Posted on by Nicholos Wethington

Planet of Lava a Former Gas Giant

Matryoshka dolls are a popular novelty for tourists going to Russia to bring home for their children. These dolls, which are hollow wooden bowling pin-shaped representations of a Russian woman (or babushka), are nested inside of each other, each doll smaller than the one that encases it.

In a perfect model of planetary matryoshka dolls, the exoplanet Corot 7-b – which is currently one of the exoplanets that is closest in size and mass to the Earth – used to be nestled inside a much larger version of itself. Corot 7-b was formerly a gas giant with a mass of 100 Earths, which is about that of Saturn. Its mass now: 4.8 times that of our planet.

How this rocky, lava-covered world got to its current state was presented at the American Astronomical Society’s meeting last week in Washington, DC by Brian Jackson of NASA’s Goddard Space Flight Center. Corot 7-b was discovered in February of 2009 by the ESA’s planet-hunting satellite, Convection, Rotation and planetary Transits(CoRoT), and has since been the subject of intense study.

The planet is about 1.7 larger in diameter than the Earth, and a little shy of five times as massive. Its star is about 1.5 billion years old, a third that of our Sun. It orbits very close to its star, which is much like our own Sun, only taking 20.4 hours to circle the star. The system lies in the constellation Monoceros, and is about 480 light-years away.

This tight orbit makes the planet extremely hot, as in 3,600 degrees Fahrenheit (1,982 degrees Celsius). That’s hot enough that the crust of the planet facing the star is an ocean of lava. Since Corot 7-b is tidally locked to its star, only one side of the planet faces the star at all times (just like we only see one side of the Moon from the Earth). On the opposite side of Corot 7-b from its star, the surface temperature is estimated to be a chilly negative 350 degrees F (negative 210 degrees C).

It rains on Corot 7-b just like it does here, though you wouldn’t want to be caught out in it. The rain on Corot 7-b is made of rock, so even the heaviest umbrella wouldn’t do much for you, and the very thin atmosphere is composed of rock vapor. In other words, we aren’t looking to Corot 7-b for signs of life. What we are looking there for is signs of planetary formation and evolution.

Jackson et al. modeled the orbit of the planet backwards, and showed that the star blew off much of the material that made up the planet in its previous incarnation as a gas giant. It previously orbited about 50 percent further out than it currently is. The stellar wind – a constant flow of charge particles from the star – interacted with the gassy atmosphere of the planet, blowing away the atmosphere.

“There’s a complex interplay between the mass the planet loses and its gravitational pull, which raises tides on the star,” Jackson said.

As it was pulled in closer to the star due to the process of tidal migration, more and more of the gas evaporated, and the orbital change of the planet slowed to the distance at which it currently orbits. Once the planet got closer to the star, it also heated up, and this heating process contributed to the mass loss of Corot 7-b. This evaporative process left only the rocky core of the planet.

“CoRoT-7b may be the first in a new class of planet — evaporated remnant cores. Studying the coupled processes of mass loss and migration may be crucial to unraveling the origins of the hundreds of hot, earthlike planets space missions like CoRoT and NASA’s Kepler will soon uncover,” Jackson said.

Many of the extrasolar planets discovered early on were gas giants that orbited close to their stars, so-called “hot Jupiters”. It’s possible that many of them will experience the same or similar fate as Corot 7-b, as we wrote about in an article last April.

Corot 7-b will likely lose more mass because of the proximity to its star, though not at the rate seen previously. What the next planetary matryoshka of Corot 7-b will look like is anyone’s guess. My prediction: turtles all the way down.

Source: NASA press release

Posted on by Nicholos Wethington

End of Shuttle Program Will Slow Florida’s Economy

NASA’s Space Shuttle, which will make its last flight sometime later this year, has been a boon to the local economy surrounding the Kennedy Space Center, which is located in Cocoa, Florida. The closest county, Brevard, is where many of the workers that help maintain and launch the shuttle reside, and because of the presence of the space center, many a bar, restaurant, and local business have thrived.

This is in part due to those that work in the space industry, both for NASA itself and many of its private contractors. There are also the thousands of tourists that flock to the region to view launches and take tours of the Kennedy Space Center. All this, however, will change once the shuttle program is finished, and with five-year gap (at least) until the Constellation program gets rolling, the “Space Coast” may take quite a hit economically.

