Posted on by Nancy Atkinson

Another Exoplanet Hunting Mission Ends: CoRoT Spacecraft Can’t be Recovered

The COROT spacecraft. Credits: CNES/D. Ducros

More bad news on the exoplanet-hunting front: While the final fate of the Kepler spacecraft remains unknown, the CoRoT (Convection, Rotation and Planetary Transits) satellite has now been officially shut down. CoRoT suffered a computer failure on November, 2, 2012 and although the spacecraft is capable of receiving navigational commands, the French Space Agency CNES reports it can no longer retrieve data from its 30-centimeter telescope. After a valiant effort to try and restore the computer, CNES announced this week that the spacecraft has been retired. CoRoT’s journey will come to a fiery end as it will be deorbited and it will burn up on re-entry in Earth’s atmosphere.

While it’s always hard to see the end of successful mission, we can’t be too sad about CoRoT, however. The mission lasted twice as long as expected and it gathered a remarkable haul of exoplanets. CoRoT looked for planetary transits — a dimming in brightness of the host star as a planet crossed in front. CoRoT was the first mission to find a planet using the transit method.

In all, CoRoT has spotted 32 confirmed planets and at least 100 more are awaiting confirmation. The mission also allowed astronomers to study the stellar physics and the interior of stars.

This is not the first computer failure for the mission. CoRoT launched in December of 2006, and in 2009 the main computer failed and has since been running on the backup computer. When the second computer failed in November, engineering teams have tried to reboot both computers, with no success.

But space radiation is tough on spacecraft, and after enduring 6 years of intense bombardment by high-energy particles in space, both computers have been deemed unrecoverable.

CNES said a series of operations will be performed to lower CoRoT’s orbit and conduct some technology experiments before passivating and deorbiting the satellite. Its journey will end as it burns up on re-entry in Earth’s atmosphere.

Family portrait of the first 15 CoRoT planets. Credit: Patrice Amoyel (CNES)
Family portrait of the first 15 CoRoT planets. Credit: Patrice Amoyel (CNES)

CoRoT discovered a diverse array of planets, mostly gas giants. Some of the planets discovered, like CoRoT-7b, orbit their star in less than 24 hours and have a blistering hot surface, while others like CoRoT-9b have an orbital period of 95 days and is one of very few known “warm” transiting exoplanets.

CoRoT was also the first to obtain measurements of the radius of brown dwarves, intermediate objects between a planet and a star, and literally opened up a whole new field of study of temporal analysis of the micro-variability of stars by measuring the frequencies and amplitudes of stellar vibrations with unprecedented precision.

CNES did not provide a timetable for CoRoT’s demise, but we’ll keep you posted.

Source: CNES

Posted on by Elizabeth Howell

Discovery! More Planets Found Orbiting In A Star Cluster

An artist's conception of an exoplanet transiting its home star. Credit: NASA's Goddard Space Flight Center

As Earthlings, we’re so used to thinking about planets being in simple orbits around a single star. But the Sun likely didn’t begin its life alone. It formed as part of a cluster of stars, all feeding from the same well of gas.

Could star clusters also host planets? Or do they have to wait for the little guys until the stars evolve and move further apart? Well, astronomers have actually just found planets — yes, two planets — orbiting Sun-like stars in a cluster 3,000 light-years from Earth.

 

These are the third and fourth star cluster planets yet discovered, but the first found “transiting” or passing across the face of their stars as seen from Earth. (The others were found through detecting gravitational wobbles in the star.)

This is no small feat for a planet to survive. In a telescope, a star cluster might look pretty benign, but up close it’s pretty darn harsh. A press release about the discovery used a lot of words like “strong radiation”, “harsh stellar winds” and “stripping planet-forming materials” in a description of what NGC 6811 would feel like.

An artist's conception of a planet in a star cluster. Credit: Michael Bachofner
An artist’s conception of a planet in a star cluster. Credit: Michael Bachofner

“Old clusters represent a stellar environment much different than the birthplace of the Sun and other planet-hosting field stars,” stated lead author Soren Meibom of the Harvard-Smithsonian Center for Astrophysics.

