galaxy news: Systems

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السبت، 8 سبتمبر 2012

Binary-Star Systems may be 'Hot Zones' for Life --New NASA Discovery

Binary-Star Systems may be 'Hot Zones' for Life --New NASA Discovery
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September 04, 2012 Binary-Star Systems may be 'Hot Zones' for Life --New NASA Discovery

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"Star-Wars" like Tatooine binary-star worlds may prove to be hot spots for the existence of smaller, rockier planets at distances where liquid water can exist. NASA's Kepler mission has just discovered multiple transiting planets orbiting two suns for the first time. The system, known as a circumbinary planetary system, is 4,900 light-years from Earth in the constellation Cygnus.

"Unlike our sun, many stars are part of multiple-star systems where two or more stars orbit one another. The question always has been -- do they have planets and planetary systems? This Kepler discovery proves that they do," said William Borucki, Kepler mission principal investigator at NASA's Ames Research Center in Moffett Field, Calif. "In our search for habitable planets, we have found more opportunities for life to exist."

Coming less than a year after the announcement of the first circumbinary planet, Kepler-16b, this discovery proves that more than one planet can form and persist in the stressful realm of a binary star. The discovery demonstrates the diversity of planetary systems in our galaxy.

Astronomers detected two planets in the Kepler-47 system, a pair of orbiting stars that eclipse each other every 7.5 days from our vantage point on Earth. One star is similar to the sun in size, but only 84 percent as bright. The second star is diminutive, measuring only one-third the size of the sun and less than 1 percent as bright.

"In contrast to a single planet orbiting a single star, the planet in a circumbinary system must transit a 'moving target.' As a consequence, time intervals between the transits and their durations can vary substantially, sometimes short, other times long," said Jerome Orosz, associate professor of astronomy at San Diego State University and lead author of the paper. "The intervals were the telltale sign these planets are in circumbinary orbits."

The inner planet, Kepler-47b, orbits the pair of stars in less than 50 days. While it cannot be directly viewed, it is thought to be a sweltering world, where the destruction of methane in its super-heated atmosphere might lead to a thick haze that could blanket the planet. At three times the radius of Earth, Kepler-47b is the smallest known transiting circumbinary planet.

The outer planet, Kepler-47c, orbits its host pair every 303 days, placing it in the so-called "habitable zone," the region in a planetary system where liquid water might exist on the surface of a planet. While not a world hospitable for life, Kepler-47c is thought to be a gaseous giant slightly larger than Neptune, where an atmosphere of thick bright water-vapor clouds might exist.

To search for transiting planets, the research team used data from the Kepler space telescope, which measures dips in the brightness of more than 150,000 stars. Additional ground-based spectroscopic observations using telescopes at the McDonald Observatory at the University of Texas at Austin helped characterize the stellar properties. The findings are published in the journal Science.

"The presence of a full-fledged circumbinary planetary system orbiting Kepler-47 is an amazing discovery," said Greg Laughlin, professor of Astrophysics and Planetary Science at the University of California in Santa Cruz. "These planets are very difficult to form using the currently accepted paradigm, and I believe that theorists, myself included, will be going back to the drawing board to try to improve our understanding of how planets are assembled in dusty circumbinary disks."

The Daily galaxy via http://www.nasa.gov/kepler

Posted at 08:45 AM | Permalink

Comments

If there is a moon orbiting Kepler 47ABc with sufficient mass to contain liquid water(MINIMUM: o.3 EARTH MASS), KST could detect it via transit duration variations(as opposed to the MORE COMMON method of transit TIMING variations, used to detect non-transiting planets in systems with at least one transiting planet). This takes a bit longer than TTVs, so it may be a few years before we have a definitive answer.

Posted by:Harry Ray |September 04, 2012 at 09:52 AM

الثلاثاء، 4 سبتمبر 2012

Getting Closer! --Kepler Mission Captures 41 New Planets in 20 Star Systems

Getting Closer! --Kepler Mission Captures 41 New Planets in 20 Star Systems
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August 27, 2012 Getting Closer! --Kepler Mission Captures 41 New Planets in 20 Star Systems

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Two newly submitted studies verify 41 new transiting planets in 20 star systems. These results may increase the number of Kepler's confirmed planets by more than 50 percent: to 116 planets hosted in 67 systems, over half of which contain more than one planet. The papers are currently under scientific peer-review.

Nineteen of the newly validated planetary systems have two closely spaced transiting planets and one system has three. Five of the systems are common to both of these independent studies. The planets range from Earth-size to more than seven times the radius of Earth, but generally orbit so close to their parent stars that they are hot, inhospitable worlds. The planets were confirmed by analyzing Transit Timing Variations (TTVs).

