclipse," astronomers can tease out the faint signal of the planet from the overwhelming light of the nearby star. Planets can't hide the heat Charbonneau and his colleagues used the Infrared Array Camera (IRAC), a Smithsonian-developed instrument aboard NASA's Spitzer Space Telescope, to observe TrES-1 in the infrared region of the spectrum. Deming and his associates used Spitzer's Multiband Imaging Photometer for Spitzer (MIPS) to observe HD 209458b. "Planets like TrES-1 are tiny and faint compared to their stars, but the one thing they can't hide is their heat," said Charbonneau. "We are like detectives. Previous clues told us the planet must be there, so we put on our 'infrared goggles' and suddenly, it popped into view." Infrared offers an advantage because the star outshines the planet by a factor of 10,000 in visible light, while in the infrared the star is only about 400 times brighter, making it easier to pick out a planet's feeble light. Astronomers compare the challenge to trying to spot a firefly buzzing next to a searchlight. Planet TrES-1 IRAC team members Lori Allen and Tom Megeath (CfA) planned the TrES-1 observations, which required precise timing to catch the system just before and after the secondary eclipse, as well as precise pointing. Their experience and familiarity with the performance of the IRAC camera were crucial in obtaining the best data possible. Allen and Megeath also provided insights into IRAC instrument features encountered during data analysis. "Teasing out the signal from TrES-1 was both challenging and exciting," said Allen. "We were actually seeing light from another world hundreds of light-years away from us, circling around another sunlike star." Although two groups previously claimed to have directly photographed an extrasolar planet, neither one is confirmed and neither orbits a sun-like star. Using Spitzer data combined with previous measurements, Charbonneau and his colleagues confirmed that TrES-1, which orbits its star at a distance of 4 million miles, has a temperature of about 1,450 degrees Fahrenheit (1060 Kelvin). They also calculated that the planet has a reflectivity of only 31%, meaning it absorbs the majority of the star's light that falls on it. CfA researcher Guillermo Torres modeled the dynamics of the TrES-1 system to constrain the planet's orbit. He determined that the orbit has been made very nearly circular by the tidal effect of the nearby star, as expected. Future exoplanet research Charbonneau is quick to point out that the achievement of directly detecting an extrasolar planet's light is only the beginning. "We've caught our first 'firefly.' Now we want to study a swarm of them." Astronomers expect the Trans-Atlantic Exoplanet Survey (TrES) network, which spotted TrES-1, to locate additional "hot Jupiters." That ground-based network is designed to spot planets orbiting bright stars, which can be more easily studied with Spitzer and other instruments. By comparing many "hot Jupiter" planets, researchers hope to determine what gases their atmospheres contain and how their composition was affected by when and how they formed. "We never imagined we would find planets as strange and varied as we have. Who knows what new worlds are waiting for us?" said Charbonneau. The paper on the TrES-1 finding is authored by Charbonneau, Allen, Megeath, and Torres; Roi Alonso (IAC), Timothy Brown (NCAR), Ronald Gilliland (STScI), David Latham (CfA), Georgi Mandushev (Lowell Observatory), Francis O'Donovan (Caltech), and Alessandro Sozzetti (University of Pittsburgh/CfA). NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center, Pasadena, Calif. JPL is a division of California Institute for Technology, Pasadena. Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.
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Astronomers announce major findings about planets outside our solar system at this Spitzer Space Telescope science news conference on March 22 from NASA Headquarters. (21min 22sec file)
The first Boeing Delta 4-Heavy rocket ignites and lifts off from pad 37B at Cape Canaveral Air Force Station on its demonstration test flight as seen through this sequence of images from a sound-activated still camera.
A second sound-activated still camera placed at pad 37B by Spaceflight Now photographer Ben Cooper provides a different view of the Delta 4-Heavy rocket launch.
This sequence of images from a sound-activated still camera fitted with a fisheye lens was stitched together to provide a unique perspective of the Lockheed Martin Atlas 5 rocket blasting off from Complex 41 with the Inmarsat spacecraft.
The fifth Lockheed Martin Atlas 5 rocket blasts off to deploy the Inmarsat 4-F1 mobile communications spacecraft into orbit. (2min 35sec file)
An extended length clip follows the Atlas 5 launch from T-minus 1 minute through ignition of the Centaur upper stage and jettison of the nose cone. (6min 43sec file)
An onboard video camera mounted to the Atlas 5 rocket's first stage captures this view of the spent solid-fuel boosters separating.
This view of the Atlas 5 launch was recorded from the Kennedy Space Center Press Site. (1min 27sec file)
The Boeing Delta 4 rocket to launch the next GOES geostationary U.S. weather satellite is rolled to Cape Canaveral's pad 37B for its spring blastoff. (2min 08sec file)
The pad erector arm lifts the Delta 4 rocket upright, standing the vehicle onto the launch table. (4min 00sec file)
The STS-114 return-to-flight space shuttle astronauts inspect Discovery's thermal tiles and wing leading edge panels during the Crew Equipment Interface Test activities at Kennedy Space Center. (2min 26sec file)
The astronauts don coveralls and go into space shuttle Discovery's payload bay for further examinations during the Crew Equipment Interface Test in the orbiter hangar. (1min 25sec file)
A long mission simulation is underway to rehearse the launch of space shuttle Discovery, the uncovering of impact damage and the decision-making process of the flight controllers and management team. (14min 31sec file)