“We thought maybe planets couldn’t easily form and survive in the stressful environments of dense clusters, in part because for a long time we couldn’t find them.”

The find, as you would expect, comes from the prolific planet-hunting NASA Kepler spacecraft that is now battling problems with pointing in the right direction. Although the telescope is in the penalty box, there still are reams of data waiting to be analyzed and released.

The planets are known as Kepler-66b and Kepler-67b, and are both approaching the size of Neptune (which is four times the size of Earth). Their parent cluster, NGC 6811, is one billion years old. Astronomers are still puzzled as to how these little worlds survived for so long.

“Highly energetic phenomena including explosions, outflows and winds often associated with massive stars would have been common in the young cluster,” stated the journal paper in Nature.

“The degree to which the formation and evolution of planets is influenced by a such a dense and dynamically and radiatively hostile environment is not well understood, either observationally or theoretically.”

Check out the entire study in the latest edition of Nature.

Source: Harvard-Smithsonian Center for Astrophysics

Posted on by Elizabeth Howell

‘Space Selfie’ Telescope Could Hunt Alien Planets … If It Raises A Cool $2M

Example of an orbital 'selfie' that Planetary Resources' ARKYD telescope could provide to anyone who donates to their new Kickstarter campaign. Credit: Planetary Resources.

A crowdfunded telescope — best known for offering “space selfies” for backers as an incentive to send money — is now considering a search for alien planets.

Planetary Resources Inc. (the proposed asteroid miners) announced a new “stretch goal” for its asteroid-hunting Arkyd-100 telescope.

If the company can raise $2 million — double its original goal — it promises to equip the Arkyd telescope to look at star systems for exoplanets. The project is still short the $1 million required to receive any money, but the target appears to be close enough now to give Planetary Resources confidence that more funds will come for new initiatives.

The motivation for planet hunting was mechanical trouble besetting the famous Kepler space telescope. Kepler recently lost the second of its four reaction wheels, devices that are used to stabilize the telescope in space as it seeks alien worlds.

Artist's conception of the Kepler Space Telescope. Credit: NASA/JPL-Caltech
Artist’s conception of the Kepler Space Telescope. Credit: NASA/JPL-Caltech

Because Kepler needs at least three reaction wheels to point towards targets, its future is uncertain. Some planet searching is still possible with ground-based observatories, however.

“With NASA’s recent equipment failure on the Kepler telescope (RIP, Kepler!), our search for extrasolar planets nearly came to a grinding halt. If we can meet our stretch goal, we can resume some of this progress by enhancing the Arkyd,” Arkyd organizers stated on their Kickstarter campaign website.

“We’re partnering with exoplanet researchers at MIT [the Massachusetts Institute of Technology] to equip citizen scientists like YOU with the tools to join a search that’s captivated us for generations.”

Arkyd would use two methods to hunt down planets:

– Transiting, or seeing the dip in a star’s brightness when a planet passes in front of it;

– Gravitational microlensing, or finding planets by measuring how the gravity of the star (and its planets) distorts light from stars and galaxies behind.

With 19 days to go, Arkyd is at about $857,000 of its preliminary $1 million goal that it must reach to receive any money.

If it can raise $1.3 million, Planetary Resources proposes to build a ground station at an undisclosed “educational partner” that would double the download speed of data from the orbiting observatory.

The project has more than 9,500 backers. Two more stretch goals will be revealed if Arkyd receives 11,000 backers and 15,000 backers, Planetary Resources stated.

More information on the Arkyd Kickstarter campaign is here.

Posted on by Tammy Plotner

ALMA and the Comet Factory

This artist’s impression shows the dust trap in the system Oph-IRS 48. The dust trap provides a safe haven for the tiny rocks in the disc, allowing them to clump together and grow to sizes that allow them to survive on their own. Credit: ESO/L. Calçada

“Ooompah, loompah, roopity rust… ALMA finds comets hiding in dust.” According to many studies over recent years, astronomers are aware planets seem to be everywhere around stars. However, just how these rocky bodies, including comets, are created is something of an enigma. Now, thanks to one sweet telescope, the Atacama Large Millimeter/submillimeter Array (ALMA), science has taken a big step forward in understanding how minuscule dust grains in a protoplanetary disk can one day evolve into a larger format.

