For the first time, astrophysicists have created a computer simulation of the formation of a spiral galaxy like the Milky Way (above).  Researchers at the University of California at Santa Cruz and the Institute for Theoretical Physics in Zurich modeled their galaxy, Eris, using a software platform called Gasoline, which allowed them to track the motion of 60 million particles of gas and dark matter for over 13 billion simulated years. Overall, the simulation required 9 months of number crunching on NASA’s Pleiades supercomputer, with supporting simulations on supercomputers at UCSC and the Swiss National Supercomputing Center.

Previous efforts to model spiral galaxies have failed, ending in disfigured galaxies with central bulges much too large for their disks, according to the researchers. But Eris’ bulge-to-disk ratio, stellar content, and other features fall in line with observations of the Milky Way. The researchers point to a realistic model of star formation as a key to Eris’ success—their high-resolution simulation allowed stars to form only in regions with a high density of particles, resulting in a more accurate distribution of stars. More than just a nice movie, the work supports the cold dark matter theory, which says that the gravitational interactions of dark matter drove the evolution of the universe. A paper detailing the Eris simulation will be published in an upcoming issue of the Astrophysical Journal.

[Read more at MSNBC and io9]

What’s the News: While the Kepler spacecraft is busy finding solar system-loads of new planets, other astronomers are expanding our idea where planets could potentially be found. One astronomer wants to look for habitable planets around white dwarfs, arguing that any water-bearing exoplanets orbiting these tiny, dim stars would be much easier to find than those around main-sequence stars like our Sun. Another team dispenses with stars altogether and speculates that dark matter explosions inside a planet could hypothetically make it warm enough to be habitable, even without a star. “This is a fascinating, and highly original idea,” MIT exoplanet expert Sara Seager told Wired, referring to the dark matter hypothesis. “Original ideas are becoming more and more rare in exoplanet theory.”

How the Heck:

• Because white dwarfs are much smaller than our Sun, an Earth-sized planet that crossed in front of it would block more of its light, which should make these planets easier to spot. So astronomer Eric Agol suggests survey the 20,000 white dwarfs closest to Earth with relatively meager 1-meter ground telescopes.
• And because white dwarfs are so cool, a planet in a white dwarfs habitable zone would be very close, meaning its transit would happen very fast. Agol says we’d only need to watch a star for 32 hours to pick up on any transiting, habitable planets.
• One leading theory about dark matter is that it’s made of theoretical particles called WIMPS (weakly interacting massive particles). It’s thought that when WIMPs collide (if, of course, they exist), they would explode. Astronomers think that these WIMP explosions could possibly heat a planet enough to make it habitable.
• There are no immediate plans to test the dark matter hypothesis, which is quite theoretical, and any plan to find dark matter-fueled planets would need to look far from here: our part of the universe doesn’t have nearly enough dark matter to bring a planet to habitability.

What’s the Context:

• In other white dwarf news, astronomers have discovered a red dwarf in an extremely tight orbit with a white dwarf.
• And others are still wrangling over what dark matter really is.
• As for exoplanets, astronomers have actually seen one—as in, with visible light—orbiting its star.

Not So Fast:

• It’s not at all clear if white dwarfs have any planets, and if so, whether any of them could possibly support water or life as we know it. For one thing, planets in the habitable zone would be tidally locked with the star—permanent scalding daylight on one side; permanent frozen nighttime on the other.
• Taking 32 hours to find a planet orbiting a white dwarf may seem like a short time, but when you’re looking at tens of thousands of stars, it adds up. Agol told UW Today, “This could take a huge amount of time, even with [a network of telescopes].”
• And just like star-orbiting planets have their Goldilocks zones (not to hot or too cold), dark matter-containing planets would need the right amount of dark matter to be habitable. “It’s not something that’s likely to produce a lot of habitable planets,” Fermilab researcher Dan Hooper told Wired. “But in very special places and in very special models, it could do the trick.” 

References: Eric Agol. “TRANSIT SURVEYS FOR EARTHS IN THE HABITABLE ZONES OF WHITE DWARFS.” doi: 10.1088/2041-8205/731/2/L31

Dan Hooper and Jason H. Steffen. “Dark Matter And The Habitability of Planets.” arXiv:1103.5086v1

Image: NASA/European Space Agency

Planetar. Substar. Failed star. Sub-stellar object. Astronomers have pinned each of these monikers on brown dwarfs, a category that has always perplexed scientists because it raises questions about what it means to be a star or a planet. And if that wasn’t enough, now they’ve discovered the coldest brown dwarf yet, blurring the line between planet and star even further.

