Kepler-20's oddball planet assortment challenges models of planet formation

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NASA's press conference on the newly discovered Earth-sized planets has just concluded, and most of the time was spent reiterating what was in our earlier report. Most of the value of listening in came from hearing the genuine enthusiasm of the scientists involved; lead author Francois Fressin of the Harvard-Smithsonian Center for Astrophysics highlighted the findings' significance by excitedly stating, "Here is where the era of exo-Earths has begun."

A lot of time was spent discussing how long it would take to figure out the masses, and thus composition, of the planets. It may happen as soon as next year: the instruments that might be sensitive enough to detect the influence of these planets on their host star will be coming on line in that time frame, and some of the Kepler team is also working on those projects. There was something said along the lines of "you can bet Kepler-20 will be one of the first places we point them."

That said, it might be possible to get some indication of their mass sooner. The Kepler-20 system is so compact that we can observe multiple passes of these planets within a few years. During those times, the proximity of the planets will allow them to interact via gravity, which will speed up some orbits while slowing down others. Careful timing of the transits may be able to detect this, allowing orbital models to constrain the masses of all the planets. This may get a bit tricky, however, because there's always the chance that we'll spot even more planets further out.

The big point of discussion that didn't make it into the paper, however, was the truly unexpected nature of Kepler-20's companions. As Harvard's David Charbonneau put it, "the architecture of that planetary system is crazy." With the new finds, we now have five planets that, as you move further from the host star, alternate between Neptune-sized and small, rocky bodies, with the furthest of the five orbiting closer than Mercury's distance from the Sun.

Our models of planet formation can account for rocky inner planets, or systems where gas giants have moved in close to a star and booted anything else out of its way, but there's nothing that can account for a collection of planets like this one.

Charbonneau said, "I really want to dare my fellow astronomers to explain how this system could have formed," and admitted there was a bit of self interest in his challenge. He's teaching planet formation at Harvard next year, and fully expects some freshman to ask him to explain Kepler-20's oddball assortment of planets.

Kepler-20's oddball planet assortment challenges models of planet formation

Kepler team spots Earth-sized planets orbiting sun-like star

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The two newly found exoplanets wouldn't look out of place in our own solar system.

Just two weeks after the confirmation of a planet that's within the habitable zone of a distant star, the Kepler team is back with the discovery of two Earth-sized planets orbiting in what is now a five-planet system (three other planets orbiting the star, Kepler-20, had been spotted earlier). Although these planets are much too hot to support liquid water, one of them (Kepler-20e) is the smallest exoplanet yet detected.

Kepler-20 was already a busy star system, with three small planets orbiting close in to the star: Kepler-20b is about twice the size of Earth and orbits once every 3.7 days; Kepler-20c is three times Earth's radius and orbits every 11 days; and Kepler-20d is 2.75 Earth radii with an orbit of 77.6 days. If that seems somewhat tightly packed, the new finds actually jam a couple more planets within the orbit of Kepler-20d. Kepler-20e has an orbit of six days, while Kepler-20f takes 19.6 days to orbit its host star.

Given that distance, it's possible to estimate the planets' radii based on the amount of light they block while transiting in front of their host star. And neither of these block very much at all. Kepler-20e results in a drop of only 82 parts-per-million in the light from its host star, which corresponds to a radius of 0.87R_e. Kepler-20f is a bit larger, with a signal of 101ppm, placing its radius at roughly that of Earth's.

The fast orbits indicate that these planets are very close to their host star, which has a surface temperature of a toasty 5,500K, a few hundred K shy of our Sun's. That makes the planets correspondingly toasty. Kepler-20e is predicted to have a surface temperature of over 1,000K, and is close enough that any hydrogen atmosphere would have been heated off. Any water on its surface would have been boiled into vapor, broken down by UV exposure, and the resulting gasses also driven off.

Kepler-20f might have been able to hold onto its water if it had formed further out and then migrated inward to its current orbit. Its surface temperature is "only" 700K, and it's far enough from the host star that it could retain a water vapor atmosphere for several billion years.

Theoretical considerations based on what we know about planet formation suggest that both of these planets are rocky, and may even have a composition similar to Earth's. To confirm this, however, would require measuring the mass of the planets. Unfortunately, the best way to do this is to measure how much they pull their host star around as their orbits take them to opposite sides of Kepler-20. Their small size leads to correspondingly small Doppler shifts, however, and those are currently below our ability to detect. Improvements expected in our telescope hardware should allow us to do so within a few years, but we're stuck with theory for now.