A little less than 400 light years from Earth is a youthful solar system cataloged as Oph IRS 48. In images taken of its outer perimeters, astronomers have picked up a vital clue in its swirling masses of dust – a crescent-shaped region dubbed a “dust trap”. Researchers feel this area may be a protective cocoon which allows rocky formations to take shape. Why is such a region important? It’s the smash-factor. When astronomers try to model dust to rocky formations, they have found the particles self-destruct… either by crashing into each other, or being drawn into the central star. In order for them to progress past a certain size, they simply must have an area of protection to allow them to grow.

“There is a major hurdle in the long chain of events that leads from tiny dust grains to planet-sized objects,” said Til Birnstiel, a researcher at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., and co-author on the paper published in the journal Science. “In computer models of planet formation, dust grains must grow from submicron sizes to objects up to ten times the mass of the Earth in just a few million years. But once particles grow larger enough, they begin to pick up speed and either collide, sending them back to square one, or slowly drift inward, thwarting further growth.”

So where can a newborn planet, comet or asteroid hide? Nienke van der Marel, a PhD student at Leiden Observatory in the Netherlands, and lead author of the article, was using ALMA along with her co-workers, to take a close look at Oph IRS 48 and discovered a torus of gas with a central hole. This absence of dust particles was very different from earlier results picked up on ESO’s Very Large Telescope.

“At first the shape of the dust in the image came as a complete surprise to us,” says van der Marel. “Instead of the ring we had expected to see, we found a very clear cashew-nut shape! We had to convince ourselves that this feature was real, but the strong signal and sharpness of the ALMA observations left no doubt about the structure. Then we realised what we had found.”

A surprise? You bet. What the team uncovered was a region where large dust grains remained captive and could continue to gain mass as more and more grains collided and melded together. Here was the “dust trap” which theorists predicted.

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So what makes it up? To keep the dust grains together and forming requires a vortex – an area of high pressure to protect them. To form this vortex, there needs to be a large object present, either a companion star or a gas-giant. Like a boat sluicing through algae-filled waters, the secondary object in the planetary disk would clear a path in its wake, producing the critical eddies and vortices needed to fashion the dust trap. While previous studies of Oph IRS 48 uncovered a rigid ring of carbon monoxide gas combined with dust, there was no observed “trap”. However, that doesn’t mean the observation was negative. Astronomers also uncovered a gap between the inner and outer portions of the solar system – a clue to the presence of the necessary large body.

The conditions were right for a possible dust trap. Enter ALMA. Now the researchers were able to see both the gas and larger dust grains at the same time. These new observations led to a discovery no other telescope had yet revealed… a lopsided bulge in the outer portion of the disk.

As van der Marel explains: “It’s likely that we are looking at a kind of comet factory as the conditions are right for the particles to grow from millimetre to comet size. The dust is not likely to form full-sized planets at this distance from the star. But in the near future ALMA will be able to observe dust traps closer to their parent stars, where the same mechanisms are at work. Such dust traps really would be the cradles for new-born planets.”

As larger particles migrate towards the areas of higher pressure, the dust trap takes shape. To validate their findings the researchers employed computer modeling to show that a high pressure region could arise from the motion of the gas at the opening edges. It matches with the observation of the Oph IRS 48 disc.

“The combination of modelling work and high quality observations of ALMA makes this a unique project”, says Cornelis Dullemond from the Institute for Theoretical Astrophysics in Heidelberg, Germany, who is an expert on dust evolution and disc modelling, and a member of the team. “Around the time that these observations were obtained, we were working on models predicting exactly these kinds of structures: a very lucky coincidence.”

“This structure we see with ALMA could be scaled down to represent what may be happening in the inner solar system where more Earth-like rocky planets would form,” said Birnstiel. “In the case of these observations, however, we may be seeing something analogous to the formation of our Sun’s Kuiper Belt or Oort Cloud, the region of our solar system where comets are believed to originate.”

Like that dream factory of our childhood, ALMA is still under construction. These unique observations were taken with the ALMA Band 9 receivers – European-made instrumentation which permits ALMA to deliver its sharpest, most detailed images so far.

