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Students at London college identify new supernova in neighboring galaxy

January 24, 2014 Leave a comment

Students in London discovered a previously unobserved supernova in one of the Milky Way’s neighboring galaxies this week and it is bright enough to be seen through a small telescope.

The supernova is located in galaxy Messier 82 and is about 12 million light years away from Earth.

Supernovae are exploding stars caused either by a collapse of the star’s core or a resumpion in nuclear fusion there. They often emit so much light and radiation that they are more visible than the galaxy in which they occur.

Some supernovae are so potent that they discharge more energy during the period in which they are visible than our sun will produce in its entire history.

The show does not last forever, though. Supernovae, once the energy visible in the aftermath of the explosion begins to dissipate, become remnants.

The M82 supernova was an accidental find.

Undergraduates in a workshop aimed at learning how to operate the CCD camera on an 0.35-meter telescope. They aimed the telescope at M82 because it is well known as a visually interesting target for night-sky watching.

Their teacher, Steve Fossey, saw something that he did not recognize from prior observations. Not being sure what it was, Fossey compared the image he took with the onboard camera to a digital archive.

Because clouds were rolling in, the group did not have much time to continue observations of the new phenomenon. So they obtained a number of long exposure images through a variety of filters, which would be helpful in determining the object’s brightness. They also imaged the object with a second telescope so that any flaw with the automated controls or other instrumentation on the first telescope could be ruled out as a cause of the “star” they had seen.

Fossey then alerted astronomers around the world, including the International Astronomical Union’s Central Bureau for Astronomical Telegrams. The CBAT catalogues supernovae.

The M82 supernova, now known as SN2014J, is the closest supernova discovered since 1987, when Supernova 1987A was identified. That supernova is about 168,000 light years away.

SN1993J, another supernova that is about the same distance away as SN2014J, was discovered in 1993.

The team of students who first saw it were surprised by their find.

“One minute we’re eating pizza, then five minutes later we’ve helped to discover a supernova,” one of them, Tom Wright, said.

Messier 82 is formally identified as NGC3034 and popularly known as the “Cigar Galaxy.” It is five times more luminous than the Milky Way galaxy.

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This mosaic image of M82 was obtained by the Hubble Space Telescope. Image courtesy Wikimedia.

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These two images show the Messier 82 galaxy on, respectively, Dec. 10, 2013 and Jan. 21, 2014. Notice the bright light in the lower image. Images courtesy University College of London/University of London Observatory,. Photography by Steve Fossey, Ben Cooke, Guy Pollack, Matthew Wilde, and Thomas Wright.

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This image shows a Celestron C35 telescope used by students at University College of London and University of London Observatory to discover supernova SN2014J. Image courtesy University College of London. Photograph by O. Usher.

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Rosetta wakes up, exploration of comet coming soon

January 22, 2014 Leave a comment

Nearly three years of quiet from a probe speeding toward a rendezvous with a distant comet ended Monday as engineers in Germany successfully reactivated the Rosetta spacecraft.

The solar-powered probe is designed to be the first to land on a comet. If all goes as planned, Rosetta will accomplish that feat in November of this year when an onboard lander alights on the head of comet 67P/Churyumov-Gerasimenko.

Rosetta will also follow the comet around the sun, another first for human space exploration.

The probe’s reactivation came at 18:18 Greenwich Mean Time (11:18 MST). The Twitter account set up for Rosetta announced it a few minutes later with a cheery “Hello, World!”

Rosetta was launched on March 2, 2004. During the 118 months that have since elapsed it has flown by the Earth three times and once around Mars. The probe was placed into hibernation at the command of engineers in Europe on June 8, 2011.

During the hibernation only the computers onboard and heaters necessary to prevent the spacecraft from freezing were functional. All other instrumentation, including that necessary to study the comet, was shut down.

The deactivation of Rosetta was necessary because the probe would travel too far from the Sun to obtain the solar energy needed to power its systems.

Reactivation occurred when a timer programmed into the spacecraft’s computer system reached the previously specified time of the event. Rosetta’s star trackers were the first instruments to come back online. Then the probe’s computer system slowed the spacecraft’s spin and oriented it toward Earth in order to transmit a signal.

“This was one alarm clock not to hit snooze on, and after a tense day we are absolutely delighted to have our spacecraft awake and back online,” Fred Jansen, the European Space Agency’s manager for the mission, said in a statement.

Now about nine million kilometers from comet 67P/Churyumov-Gerasimenko, Rosetta will enter an orbit around the comet in May.

In November, after Rosetta has had time to slow down enough time to synchronize its velocity with the comet, a smaller craft called Philae will land on it.

Philae, which has a mass of about 100 kilograms, is much smaller than the nucleus of the comet.

“The comet itself, it’s about four kilometers across,” Michael R. Combi, a professor in the University of Michigan’s Department of Atmospheric, Oceanic, and Space Sciences and a member of the Rosetta scientific research team, said. “The lander is very small. I don’t think it’s two feet across.”

Philae will contend with landing on a surface that exhibits very little gravity. Unlike Earth, where there is enough gravity to hold soil and rock in place, the environment on a small comet like 67P/Churymov-Gerasimenko does not have enough to hold all solid material in place.

“It’s fairly fluffy,” Combi said. “There’s almost no gravity at the surface of an object that small.”

The comet has about 1,000 times less gravity than does Earth.

The lander will study 67P/Churyumov-Gerasimenko’s nucleus, and determine the chemical composition of the materials found there, while being secured to the comet’s nucleus by two harpoons.