The end of the shuttle program will potentially eliminate as many as 7,000 – 8,000 jobs, some of which will need to be filled once again when the Constellation program is in full swing. But during the gap, many workers are expected to vacate the area in search of jobs elsewhere. This will impact the local economy that relies on these residents, and as many as 14,000 workers in the area may be indirectly affected.

According to a state study, in the 2008 fiscal year NASA generated $4.1 billion dollars in revenue and benefits for the state. $2.1 billion of that was in household income, and over 40,000 jobs were created due to NASA-related activities.

The local unemployment rate has already risen to 11.9 percent at present, largely due to the nationwide economic problems. Housing and construction have taken a hit as well, and will continue to suffer as the area sees the space workers leave.

This is the second time in NASA’s history that they’ve had to wind down a human space program, the first being the Apollo missions which ended in 1972. After the end of Apollo, Brevard county saw a dramatic downturn in the economy, as 10,000 workers left the region to find jobs and unemployment rose to 15 percent.

Estimations of the economic aftereffects of the end of the shuttle program aren’t as grim as those figures for the post-Apollo period, but there will be repercussions nonetheless.

There are several other factors that complicate the renewal of these lost jobs once the Constellation program starts up in earnest. Since Constellation utilizes a non-reusable launch system, fewer workers will be needed for repair and retrofit between launches.

Frank DiBello of the state agency Space Florida told Florida Today, “There is no escaping the transition that will occur when we go from a very labor intensive, reusable space flight system to one that is expendable. Simply by its nature, it is going to take a smaller workforce.”

Almost one-third of the current NASA employees working on the shuttle are up for retirement, so these posts would have been vacated anyway, and approximately 2,000 civil servants for NASA will retain their jobs over the gap between programs.

Though the region surrounding the Kennedy Space Center will surely struggle these next few years, it’s possible that many aerospace workers will flock to the private space industry during the gap, and companies like Virgin Galactic will benefit.

Source: Florida Today, Reuters

Posted on by Nicholos Wethington

Help Wish Buzz Aldrin a Happy 80th Birthday

Aldrin turns 80 years old on January 20th, 2010. Happy birthday, Buzz! Image Credit:NASA” src=”http://www.universetoday.com/wp-content/uploads/2010/01/260985main_01_BuzzAldrinMoon_800-600-580×435.jpg” alt=”” width=”580″ height=”435″ />On January 20th, former astronaut Buzz Aldrin – who was the second man to walk on the Moon and has been a longtime advocate of space exploration – will turn 80 years old. Wouldn’t you like to send him some birthday wishes? Well, you can! The Planetary Society is collecting birthday wishes to be put on a “ginormous card” honoring his 80th trip around the Sun. Originally, the card was to be presented at a ceremony where Stephen Hawking would also receive the Planetary Society’s Cosmos Award, but Hawking has been advised by his doctors to refrain from flying to California for the event.

The birthday card, which already has birthday wishes from people around the world, will still be presented to Buzz Aldrin, so be sure to go wish him a happy birthday using this link.

Source: The Planetary Society blog

Posted on by Nicholos Wethington

Another Antimatter Supernova Discovered

Here’s another extremely explosive supernova that can be chalked up to the production of antimatter in the core of the star: Y-155. These types of supernova explosions – which can be ten times brighter than the already spectacular explosion of a Type Ia supernova – have been theorized to exist for over forty years. About a month ago, we reported on the first observations of one of these types of supernovae, and at the American Astronomical Society super-meeting yesterday, Peter Garnavich of the University of Notre Dame presented on the observation of a second.

The star Y-155 was a whopping large star, with a mass of over 200 times that of our Sun. In these types of stars, energetic gamma rays can be created by the intense heat in the core of the star. These gamma rays in turn make pairs of electrons and positrons, or antimatter pairs. Since so much energy goes to the creation of these pairs, the pressure pushing outwards on the star weakens, and gravity swoops in to collapse the star, generating a supernova of enormous proportions.