It’s name is CFBDSIR J1458+1013B, and may be cooler than the boiling point of water (at the pressure of Earth’s atmosphere). This strange body is about 75 light-years from us, where it orbits its binary partner, another brown dwarf. Using the infrared capabilities of the 10-meter Keck II Telescope on Mauna Kea, University of Hawaii researcher Michael Liu and his team estimated the brown dwarf’s temperature, and have a ballpark range for its mass: between 6 and 15 times the mass of Jupiter.

It’s special because it may be a class Y dwarf (temperature less than 225 degrees Celsius (440 F)), a type of object whose existence astronomers had predicted but never actually found. Before this candidate arose, the coolest known brown dwarf was in the T spectral class; while there have been a few Y-class candidates in the past, scientists have a better grasp on the temperature of this one: 97 degrees Celsius, plus or minus 40C.

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Young. Old. Scalding hot. Icy cold. Terrestrial midgets. Gas giants. As the cavalcade of planets spotted beyond our solar system continues to grow, we get to see worlds of all sorts—and we get to speculate on the staggering number of exoplanets that might inhabit just our own galaxy.

Today’s first piece of otherworldly news involves baby exoplanets. Astronomer Christian Thalmann says his team may have spotted planets in the process of forming around three different stars, the first time scientists have spotted the process in action.

An infant star forms from a collapsing cloud of dust and gas and gathers a dense, flat disk of material that rotates with the star like a record album. The material in the disk will eventually clump up into nascent planets. Theoretical models of planet formation predicted that those protoplanets should suck up more gas and dust with their gravity, clearing a wide gap in the otherwise solid disk. [Wired]

Peering at young stars like T Chamaeleontis (T Cha) LkCa15 and AB Auriga, Thalmann and colleagues saw those telltale gaps in the dusty rings (their study is forthcoming in the Astrophysical Journal Letters). The stars are much like our own sun, so these pictures of infant solar systems could resemble what our own looked like as a baby. But though the stars are nearby in cosmic terms—T Cha lies just 350 light years away—the gaps are faint enough that it’s difficult to tell for certain if newly forming planets, and not the influence of binary stars or other objects, are creating them.

If Thalmann’s team is right, catching the birth of new worlds would be a great scientific coup. Our galaxy, however, isn’t exactly hurting for planets.

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For months we here at DISCOVER have been waiting impatiently for the Kepler mission to open up its vault of new exoplanets, hopefully filled with a bevy of Earth-like worlds and other exotic planets. Today planet lovers got a new peek at the Kepler findings, and those findings are stunning.

First, the Kepler scientists announced more than 1,200 candidate planets, which got DISCOVER blogger Phil Plait excited:

This is incredible! Even though I was expecting a number like this, actually hearing it for real is stunning. In 15 years we’ve found about 500 planets orbiting other stars, but in the almost two years since Kepler launched it may have easily tripled that number! Now, to be careful: these are candidate planets, which means they have not been confirmed. But in most cases these look pretty good, and if these numbers hold up it indicates that our galaxy is lousy with planets. They’re everywhere.

While those 1,200 are candidates, astronomers have confirmed a peculiar and fascinating set of six. From Phil Plait:

Using NASA’s orbiting Kepler observatory, astronomers have found a complete solar system of six planets orbiting a sun-like star… and it’s really weird: five of the six planets huddle closer to their star than Mercury does to the Sun!

None of them is what I would call precisely earth-like — they’re all more massive and much hotter than Earth — but their properties are intriguing, and promise that more wonderful discoveries from Kepler are coming.

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ESO/L. Calçada

More than a trillion pixels from a million-plus images, combined to create the most detailed map of the universe ever created—one that would require a wall of a half-million HDTVs to properly appreciate. Not bad for something that looks a little like tan carpeting.

What you’re seeing is about one-third of the sky, imaged by the Sloan Digital Sky Survey, which has been assembling images from Apache Point Observatory in New Mexico for more than a dozen years to image the cosmos in unprecedented detail.

It replaces an image that is now over half a century old, created on photographic plates by the Palomar Sky Survey in the 1950s but still used by astronomers today. It contains 10 times as many objects – such as galaxies, stars and nebulae – as the Palomar survey and scientists hope it will be used for decades to come by astronomers hunting for everything from dark matter to planets orbiting other stars. [The Guardian]

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New sea creatures, humongous stars, and cockroach antibiotics: Those are just a few reader favorites from this year in science. As 2010 comes to a close, we bring you a dozen of the most popular 80beats posts of the year.

