From Phil Plait:
Astronomers have announced the discovery of a planet with about three times the Earth’s mass orbiting the nearby red dwarf star Gliese 581. That in itself is cool news; a planet like that is very hard to detect.
But the amazing thing is that the planet’s distance from the star puts it in the Goldilocks Zone: the region where liquid water could exist on its surface!
Gliese 581 is about 20 light years away, and astronomers think the planet in the habitable zone is one of at least six in that star system. The new exoplanet orbits much closer to its star than Earth orbits the sun, but its star is a red dwarf, so it needs to be closer to stay warm enough to support liquid water.
But just how like the Earth is this new world? And what does it mean for the prevalence of ‘Goldilocks” planets out there? To find out, read the rest of the post at Bad Astronomy. And check out the scientists’ paper about Gliese 581 (pdf).
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Image: ESO
The one ring is back, and it’s beautiful.
What you see here is the aftermath of stellar death, rediscovered after NASA temporarily lost the ability to watch it play out. Astronomers tracked supernova 1987A after its discovery that year, picking up insights into what happens after a huge star expends itself. But in 2004, the Hubble Space Telescope‘s Space Telescope Imaging Spectrograph went kaput. The May 2009 space shuttle servicing mission repaired this eye in the sky, leading to a study in this week’s edition of the journal Science that reveals what’s behind this fluorescent view, and why that ring shines so brightly.
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The two newest planets spied by the Kepler space telescope are locked in a forever back-and-forth.
When Kepler’s scientists saw a star 2,000 light years away dim slightly, they knew there was the chance it was the telltale signature of a planet passing in front. But when the calculations were done and the confirmation came in, they found a surprise—what they’d seen was actually two planets transiting in front of the star.
NASA says it’s the first time they’ve ever caught such a sight, and today the scientists officially announced the finding with a study in Science. While other studies have found multiple planets around a single star–in fact, it happened earlier this week–those studies have used different planet-detection techniques like the wobble method.
The two worlds, both gas giants, do more than orbit the same star on the same plane, though. They push and pull each other in a motion that keeps the two exoplanets close to arithmetic celestial perfection. Kepler-9B, the larger, orbits the star in 19.24 days on average, the astronomers saw. Kepler-9c, the smaller, completes a revolution in an average of 38.91 days. But every time the scientists checked, 9b’s orbit was getting 4 minutes longer, while 9c’s shrank by 39 minutes.
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In August 2006, Pluto received its official demotion to dwarf planet status, taking our solar system down to eight planets. In August 2010, exoplanet hunters say they’ve found a haul of new worlds around a single star; that alien solar system may have seven known planets, meaning the system could be more like our home system than any ever discovered. And one of those worlds could be the smallest exoplanet ever found, too.
The star these planets orbit is called HD 10180, and it lies 127 light years from here. Astronomers at the European Southern Observatory in Chile used a spectrograph called HARPS to track tiny variations in the starlight caused by the pull of the planets.
It found clear evidence for five giant planets similar in size to Uranus or Neptune in our own solar system. But there were also tantalising signs that two other planets are also present, one of which would be the smallest, or least-massive, yet found orbiting another star [Christian Science Monitor].
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August has been quite the success story for the use of crowdsourcing—farming out work to willing humans or bored computers—to make scientific discoveries. Last week a study showed how citizen scientists helped unravel the structure of proteins by playing a video game. Today, a study in Science documents a newly discovered pulsar—newly discovered by the computers of amateurs, that is.
This find was the first of its kind for Einstein@Home, a project that uses the downtime of a network of volunteer computers to hunt for gravity waves and radio signals. (The more famous SETI@Home uses computer free time to seek out alien signals.) The idling PC of Chris and Helen Colvin of Ames, Iowa, detected the signature of the pulsar now called J2007 for short, which was confirmed by a computer in Germany owned by Daniel Gebhardt.
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I like the Milky Way. I dare say it’s my favorite galaxy, being home and all. But a blue star called HE 0437-5439 is in one big hurry to leave.
The star is zooming away from the Milky Way’s center at 16 million miles per hour, three times faster than our own sun glides across the galaxy. Astronomers had spotted the hasty traveler before—it’s one of 16 known “hypervelocity” stars. Now, with the help of the Hubble Space Telescope, Warren Brown of the Harvard-Smithsonian Center for Astrophysics traced the path of the star back to the event that allowed it to reach such great speed: a meeting with a black hole.
A hundred million years ago this star was one of three traveling together at a more sedate pace.
