SUBARU Telescope image of the protoplanetary disk around the young star LkCa 15. Credit: MPIA (C. Thalmann) & NAOJ
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Chalk up a sizzling success for the HiCIAO planet-hunter camera on the Subaru Telescope in Hawaii: it’s captured this unprecedented image of a stellar disk similar in size to our own solar system, featuring rings and gaps that are associated with the formation of giant planets.
The lead image shows a bright arc of scattered light, in white, from the protoplanetary disk around the young star LkCa 15. LkCa 15 is in the center of the image, blacked out. The arc’s sharp inner edge traces the outline of a wide gap in the disk. The gap is decidedly lopsided – it is markedly wider on the left side – and has most likely been carved out of the disk by one or more newborn planets that orbit the star.
The disk gap is large enough to house the orbits of all the planets in our own Solar System. “We haven’t detected the planets themselves yet,” said Christian Thalmann, who led the LkCa 15 study while on staff at the Max Planck Institute for Astronomy.”But that may change soon.”
LkCa 15, aged a few million years, is in the Taurus constellation about 450 light years away.
The observations are part of a systematic survey called SEEDS, or the Strategic Explorations of Exoplanets and Disks with Subaru Project, with a goal to search for planets and disks around young stars using HiCIAO, a state-of-the-art high-contrast camera designed specifically for this purpose. The lead investigator on the project is Motohide Tamura at the National Astronomical Observatory of Japan, but it’s a collaborative effort with international participation. Their first significant discovery — an exoplanet candidate around a sun-like star — was announced in December.
Besides LkCa 15, the researchers have also captured a sharp images of the protoplanetary disk around the very young star AB Aur in the constellation Auriga, “the Charioteer.” Lead researcher Jun Hashimoto, of the National Observatory of Japan, and his team report nested rings of material that are tilted with respect to the disk’s equatorial plane, and whose material, intriguingly, is not distributed symmetrically around the star – irregular features that indicate the presence of at least one very massive planet.
Recent images of AB Aur taken by HiCIAO (top left), compared with an image taken in 2004 by its predecessor instrument CIAO (top right). The new images give a much more detailed view of the inner regions (bottom left; with explanations bottom right): Intricate bright and dark patterns indicate the presence of different rings of matter. The fact that their centers do not coincide with the position of the star and the other irregularities point to the existence of a massive giant planet which is sweeping up the material between the rings. Credit: NAOJ/J. Hashimoto
The researchers point out that no other telescopes, whether ground-based or in space, have ever penetrated so close to a central star, showing the details of its disk.
Planetary systems like our own share a humble origin as mere by-products of star formation. A newborn star’s gravity gathers leftover gas and dust in a dense, flattened disk of matter orbiting the star. Clumps in the disk sweep up more and more material, until their own gravity becomes sufficiently strong to compress them into the dense bodies we know as planets.
Flocculent Spiral NGC 2841, in the constellation Ursa Major. Credit: NASA, ESA and Hubble
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The Flocculent Spiral NGC 2841, shown above, is known for its profusion of young, blue stars. And yet, until recently, astronomers haven’t been able to use those stars as windows into the still-mysterious phenomenon of star formation.
Hubble’s most recent wide-field camera upgrade is changing that.
The new Wide Field Camera 3 (WFC3) was installed on Hubble in May 2009 during Servicing Mission 4, and replaces the Wide Field and Planetary Camera 2. The new camera is optimized to observe in the infrared and ultraviolet wavelengths emitted by newborn stars, shown by the bright blue clumps in the lead image. Thus, it can peer behind the veil of dust that would otherwise hide those stars from view.
The image shows a lot of hot, young stars in the disc of NGC 2841, but in reality there are just a few sites of current star formation where hydrogen gas is collapsing into new stars. It is likely that these fiery youngsters destroyed the star-forming regions in which they were formed.