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For more great stories from the year in science, check out DISCOVER’s Top 100 Stories of the Year.

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On her first true flight as an observatory, NASA’s plane-based infrared telescope (the Stratospheric Observatory for Infrared Astronomy, aka SOFIA) took a close look at Orion and other star clusters overnight on November 30th.

“The early science flight program serves to validate SOFIA‘s capabilities and demonstrate the observatory’s ability to make observations not possible from Earth-based telescopes,” said Bob Meyer, NASA’s SOFIA program manager. “It also marks SOFIA‘s transition from flying testbed to flying observatory, and it gives the international astronomical research community a new, highly versatile platform for studying the universe.” [press release]

SOFIA is a highly modified Boeing 747SP jetliner that now includes a 100-inch German telescope (bigger than the Hubble’s!). These early observations were made with a general-use mid-infrared camera called FORCAST designed by a group at Cornell University.

Since SOFIA cruises at altitudes between 39,000 and 45,000 feet above sea level, it’s above 99 percent of the atmosphere’s water vapor (which normally blocks infrared light from reaching earth). The camera captures images using these infrared rays, producing detailed pictures that couldn’t be taken from earth.

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A study by Yale astronomer Pieter van Dokkum just took the estimated number of stars in the universe—100,000,000,000,000,000,000,000, or 100 sextillion—and tripled it. And you thought nothing good ever happens on Wednesdays.

Van Dokkum’s study in the journal Nature focuses on red dwarfs, a class of small, cool stars. They’re so small and cool, in fact, that up to now astronomers haven’t been able to spot them in galaxies outside our own. That’s a serious holdup when you’re trying to account for all the stars there are.

As a consequence, when estimating how much of a galaxy’s mass stars account for – important to understanding a galaxy’s life history – astronomers basically had to assume that the relative abundance of red-dwarf stars found in the Milky Way held true throughout the universe for every galaxy type and at every epoch of the universe’s evolution, Dr. van Dokkum says. “We always knew that was sort of a stretch, but it was the only thing we had. Until you see evidence to the contrary you kind of go with that assumption,” he says. [Christian Science Monitor]

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A fascinating discovery from today’s edition of the journal Science: Astronomers from Germany report a new exoplanet with two startling characteristics. First, it closely orbits a star that has already exhausted its hydrogen supply and moved past the red giant stage, so this hot Jupiter has so far survived without being evaporated (despite its proximity—just 0.12 astronomical units).

But second, and most striking: This planet and star came from another galaxy.

From Phil Plait:

OK, first, this planet is in our own Milky Way galaxy. The star, called HIP 13044, is about 2000 light years away, well inside our galaxy. So how do we know it’s from a different galaxy? All the stars in our galaxy orbit the galactic center, like planets orbit around a star. But many years ago, astronomers noticed that many stars in the sky have the same sort of motion as they orbit, as if they all belong to streams of stars, flowing like water in a river. Many such streams exist, and eventually astronomers figured out that these were the leftover remnants of entire small galaxies that had collided with, been torn apart, and basically eaten by our Milky Way.

HIP 13044 is part of one of those streams, called the Helmi Stream. It’s the remains of a dwarf galaxy the Milky Way tore apart probably more than 6 billion years ago. So the star and its planet formed in an actual other galaxy, one that either orbited the Milky Way or had an unfortunately too-close pass to it. Either way, wow!

During a web conference this morning, study coauthor Rainer Klement said we shouldn’t be surprised the star and planet are still together even though our galaxy tore theirs apart. Galaxies are structures of stars, but the stars themselves are still so far away that even during a galactic breakup they don’t pass near enough to one another to gravitationally influence a planet. “The timescale upon which such stars play a role is larger than the age of the universe,” he said.

Read the rest of Phil’s post at Bad Astronomy.

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DISCOVER: How Long Until We Find a Second Earth?

Image: ESO

The universe abounds with Earth-sized planets. That hopeful notion has been reinforced by individual planets finds like possible Goldilocks planet Gliese 581g, by the hordes of planet candidates discovered by the Kepler mission, and now, by a census of a small space in the sky that tells us one in four sun-like stars should possess worlds that are close to the size of Earth.

Take a moment to think about that: One in four.

In Science, exoplanet hunters Geoffrey Marcy and Andrew Howard published their team’s census of 166 nearby stars like ours, of which they picked 22 at random to investigate for planets. They watched the stars’ doppler shifts to hunt for planets over the last five years, and used the results to extrapolate how common terrestrial planets must be far beyond just this set of stars.