In closely packed systems, the gravitational pull of the planets causes the acceleration or deceleration of a planet along its orbit. These "tugs" cause the orbital period of each planet to change from one orbit to the next. TTV demonstrates that two transiting planet candidates are in the same system and that their masses are planetary in nature.

"These systems, with their large gravitational interactions, give us important clues about how planetary systems form and evolve," said lead researcher Jason Steffen, the Brinson postdoctoral fellow at Fermilab Center for Particle Astrophysics in Batavia, Ill. "This information helps us understand how our own solar system fits into the population of all planetary systems." The two research teams used data from NASA's Kepler space telescope, which measures dips in the brightness of more than 150,000 stars, to search for transiting planets.

"The sheer volume of planet candidates being identified by Kepler is inspiring teams to look at the planet confirmation and characterization process differently. This TTV confirmation technique can be applied to large numbers of systems relatively quickly and with little or no follow-up observations from the ground," said Natalie Batalha, Kepler mission scientist at NASA's Ames Research Center, Moffett Field, Calif. "Perhaps the bottleneck between identifying planet candidates and confirming them just got a little wider."

The diagram below shows the newly submitted transiting planets in green along with the unconfirmed planet candidates in the same system in violet. The systems are ordered horizontally by increasing Kepler number and KOI designation and vertically by orbital period.

41newtransit

More information: see: J Steffen et al, 2012, Transit Timing Observations from Kepler: VII; and, Ji-Wei Xie, 2012, Transit Timing Variation of Near-Resonant KOI Pairs.

The Daily Galaxy via Provided by NASA Kepler Mission

Posted at 08:44 AM | Permalink

Comments

Good work! Find us a suitable planet so we can get off this rock.

Posted by:Bigfan |August 28, 2012 at 03:08 AM

It'd be nice if we could enlarge the diagram at the bottom of the page, it might be possible to read it then! Editor's Note: Oh, Ruth...then what fun would it be.

Posted by:Ruth Mc |August 28, 2012 at 09:33 AM

Actually, it would. But I'll let you off for that barbed comment seeing as no-one is particularly cheerful when they have a long day at work looming ahead...

Posted by:Ruth Mc |August 29, 2012 at 09:24 AM

الأحد، 29 يوليو 2012

"The Seven Minutes of Terror" --All Systems "Go" for NASA's August 5th Landing on Mars

"The Seven Minutes of Terror" --All Systems "Go" for NASA's August 5th Landing on Mars
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July 17, 2012 "The Seven Minutes of Terror" --All Systems "Go" for NASA's August 5th Landing on Mars

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NASA's most advanced planetary rover, the 1-ton Curiosity , the centerpiece of the Mars Science Laboratory (MSL) mission, is slated to land at the Gale Crater on the night of Aug. 5 to look for chemical evidence of ancient life preserved within exposures near the base of a five-kilometers high mound of layered materials at the center of Gale crater (above). However, getting the Curiosity rover to the surface of Mars will be a hair-raising event --that has been nicknamed the "seven minutes of terror."

"The Curiosity landing is the hardest NASA mission ever attempted in the history of robotic planetary exploration," said John Grunsfeld, associate administrator for NASA's Science Mission Directorate, at NASA Headquarters in Washington. "While the challenge is great, the team's skill and determination give me high confidence in a successful landing."

To achieve the precision needed for landing (see diagram at bottom of page) safely inside Gale Crater, the spacecraft will fly like a wing in the upper atmosphere instead of dropping like a rock. To land the 1-ton rover, an airbag method used on previous Mars rovers will not work. Mission engineers at NASA's Jet Propulsion Laboratory in Pasadena, Calif., designed a "sky crane" method for the final several seconds of the flight. A backpack with retro-rockets controlling descent speed will lower the rover on three nylon cords just before touchdown.

During a critical period lasting only about seven minutes, the Mars Science Laboratory spacecraft carrying Curiosity must decelerate from about 13,200 mph (about 5,900 meters per second) to allow the rover to land on the surface at about 1.7 mph (three-fourths of a meter per second). Curiosity is scheduled to land at approximately 10:31 p.m. PDT on Aug. 5 (1:31 a.m. EDT on Aug. 6).

"Those seven minutes are the most challenging part of this entire mission," said Pete Theisinger, the mission's project manager at JPL. "For the landing to succeed, hundreds of events will need to go right, many with split-second timing and all controlled autonomously by the spacecraft. We've done all we can think of to succeed. We expect to get Curiosity safely onto the ground, but there is no guarantee. The risks are real."

