Astronomy Archives

April 6, 2009December 24, 2015 by Anne Minard

New Image Reveals M33 is Bigger Than Thought (and it’s Headed Our Way)

The Triangulum Galaxy. Image credit: NASA/JPL-Caltech/University of Arizona

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NASA’s Spitzer Space Telescope has captured this new image of M33, also known as the Triangulum Galaxy, and released it as part of the “Around the World in 80 Telescopes” event for the International Year of Astronomy.

Besides the pretty colors, the new image reveals something else about M33: it’s more than meets the eye.

M33 is located about 2.9 million light-years away in the constellation Triangulum. It is a member of what’s known as our Local Group of galaxies. Along with our own Milky Way and Andromeda, the group of about 50 galaxies travels together in the universe, bound to one another by gravity. In fact, M33 is one of the few galaxies that is moving toward the Milky Way despite the fact that space is expanding, causing most galaxies in the universe to grow farther and farther apart.

The new image reveals M33 to be surprising large – bigger than its visible-light appearance would suggest. With its ability to detect cold, dark dust, Spitzer can see emission from cooler material well beyond the visible range of M33’s disk. Exactly how this cold material moved outward from the galaxy is still a mystery, but winds from giant stars or supernovas may be responsible.

The image is a three-color composite showing infrared observations from two of Spitzer instruments. Stars appear as glistening blue gems (several of which are actually foreground stars in our own galaxy), while dust rich in organic molecules glows green. The diffuse orange-red glowing areas indicate star-forming regions, while small red flecks outside the spiral disk of M33 are probably distant background galaxies.

As for the technical details, the blue parts of the image represents combined 3.6- and 4.5-micron light, and green shows light of 8 microns, both captured by Spitzer’s infrared array camera. Red is 24-micron light detected by Spitzer’s multiband imaging photometer.

Source: NASA’s Spitzer site

April 4, 2009March 24, 2012 by Fraser Cain

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April 3, 2009December 24, 2015 by Anne Minard

Humble Little Pulsar Puts on a Big Show

This is a quiz.

This X-ray nebula pictured above measures 150 light-years across. At its center is a very young and powerful pulsar known as PSR B1509-58, or B1509 for short.

How big is the pulsar?

B1509 is only 12 miles (19 km) across!

The small, dense pulsar is a rapidly spinning neutron star which is spewing energy out into the space around it to create complex and intriguing structures, including one that resembles a large cosmic hand. In this image, the lowest energy X-rays that Chandra detects are red, the medium range is green, and the most energetic ones are colored blue. Astronomers think B1509 is about 1,700 years old, and located about 17,000 light years away.

Neutron stars are created when massive stars run out of fuel and collapse. B1509 is spinning completely around almost seven times a second and is releasing energy into its environment at a prodigious rate — presumably because it has an intense magnetic field at its surface, estimated to be 15 trillion times stronger than the Earth’s magnetic field.

The combination of rapid rotation and ultra-strong magnetic field makes B1509 one of the most powerful electromagnetic generators in the Galaxy, pushing an energetic wind of electrons and ions away from the neutron star. As the electrons move through the magnetized nebula, they radiate away their energy and create the elaborate nebula seen by Chandra.

In the innermost regions, a faint circle surrounds the pulsar, and marks the spot where the wind is rapidly decelerated by the slowly expanding nebula. In this way, B1509 shares some striking similarities to the famous Crab Nebula. However B1509’s nebula is 15 times wider than the Crab’s diameter of 10 light years.

Finger-like structures extend to the north, apparently energizing knots of material in a neighboring gas cloud known as RCW 89. The transfer of energy from the wind to these knots makes them glow brightly in X-rays (orange and red features to the upper right). The temperature in this region appears to vary in a circular pattern around this ring of emission, suggesting that the pulsar may be precessing like a spinning top and sweeping an energizing beam around the gas in RCW 89.

The image was released today as part of the ongoing “100 Hours of Astronomy” celebration, which is just one of many global activities as part of the International Year of Astronomy 2009.

Video, additional images and other information on this result can be found at the Chandra sites run by Harvard and NASA.

April 3, 2009December 24, 2015 by Anne Minard

And the Winner Is …

Earlier this week, the Hubble Space Telescope photographed the winning target in the Space Telescope Science Institute’s “You Decide” competition in celebration of the International Year of Astronomy.