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Looking at a planetary nebula 6,500 light years away, scientists recognized an old friend: the buckyball. The large, soccer ball-shaped molecule–made from bonding 60 carbon atoms together–was first seen in a lab in 1985. In a paper published today in Science, scientists confirm the first known extraterrestrial existence of the rare carbon balls.
The buckyballs’ planetary nebula, called TC 1, surrounds a white dwarf star. Using NASA’s Spitzer Space Telescope, a team led by Jan Cami of the University of Western Ontario observed traces of the the 60-atom balls and their 70-atom cousins while looking at light coming from the white dwarf.
When light hits molecules and atoms, they will vibrate in specific, measurable ways–a field of science known as spectroscopy. One of Cami’s colleagues, who was studying Tc 1, found some unfamiliar fingerprints in the nebula’s infrared light. Cami recognized them as carbon’s 60-atom configuration and its favored 70-atom carbon partner. [Discovery News]
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Welcome to the Tarantula Nebula, home to heavy-weight stars. Using data from the Hubble Space Telescope and Very Large Telescope in Chile, scientists have found a star estimated at about 265 times the mass of the sun. That makes it by far the most massive star ever found, and challenges astronomers’ notions of just how big a star can get.
The Tarantula Nebula is 165,000 light years away in the the Large Magellenic Cloud galaxy. This star, called R136a1, is located in the R136 stellar cluster; with 10 million times the luminosity of the sun, it’s the brightest of a bevy of massive stars recently discovered. The finding, published earlier this month in the Monthly Notices of the Royal Astronomical Society, may require scientists to come up with a new stellar life cycle for the most massive stars. The life a star leads depends on its mass, and the previously estimated mass limit was thought to be around 150 times the sun’s mass.
Lead author Paul Crowther explains that the big guy falls into the stellar category of “blue supergiants,” which are still a mystery from start to finish: It’s not clear whether a star can be born this big, or whether it grows through mergers.
Supergiants also remain as much of a puzzle at the end of their lives. Although all will eventually go supernova, the type of explosion they will generate is unknown. They could form neutron stars or black holes or obliterate themselves. Whatever their fate is, he says, “We still can’t say.” [ScienceNOW]
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Our sun and a much bigger star that resides 10,000 light years away have something in common: the way they were born. Though scientists had previously wondered if stars 10 to 20 times the sun’s size required a different setup to grow, new observations show that both our sun and plus-sized stars can form from large hoops of dust called accretion disks.
Astronomers arrived at the findings, published online today in Nature, by weaving together observations from two observatories–the Very Large Telescope Interferometer of the European Southern Observatory in Chile and NASA’s orbital Spitzer Space Telescope. Researchers combined the observatories’ power to get a “virtual” telescope of much better resolution, the equivalent of one with a 280-foot mirror.
Lead researcher Stefan Kraus and his colleagues took a close peek at a 60,000-year-old stellar infant about 20 times our sun’s mass, called IRAS 13481-6124. The researchers were able to piece together temperature data to make a model of stellar birth that might resemble something from our 4.6 billion-year-old sun’s baby-book.
The team’s observations yielded a jackpot result: the discovery of a massive disk of dust and gas encircling the giant young star. “It’s the first time something like this has been observed,” Kraus said. “The disk very much resembles what we see around young stars that are much smaller, except everything is scaled up and more massive.” [Jet Propulsion Laboratory]
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The most violent winds in our own solar system whip around the Great Dark Spot of Neptune at 1,200 miles per hour, making the worst storms here on Earth look like kid stuff. But when astronomers trained their telescopes on one of the longest-studied planets around another star, suddenly even Neptune didn’t look so impressive. This week in Nature, astronomers say that the exoplanet HD 209458 b has a super-storm whose winds rage at 3,000 to 6,000 mph.
The exoplanet (which we’ll call by its friendlier nickname, Osiris) sits 150 light years from here, in the neighborhood of the constellation Pegasus. It’s an old friend, too. Osiris was the first exoplanet seen transiting in front of its star back in 1999. A decade later, though, with technology a decade more advanced, the team could spy on Osiris with the a spectrometer at the Very Large Telescope in Chile and track its carbon monoxide signature.
In fact, the VLT’s data is so good that the astronomers could see not only the planet’s orbital speed, but also the relative speed of the gas on its surface, according to study author Ignas Snellen.
“We see this clear change in velocity” of HD 209458 b, Snellen says. “There’s also an offset—the gas during the transit seems to be moving toward us.” The carbon monoxide appears to be flowing at two kilometers per second, or roughly 7,000 kilometers [~4,350 miles] per hour [Scientific American].