The one caveat from all of this is that these signals haven't been confirmed with another piece of hardware, something the Kepler team normally requires before shifting something from the "candidate" to "confirmed" category. In this case, they have been able to call these candidates confirmed by showing that all the other possible sources of a signal are extremely unlikely. The host star shows no sign of having a companion brown dwarf or other dim star, based on the lack of any wobbles in its orbit. The chances that a second star in the same line of sight has a large planet that's producing these signals are very, very small.

The previous find of planets in this system also boost the odds that the new signal comes from a planet, since we already know that things are orbiting in the right plane to pass between Earth and Kepler-20. As a result, the authors conclude that these signals come from small planets with a greater than three sigma certainty (something that the Higgs hunters wouldn't find satisfying, but good enough for an astronomer).

NASA will be holding a press conference on the results shortly; we'll update this story if any additional information is provided during the event.

Kepler team spots Earth-sized planets orbiting sun-like star

The Milky Way's black hole may spring to life in 2013

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The gas cloud's path (red) takes it past many of the stars that orbit our galaxy's central black hole.

Quasars, the brightest objects we're aware of, are powered by the supermassive black holes that are thought to reside at the center of every galaxy. But many galaxies fail to feed their black holes enough matter, leading to a body that's quiet and difficult to detect. Our own galaxy's central black hole, called Sgr A*, falls into the latter category. We can detect it at wavelengths up to the X-ray range, but it's dim enough that we'd have a hard time spotting it if it weren't so close.

That may be about to change, however. Astronomers have spotted a cloud of gas with a mass about three times that of Earth that's on a trajectory that will have it pass close to Sgr A* in 2013. When it does, it may feed matter into the black hole's accretion disk, powering a sudden surge in Sgr A*'s output.

Since Sgr A* doesn't emit much in the way of radiation, a lot of what we've learned about it comes from tracking the stars that orbit it at close range; many of these have eccentric orbits that take them very close to the black hole. The Very Large Telescope has a program set up to perform periodic observations of the stars in order to track their orbits closely. It was during these observations that the team "discovered an object moving at about 1,700 km/s along a trajectory almost straight towards Sgr A*."

Observations of its emissions indicated that the object was a gas cloud that was much more dense than the material that's typically found in the area, and cooler as well. It's not quite heading straight at Sgr A*, but it's on a highly eccentric orbit that will take it extremely close to the body—36 light hours by the summer of 2013 (for comparison, the Voyager spacecraft are over a dozen light hours from the Earth). As a result of this plunge, the black hole's gravity has been accelerating the gas within the time we've been observing it; its total velocity (including some motion that's not towards the black hole) has increased from 1,200 km/s to nearly double that speed over the last seven years.

In the nearly 20 years we've been observing Sgr A*, only two stars have ever come closer to it. But stars are held together by gravity; this cloud is too diffuse to have that sort of coherence. As a result, the authors expect that it will undergo dramatic changes as it blasts in to the neighborhood of the black hole. The shock of hitting the low-density, high-temperature gas will compress the cloud even as the black hole's gravity starts to stretch it out along the direction of its orbit. This could eventually split the cloud into multiple fragments, each of which may take a slightly different path around the black hole.

As these fragments reach the point in the orbit closest to black hole, its temperatures may reach 10⁶K, hot enough for it to start emitting X-rays.

But that may not be the only fireworks. If the cloud does end up fragmenting, then there's a chance that one of the fragments will end up feeding into the accretion disk surrounding the black hole. "This could in principle release up to around 10⁴⁸ erg over the next decade," the authors estimate. We'll have to wait and see, but you can be sure lots of electronic eyes will be watching.

In the meantime, when nothing in particular happens in 2012, the cloud's destruction may end up providing a new bit of excitement for doomsday aficionados.

The Milky Way's black hole may spring to life in 2013

Surprising Comet Lovejoy Now Becoming Merry and Bright

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Comet Lovejoy photographed remotely with the FRAM telescope in Argentina on Dec. 17 by a Czech team of Jakub Cerny, Jan Ebr, Martin Jelinek, Petr Kubanek, Michael Prouza and Michal Ringes. Click to see the original image and more on the kommet.cz website.

It was almost a pre-holiday miracle that Comet Lovejoy survived its close encounter with the Sun on Dec. 15, 2011. But now, the feisty comet is making a ‘merry and bright’ comeback, re-sprouting its tail and showing up brilliantly when seen with binoculars and in telescopic images from southern hemisphere skywatchers.

