When a giant cloud of interstellar gas and dust collapses to form a new cluster of stars, only a small fraction of the cloud’s mass ends up in stars. Scientists have never been sure why. But a new study provides insights into the role magnetic fields might play in star formation, and suggests more than the influence of gravity should be taken into account in computer models of stellar birth.
Gravity favors star formation by drawing material together, so if most material does not coalesce into stars, some additional force must hinder the process. Magnetic fields and turbulence are the two leading candidates. Magnetic fields channel flowing gas, making it hard to draw gas from all directions, while turbulence stirs the gas and induces an outward pressure that counteracts gravity.
“The relative importance of magnetic fields versus turbulence is a matter of much debate,” said astronomer Hua-bai Li of the Harvard-Smithsonian Center for Astrophysics. “Our findings serve as the first observational constraint on this issue.”
Li and his team studied 25 dense patches, or cloud cores, each one about a light-year in size. The cores, which act as seeds from which stars form, were located within molecular clouds as much as 6,500 light-years from Earth.
The degree of polarization of light from the clouds is influenced by the direction and strength of the local magnetic fields, so the researchers measured polarization to determine magnetic field strength. The fields within each cloud core were compared to the fields in the surrounding, tenuous nebula.
The magnetic fields tended to line up in the same direction, even though the relative size scales (1 light-year-sized cores versus 1000 light-year-sized nebulas) and densities were different by orders of magnitude. Since turbulence would tend to churn the nebula and mix up magnetic field directions, their findings show that magnetic fields dominate turbulence in influencing star birth.
“Our result shows that molecular cloud cores located near each other are connected not only by gravity but also by magnetic fields,” said Li. “This shows that computer simulations modeling star formation must take strong magnetic fields into account.”
In the broader picture, this discovery aids understanding of how stars and planets form and, therefore, how the universe has come to look the way it is today.
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One of the mysteries of Earth science is hotspots. While most volcanoes are found at plate boundaries, where two tectonic plates are rubbing against each other, volcanic hotspots can be anywhere, even in the middle of continents. What causes volcanic hotspots? One theory is the idea of a mantle plume.
A mantle plume is kind of like what’s going on inside a lava lamp. As the light heats up the wax in a lava lamp, it rises up through the oil in large blobs. These blobs reach the top of the lamp, cool and then sink back down to be heated up again.
Inside the Earth, the core of the Earth is very hot, and heats up the surrounding mantle. Heat convection in the mantle slowly transports heat from the core up to the Earth’s surface. These rising columns of heat can come up anywhere, and not just at the plate boundaries. Geologists did fluid dynamic experiments to try and simulate mantle plumes, and they found they formed long thin conduits topped by a bulbous head.
When the top of a mantle plume reaches the base of the Earth’s lithosphere, it flattens out and melts a large area of basalt magma. This whole region can form a continental flood basalt, which only lasts for a few million years. Or it can maintain a continuous stream of magma to a fixed location; this is a hotspot.
As the lithosphere continues to move through plate tectonics, the hotspot appears to be shifting its position over millions of years. But really the hotspot is remaining in a fixed location, and the Earth’s plates are shifting above it.
Two of the most famous places that might have mantle plumes underneath them are the Hawaiian Islands and Iceland.
We have written many articles about volcanoes and the interior of the Earth for Universe Today. Here’s an article about the difference between magma and lava, and here’s an article about magma chambers.
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Seen from space, the Earth’s atmosphere is incredibly thin, like a slight haze around the planet. But the atmosphere has several different layers that scientists have identified; from the thick atmosphere that we breathe to the tenuous exosphere that extends out thousands of kilometers from the Earth. Let’s take a look at the different atmosphere layers.
Scientists have identified 5 distinct layers of the atmosphere, starting with the thickest near the surface, and then thinning out until it eventually merges with space.
The troposphere is the first layer above the surface of the Earth, and it contains 75% of the Earth’s atmosphere, and 99% of its water. Breathe in, that’s the troposphere. The average depth of the troposphere is about 17 km high. It gets deeper in the tropical regions, up to 20 km, and then shallower near the Earth’s poles – down to 7 km thick. Temperature and pressure are at the their highest at sea level, and then decrease with altitude. The troposphere is also where we experience weather.
The next atmosphere layer is the stratosphere, extending above the troposphere to an altitude of 51 km. Unlike the troposphere, temperature actually increases with height. Commercial airlines will typically fly in the stratosphere because it’s very stable; above weather, and allows them to optimize burning jet fuel. You might be surprised to know that bacterial life survives in the stratosphere.