The winning object, above, received 67,021 votes out of the nearly 140,000 votes cast for the six candidate targets.

Arp 274, also known as NGC 5679, is a system of three galaxies that appear to be partially overlapping in the image, although they may be at somewhat different distances. The spiral shapes of two of these galaxies appear mostly intact. The third galaxy (to the far left) is more compact, but shows evidence of star formation.

Two of the three galaxies are forming new stars at a high rate. This is evident in the bright blue knots of star formation that are strung along the arms of the galaxy on the right and along the small galaxy on the left.

The largest component is located in the middle of the three. It appears as a spiral galaxy, which may be barred. The entire system resides at about 400 million light-years away from Earth in the constellation Virgo.

Hubble’s Wide Field Planetary Camera 2 was used to image Arp 274. Blue, visible, and infrared filters were combined with a filter that isolates hydrogen emission. The colors in this image reflect the intrinsic color of the different stellar populations that make up the galaxies. Yellowish older stars can be seen in the central bulge of each galaxy. A bright central cluster of stars pinpoint each nucleus. Younger blue stars trace the spiral arms, along with pinkish nebulae that are illuminated by new star formation. Interstellar dust is silhouetted against the starry population. A pair of foreground stars inside our own Milky Way are at far right.

The International Year of Astronomy is the celebration of the 400th anniversary of Galileo’s first observations with a telescope. The ongoing “100 Hours of Astronomy,” April 2 to 5, is part of the fun, geared toward encouraging as many people as possible to experience the night sky.

Image credit: NASA, ESA, and M. Livio and the Hubble Heritage Team (STScI/AURA)

For images, videos, and more information about Arp 274, visit the Hubble site, the Hubble Heritage Project , NASA’s Hubble site or 100 Hours of Astronomy.

April 2, 2009December 24, 2015 by Anne Minard

Titan (Weirdness) is More Than Meets The Eye

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Think Titan looks pretty round?

Not quite, according to new data released today by the Cassini radar team — and slight irregularities in the shape of the bizarre moon may account for the concentration of lakes at the highest latitudes, among other perplexing features.

The radar image above, obtained by Cassini’s radar instrument during a near-polar flyby in 2007, shows a big island smack in the middle of one of the larger lakes imaged on Saturn’s moon Titan. The island is about 90 kilometers (62 miles) by 150 kilometers (93 miles) across, about the size of Kodiak Island in Alaska or the Big Island of Hawaii. The image is centered at about 79 north degrees north (north is left) and 310 degrees west, adding weight to the theory that most of Titan’s lakes occur near the poles.

Titan is an intriguing object partly because its climate cycles are reminiscent of Earth’s, but tend to rely on hydrocarbons like methane and ethane instead of water — which couldn’t exist in a liquid state at temperatures hundreds of degrees below zero. Methane and ethane fill the air with a smoggy haze that rains down as ash. Sometimes it’s washed away by hydrocarbons that flow like gasoline and collect in black lakes with surfaces as smooth as glass.

Cassini has been orbiting Saturn for four years, observing Titan periodically with multiple radar instruments. A research team led by Howard Zebker, a geophysicist at Stanford University, has been using the radar data to estimate the surface elevation. Combined, two instruments — a nadir-pointing radar altimeter and a multiple-beam synthetic aperture radar (SAR) imaging system — measure the time delay of the altimeter echoes and the precise radar beam angles to points on the surface.

“These techniques show that the poles of Titan lie at lower elevations than the equator, and that the topography also varies longitudinally,” the authors report in today’s Science Express..

“If we posit that the lakes are surface expressions of a more or less continuous liquid organic ‘water table,’ then the lower elevations of the poles could lead to the observed preponderance of lakes at high latitudes,” they add. In other words, the lower elevations of poles may make them the only places where any continuous, liquid “water table” would be close enough to the moon’s surface to appear as lakes.

Titan’s overall shape, they suggest, might be that a sphere slightly flattened at the top and bottom. The exact mechanisms behind the oblate shape are unclear. Titan is also elongated toward Saturn, due to the tides raised by Saturn’s gravity.

Source: The paper appears online at the S cience Express website. More Titan images are available at the Cassini website.

April 2, 2009December 24, 2015 by Anne Minard

New View of Young, High-Mass Binary Star at Heart of Orion

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A new glimpse inside the heart of Orion has confirmed the separation between the binary star system that orbit each other so closely, astronomers once believed they could be a single star.