“It was a big surprise that after going through the solar atmosphere it re-emerged with a beautiful tail,” Karl Battams told Universe Today. Battams is with Naval Research Laboratory and has been detailing the Comet Lovejoy’s incredible journey on the Sungrazing Comets website. “And basically within a day it was as bright after the encounter as it was before.”

The beautiful image above was taken on Dec. 17, 2011, clearly showing two gorgeous tails on Comet Lovejoy. See more from the Czech team that took the image at their website,Kommet.cz.

As much as this comet has surprised everyone, no one is going out on a limb and predicting it will become visible with the naked eye. But who knows? The comet’s discoverer, Austrailian amateur astronomer Terry Lovejoy was able to image the comet in the day time!” I am hopeful of a nice binocular comet low in the dawn around Christmas time,” Lovejoy said on the Ice in Space website.

Comet Lovejoy in the early morning hours of Dec. 20, 2011. Credit: Ian Musgrave, Adelaide, South Australia, Australia

“Southern hemisphere viewers can see it now early in the morning,” Battams said via phone this morning. “It is going to become increasingly easy for them to see as it moves away from the Sun. I’m not sure it will increase in brightness anymore, as it has leveled off a little bit now. Odds are stacked in the favor of a nice nighttime show for southern viewers, and gradually it will fade away.”

Of course, Comet Lovejoy isn’t the only comet that has survived a close encounter with the Sun; in fact, some comets have even brightened to naked eye visibility after surviving a scorching from the Sun. The “Great Comets” of 1843 and 1882, and Comet Ikeya-Seki of 1965 were all Kreutz sungrazers – like Comet Lovejoy — and they all became brilliant after their solar encounters, with extraordinarily long tails.

Normally these comets don’t survive and are completely obliterated by the Sun. But the few that do – only 2 or 3 a century — can be very bright.

I had asked Battams on Friday – just after the comet emerged from behind the Sun – his thoughts on Comet Lovejoy and if it might follow the example of those previous surviving sungrazers.

“All bets are off as far as I’m concerned,” he wrote via email. “We thought this was a relatively small one — maybe a hundred or two meters in diameter. Clearly it can’t be. I did not expect it to survive perihelion as anything more than a diffuse blob that would rapidly dissipate. Instead it is pretty much as bright as it was before, just with less of a tail now.”

So keep a lookout for the holiday comet of 2011, the merry and bright Comet Lovejoy!

Surprising Comet Lovejoy Now Becoming Merry and Bright

Missions that Weren’t: NASA’s Manned Mission to Venus

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Venus as seen by the Pioneer orbiter in 1979. Image Credit: NASA/courtesy of nasaimages.org

In the mid-1960s, before any Apollo hardware had flown with a crew, NASA was looking ahead and planning its next major programs. It was a bit of a challenge. After all, how do you top landing a man on the Moon? Not wanting to start from scratch, NASA focused on possible missions that would use the hardware and software developed for the Apollo program. One mission that fit within these parameters was a manned flyby of our cosmic twin, Venus.

As one of our neighbouring planets, a mission to Venus made sense; along with Mars, it’s the easiest planet to reach. Venus was also a mystery at the time. In 1962, the Mariner 2 spacecraft became the first interplanetary probe. It flew by Venus, gathered data on its temperature and atmospheric composition before flying off into a large heliocentric orbit. But there was more to learn, making it a destination worth visiting.

A scale comparison of terrestrial planets Mercury, Venus, Earth, and Mars. That Earth and Venus are of a similar size led many to draw comparisons between the planets before better scientific experiments revealed Venus is closer to the Earth inside out. Image Credit: NASA/courtesy of nasaimages.org

But beyond being relatively practical with great potential for scientific return, a manned mission to Venus would prove that NASA’s spacecraft and astronauts were up for the challenges of long-duration interplanetary flight. In short, it would give NASA something exciting to do.

The mission proposal was published early in 1967. It enhanced the Apollo spacecraft with additional modules, then took the basic outline of an Apollo mission and aimed it towards Venus instead of the Moon.

The crew would launch on a Saturn V rocket in November of 1973, a year of minimal solar activity. They would reach orbit in the same Command and Service Modules (CSM) that took Apollo to the Moon. Like on Apollo, the CSM would provide the main navigation and control for the mission.

Going to the Moon, Apollo missions had the crew turn around in the CSM to pull the LM out of its launch casing. On the mission to Venus, the crew would do the same, only instead of an LM they would dock and extract the Environmental Service Module (ESM). This larger module would supply long-duration life support and environmental control and serve as the main experiment bay.