Above that is the mesosphere, which starts at about 50-85 km above the Earth’s surface and extends up to an altitude of 80-90 km. Temperatures decrease the higher you go in the mesosphere, reaching a low of -100 °C, depending on the latitude and season.
Next comes the thermosphere. This region starts around 90 km above the Earth and goes up to about 320 and 380 km. The International Space Station orbits within the thermosphere. This is the region of the atmosphere where ultraviolet radiation causes ionization, and we can see auroras. Temperatures in the thermosphere can actually reach 2,500 °C; however, it wouldn’t feel warm because the atmosphere is so thin.
The 5th and final layer of the Earth’s atmosphere is the exosphere. This starts above the thermosphere and extends out for hundreds and even thousands of kilometers. Air molecules in this region can travel for hundreds of kilometers without bouncing into another particle.
An artist’s impression of Gliese 581d, an exoplanet about 20.3 light-years away from Earth, in the constellation Libra. Credit: NASA
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The holy grail in the search for extrasolar planets will be the discovery of Earthlike planets orbiting other stars. With better telescopes and techniques, astronomers will eventually be able to even detect the atmospheres of extrasolar planets and determine if there’s life there. Although Earth-sized planets are impossible to detect with current observatories, astronomers are now finding super earths.
A super Earth is a terrestrial planet orbiting a distant star. But instead of having the mass of our own planet, it might have 2, 5, or even 10 times the mass of the Earth. Although that makes them large, very massive planets, they’re not as large or massive as gas giants.
And just because they’re called super Earths doesn’t mean they’re habitable, or even Earthlike in climate at all. Super Earths could be orbiting close to their parent star, or well outside the solar system’s habitable zone.
Scientists haven’t completely settled on a definition for super Earths. Some believe a planet should be considered a super Earth if it’s a terrestrial planet between 1 and 10 Earth masses, while others think it should be between 5 and 10 Earth masses.
The first super Earth ever discovered was found in 1991 orbiting a pulsar. Obviously that wouldn’t really be a very habitable place to live. The first super earth found orbiting a main sequence star was found in 2005, orbiting the star Gliese 876. It’s estimated to have 7.5 times the mass of the Earth, and orbits its parent star every 2 days. With such a short orbital period, you can expect that it’s orbiting very close to its parent star. Temperatures on the surface of the planet reach 650 kelvin.
The first super earth found within its star’ habitable zone was Gliese 581 c. It’s estimated to have 5 Earth masses, and orbits its parent star at a distance of 0.073 astronomical units (1 AU is the average distance from the Earth to the Sun). That’s pretty close to the star, and Gliese 581 c would probably have a runaway greenhouse effect, similar to Venus. But right beside that is Gliese 581 d, with a mass of 7.7 Earths and an orbit of 0.22 AU. This planet could very well have liquid water on its surface.
The smallest super Earth discovered so far is MOA-2007-BLG-192Lb, which has only 3.3 times the mass of the Earth, and was orbiting a brown dwarf star. But this record will probably be beaten by the time you read this, as planet hunters get better. It’s only a matter of time before a true Earthlike planet is discovered.
We also recorded an episode of Astronomy Cast dealing with the different kinds of extrasolar planets you can find. Listen to it here. Episode 125: A Zoo of Extrasolar Planets.
M81. Image credit: NASA/JPL-Caltech/ESA/Harvard-Smithsonian CfA
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If you haven’t yet succumbed to the temptation of Galaxy Zoo, a new add-on to the popular citizen scientist project just might catapult you into joining the thousands of people who are clicking and classifying. Galaxy Zoo has now teamed up with Microsoft’s World Wide Telescope to allow users to immerse themselves in the universe and be able to easily create videos and sky tours that can be customized and shared with friends and family. “Now there is an easy way to inflict your favorites on others,” said Galaxy Zoo team member Dr. Pamela Gay.
The new Sky Tour tool, available here was created by two of Gay’s students at Southern Illinois University Edwardsville, sophomores Jarod Luebbert and Mark Sands.
On Galaxy Zoo, the Zooites work with isolated images of galaxies to classify them by shape and other features. Coordinating with WWT allows users to see the galaxies in their home environments on the sky. “It’s so easy to classify a few hundred — or even a few thousand galaxies and think you’ve seen a reasonable chunk in the sky,” Gay told Universe Today. “But then you start looking at them in WWT and realize each galaxy is just a pinhead of light in a vast, vast sky. Jarod and Mark’s work really gives us a since of scale and how small we all are.”
To give you a taste of how this interface works, Luebbert and Sands created a great teaser video.