“These observations show that ALMA is capable of delivering transformational science, even with less than half of the full array in use,” says Ewine van Dishoeck of the Leiden Observatory, who has been a major contributor to the ALMA project for more than 20 years. “The incredible jump in both sensitivity and image sharpness in Band 9 gives us the opportunity to study basic aspects of planet formation in ways that were simply not possible before.”

Original Story Source: ESO News Release. For further reading: NRAO News Release.

Posted on by Jason Major

Flying Space Toasters: Electrified Exoplanets Really Feel the Heat

Artist's concept of Jupiter-sized exoplanet that orbits relatively close to its star (aka. a "hot Jupiter"). Credit: NASA/JPL-Caltech)
Artist's concept of Jupiter-sized exoplanet that orbits relatively close to its star (aka. a "hot Jupiter"). Credit: NASA/JPL-Caltech)

Overheated and overinflated, hot Jupiters are some of the strangest extrasolar planets to be discovered by the Kepler mission… and they may be even more exotic than anyone ever thought. A new model proposed by Florida Gulf Coast University astronomer Dr. Derek Buzasi suggests that these worlds are intensely affected by electric currents that link them to their host stars. In Dr. Buzasi’s model, electric currents arising from interactions between the planet’s magnetic field and their star’s stellar wind flow through the interior of the planet, puffing it up and heating it like an electric toaster.

In effect, hot Jupiters are behaving like giant resistors within exoplanetary systems.

Many of the planets found by the Kepler mission are of a type known as “hot Jupiters.” While about the same size as Jupiter in our own solar system, these exoplanets are located much closer to their host stars than Mercury is to the Sun — meaning that their atmospheres are heated to several thousands of degrees.

One problem scientists have had in understanding hot Jupiters is that many are inflated to sizes larger than expected for planets so close to their stars. Explanations for the “puffiness” of these exoplanets have generally involved some kind of extra heating process — but no model successfully explains the observation that more magnetically active stars tend to have puffier hot Jupiters orbiting around them.

“This kind of electric heating doesn’t happen very effectively on planets in our solar system because their outer atmospheres are cold and don’t conduct electricity very well,” says Dr. Buzasi. “But heat up the atmosphere by moving the planet closer to its star and now very large currents can flow, which delivers extra heat to the deep interior of the planet — just where we need it.”

More magnetically active stars have more energetic winds, and would provide larger currents — and thus more heat — to their planets.

The currents start in the magnetosphere, the area where the stellar wind meets the planetary magnetic field, and enter the planet near its north and south poles. This so-called “global electric circuit” (GEC) exists on Earth as well, but the currents involved are only a few thousand amps at 100,000 volts or less.

On the hot Jupiters, though, currents can amount to billions of amps at voltages of millions of volts — a “significant current,” according to Dr. Buzasi.

A Spitzer-generated exoplanet weather map showing temperatures on a hot Jupiter HAT-P-2b.
A Spitzer-generated exoplanet weather map showing temperatures on hot Jupiter HAT-P-2b.

“It is believed that these hot Jupiter planets formed farther out and migrated inwards later, but we don’t yet fully understand the details of the migration mechanism,” Dr. Buzasi says. “The better we can model how these planets are built, the better we can understand how solar systems form. That in turn, would help astronomers understand why our solar system is different from most, and how it got that way.”

Other electrical heating processes have previously been suggested by other researchers as well, once hints of magnetic fields in exoplanets were discovered in 2003 and models of atmospheric wind drag — generating frictional heating — as a result of moving through these fields were made in 2010.

(And before anyone attempts to suggest this process supports the alternative “electric universe” (EU) theory… um, no.)

“No, nothing EU-like at all in my model,” Dr. Buzasi told Universe Today in an email. “I just look at how the field aligned currents that we see in the terrestrial magnetosphere/ionosphere act in a hot Jupiter environment, and it turns out that a significant fraction of the resulting circuit closes inside the planet (in the outer 10% of the radius, mostly) where it deposits a meaningful amount of heat.”

This work will be presented at the 222nd meeting of the American Astronomical Society on June 4, 2013.