These types of supernovae have been dubbed “pair-instability” supernovae, and once they explode, there is nothing left: in other types of supernovae, a neutron star or black hole can form out of the remnants of the star, but pair-instability supernovae explode with such force that there is nothing left where the core of the star once existed. In addition to supernova 2007bi, which we reported on in December of 2009, the supernova 2006gy is another candidate for this type of supernova.

Y-155, which lies in the constellation Cetus, was discovered as part of the Equation of State: SupErNovae trace Cosmic Expansion,”ESSENCE”, search for stellar explosions. During the 6-year search, a team of international astronomers led Christopher Stubbs of Harvard University collaborated to find Type Ia supernovae as a means to measure the expansion of the Universe. These types of supernovae explode with a characteristic luminosity, making them excellent candidates to measure distances in the Universe. The team utilized the National Optical Astronomy Observatory’s (NOAO) 4-m Blanco telescope in Chile.

Y-155 was discovered in November of 2007, during the last weeks of the project, using the Blanco telescope. Once the initial discovery was made, followup observations using the Keck 10-m telescope in Hawaii, the Magellan telescope in Chile, and the MMT telescope in Arizona revealed the redshifting of the light due to the expansion of the Universe to be about 80%, meaning that the star is very far away, and thus very old. Y-155 is estimated to have undergone a supernova approximately 7 billion years ago.

According to Garnavich, the team calculated the star to be generating 100 billion times the energy of the Sun at its peak. To accomplish this, it must have synthesized between 6 and 8 solar masses of nickel 56, which is what gives Type Ia supernovae their brightness. For comparison, the typical Type Ia supernova burns 0.4-0.9 solar masses of nickel 56.

Y-155 has been shown by deep imaging with the Large Binocular Telescope in Arizona to reside in a galaxy that is rather small. Smaller galaxies are usually low in heavier atoms. The gas out of which this and other types of ultra-massive stars form is relatively pristine, composed largely of hydrogen and helium. Supernova 2007bi, the first-observed pair-instability supernova, grew up in a galaxy remarkably like that of Y155.

This means that when astronomers look for other types of pair-instability supernovae, they should find more of them in smaller galaxies that existed near the beginning of the Universe, before other supernovae synthesized heavier elements and spread them around.

Source: Physorg

Posted on by Nicholos Wethington

Supernova Simulations Point to White Dwarf Mergers

Type Ia supernovae, some of the most violent and luminous explosions in the Universe, have become a handy tool for astronomers to measure the size and expansion of the Universe itself. Because they explode with a rather specific peak luminosity, they can be used as “standard candles” to measure distances. New research presented at the American Astronomical Society meeting this week points to the increased likelihood that the mergers of the stars that create these explosions, white dwarfs, is more likely than previously thought, and could explain the properties of some Type Ia supernovae that are curiously less luminous than expected.

Research presented by Rüdiger Pakmor et al. from the Max-Planck Institute for Astrophysics in Garching, Germany simulated the merger of two white dwarfs in a binary system, and showed that these simulations match previously observed supernovae with odd characteristics, specifically that of 1991bg. That supernova, and others observed since, was curiously less luminous than should have been expected if it were a Type Ia supernovae.

Type Ia supernovae occur when there are two stars orbiting each other in a binary system. In one scenario, one of the stars becomes a white dwarf, a small but very, very dense star, and steals matter from the other, pushing itself over the Chandrasekhar limit – 1.4 times the mass of the Sun – and undergoing a thermonuclear explosion.

Another cause for these types of supernovae could be the merger of both the stars in the system. In the scenario analyzed by these researchers, both stars were white dwarfs of masses just under that of the Sun: .83-0.9 solar masses.

The researchers showed that as the system loses energy due to the emission of gravitational waves, the two white dwarfs approach each other. As they merge, part of the material in one of the stars crashes into the other and heats up the carbon and oxygen, creating a thermonuclear explosion seen in Type Ia supernovae.

You can watch an animation of the simulated merger courtesy of the Max-Planck Institute’s Supernova Research Group right here.

Observations of supernovae like 1991bg show them to burn a smaller amount of nickel 56, about 0.1 solar masses, than regular Type Ia supernovae, which typically burn 0.4-0.9 solar masses of nickel. This makes them less luminous, because the radiative decay of the nickel is one of the phenomenon that gives the luminous display of Type Ia supernovae its punch.