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Where once there was a star 20 times the size of our sun, now there is a record breaker. Astronomers report this week in Nature that when the huge star went supernova, it collapsed into a neutron star that is heaviest they’ve ever seen, with twice the mass of our sun compacted into a tiny space. Aside from taking its place in the record books, this massive monster could reveal what truly goes on deep in the heart of a deceased star.

The neutron star is part of a binary star system called J1614-2230, in which it and a white dwarf are locked in a spin cycle. Thanks to the neutron star’s steady emission of radio waves and a handy trick of relativity, scientists can measure the size of the two objects despite the fact that they’re 3,000 light years from here.

The astronomers took detailed measurements of the radio pulses that reached Earth. As these pulses, which originate from the rotation of the neutron star, passed by the companion white dwarf, their timing was delayed due to the highly warped nature of spacetime—an effect known as Shapiro delay. In a highly inclined, nearly edge-on system such as J1614-2230 the effect allows astronomers to make very accurate measurements both of the neutron star and its companion. [Ars Technica]

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From Phil Plait:

The record for the most distant object in the Universe ever seen has been smashed: a galaxy has been found at the staggering distance of 13.1 billion light years!

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It’s so dim that the faintest star you can see with your unaided eye is 4 billion times brighter. Its distance is simply numbing; the Universe itself is only 13.7 billion years old, so the light from this object began its journey on its way to Earth just 600 million years after the Universe itself formed.

Head to the full post at Bad Astronomy for all the details about how astronomers used the Hubble Space Telescope to find this faraway galaxy, and what the discovery tells us about the infant universe.

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When the universe was young, massive galaxies formed quickly but surprisingly peacefully. Researchers say they’ve found evidence that these galaxies didn’t grow by sucking up the remnant materials from supernovae or by violent collisions with other galaxies–instead they were fed by streams of cold gas that were funneled into their central star-forming region.

Astronomers using the European Southern Observatory’s Very Large Telescope in Chile have observed three primeval galaxies with patches of star formation near their centers, away from the heavy elements that signal the remains of previous stars. The team found that these galaxies were sucking in cool hydrogen and helium from the space between galaxies as fuel. “It solves the problem of providing to the galaxies fuel to form their stars in a continuous way, without having to invoke violent mergers and galaxy interactions,” said study researcher Giovanni Cresci. [SPACE.com]

The study, published in Nature, describes three galaxies that formed just 2 billion years after the Big Bang–which created lots of hydrogen and helium to feed hungry, growing galaxies, but created few heavier elements. Those formed later in stars and supernovae.

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Image: L. Calcada (ESO)

A group of Swiss astronomers announced yesterday at the International Astronomical Union’s annual meeting in Turin, Italy, that they couldn’t detect the “goldilocks” exoplanet found by U.S. researchers a few weeks ago. That news of that planet, dubbed Gliese 581g, generated much excitement, since researchers said it was only three times the size of Earth, and it appeared to lie in the habitable zone where liquid water could exist on the surface.

It didn’t take long for some cold water to be thrown on the astronomical community and the space-loving public. Presenter Francesco Pepe and his colleagues claim that it will be years before the data is clear enough to see such a planet.

“We do not see any evidence for a fifth planet … as announced by Vogt et al.,” Pepe wrote Science in an e-mail from the meeting. On the other hand, “we can’t prove there is no fifth planet.” No one yet has the required precision in their observations to prove the absence of such a small exoplanet, he notes. [ScienceNOW].

Such small planets are very hard to find. Astronomers discover these planets by calculating how they interact with the star they orbit, making it wiggle ever so slightly. The American team that identified the planet a few weeks ago saw the wiggles when analyzing a combination of two sets of data.

Astronomer Paul Butler, a member of the U.S. team who is at the Carnegie Institution for Science in Washington, D.C., says he can’t comment on the Swiss work because he wasn’t at the meeting and the data are unpublished. He notes, however, that more observations will likely be needed to solidify the existence of Gliese 581g. “I would expect that on the time scale of a year or two this should be settled.” [ScienceNOW].

There will be more information available when the Swiss team releases its data and methods, but for now you might want to unpack your bags.

Related content:
Bad Astronomy: Possible earthlike planet found in the Goldilocks zone of a nearby star!
Discoblog: So, How Long Would It Take to Travel to That Exciting New Exoplanet?
80beats: New Telescope Could Reveal a Milky Way Packed With Habitable Planets
Bad Astronomy: HUGE NEWS: first possibly Earthlike extrasolar planet found!
80beats: Don’t Pack Your Bags Yet—New Planet-Finder Hobbled by Electronic Glitch

Image: NSF