An artist's impression of the Mariner 2 probe. Image Credit: NASA/courtesy of nasaimages.org

With these two pieces mated, the upper S-IVB stage of Saturn V would propel the spacecraft towards Venus. Once its fuel store was spent, the crew would repurpose the S-IVB into an additional habitable module. Using supplies stored in the ESM, they would turn the rocket stage into their primary living and recreational space. On its outside, an array of solar panels would power each piece of the spacecraft throughout the mission.

The crew would spend 123 days traveling to Venus. Ten hours of each day would be dedicated to science, mainly observations of the solar system and beyond with a telescope mounted in the ESM. UV, X-ray, and infrared measurements could create a more complete picture of our corner of the universe. The rest of each day would be spent sleeping, eating, exercising, and relaxing — a full two hours of every day would be dedicated to unstructured leisure, a first for astronauts.

Like Mariner 2 before them, the crew would flyby Venus rather than go into orbit. They would only have 45 minutes to do close optical observations and deploy probes that would send back data on the Venusian atmosphere in realtime.

After the flyby, the spacecraft would swing around Venus and start its 273 day trip back to Earth. Like on an Apollo lunar mission, the crew would transfer back into the Command Module before reentry taking anything that had to return to Earth with them. They would jettison the S-IVB, the ESM, and the Service Module, switch the CM to battery power, and plunge through the atmosphere. Around December 1, 1974, they would splashdown somewhere in the Pacific Ocean.

Though worked out in great detail, the proposal was a thought experiment rather than something NASA was seriously considering. Nevertheless, Apollo-era technology would have managed the mission.

Missions that Weren’t: NASA’s Manned Mission to Venus

Curiosity Starts First Science on Mars Sojurn – How Lethal is Space Radiation to Life’s Survival

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NASA's Mars Science Laboratory Curiosity rover is currently cruising to Mars and is already investigating the lethality of the interplanetary space radiation environment to humans. After touchdown, Curiosity will investigate Mars' past or present ability to sustain microbial life. Credit: NASA/JPL-Caltech

Barely two weeks into the 8 month journey to the Red Planet, NASA’s Curiosity Mars Science Lab (MSL) rover was commanded to already begin collecting the first science of the mission by measuring the ever present radiation environment in space.

Engineers powered up the MSL Radiation Assessment Detector (RAD) that monitors high-energy atomic and subatomic particles from the sun, distant supernovas and other sources.

RAD is the only one of the car-sized Curiosity’s 10 science instrument that will operate both in space as well as on the Martian surface. It will provide key data that will enable a realistic assessment of the levels of lethal radiation that would confront any potential life forms on Mars as well as Astronauts voyaging between our solar systems planets.

“RAD is the first instrument on Curiosity to be turned on. It will operate throughout the long journey to Mars,” said Don Hassler, RAD’s principal investigator from the Southwest Research Institute in Boulder, Colo.

These initial radiation measurements are focused on illuminating possible health effects facing future human crews residing inside spaceships.

Video Caption: The Radiation Assessment Detector is the first instrument on Curiosity to begin science operations. It was powered up and began collecting data on Dec. 6, 2011. Credit: NASA

“We want to characterize the radiation environment inside the spacecraft because it’s different from the radiation environment measured in interplanetary space,” says Hassler.

RAD is located on the rover which is currently encapsulated within the protective aeroshell. Therefore the instrument is positioned inside the spacecraft, simulating what it would be like for an astronaut with some shielding from the external radiation, measuring energetic particles.

“The radiation hitting the spacecraft is modified by the spacecraft, it gets changed and produces secondary particles. Sometimes those secondary particles can be more damaging than the primary radiation itself.”

“What’s new is that RAD will measure the radiation inside the spacecraft, which will be very similar to the environment that a future astronaut might see on a future mission to Mars.”

Curiosity Mars Science Laboratory (MSL) Spacecraft During Cruise with Navigation Stars. Artist's concept of Curiosity during its cruise phase between launch on Nov. 26, 2011 and final approach to Mars in August 2012. Credit: NASA/JPL-Caltech

Curiosity’s purpose is to search for the ingredients of life and assess whether the rovers landing site at Gale Crater could be or has been favorable for microbial life.

The Martian surface is constantly bombarded by deadly radiation from space. Radiation can destroy the very organic molecules which Curiosity seeks.

“After Curiosity lands, we’ll be taking radiation measurements on the surface of another planet for the first time,” notes Hassler.