Image from NASA's Galaxy Evolution Explorer (GALEX), via the NASA/IPAC Extragalactic Database
NGC 2841 is about 46 million light years away in the constellation Ursa Major. It’s part of a common group of galaxies called flocculent spirals; flocculent means fluffy or wooly-looking. Rather than boasting well-defined spiral arms, these galaxies display patchy stellar distribution.
Star formation is one of the most important processes shaping the Universe; it plays a pivotal role in the evolution of galaxies and it is also in the earliest stages of star formation that planetary systems first appear. Yet there is still much that astronomers don’t understand, such as how the properties of stellar nurseries vary according to the composition and density of the gas present, and what triggers star formation in the first place. The driving force behind star formation is particularly unclear for flocculent spirals.
An international team of astronomers is using Hubble’s WFC3 to study a sample of nearby, but wildly differing, locations where stars are forming. The observational targets include both star clusters and galaxies, and star formation rates range from the baby-booming starburst galaxy Messier 82 to the much more sedate star producer NGC 2841.
Detailed credit information for the lead image: NASA, ESA and the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration Acknowledgment: M. Crockett and S. Kaviraj (Oxford University, UK), R. O’Connell (University of Virginia), B. Whitmore (STScI) and the WFC3 Scientific Oversight Committee.
Representation of the timeline of the universe over 13.7 billion years, and the expansion in the universe that followed. Credit: NASA/WMAP Science Team.
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Editor’s note: The article “The Universe Could be 250 Times Bigger Than What is Observable” sparked a sizable discussion among our readers, with several suggesting UT should have a series of articles about cosmology — a Cosmology 101, if you will. Our newest writer, Vanessa D’Amico, who wrote the aforementioned article, begins the Cosmology 101 series today, starting at the very beginning.
How did the universe get its start? It’s one of the most pressing questions in cosmology, and likely one that will be around for a while. Here, I’ll begin by explaining what scientists think they know about the first formative seconds of the universe’s life. More than likely, the story isn’t quite what you might think.
In the beginning, there was… well, we don’t really know. One of the most prevalent misconceptions in cosmology is that the universe began as an immensely small, inconceivably dense collection of material that suddenly exploded, giving rise to space as we know it. There are a number of problems with this idea, not least of all the assumption implicit in an event termed the big “bang.” In truth, nothing “banged.” The notion of an explosion brings to mind an expanding tide of material, gradually filling the space around it; however, when our universe was born, there was no space. There was no time either. There was no vacuum. There was literally nothing.
Then the universe was born. Extremely high energies during the first 10-43 seconds of its life make it very difficult for scientists to determine anything conclusive about the origin of the cosmos. Of course, if cosmologists are correct about what they believe may have happened next, it doesn’t much matter. According to the theory of inflation, at about 10-36 seconds, the universe underwent a period of exponential expansion. In a matter of a few thousandths of a second, space inflated by a factor of about 1078, quickly separating what were once adjoining regions by unfathomable distances and blowing up tiny quantum fluctuations in the fabric of spacetime.
Inflation is an appealing theory for a number of reasons. First of all, it explains why we observe the universe to be homogeneous and isotropic on large scales – that is, it looks the same in all directions and to all observers. It also explains why the universe visually appears to be flat, rather than curved. Without inflation, a flat universe requires an extremely fine-tuned set of initial conditions; however, inflation turns this fine-tuning into a trick of scale. A familiar analogy: the ground under our feet appears to be flat (even though we know we live on a spherical planet) because we humans are so much smaller than the Earth. Likewise, the inflated universe is so enormous compared to our local field of view that it appears to be spatially flat.
As the theory goes, the end of inflation gave way to a universe that looked slightly more like the one we observe today. The vacuum energy that drove inflation suddenly transformed into a different kind of energy – the kind that could create elementary particles. At this point (only 10-32 seconds after the birth of the universe), the ambient temperature was still far too hot to build atoms or molecules from these particles; but as the seconds wore on, space expanded and cooled to the point where quarks could come together and form protons and neutrons. High-energy photons continued to dart around, continually striking and exciting charged protons and electrons.