The research team, led by Stefan Kraus and Gerd Weigelt from the Max-Planck-Institute for Radio Astronomy (MPIfR) in Bonn, Germany, used ESO’s Very Large telescope Interferometer (VLTI) to obtain the sharpest ever image of the young double star Theta 1 Ori C in the Orion Trapezium Cluster.

The binary stars represent the most massive star in the nearest high-mass star-forming region to Earth.

Theta 1 Ori C is the dominant and most luminous star in the Orion star nursery. Located at a distance of only about 1,300 light years, it provides a unique laboratory to study the formation process of high-mass stars in detail. The intense radiation of Theta 1 Ori C is ionizing the whole Orion nebula. With its strong wind, the star pair also shapes the famous Orion proplyds, young stars still surrounded by their protoplanetary dust disks.

Although Theta 1 Ori C appeared to be a single star, both with conventional telescopes and the Hubble Space Telescope, the team discovered the existence of a close companion.

“VLTI interferometry with the AMBER instrument allowed us, for the first time, to obtain an image of this system with the spectacular angular resolution of only 2 milliarcseconds”, says Stefan Kraus. “This corresponds to the resolving power of a space telescope with a mirror diameter of 130 meters.”

The new image clearly separates the two young, massive stars of this system. The observations have a spatial resolution of about 2 milliarcseconds, corresponding to the apparent size of a car on the surface of the Moon.

The VLTI image reveals that in March 2008 the angular distance between the two stars was only about 20 milliarcseconds. Additional position measurements of the binary system have been obtained over the last 12 years using the technique of bispectrum speckle interferometry with 3.6- to 6-meter-class telescopes, allowing high-angular resolution observations even at visual wavelengths down to 440 nm.

The collection of measurements shows that the two massive stars are on a very eccentric orbit with a period of 11 years. Using Kepler’s third law, the masses of the two stars were derived to be 38 and 9 solar masses. Furthermore, the measurements allow a trigonometric determination of the distance to Theta 1 Ori C and, thus, to the very center of the Orion star-forming region.

The resulting distance of 1,350 light-years is in excellent agreement with the work of another research group led by Karl Menten, also from MPIfR, who measured trigonometric parallaxes of the nonthermal radio emission of Orion Nebula stars using the Very Long Baseline Array. These results are important for studies of the Orion region as well as the improvement of theoretical models of high-mass star formation.

The researchers say the results highlight new possibilities of high-resolution stellar imaging achievable with infrared interferometry. The technique allows astronomers to combine the light from several telescopes, forming a huge virtual telescope with a resolving power corresponding to that of a single telescope with 200 meters diameter.

“Our observations demonstrate the fascinating new imaging capabilities of the VLTI,” said Gerd Weigelt. “This infrared interferometry technique will certainly lead to many fundamental new discoveries.”

LEAD IMAGE CAPTION: VLTI/AMBER image of Theta 1 Ori C in the Orion Trapezium Cluster, plus position measurements of the binary system obtained over the last 12 years. Credit: Max Planck Institute/VLTI/AMBER

Sources: Max Planck Institute press release (emailed through Eurekalert), and the original paper.

April 1, 2009December 24, 2015 by Anne Minard

New Study: Some Massive Galaxies Were Practically Born That Way

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New research is casting doubt on the prevailing view that the heaviest galaxies in the universe started out small and gained mass by devouring other matter that ventured too close.

Peering at galaxies two-thirds of the way back in time to the Big Bang, an international team of astronomers is suggesting that some of the giants we see today were just as massive in that earlier age as they are now.

The new findings were released today in the journal Nature.

Lead author Chris Collins, an astronomer at the United Kindgdom’s Liverpool John Moores University, and his colleagues made their discovery using one of the largest optical telescopes in the World, called Subaru (named after the Japanese word for the Pleiades star cluster), located on the Island of Hawaii and owned by the National Observatory of Japan.

They focused on brightest cluster galaxies (BCGs), located at the centers of galaxy clusters. The massive galaxies constitute a separate population from bright elliptical galaxies, and both their predictability and extreme luminosity have motivated their use as standard candles for cosmology, the authors point out.