RAD was built by a collaboration of the Southwest Research Institute, together with Christian Albrechts University in Kiel, Germany with funding from NASA’s Human Exploration Directorate and Germany’s national aerospace research center, Deutsches Zentrum für Luft- und Raumfahrt.

“What Curiosity might find could be a game-changer about the origin and evolution of life on Earth and elsewhere in the universe,” said Doug McCuistion, director of the Mars Exploration Program at NASA Headquarters in Washington. “One thing is certain: The rover’s discoveries will provide critical data that will impact human and robotic planning and research for decades.”

Curiosity was launched from Florida on Nov. 26. After sailing on a 254 day and 352-million-mile (567-million-kilometer) interplanetary flight from the Earth to Mars, Curiosity will smash into the atmosphere at 13,000 MPH on August 6, 2012 and pioneer a nail biting and first-of-its-kind precision rocket powered descent system to touchdown inside layered terrain at Gale Crater astride a 3 mile (5 km) high mountain that may have preserved evidence of ancient or extant Martian life.

Miraculously, NASA’s Opportunity Mars rover and onboard instruments and cameras have managed to survive nearly 8 years of brutally harsh Martian radiation and arctic winters.

Curiosity MSL science instruments are state-of-the-art tools for acquiring information about the geology, atmosphere, environmental conditions, and potential biosignatures on Mars. Credit: NASA

Curiosity Starts First Science on Mars Sojurn – How Lethal is Space Radiation to Life’s Survival

Soyuz Rolls Out to Launch Pad; Crew Works on Science

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The Soyuz TMA-03M spacecraft is on the launch pad at Baikonur Cosmodrome in Kazakhstan. Credit: NASA

Expedition 30 Commander Dan Burbank updates software for the SOdium LOading in Microgravity experiment. Credit: NASA TV

The Soyuz TMA-03M spacecraft that will carry new Expedition 30 Flight Engineers Oleg Kononenko, Don Pettit and Andre Kuipers into space rolled out to the launch pad Monday at Baikonur Cosmodrome in Kazakhstan. The launch is scheduled for Wednesday at 8:16 a.m. EST, with NASA TV coverage beginning at 7:30 a.m. The Soyuz will dock to the International Space Station Friday morning.
› Watch NASA TV
Aboard the station, Expedition 30 Commander Dan Burbank worked with the Biomechanical Analysis of Treadmill Exercise on the International Space Station, or Treadmill Kinematics, experiment. Treadmill Kinematics studies the difference between exercising on a treadmill in space and on Earth. It is the first rigorous investigation to determine the most beneficial treadmill exercise conditions to maintain or improve crew health during long-duration spaceflight.
› Read more about Treadmill Kinematics
Burbank also continued his work with the Preliminary Advanced Colloids Experiment-2, or PACE-2. Housed in the Fluids Integrated Rack, PACE-2 studies the effects of vibration on particles suspended in fluid in the space environment. This work aids in the development and optimization of crew procedures for the future Advanced Colloids Experiment, also known as ACE, which will fly samples that may have an important impact on our understanding of fundamental physics.
› Read more about PACE-2
Additionally, he updated software for the SOdium LOading in Microgravity (SOLO) experiment. SOLO researches the ways in which the human body retains fluid and salt during bed rest and space flights. Subject crew members follow a diet of constant low or normal sodium intake and increased fluid consumption.
› Read more about SOLO
Flight Engineer Anton Shkaplerov worked on the Seiner experiment. This is a Russian experiment that examines the oceans below, documents their characteristics and then correlates that to certain bioproductive areas that impact the fishing industry.
› Read more about Seiner
Shkaplerov and Flight Engineer Anatoly Ivanishin worked to replace several of the panels, fuses and batteries inside the complex’s Russian segment.
All three crew members continued unpacking supplies from the ISS Progress 45 cargo craft, which arrived at the station on Nov. 2.

Soyuz Rolls Out to Launch Pad; Crew Works on Science

NASA finds smallest ever black hole by its 'heartbeat' (video)

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NASA's found the smallest black hole it's ever seen, thanks to the Rossi X-Ray Timing Explorer (RXTE) -- weighing three times less than our own sun, it's near the bottom weight limit for the super-heavy phenomena. It was discovered by its unique "heartbeat", an X-Ray emission that takes place when gas sucked from a nearby star is swirled around the event horizon until friction causes it to super-heat. The disc then repeats the process every 40 seconds and when examined, looks just like the readout on anECG machine. After the break we've got a video that talks you through it all and we won't mind if you start booming "Space... the final frontier..." halfway through -- we did too.

NASA finds smallest ever black hole by its 'heartbeat' (video)