(The music on the video is great! Even though the video says “Starts Tomorrow,” tomorrow has now arrived, and the Sky Tour tool is available to use.)
GZ users need to classify at least 100 galaxies before the Sky Tour tool works with their “favorites.”
Tours can be created and customized with music, pictures, and logos. Other new features include sharing directly to networking sites, and competition with other Galaxy Zoo users.
But how do college students get a chance to work on a project with Microsoft and world class astronomers?
“We knew the job opportunity had become available that they wanted two teammates who would work well together for an excellent and educational project dealing with GalaxyZoo,” Sands told Universe Today. “Jarod and I being close friends, were encouraged to apply for this position by a fellow Zoo team member, Scott Miller. After being hired, we were accepted by the rest of the team and got right to work.”
Gay and Galaxy Zoo founder Chris Lintott presented the two students with a proposal they had sent to Microsoft explaining a very detailed approach to integrating Microsoft WorldWide Telescope with GalaxyZoo.
“The synopsis was simple, and we were to merge the creation of WorldWide Telescope tours with GalaxyZoo user favorites,” Sands said, “as well as implement a WordPress (a popular blogging software) plugin for educators to create WWT tours for podcasts (a project to be released in December). With no strict direction, Pamela allowed us to go wild and be creative with our own ideas.”
The two students began formulating ideas and creating dozens of mockups. Then in July, Sands and Luebbert found themselves arriving at Microsoft Research Building 99 in Redmond, WA collaborating directly with the architects of WorldWide Telescope.
Sands said WWT architect Jonathan Fay and Peter Turcan were readily available to help with the Galaxy Zoo project and were extremely helpful, as well as Kim Rush. Yan Xu from Microsoft worked directly with Gay and Lintott on the GalaxyZoo proposal.
“It was a blast to work with them and they helped us out a lot,” said Luebbert. “Even though the original idea came from Pamela and Chris, Mark and I added our own touches as we went along.”
“Working with Microsoft was an unimaginable experience,” Sands said. “There are some fantastic people who work there and deserve just as much attention as we do. I speak for both of us when I say we had a lot of fun working with them, even if it only lasted two weeks.”
The GZ/WWT integration has received great reviews from the users. “The ability of Galaxy Zoo’s volunteers to find interesting objects never ceases to amaze me,” said Lintott. “I’m looking forward to sitting back and enjoying their tours of the Universe.”
The citizen scientists of Galaxy Zoo have classified more than 100 million classifications galaxies since its launch in July 2007. Additionally, results from users have inspired more than 15 scientific papers to date.
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The International Space Station, or ISS, is the largest object every built by humans in space. And because it’s so large, it’s also very bright; easily visible with the unaided eye. The ISS also follows an orbital track that takes over different parts of the Earth. That means if you know the right time, you can go out and watch the station pass right over. But you need to know the right time, and that requires some kind of ISS tracking tool. Let’s take a look at some ISS tracking tools you can use to tell you when you should head outside and look up.
The best place to track ISS is from NASA’s human space flight ISS tracking page. This site will tell you the current location of the International Space Station, and space shuttles currently in flight, and the Hubble Space Telescope. The problem is that this tells you where the space station is right now, and not when it’s going to be passing through your skies… at night.
A better tool for that is the ISS sightings page. You download an applet that lets you put in your place on Earth and it gives you some upcoming dates and times that the station will be passing overhead. There’s also a quick drop down box, where you can select your location from many places in the world.
Another great tool is Heavens Above. It allows you to track the current position of thousands of satellites, including ISS and the space shuttles, when they’re in orbit.
So use one of these tools for ISS tracking, and then head outside and see if you can see the station with your own eyes.
Hubble images of the Omega Centauri starfield from 2002, left, and from 2009, right.
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“This marks a new beginning for Hubble,” said Ed Weiler, associate administrator for NASA’s Science Mission Directorate at today’s press briefing at NASA Headquarters to showcase the images from Hubble following Servicing Mission 4. “The telescope was given an extreme makeover and is now significantly more powerful than ever — well equipped to last well into the next decade.”
But how much more powerful is Hubble? Are there any discernible differences between the old images from Hubble and the new ones released today? You better believe it. Above is the star field of Omega Centauri before (2002) and after (2009).
See more comparisons below.
Butterfly Nebula before and after. Credit: NASA/Hubble team. Collage by Stuart Atkinson
Here’s an earlier image of the Butterfly Nebula (NGC 6302, or the Bug Nebula) with the one released today. (Thanks to Stu Atkinson for the comparison image.)