So what happened next? How did this chaotic soup of matter and radiation become the vast expanse of organized structure that we see today? What’s going to happen to the universe in the future? And how do we know that this is the way the story unfolded? Make sure to check out the next few installments of Cosmology 101 for the answers to these questions and more!
Siding Spring Comet via WISE. credit: NASA/JPL-Caltech/UCLA
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An old story got new legs this week as word went viral of a possible new 9th planet in our solar system – a gas giant bigger than Jupiter – which could be hiding somewhere in the Oort Cloud, just waiting to be found.
An article this week in The Independent suggested the new planet, called Tyche, had already been found among data from the WISE mission. This prompted the WISE team to post a rebuttal on their Facebook page: “Not true. A pair of scientists published a paper stating that if such a big planet exists in the far reaches of the Solar System, then WISE should have seen it. That is true. But, analysis over the next couple of years will be needed to determine if WISE has actually detected such a world or not.”
To make sense of this all, Universe Today sought out a scientist who has looked at the outer solar system as much as anyone, if not more: Mike Brown, of Eris, Haumea and Makemake fame – to get his take on Tyche.
“Yes,” said Brown, “this is all getting pretty funny these days!”
The story starts at least a decade ago. For years John Matese of the University of Louisiana at Lafayette and colleague Daniel Whitmire have been trying to figure out why many of the comets that originate from way out in the distant-most part of our solar system — the Oort Cloud — have strange orbits that don’t jive with theories of how comets should behave. The two scientists first suggested that the gravitational influence from a dark companion to the Sun — a dim brown-dwarf or red-dwarf star — was sending comets careening towards the inner solar system. They called it Nemesis, (another thing that went viral), but the Nemesis idea has widely been refuted.
Last year, Matese and Whitmire suggested that possibly a large planet four times the mass of Jupiter in the Oort Cloud could explain why long-period comets appear to be clustered in a band inclined to the ecliptic instead of coming from random directions. (Here’s their paper.)
Then came a revival of their theory with several articles about it this week, reporting it as seemingly fact.
Could there possibly be a giant planet 500 times as distant as Neptune?
“Absolutely,” Brown said. “Many people have speculated about such possibilities for a long time. It’s an intriguing idea because, well, it would be fun, to say the least.”
But beyond fun and excitement, is there actually any evidence for it?
The layout of the solar system, including the Oort Cloud, on a logarithmic scale. Credit: NASA
“Well, the quality of the data that Matese and Whitmire have to work with is pretty crummy –no fault of their own — it’s just the historical record of where comets have come from,” Brown said in an email. “I don’t believe that anyone understands the ins and outs of the data set well enough to really draw a robust conclusion. But, Matese and Whitmire did the best they could and think the data point to something out there.”
Does Brown think there is really something out there?
“Well,” he said, “if I had to bet one way or another I’d bet no. The data don’t convince me, and there is no other hint anywhere that such a thing is real. So I’m pretty skeptical.”
That being said, however, Brown believes WISE really does have a good chance of detecting this type of object way out there – if it exists — even if the predictions have nothing to do with the real object.
“This is something that people will absolutely be looking for when the data are released,” Brown said, “and, indeed, the WISE team is undoubtedly already looking for — not because of the prediction, but simply because it’s the right way to search this unknown region of the solar system!”
So don’t worry about the International Astronomical Union having to confirm or name a new planet in our solar system, at least for now.
Here’s a chance to practice your French countdown skills: watch today’s successful launch of the European Space Agency’s Automated Transfer Vehicle “Johannes” on a Arianespace Ariane 5 rocket blasted off on Feb. 16, 2011, carrying the “Johannes Kepler” cargo-carrying vehicle to the International Space Station. It will take eight days for the ATV to arrive and dock to the aft end of the International Space Station’s Zvezda Service Module. This is the second of ESA’s resupply vehicles, and is loaded with about seven tons of supplies and propellant for use by the six crew members on the ISS.