Analysing the light from these remote galaxies, the astronomers effectively weighed them and found that despite feeding on a constant diet of small galaxies, the heaviest galaxies have not increased their weight over the last 9 billion years. In a universe whose age is 13.7 billion years old, these results spark a debate as to how these galaxies put on so much weight in the first few billion years after the Big Bang.

“Current predictions using simulations run on super computers suggest that at such a young age these galaxies should be only 20 percent of their final weight, so to find galaxies so large suggests that galaxy formation is a much more rapid process than we previously thought,” Collins said, “and perhaps the theories are missing some important physics.”

John Stott, Collin’s colleague at LJMU and a co-author on the paper, said the team was “surprised to find that the largest and brightest galaxies in the Universe have remained essentially unchanged for the last 9 billion years, having grown rapidly soon after the Big Bang.”

One possibility being considered is that the galaxies formed by the collapse of an already massive cloud at the dawn of the universe.

MORE ABOUT LEAD IMAGE: The image shows the central 1.5 x 1.5 arc min of the cluster corresponding to 0.75 Mpc at this distance. The clusters X-ray emission is used to pinpoint the location of the brightest galaxy in the cluster as shown by the green contours which represent the X-ray intensity as measured by the XMM-Newton X-ray satellite.

Source: LJMU’s Astrophysics Research Institute

March 31, 2009April 26, 2016 by Anne Minard

New Bill Would Extend Shuttle Life, but NASA Doesn’t Need the Time

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The Senate Budget Committee has given the green light to fund NASA’s shuttle program past the end of 2010, when the program is set to retire.

But NASA isn’t asking for an extension.

Florida Sen. Bill Nelson requested the $2.5 billion provision, which was included in the broader five-year spending plan that passed committee Monday afternoon. His office argues that launching nine missions in 18 months puts too much pressure on the agency, and could compromise safety.

NASA is preparing to launch the shuttle Atlantis on May 12 for a servicing mission of the Hubble Space Telescope, and the eight remaining missions are dedicated to completing the International Space Station.

“We are confident that we can fly out the shuttle manifest before the end of 2010,” said John Yembrick, a spokesman out of NASA’s Washington headquarters.

Nelson’s office isn’t as optimistic.

“Given that there are roughly only 18 months but nine flights left, we have a concern that may be unrealistic,” said Dan McLaughlin, a spokesman for Nelson’s office. He cited the Challenger and Columbia accidents, where “the investigation board in both cases identified scheduling pressure as a contributing factor to those accidents.”

orion — Artist's rendering of the next-generation Orion crew exploration vehicle docked to a lunar lander in lunar orbit. (Obsolete configuration.) Credit: Lockheed Martin Corp.

In the past, NASA has been “overly optimistic about schedules for shuttle missions,” McLaughlin said. But in reality, the agency has gotten four or five launches off the ground in each of the past several years. “It doesn’t take but a bad hurricane season and the best laid plans can fall apart. Could NASA do it? Yeah. But a lot of things would have to go right.”

The $2.5 billion provision, if it passes the full Senate and House, would alleviate the pressure, Nelson thinks, by opening up the possibility for additional funding in 2011 — and allow NASA to proceed with safety as a first concern. The measure would soften a firm line both the Bush and Obama administrations have taken on retiring the program by the end of 2010.

The Budget Committee’s decision sends a strong signal that the shuttle shouldn’t be retired on a date-certain, but only when all the missions are completed, Nelson reportedly said immediately after the Thursday vote.

ares-collage1 — Concept of Ares I, left, the crew launch vehicle and Ares V, the cargo launch vehicle. Credit: NASA/Marshall Space Flight Center

Meanwhile, NASA is looking forward to the next generation of launch vehicles, Orion (above, concept credit Lockheed Martin Corp.) and the Ares series. The vehicles are designed to return people to the moon — and perhaps even Mars — to live and explore. The first Ares test flight is planned for later this year.

The gap between the planned shuttle retirement in 2010, and the availability of the next generation launch vehicles, will be five years. During that time the United States is likely to partner with Russia to use Soyuz launch vehicles for low-orbit work and as the space station’s docked emergency vehicle — which is part of the astronauts’ escape plan in the event of debris hits or other dangers aboard the ISS.

It is also possible that commercial vehicles could rise to the challenge before 2015, NASA’s Yembrick said. NASA has awarded two contracts to companies that will deliver cargo to the space station after the retirement of the space shuttle: Orbital Sciences Corp. of Dulles, Virginia, and Space Exploration Technologies (SpaceX) of Hawthorne, California.