Scientists at today’s briefing said the new instruments are more sensitive to light and therefore will significantly improve Hubble’s observing efficiency. The space telescope is now able to complete observations in a fraction of the time that was needed with earlier generations of Hubble instruments.
Stephan's Quintet from 2000 (left) and 2009 (right) Credit: NASA/ESA Hubble Team
And here’s Stephan’s Quintet from 2000 (left) and 2009 (right).
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A volcano erupts when hot magma from beneath the surface of the Earth breaks through the crust. Some of it comes out as lava, hot ash, gasses, pyroclastic flows, and even chunks of rock that rain down around the volcano. Any chunk of rock spewed out of a volcano that’s larger than 65 mm in diameter (2.5 inches) is considered to be a volcanic bomb, or lava bomb.
These volcanic bombs can be large, and they can be thrown tremendous distances away from the volcanic vent. In the 1935 eruption of Mount Asama in Japan, bombs measuring 5 meters in diameter were thrown 600 meters from the vent. And a volcano in Columbia killed 6 people near the summit with an eruption of volcanic bombs.
There are several different kinds of bombs that can occur, depending on the type of lava, and the force of the eruption:
Bread crust bombs have a cracked surface. The outer shell of the bomb cools, but the hot gasses inside are still expanding and crack the outer layer of the rock.
Core bombs is a chunk of lava that has cooled around some kind of solid core, like a piece of basalt. If you slice open the bomb, you’ll see the harder core, surrounded by porous pumice.
Cow pie bombs look like a big cow patty. They aren’t fully hardened when they hit the ground, and flatten out on impact.
Explosion bombs have a break in their side where hot gas inside the bomb blasted out.
Fusiform bombs are elongated and streamlined, forming their shape as they harden in flight
Ribbon bombs are long skinny strips of lava, thrown from the volcano, which then break when they impact the ground.
Slag bombs look like smelter slag, and have a very glassy, porous exterior.
Teardrop bombs look like rocky raindrops. They blast out of the volcano as liquid, and then solidify into a raindrop shape.
We have written many articles about volcanoes for Universe Today. Here’s an article about volcanoes for kids, and here’s an article about volcanic blocks; another type of rock that can be ejected from a volcano.
Here’s a great article that explains each of the different kinds of volcanic bombs in more detail. And here are some large volcanic bombs that landed around Mount Lassen.
The Butterfly Nebula, as see by the Hubble Space Telescope. Credit: NASA, ESA, and the Hubble SM4 ERO Team
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Hubble is back! The wait is over and here are the new Hubble telescope images from the newly refurbished space telescope. Above is an image taken by the Wide Field Camera 3 (WFC3), a new camera aboard NASA’s Hubble Space Telescope, installed by NASA astronauts in May 2009, during the servicing mission to upgrade and repair the 19-year-old Hubble telescope. This is a planetary nebula, catalogued as NGC 6302, but more popularly called the Bug Nebula or the Butterfly Nebula.
NGC 6302 lies within our Milky Way galaxy, roughly 3,800 light-years away in the constellation Scorpius. The glowing gas is the star’s outer layers, expelled over about 2,200 years. The “butterfly” stretches for more than two light-years, which is about half the distance from the Sun to the nearest star, Alpha Centauri.
And there’s more!
Omega Centauri. Credits: NASA, ESA and the Hubble SM4 ERO Team
This one is absolutely awesome! This zoom into the globular star cluster Omega Centauri converges onto the Hubble Wide Field Camera 3’s panoramic view of 100,000 stars lying in the center of the cluster. The stars vary in age and change color as they get older. Most of them are middle-aged, yellowish stars like our Sun. But as they near the end of their lives, they balloon into red giants, and later still, into hot, blue stars.
Stephan's Quintet. Credit: NASA, ESA, and the Hubble SM4 ERO Team
This portrait of Stephan’s Quintet, also known as Hickson Compact Group 92, was taken by the new Wide Field Camera 3 (WFC3) aboard NASA’s Hubble Space Telescope. Stephan’s Quintet, as the name implies, is a group of five galaxies. The name, however, is a bit of a misnomer. Studies have shown that group member NGC 7320, at upper left, is actually a foreground galaxy about seven times closer to Earth than the rest of the group.
Three of the galaxies have distorted shapes, elongated spiral arms, and long, gaseous tidal tails containing myriad star clusters, proof of their close encounters. These interactions have sparked a frenzy of star birth in the central pair of galaxies. This drama is being played out against a rich backdrop of faraway galaxies.
The image, taken in visible and infrared light, showcases WFC3’s broad wavelength range.