After yesterday’s scrub of Johannes Kepler, NASA had said that a launch of the ATV today (Wednesday) might delay the launch of space shuttle Discovery for STS-133. However, today, NASA said that might not be the case. Officials will decide Discovery’s launch date at the Flight Readiness Review on February 18. Currently, STS-133’s launch is scheduled for Feb. 24.
On April 12, 2011, everyone with the least bit of interest in space should be rockin’ the house. It’s the 50th anniversary of Yuri Gagarin’s flight, the first human to launch to space. As of this writing there are 109 Yuri’s Night events in 27 countries on 5 continents on 2 worlds (#2 is in Second Life.) Take a look at the Yuri’s Night website to see if there is an event near you. If not, start your own!
There is also a Yuri’s Night 2011 Video Contest, which is an open source competition to engage the public to create tribute videos for this 50th Anniversary of Human Spaceflight. The best videos will be shared at events around the world and the winners will receive $500. The deadline for submission is April 1, 2011. There will be online voting for the winner.
Tempel 1, as Seen by Two Spacecraft. These two images show the different views of comet Tempel 1 seen by NASA's Deep Impact spacecraft (left) and NASA's Stardust spacecraft (right). Two craters, about 300 meters (1,000 feet) in diameter, help scientists locate the area hit by the impactor released by Deep Impact in July 2005. The dashed lines correlate the features. Stardust approached the comet from a different angle on Feb. 14, 2011. Credit: NASA/JPL-Caltech/University of Maryland/Cornell
Tempel 1 is the first comet to receive a second visit by probes from Earth.
Comets have continuously smashed into Earth over the eons and delivered vast quantities of key ingredients – such as water and organic molecules – that may have sparked the formation of life on the early Earth.
NASA approved the use of the already orbiting Stardust-NExT spacecraft to follow up on the science discoveries by Deep Impact as the best and most economical way to try and locate the crater blast site, image new terrain and look for changes on the comets surface since the 2005 mission as the comet also completed another orbit around our Sun and eroded due to solar heating.
The human made crater is about 150 meters wide and was formed by a 375 kilogram (800 pound) projectile propelled into the speeding path of Comet Tempel 1 by the Deep Impact mothership in 2005.
Tempel 1 Impact Site.
This pair of images shows the before-and-after comparison of the part of comet Tempel 1 that was hit by the impactor from NASA's Deep Impact spacecraft. The left-hand image is a composite made from images obtained by Deep Impact in July 2005. The right-hand image shows arrows identifying the rim of the crater caused by the impactor. The crater is estimated to be 150 meters (500 feet) in diameter. This image also shows a brighter mound in the center of the crater likely created when material from the impact fell back into the crater. Credit: NASA/JPL-Caltech/University of Maryland/Cornell
Stardust-NExT took 72 high resolution science images of the comet during the Valentine’s Day encounter flyby on Feb, 14 at 11:40 p.m. EST (8:40 p.m. PST). The probe absolutely had to be precisely navigated to exactly hit the aim point for sequencing the images to match the right moment in the erratic rotation of the volatile comet.
The results of the Stardust-NExT mission were announced at a post encounter new briefing after most of the images and science data had streamed back to Earth. The science team and NASA said that all the mission objectives were accomplished.
“If you ask me was this mission 100 percent successful in terms of the science, I’d have to say no. It was 1000 percent successful!” said Stardust-NExT principal investigator Joe Veverka of Cornell University, Ithaca, N.Y., at the news briefing.
“We found the Deep Impact crater. We see erosion in comparison to 2005. So we do see changes. Erosion on the scale of 20 to 30 meters of material has occurred in the five or six years since we took the first picture. We are seeing a change, but we have to spend time quantifying the changes and understanding what they mean.”