“We want to measure all we can, how much material is coming off the comet as it goes around the sun,” Combi said.    

He explained that ice is the dominant material on a comet’s nucleus, and that it sublimates, or changes phase from a solid to a gas, as the comet heats up on approach to the sun. One of the mission’s goals is to understand the mechanics of this sublimation process.

Rosetta also aims to help scientists gain a better understanding of the specific chemical makeup of comets.

“Practically all seem to be dominated by water ice,” Combi said. “Then there’s this rocky, dusty material and some organic material. There’s a whole host of other volatiles – carbon dioxide, carbon monoxide, methanol. Most comets seem to have those materials in them, but the ratios do vary.”

 One unique feature of the mission will be to allow the measurement of carbon dioxide in the nucleus, a task that is not possible from Earth.

 “It’s very difficult to observe some of the chemical species when they’re far away and faint,” Combi said in a statement. “Carbon dioxide is probably the second most abundant species at most comets, but it’s not been observed in the thousands we’ve looked at from Earth.”

 Another priority will be to study the solar wind, which can produce solar storms.

 Composed of a stream of charged particles, the solar wind exhibits different velocities at different locations on the sun. Since Earth’s orbit takes it closest to the equator of the sun, it is difficult for scientists to study the dynamics of the solar wind at higher solar latitudes.

 “But comets pass through all of it. With their help, we can study the fast solar wind,” Tomas Gombosi, a professor of engineering in UM’s Department of Atmospheric, Oceanic, and Space Sciences and another researcher on the Rosetta team, said in a statement.

 Of course, as relics from the earliest days of the solar system, Rosetta should also provide significant insights about the distant past of our stellar neighborhood.

“Comets, more than most other objects in the solar system, preserve information about the solar system when it was formed,” Gombi explained.

The Rosetta mission was designed to replace a similar undertaking conceived by NASA called the Comet Rendezvous Asteroid Flyby during the 1980s. That proposed mission would have involved flying a probe alongside a comet for three years. It was cancelled in 1992 as a result of budget constraints facing the American space agency at that time.

The Rosetta mission will end in 2015 after completing the orbit of the sun alongside comet 67P/Churyumov-Gerasimenko.

The Rosetta spacecraft will come closest to the sun on Aug. 13, 2015, when it and the comet are about 185 million kilometers away from our star.

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Artist’s conception of orbiter Rosetta and lander Philae at comet 67P/Churyumov-Gerasimenko courtesy European Space Agency.

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Graphic showing dust composition of cometary nucleus courtesy University of Michigan; graphic by Valeriy Tenishev.

NOTE: This article also appears at Examiner.com.

NASA Image of the Day, Jan. 4, 2013

January 4, 2014 Leave a comment

NASA Image of the Day, Jan. 4, 2013

This mosaic image was taken on Jan. 4, 2004, by the navigation camera on the Mars Exploration Rover Spirit. It shows a 360-degree panoramic view of the rover on the surface of the Red Planet. Spirit operated for more than six years after landing in January 2004, driving 7.73 kilometers (4.8 miles), more than twelve times the goal set by mission planners.

Spirit was the first robot to reach the peak of a hill on another planet. Even after the machine’s right front wheel failed in 2006, Spirit explored another half-mile of Mars’ surface.

Spirit transmitted to Earth more than 124,000 images, ground material from the surface of 15 rocks, and prepared 92 other surfaces for inspection with spectrometers and a microscopic imager.

Spirit’s sister rover, Opportunity, is still active on the surface of Mars. You can see highlights of the Mars Exploration Rovers’ mission at http://mars.nasa.gov/mer10/.

Image courtesy NASA, Jet Propulsion Laboratory.

Happy Perihelion Day

January 4, 2014 Leave a comment

Winter started in the northern hemisphere, and summer began on the southern half of the planet, more than two weeks ago, but today marks Earth’s closest approach to the Sun during 2014.

Our planet reached the perihelion of its orbit at 12:00 UST (5:00 am MST). At that time the center of Earth was 147,104,780 kilometers away from the center of the Sun.

Earth does not orbit the Sun in a circle; instead, the planet follows an elliptical orbit. That means we are at times closer to the Sun and at times farther from the Sun.

The point at which we are the farthest from the Sun during the year is called aphelion.

The two benchmarks of Earth’s orbit do not fall on the same day each year. In fact, perihelion aligned with the winter solstice in the northern hemisphere back in 1246 AD. The two events will not again occur on the same day for a very long time. In fact, in the year 6000 AD perihelion will occur on the same day as the northern hemisphere’s spring equinox. Perihelion occurred on the summer solstice about 11,000 years ago.

By the way, seasons on Earth have very little to do with the planet’s distance from its star. We experience winter, spring, summer, and autumn primarily because Earth is tilted on its axis.

Aphelion comes in early July, when Earth will be about three percent farther from the Sun than it is today.

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Graphic courtesy National Atmospheric & Oceanic Administration

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The Sun at Earth’s perihelion on Jan. 2, 2013; Solar Dynamics Observatory image courtesy NASA.

First month of 2014 features two new moons

January 1, 2014 1 comment

The new year will be graced quickly by two new moons, as January will see them occur on New Years Day and again on Jan. 30.

It will be four more years before two new moons in one month will be seen again, as that situation will not recur until January of 2018.

Both of the new moons occurring this month are so-called “super moons,” so named because Luna is at or very near the closest point to Earth that it ever reaches in its orbit.

This post at Skywatch includes an image of the New Years Day new moon provided by the U.S. Naval Observatory.

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