In early June, a NASA spacecraft in orbit around the Red Planet, called Mars Odyssey, suffered a malfunction on one of its reaction wheels, an instrument that helps control the probe's attitude in space.* "Odyssey looks like it may not be where we expect it to be," said Doug McCuistion, director of the Mars Exploration Program at NASA Headquarters.

The glitch does not pose a risk to Curiosity's impending arrival at the Red Planet, officials said. But Mars Odyssey's original orbit would have given it a complete view of Curiosity's landing, so the probe had been pegged to act as an orbiting outpost to relay communications and data back to mission managers on Earth.

With Odyssey in the picture, mission managers may be able to confirm Curiosity's touchdown by 10:31 p.m. PDT on Aug. 5 (1:31 a.m. EDT Aug. 6). Without Odyssey, however, mission controllers may not know the outcome of the landing maneuver until 10:35 p.m. PDT or later.

During the initial weeks after the actual landing, JPL mission controllers will put the rover through a series of checkouts and activities to characterize its performance on Mars, while gradually ramping up scientific investigations. Curiosity then will begin investigating whether an area with a wet history inside Mars' Gale Crater ever has offered an environment favorable for microbial life.

"Earlier missions have found that ancient Mars had wet environments," said Michael Meyer, lead scientist for NASA's Mars Program at NASA Headquarters. "Curiosity takes us the next logical step in understanding the potential for life on Mars."

Curiosity will use tools on a robotic arm to deliver samples from Martian rocks and soils into laboratory instruments inside the rover that can reveal chemical and mineral composition. A laser instrument will use its beam to induce a spark on a target and read the spark's spectrum of light to identify chemical elements in the target.

Other instruments on the car-sized rover will examine the surrounding environment from a distance or by direct touch with the arm. The rover will check for the basic chemical ingredients for life and for evidence about energy available for life. It also will assess factors that could be hazardous for life, such as the radiation environment.

"For its ambitious goals, this mission needs a great landing site and a big payload," said McCuistion. "During the descent through the atmosphere, the mission will rely on bold techniques enabling use of a smaller target area and a heavier robot on the ground than were possible for any previous Mars mission. Those techniques also advance us toward human-crew Mars missions, which will need even more precise targeting and heavier landers."

The chosen landing site is beside a mountain informally called Mount Sharp. The mission's prime destination lies on the slope of the mountain. Driving there from the landing site may take many months.

Because of its history, 96-mile wide Gale Crater crater with its strangely sculpted mountain --three times higher than the Grand Canyon is deep--is the ideal place for Curiosity to conduct its mission of exploration into the Red Planet's past. Researchers plan to use Curiosity to study layers in the mountain that hold evidence about wet environments of early Mars.

"This may be one of the thickest exposed sections of layered sedimentary rocks in the solar system," said Joy Crisp, MSL Deputy Project Scientist from NASA's Jet Propulsion Laboratory. "The rock record preserved in those layers holds stories that are billions of years old -- stories about whether, when, and for how long Mars might have been habitable."

An instrument on Curiosity can check for any water that might be bound into shallow underground minerals along the rover's path. Today the Red Planet is a radiation-drenched, bitterly cold, bleak world. Enormous dust storms explode across the barren landscape and darken Martian skies for months at a time. But data from the Mars Reconnaissance Orbiter suggest that Mars once hosted vast lakes and flowing rivers.

"Gale Crater and its mountain will tell this intriguing story," says Matthew Golombek, Mars Exploration Program Landing Site Scientist from JPL. "The layers there chronicle Mars' environmental history."

"Be patient about the drive. It will be well worth the wait and we are apt to find some targets of interest on the way," said John Grotzinger, MSL project scientist at the California Institute of Technology in Pasadena. "When we get to the lower layers in Mount Sharp, we'll read them like chapters in a book about changing environmental conditions when Mars was wetter than it is today."

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The Daily Galaxy via NASA Curiosity Mission

Posted at 09:00 AM | Permalink

Comments

Sounds like a pretty good plan dude. Wow.
www.Privacy-Been.tk

Posted by:ZundoRannYankDenn |July 17, 2012 at 10:27 AM

This is amazing. All the best to NASA scientists and the human ingenuity.

Posted by:Dayanand Sutar |July 21, 2012 at 01:45 PM

Can't wait!

Posted by:Ruth Mc |July 23, 2012 at 06:48 AM