“We saw a lot of new territory. It’s amazing with lots of layers. There is lots of surface sublimation. We had to arrive at precisely the right time in order to see new and old territory.”
“We had monitored the comets rotation for several years. And we got the longitude almost perfect within 1 or 2 degrees,” Veverka said.
Tempel 1 Impact Site
Credit: NASA/JPL-Caltech/University of Maryland/Cornell
It took a few years of careful study to deduce the comets complex rotational patterns which change as the body orbits in a wide orbital path between Mars and Jupiter and is heated by the sun.
Peter Schultz, a science team co-investigator agreed and showed the comparison images.
“We saw the crater,” said Schultz, of University. “It’s subdued; it’s about 150 meters across and has a small central mound in the center. It looks as if from the impact, the stuff went up and came back down. So we did get it, there’s no doubt. I think one of the bottom-line messages is that this surface of the comet where we hit is very weak. It’s fragile. So the crater partly healed itself.”
“It was about the size we expected. But more subdued.”
The probes mission is almost complete since it has very little fuel left. The remaining science data from the flyby is being sent back and some outbound data is being collected.
“This spacecraft has logged over 3.5 billion miles since launch, and while its last close encounter is complete, its mission of discovery is not,” said Tim Larson, Stardust-NExT project manager at JPL. “We’ll continue imaging the comet as long as the science team can gain useful information, and then Stardust will get its well-deserved rest.”
Stardust-NExT is a repurposed spacecraft that has journeyed nearly 6 billion kilometers since it was launched in 1999.
Initially christened as Stardust, the spaceships original task was to fly by Comet Wild 2 in 2004. It also collected priceless cometary dust particles from the coma which was safely parachuted back to Earth inside a return canister in 2006. High powered science analysis of the precious comet dust will help researchers discern the origin and evolution of our solar system.
This was humanities first revisit to a comet and at a bargain basement price by using an old spacecraft already in space.
“The cost was just $29 Million dollars. A new Discovery class mission costs $300 to 500 Million. So that’s maybe 6% the cost of developing and launching a new mission,” said Ed Weiler, the associate administrator for NASA’s Science Mission Directorate at NASA HQ in Washington, DC.
Read more about the Stardust-NExT Flyby and mission in my earlier stories here, here, here and here
Changes to Smooth Terrain (Annotated)
This image layout depicts changes in the surface of comet Tempel 1, observed first by NASA's Deep Impact Mission in 2005 (top right) and again by NASA's Stardust-NExT mission on Feb. 14, 2011 (bottom right). Between the two visits, the comet made one trip around the sun. The image at top left is a wider shot from Deep Impact. The smooth terrain is at a higher elevation than the more textured surface around it. Scientists think that cliffs, illustrated with yellow lines to the right, are being eroded back to the left in this view. The cliffs appear to have eroded as much as 20 to 30 meters (66 to 100 feet) in some places, since Deep Impact took the initial image. The box shows depressions that have merged together over time, also from erosion. This erosion is caused by volatile substances evaporating away from the comet. Credit: NASA/JPL-Caltech/University of Maryland/Cornell
Here’s this week’s image for the Where In The Universe Challenge, to test your visual knowledge of the cosmos. You know what to do: take a look at this image and see if you can determine where in the universe this image is from; give yourself extra points if you can name the spacecraft/telescope responsible for the image. We’ll provide the image today, but won’t reveal the answer until later. This gives you a chance to mull over the image and provide your answer/guess in the comment section. Please, no links or extensive explanations of what you think this is — give everyone the chance to guess.
UPDATE: The answer is now posted below.
While the explosion of Praxis might have looked like this if Nicholas Meyer would have filmed Star Trek VI in X-Ray, this is in fact an image of the core of M87, a galaxy in the constellation of Virgo. This image was taken in 2004 with the Chandra’s X-ray telescope, and showed what was believed to be three rings associated with the galaxy’s core and jet. See more about this image on the Chandra website.