“With our detailed explosion simulations, we could predict observables that indeed closely match actual observations of Type Ia supernovae,” said Friedrich Röpke, a co-author of the paper.

Their simulations show that when the two white dwarfs merge, the density of the system is less than in typical Type Ia supernovae, and thus less nickel is produced. The researchers note in their paper that these types of white dwarf mergers could comprise between 2-11 percent of the Type Ia supernovae observed.

Understanding the mechanisms that create these fantastic explosions is a necessary step in getting a handle on both the extent of our Universe and its expansion, as well as the diversity of Type Ia supernovae themselves.

If you would like to learn more about their research and the details of their computer modeling, the paper is available on Arxiv here. Their results will also be published in the January 7, 2010 edition of Nature.

Source: AAS press release, Arxiv paper

Posted on by Nicholos Wethington

Epsilon Aurigae Eclipse Mystery Solved with Your Help

If you’ve been helping out with the Citizen Sky project to monitor Epsilon Aurigae, then congratulations – the first of the results are in! Donald W. Hoard, a research scientist at Caltech announced the findings at the American Astronomical Society meeting in Washington, D.C. this morning. We invited our readers to participate in monitoring the star in August of 2009, and combined with observations from Spitzer, a 200-year old mystery has potentially been solved.

Epsilon Aurigae is a bright star in the constellation Auriga. It began to dim in brightness last August, which it does every 27 years. The star dims for over 2 years, with a slight brightening in the middle of the eclipse, making it the longest known orbital period for a stellar eclipse. The Citizen Sky project invited professional and amateur astronomers alike to aid in the observation of the star during this eclipse.

What exactly passes in front of the star was a mystery, though it was thought that a large disk of material with two stars orbiting tightly in the center is the cause of the eclipse. The disk itself is pretty huge – on the order of 8 astronomical units. There is a slight brightening during the middle of the eclipse that led astronomers to believe there is a hole created by the two stars in the center.

“If [Epsilon Aurigae] were an F star, with about 20 times the mass of the Sun…a single B star at the center of the disk doesn’t have enough mass to explain the orbital dynamics,” Hoard said. Other possibilities proposed were the presence of a black hole at the center of the disk, but there were no telltale X-rays coming from the system that would show a black hole was heating up matter in the disk.

Through observations by astronomers that participated in the project, as well as observations made by the Spitzer space telescope, a major revision of the properties of Epsilon Aurigae itself were in order.

“What we were most pleased to find an answer to… was that the results strongly tip towards a 2 solar-mass dying star. Sometime in the next few thousand years it will emerge as a planetary nebula,” Hoard said.

This means that instead of being a 20 solar-mass F-star supergiant, Epsilon Aurigae is in fact a 2 solar-mass F-star which is in the last stages of its life, and thus giant in size – about 300 Suns across. This, combined with a single B-star of about 5.9 solar masses at the center of the disk that orbits Epsilon Aurigae fit the observations very well, Hoard said.

Arne Henden of the American Association of Variable Star Observers (AAVSO), commenting on Hoard’s presentation at the press conference, said “Don says that we solved it, and I disagree. We need to determine the nature of the dusty disk that is involved – these are things that you see around young stellar objects, not older stellar objects.”

Hoard said that there was a curious property of the disk in that it was composed of larger grains of dust – more like grains of sand than microscopic dust motes.

“The observations that are being made by Citizen Sky project…will hopefully help answer this by providing answers about the composition of the disk and the temperature zones as the eclipse continues. We have these results in large part due to the effort of this huge group of citizen astronomers that are observing Epsilon Aurigae,” he said.

Epsilon Aurigae is still undergoing its eclipse, though the first phase ended right around the New Years Eve 2009. It will continue to be dim until early 2011, when it will begin to brighten again. There is still a lot to be answered about this system, and your help is needed, so keep (or start) observing and reporting! For more information on how to do so, visit Citizen Sky.

Source: AAS press conference on USTREAM, Citizen Sky press release

Posted on by Nicholos Wethington

Moon Rock Will Return to Space Aboard Endeavour

CREDIT: ONORBIT.COM/EVEREST

In May of last year, we followed the story of former astronaut Scott Parazynski, as he climbed Mt. Everest to collect a piece of the mountain and test out equipment for NASA. During the climb, Parazynski carried a Moon rock that was brought to the Earth by the Apollo 11 mission. Though the journey of this rock has been rather long, it is about to come to an end.