“Once they’ve proven that they can successfully deliver cargo, we also may one day look at purchasing crew services,” Yembrick said. “We don’t want to speculate when that may occur.”

Sources: Spaceref, interviews with Dan McLaughlin and John Yembrick.

March 26, 2009December 24, 2015 by Anne Minard

New Views of Spring on Mars

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New high-resolution images taken last month of Mars’ south polar region are revealing signs of spring that are decidedly Martian.

The image above features a spider trough network left behind as seasonal dry ice caps have sublimated away in the warmer temperatures. It’s part of a new series of images released this week by the University of Arizona’s High Resolution Imaging Experiment, or HiRISE, aboard NASA’s Mars Reconnaissance Orbiter.

See more information and photos below.

The gas beneath the ice cap can flow in the same places year after year, eroding troughs in the surface of the planet.

“What happens on Mars, we think, is that as the seasonal ice cap thins from the bottom, gas underneath the cap builds up pressure,” said HiRISE deputy principal investigator Candice J. Hansen-Koharcheck of the NASA Jet Propulsion Laboratory in Pasadena, California.

“And where gas under the ice finds a weak spot or a crack, it will flow out of the opening, often carrying a little dust from the surface below.”

The next HiRISE image shows how dust that has been carried to the surface by gas jetting through the ice cap is blown about by prevailing winds before settling in fan-shaped deposits atop the ice cap. Varying orientations suggest that as the ice layer thins, a set of gas jets becomes active, they die down, then further away another set starts up at a later time with a different prevailing wind direction.

co2-jets — NASA/JPL/University of Arizona

Many jets appear to be active at the same time since numerous fans are all deposited in the same direction: this next, closer image is an example of such an occurrence.

co2-jets-closeup — Credit: NASA/JPL/University of Arizona

This southern hemisphere crater has gullies on its north and northeast walls. Gullies are proposed to be carved by liquid water originating from the subsurface or melting ice/snow on the surface.

Dark dunes are visible on the crater floor. Lighter, smaller dunes rim the south side of the crater floor. The entire scene, pictured below, has a pitted texture, suggesting that ground ice was once present in this region. When ground ice sublimates (goes from a solid directly to a gas), it leaves behind empty spaces in the soil that turn into pits as the remaining overlying soil collapses to fill them.

The full set of new HiRISE Mars images is here. Check out all the downloadable formats and sizes, with some even designed to fit an iPhone screen!

Source: Lori Stiles, at the University of Arizona

March 25, 2009December 24, 2015 by Fraser Cain

What is Lava?

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As you probably know, lava is the molten rock that comes out of volcanoes during eruptions. But what is it? What is lava, and how does it get so hot?

You’re standing on the Earth’s crust right now. But beneath your feet, the interior of the Earth gets must hotter. About 30 km beneath the Earth’s crust is the mantle; a vast region of hot rock that can be thousands of degrees. Although the mantle is mostly solid, it can form pockets of liquid rock called magma. This lava is much less dense than the surrounding rock, and so it “floats” up to the surface of the Earth through cracks and weaknesses in the Earth’s crust.

When it finally reaches the Earth’s surface and escapes, geologists call this hot rock magma. It’s still the same stuff, it’s just at the surface of the Earth now. Different kinds of lava will flow at different speeds when they erupt from a volcano. The least thick can flow in great rivers of molten rock for many kilometers. The thicker lava doesn’t flow very far at all, piling up around the volcanic vent, and creating the familiar cone shaped volcano. The thickest stuff doesn’t really flow at all, it just plugs up the volcano’s plumbing, and can lead to powerful explosions.

Lava can range in temperature from about 750 degrees C to more than 1100 C. The temperature of the lava actually depends on the composition of the minerals in it. Some contain large amounts of aluminum, potassium and calcium, while others have iron and magnesium.

We have written many articles about volcanoes for Universe Today. Here’s an article about how a volcano triggered a lightning storm, and here’s an article about the temperature of lava.

Want more resources on the Earth? Here’s a link to NASA’s Human Spaceflight page, and here’s NASA’s Visible Earth.

We have also recorded an episode of Astronomy Cast about Earth, as part of our tour through the Solar System – Episode 51: Earth.