Followup observations reveals actually just two circular rings with radii of 45 thousand and 55 thousand light years, respectively. These features are likely sound waves produced by earlier explosions about 10 million and 14 million years ago.
Check back next week for another test of your visual knowledge of the cosmos.
Up to two-thirds of Earth’s permafrost likely will disappear by 2200 as a result of warming temperatures, unleashing vast quantities of carbon into the atmosphere, says a new study by the University of Colorado Boulder’s Cooperative Institute for Research in Environmental Sciences (CIRES).
The carbon resides in permanently frozen ground that is beginning to thaw in high latitudes from warming temperatures, which will impact not only the climate but also international strategies to reduce fossil fuel emissions, said CU-Boulder’s Kevin Schaefer, lead study author. “If we want to hit a target carbon dioxide concentration, then we have to reduce fossil fuel emissions that much lower than previously thought to account for this additional carbon from the permafrost,” he said. “Otherwise we will end up with a warmer Earth than we want.” Continue reading “Study: Thawing Permafrost Could Accelerate Global Warming”
False color image of the Lockman-hole area of the sky at infrared wavelengths as imaged by the Herschel Space Observatory. Credit: ESA/SPIRE Consortium/HerMES Consortium
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When it comes to forming stars, the size of a galaxy does matter, according to research out today in the online version of Nature.
But it doesn’t have to be as massive as we once thought.
Alexandre Amblard, an astrophysicist at the University of California, Irvine, and his colleagues used new data from the Herschel Space Observatory to peer into Lockman Hole area of the sky, where extragalactic light comes from star-forming galaxies out of reach for even the world’s most powerful telescopes.
The Lockman Hole is a patch of the sky, 15 square degrees, lying roughly between the pointer stars of the Big Dipper.
Called submillimetre galaxies, the study subjects emit light at wavelengths between the radio and infrared parts of the spectrum, so studying them requires novel approaches borrowing from both radio and optical astronomy. The galaxies by themselves are too blurry to be resolved with individual far-infrared telescopes – but their average properties can be observed and analyzed, which is exactly what Amblard and his colleagues did.
The authors measured variations in the intensity of extragalactic light at far-infrared wavelengths, and derived statistics for the level of clustering of light halos. They assume that the clustering reflects the underlying distribution of dark matter, and fit the data to a halo model of galaxy formation, which connects the spatial distribution of galaxies in the Universe to that of dark matter.
Distribution of dark matter when the Universe was about 3 billion years old, obtained from a numerical simulation of galaxy formation. The left panel displays the continuous distribution of dark matter particles, showing the typical wispy structure of the cosmic web, with a network of sheets and filaments, while the right panel highlights the dark matter halos representing the most efficient cosmic sites for the formation of star-bursting galaxies with a minimum dark matter halo mass of 300 billion times that of the Sun. Credit: VIRGO Consortium/Alexandre Amblard/ESA
Amblard and his colleagues discovered an enormous fact: the ‘haloes’ of dark matter that surround the Universe’s most active star-forming galaxies are each more massive than about 300 billion solar masses.
What’s even more interesting is that the new threshold for star formation is actually smaller than some previous estimates.
“I think there was one prediction that put the number around 5000 billion times that of the sun, but that was just a prediction from a theory of galaxy formation.“ said Asantha Cooray, also an astrophysicist at UC Irvine and second author on the new paper. “The general consensus was that it may be between 100 to 1000 billion times the sun. We now have a more precise answer from this work.”
Cooray said he’s most excited “that we can look at a detailed image of the sky showing distant, star-forming galaxies and infer not only details about the stars and gas in those galaxies but also about the amount of dark matter needed to form such galaxies. Beyond inferring the presence, we still don’t know exactly what dark matter is.”
The results appear online ahead of print today on Nature’s website.