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When you saw the Hale-Bopp comet, you may have seen material from a distant star passing by. In a new study, a team of astronomers argues that most of the comets that streak through our solar system were actually born in other solar systems.
Given their eccentric orbits and infrequent visits, comets seem like worthy candidates for an exotic origin. But the prevailing thinking said no, they are rather ordinary. Researchers thought most of the comets that pay us a visit initially formed from the sun’s protoplanetary disk—the same swirling mass that formed our own planet—and came to reside in the weird Oort cloud region at the periphery of our solar system. From there, the gravitational bullying of larger bodies can dislodge a few like Halley’s Comet or Hale-Bopp, which swerve into an orbit that sees them visit the inner solar system now and then.
In a study in Science this week, researchers led by Harold Levison posit a different idea: Many of the comets hanging around our solar system are stolen. It goes like this:
Like most stars, the sun may very well have been created in a tightly nestled birth cluster, a stellar nursery with tens, hundreds or possibly even thousands of stars. During millions of years of intimate infancy, the newborn stars could have exchanged vast numbers of comets from the fringes of their disks, each of them winding up with an ensemble of hand-me-downs from their stellar siblings [Scientific American].
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What do you see in this image?
“One is a Valentine’s Day heart, and the other is a surgical heart that you have in your body,” said Ned Wright of the University of California, Los Angeles, who presented the image May 24 at a meeting of the American Astronomical Society. [Wired]
This infrared image is from WISE, more technically known as the Wide-field Infrared Survey Explorer, a NASA space telescope launched on December 14, 2009. Orbiting Earth at an altitude of 326 miles, WISE snaps an infrared picture every eleven seconds. This one, of the so-called Heart and Soul nebulae, is made from 1,147 of these images stitched together.
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For lovers of stellar beauty, the Herschel space telescope may have already earned its keep. Just one year after its launch, researchers from the European Space Agency have released this stunning image of a massive star being born in a vast bubble of cold dust.
Herschel’s far-infrared detectors are finely attuned to stellar nurseries. When a star begins to form, the dust and gas surrounding it heats up to a few tens of degrees above absolute zero, and it begins to emit far-infrared wavelengths. In the galactic bubble shown, known as RCW 120, the newborn star is the white blob at the bottom of the bubble.
The “baby” star is perhaps a few tens of thousands of years old. It is some eight to 10 times the mass of our Sun but is surrounded by about 200 times as much material. If more of that gas and dust continues to fall in on the star, the object has the potential to become one of the Milky Way Galaxy’s true giants [BBC].
Giant stars pose a particular challenge to our understanding of star formation, researchers say. Present theories suggest that stars that are larger than about 10 solar masses shouldn’t exist, because their fierce radiation should blast away the clouds that feed them materials to grow on. Yet astronomers have spotted stars that have 120 times the mass of our Sun.
Click through the gallery for a couple more amazing shots from Herschel.
Astronomers keep turning up new exoplanets, and as the count rises, they keep edging closer to finding worlds like our own pale blue dot. Astronomer Jay Farihi thinks Earth-like worlds might be even more common in the universe than previously expected, based on evidence from rocky planets few astronomers are studying: The ones that don’t exist anymore.
Farihi’s research subjects are white dwarfs. In our galaxy, about 90 percent of stars will end their lives in this incredibly dense state once the star sheds its outer material and only the core remains. This is the fate of our sun. White dwarfs usually have atmospheres composed of the light elements helium and hydrogen, as the heavy elements have settled to the core. But about 20 percent of white dwarfs are different, showing heavy elements—what astronomers call “metals”—in their atmospheres. For decades, astronomers attributed this metallic pollution to the interstellar medium, the thin gas that permeates the space between stars. The idea was that white dwarfs were old stars that had been on several orbits around the Milky Way and had picked up bits of the interstellar medium as they went around [Space.com]. But Farihi thinks those elements are evidence of something else.
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Astronomers have discovered the closest new star to us that’s been spotted in 63 years. Though “star” might be a stretch, depending upon whom you ask.
The new find, UGPS 0722-05, is less than 10 light years from here. But sky-watchers missed it for so long because it’s a brown dwarf, a member of the murky class of celestial objects that linger between gas giant planets and low-mass stars. Brown dwarfs have so little mass that they never get hot enough to sustain the nuclear fusion reactions that power stars like the sun. Still, they do shine, because they glow from the heat of their formation, then cool and fade [New Scientist]. This dwarf’s temperature is somewhere between 266 and 446 degrees Fahrenheit, making it the coldest scientists have even seen. With its minimal activity, the brown dwarf gives off just 0.000026 percent the amount of light that our sun does.
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