Eta Carinae from Hubble's STIS instrument. Credit: NASA, ESA, and the Hubble SM4 ERO Team
Observations by the newly repaired Space Telescope Imaging Spectrograph (STIS) on Hubble reveals the signature balloon-shaped clouds of gas blown from a pair of massive stars called Eta Carinae. This new observation shows some of the chemical elements that were ejected in the eruption seen in the middle of the 19th century.
STIS analyzed the chemical information along a narrow section of one of the giant lobes of gas. In the resulting spectrum, iron and nitrogen define the outer boundary of the massive wind, a stream of charged particles, from Eta Car A, the primary star. The amount of mass being carried away by the wind is the equivalent one sun every thousand years. While this “mass loss” may not sound very large, in fact it is an enormous rate among stars of all types. A very faint structure, seen in argon, is evidence of an interaction between winds from Eta Car A and those of Eta Car B, the hotter, less massive, secondary star.
Eta Car A is one of the most massive and most visible stars in the sky. Because of the star’s extremely high mass, it is unstable and uses its fuel very quickly, compared to other stars. Such massive stars also have a short lifetime, and we expect that Eta Carinae will explode within a million years.
Hubble Early Release Observation of Barred Spiral NGC 6217. Credit: NASA, ESA, and the Hubble SM4 ERO Team
This image of barred spiral galaxy NGC 6217 is the first image of a celestial object taken with the newly repaired Advanced Camera for Surveys (ACS) aboard the Hubble Space Telescope. The camera was restored to operation during the STS-125 servicing mission in May to upgrade Hubble. The barred spiral galaxy NGC 6217 was photographed on June 13 and July 8, 2009, as part of the initial testing and calibration of Hubble’s ACS. The galaxy lies 6 million light-years away in the north circumpolar constellation Ursa Major. The blue haze at the edges are baby stars being born.
About Hubble’s repair, NASA’s Ed Weiler said, “The astronauts basically did a total repair job on Hubble, and fixed two instruments that haven’t been working for a long time. It’s not an 19 year old telescope, it’s a new telescope again.”
NASA admisinatrator Charlie Bolden, who participated in an earlier Hubble repair mission, said at the press conference unveiling the new images that “after almost twenty years of service we are so proud and honored to part of the Hubble story. The telescope is now equipped to last well into the next decade. Hubble is one of the most accomplished scientific instruments ever, and it has captured the imagination of people everywhere.”
And here’s one more: a full view of Jupiter with the impact scar visible. Jupiter from the newly refurbished Hubble. Credit: NASA, ESA, M. Wong (Space Telescope Science Institute, Baltimore, Md.), H. B. Hammel (Space Science Institute, Boulder, Colo.), and the Jupiter Impact Team
The ISS and Discovery on Sept. 1, 2009. Credit: Paolo Beltrame
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Paolo Beltrame from Italy sent us this amazing montage of images he took of space shuttle Discovery docked to the ISS on September 1, 2009. See the incredible details visible of the space station and docked shuttle! Paolo is with the Circolo AStrofili Talmassons (Amateur Astronomers Club in Talmassons, or CAST) who have an impressive observatory (take a look at Paolo’s website). He took these selected images from a 2-minute movie taken with a TourcamPro webcam. As impressive as Paolo’s astrophotos are, however, he says his real passion is viewing the night sky with the naked eye. His motto is “Lasciate che i fotoni vengano a me!” (Let the photons come to me!) See a close up of Paolo’s best shot of the ISS/shuttle below, as well as images from other astrophotographers of Tuesday evening’s pass of the shuttle and ISS as they flew in tandem after Discovery undocked from the station on Tuesday afternoon. There’s also video from the shuttle’s flyaround.
The ISS and shuttle on Sept. 1, 2009 at 3:03 UT. Credit: Paolo Beltrame
Below is Kevin Jung’s image of the ISS and shuttle as they flew in tandem over Grand Rapids, Michigan: Formation Flyover. Credit: Kevin Jung
Kevin made it home just in time to take this image, and he said the pair of spacecraft went just below Lyra, and you can make out some of the other things in the field, as well. Click the image to see more of Kevin’s handiwork.
And here’s my feeble attempt to image the tandem flyover from my yard in Illinois: ISS, shuttle and a star. Credit: N. Atkinson
Can anyone guess what the star in the picture might be?
Finally, enjoy some video of the shuttle’s fly-around of the ISS following undocking. This video just shows the the shuttle due to the lack of Ku band downlink availability. Video of the station from the orbiter was not available, but we’ll post it here later if it becomes available.