The rock, along with a piece of Mt. Everest that Parazynski collected, will travel to the International Space Station during the next Space Shuttle mission. It and the Mt. Everest rock will be displayed in the Tranquility (*cough* Colbert *cough*) module, which is part of the payload of STS-130.

Endeavour is currently scheduled to launch on February 7th, 2010 and will carry the Tranquility module, which will provide more life-support systems for the ISS, as well as a seven-windowed cupola that will be used as an observation and control room for control of the robotic arm outside the station.

Interestingly enough, the rock originated in the Sea of Tranquility on the Moon, and will be returning to be displayed inside the Tranquility module itself.

The Moon rock and piece of Mt Everest will be presented by Parazynski to STS-130 commander George Zamka this Wednesday, January 6th. You can watch the presentation on NASA TV at 3:30pm CST.

Source: NASA press release

Posted on by Nicholos Wethington

Could A Faraway Supernova Threaten Earth?

Supernovae, just like any other explosions, are really cool. But, just like any other explosion, it’s preferable to have them happen at a good distance. The star T Pyxidis, which lies over 3,000 light-years away from the Earth in the constellation Pyxis, was previously thought to be far enough away that if anything happened in the way of a supernova, we’d be pretty safe.

According to Edward Sion, Professor of Astronomy and Physics at Villanova University, T Pyxidis may be in fact a “ticking time bomb,” and potential threat to the Earth if it were to go supernova, which it may do sometime in the future, though very, very far in the future on our timescale: by Scion’s calculations, at least 10 million years.

Sion presented his findings at the American Astronomical Society Meeting in Washington, D.C. earlier today. T Pyxidis, which lies in the constellation Pyxis, is what is called a recurring nova. The star, which is a white dwarf, accretes gas from a companion star. As the amount of matter increases in the white dwarf, it occasionally builds up to the point where there is a runaway thermonuclear reaction in the star, and it ejects large quantities of material.

T Pyxidis has had five different outbursts over the course of observations of the star. It was the American Association of Variable Star Observers’ variable star of the month in April, 2002.  The first was in 1890, followed by another outburst in 1902 (these two were discovered much later on photographic plates in the Harvard plate collection). The next three were in 1920, 1944 and 1967. Its average for outbursts is about 19 years, but there hasn’t been one since the 1966 brightening.

The distance estimate to T Pyxidis, revised to 3,260 light-years from the previously estimated distance of 6,000 light-years has prompted a reconsideration of the details about the white dwarf. Hubble images that have been taken of the star would then have to be re-examined so as to revise the amount of mass the star is expected to be ejecting.

If the recurring novae are ejecting enough material, then the white dwarf would stay small enough to continue to go through the phase of recurring novae. However, if the shells of gas repeatedly ejected by the star do not carry enough mass away, it would eventually build up to pass the Chandrasekhar limit – 1.4 times the mass of the Sun – and become a Type Ia supernova, one of the most destructive events in our Universe.

Sion concluded the presentation with the statement (shown here on his last powerpoint slide) that “A Type Ia supernova exploding within 1000 parsecs of Earth will greatly affect our planet”

A supernova within 100 light-years of the Earth would likely be a catastrophic event for our planet, but something as far out as T Pyxidis may or may not damage the Earth. One of the journalists in attendance pointed out this possibility during the questions session and Sion said that the main danger lies in the amount of X-rays and gamma rays that stream from such an event, which could destroy the protective ozone layer of the Earth and leave the planet vulnerable to the ultraviolet light streaming from the Sun.

There remains some doubt as to whether T Pyxidis will go supernova at all. There is a good treatment of this subject in “The Nova Shell and Evolution of the Recurrent Nova T Pyxidis” by Bradley E. Schaefer et al. on Arxiv.

If you’re worried about the dangers of exploding stars, you should check out this video by Phil Plait, the Bad Astronomer. He’ll calm you down.

Source: AAS Press Conference on USTREAM, Space.com

Posted on by Nicholos Wethington

Intergalactic Connection is Older, Longer than Thought

Our galaxy has a streamer, though it’s not like the ones you had on your bike as a kid: this streamer is a flow of largely hydrogen gas that originates in the Large and Small Magellanic Clouds, two of our closest galactic neighbors. New observations of the stream have helped to revise its age and extent, and show it to be longer and much older than previous estimates.

The Magellanic Stream, which was discovered over 30 years ago, flows from the two galaxies closest to the Milky Way, the Large and Small Magellanic Clouds. These clouds, which are actually two irregular dwarf galaxies, are 150,000 to 200,000 light-years away, and are visible in the southern hemisphere.

The stream connects up with the Milky Way about 70,000 light years from the Solar System, in the constellation of the Southern Cross.

Using the Green Bank Telescope (GBT), a team of astronomers took over 100 hours of observations of the streamer. These observations were combined with those from other radio telescopes, including the Aricebo telescope in Puerto Rico, to further constrain both its extent and age.

Their observations were presented at the American Astronomical Society’s meeting in Washington D.C., and a paper has been submitted to the Astrophysical Journal. The team included David Nidever and Steven Majewski of the Department of Astronomy at the University of Virginia, Butler Burton of the Leiden Observatory and the National Radio Astronomy Observatory and Lou Nigra of the University of Wisconsin.

Previous observations of the stream showed it to have gaps between the Magellanic Clouds and where it enters the Milky Way, but these revised observations show it to be one continuous stream between the three galaxies. The stream is also at least forty percent longer that previously estimated.

The Magellanic Stream was also determined by the astronomers to be much older than had been estimated before: up from 1.75 billion years old to 2.5 billion years old. Just how does this long-lived intergalactic trail of hydrogen crumbs start off in the Magellanic Clouds?

“The new age of the stream puts its beginning at about the time when the two Magellanic Clouds may have passed close to each other, triggering massive bursts of star formation. The strong stellar winds and supernova explosions from that burst of star formation could have blown out the gas and started it flowing toward the Milky Way,” said David Nidever in a NRAO press release.

By getting a better picture of how the gas flows from the Magellanic Clouds into the Milky Way, astronomers have been able to determine with better accuracy just how far away the two galaxies are, as well as their  interactions with the tidal forces of the Milky Way.

This team has collaborated before on the exploration of the Magellanic Stream and its origins. You can read about their previous findings on Arxiv right here, which were also published in the Astrophysical Journal.

Source: NRAO press release

Posted on by Nicholos Wethington

ALMA Telescope Links Third Antenna

Well, they’re 1/22 of the way there: the Atacama Large Millimeter/submillimeter Array (ALMA), planned to be one of the largest ground-based observatories in the world, successfully linked 3 of its 66 antennas together. This is the next step in working out all of the bugs associated with linking together the whole array, which should happen sometime in 2012.

ALMA is a “microwave” telescope array that will be the largest such ground-based observatory in the world once it is completely online. Telescopes like ALMA are called interferometers because they use the principle of very-long baseline interferometry – by linking separate telescopes together, a larger telescope of the effective resolution of the distance between the separate elements is achieved.

We reported on the first image taken by two of the antennas back in November. Information from a pair of the antennas was gathered to test the electronic functioning of the system, but errors from the system itself and those that creep in because of the atmosphere were weeded out by this latest test that included a third antenna. This test is called a “closure phase”, essentially the self-calibration of the antennas in terms of reconciling the information they are taking in with the signals present from noise.

Fred Lo, director of the National Radio Astronomy Observatory (NRAO) – which is the contributing organization of North America to the ALMA array – said of the test in a press release,”This successful test shows that we are well on the way to providing the clear, sharp ALMA images that will open a whole new window for observing the Universe. We look forward to imaging stars and planets as well as galaxies in their formation processes.”

ALMA can gather information in the electromagnetic spectrum at a wavelength that is less than 1 millimeter. Because the planned array is so large, it will eventually be able to resolve unprecedented images of some of the first galaxies to form after the Big Bang, and will also be able to capture the formation of planets around stars, as well as information on the late stages in the life of stars.

ALMA is located in the Atacama desert in Chile at about 5,000 meters (16,500 feet) above sea level. This high and dry location allows the telescope to receive more of the light in the submillimeter; water vapor in the atmosphere of the Earth absorbs light in this part of the spectrum.

Source: NRAO press release