Universe Today

April 8, 2009December 24, 2015 by Fraser Cain

Lava Flow

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When you think of volcanoes, you immediately think of lava flows. These are the familiar rivers of lava pouring down the sides of the volcano, burning everything in their path, covering up building and generally ruining things. Well, you might be surprised to know that lava flows are the least hazardous way a volcano can kill you.

Molten rock is much thicker than a liquid like water. Even lava flows with the least viscosity (the least thick), will only flow at a maximum speed of a few kilometers per hour. You can easily out run a lava flow, and that’s why people are rarely killed by them. Building and trees, which are stuck to the ground, aren’t so lucky.

How far the lava flow goes depends on its viscosity. Lava flows made of basalt, like you might find in Hawaii, have very low viscosity, and so they can flow as much as 4 km away from the source and have a thickness of 10 meters. Thicker lava flows only get about 1 kilometer away from the source, but can be as thick as 100 meters.

People aren’t really at risk from lava flows, but they can do a tremendous amount of property damage. If the intense heat doesn’t set your house on fire, the slow moving wall of liquid rock will certainly knock it over and crush it to pieces. Entire towns built close to volcanoes have been overrun by lava flows, destroying houses and cars, encasing everything in meters of rock. Once an eruption is over, the lava flow can take days or even years to cool down.

Engineers have tried to battle nature, coming up with all kinds of ways to stop lava flows – few successful. In Italy, engineers have installed retaining walls to try and slow down lava flows coming down the side of Mount Etna, on the island of Sicily. These walls did slow down the lava flows enough that they didn’t reach inhabited land. In Hawaii, engineers bombed narrow lava tubes, forcing the lava to lose energy. And in Iceland, firefighters sprayed water on lava flows for nearly 5 months, cooling it so that it solidified early and didn’t block an important port.

We have written many articles about volcanoes for Universe Today. Here’s an article about the tallest volcano on Earth, and here’s an article about types 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.

Reference:
USGS Volcanoes: Lava Flows and Their Effects

April 8, 2009December 24, 2015 by Nancy Atkinson

Where In The Universe #50

Its time once again for another Where In The Universe Challenge. The goal of this challenge is to test your skills and knowledge of the cosmos. Guess where in the Universe this image is from, and give yourself extra points if you can guess which spacecraft is responsible for the image. Post your guess in the comment section (no links to hints please!) and check back tomorrow for the answer. Good luck!

UPDATE: The answer has now been posted below. (Don’t peek before you make your guess!)

This image is a zoomed in look at one region of the Rosette Nebula, taken by the Chandra X-ray Telescope, showing a group of hot, young stars. The nebula is about 5,000 light years from Earth, and we see it in the constellation Monoceros. The colors represent various levels of X-ray energy: red shows low-energy (0.5-2 keV) and blue shows high-energy (2-8 keV) X-rays. Chandra took the image back in January of 2001. For more info on the image and the Rosette Nebula, check out the Chandra website and their description of the image.

Hope you enjoyed this image — check back next week for another WITU Challenge!

April 8, 2009December 24, 2015 by Tammy Plotner

IYA Live Telescope Today – Alpha Centauri and Eta Carinae

On April 8, 2009 the IYA Live Telescope was busy broadcasting from the Southern Galactic Telescope Hosting facility and fulfilling your “100 Hours of Astronomy” requests. Are you ready to take a look at the video that came from the adventure and to add it to our library? Then come along as we view Alpha Centauri for Astrochick and Eta Carinae for Vino…

The following factual information is a cut and paste from Wikipedia:

Alpha Centauri – Constellation: CENTAURUS

Alpha Centauri, also known as Rigil Kentaurus, Rigil Kent, or Toliman, is the brightest star in the southern constellation of Centaurus and an established binary star system, Alpha Centauri AB. To the unaided eye it appears as a single star, whose total visual magnitude identifies it as the third brightest star in the night sky.

Alpha Centauri is the closest star system to the Solar System, being only 1.34 parsecs, or 4.37 light years away from our Sun. “Alpha Centauri” (“Rigil Kentaurus”) is the name given to what appears as a single star to the unaided eye (and to our small telescope), the brightest star in the southern constellation of Centaurus. With the aid of a larger telescope, Alpha Centauri can be resolved into a binary star system in close orbit. This is known as “Alpha Centauri AB” system.

Eta Carinae: CARINA

Eta Carinae is a hypergiant luminous blue variable star in the Carina constellation. Its luminosity is about four million times that of the Sun and, with an estimated mass of between 100 and 150 solar masses, it is one of the most massive stars yet discovered. Because of its mass and the stage of life, it is expected to explode in a supernova in the astronomically near future.

This object is currently the most massive nearby star that can be studied in great detail. While it is possible that other known stars might be more luminous and more massive, Eta Carinae has the highest confirmed luminosity based on data across a broad range of wavelengths; former prospective rivals such as the Pistol Star have been demoted by improved data.

Stars in the mass class of Eta Carinae, with more than 100 times the mass of the Sun, produce more than a million times as much light as the Sun. They are quite rare — only a few dozen in a galaxy as big as the Milky Way. They are assumed to approach (or potentially exceed) the Eddington limit, i.e., the outward pressure of their radiation is almost strong enough to counteract gravity. Stars that are more than 120 solar masses exceed the theoretical Eddington limit, and their gravity is barely strong enough to hold in their radiation and gas.

We would very much like to thank Astrochick and Vino for their suggestions and we hope you like the view! There’s still plenty of time to place more requests, so just add them on at our IYA Remote Telescope Request Page and we’ll get ‘er done! As always, you can visit the remote telescope by clicking on the IYA “LIVE Remote Cam” Logo to your right. We’ll be broadcasting whenever skies are clear and dark in Central Victoria! Enjoy…

(Information Source: Wikipedia)

April 8, 2009December 24, 2015 by Tammy Plotner

IYA Live Telescope – UT Reader Requests

The IYA Live Telescope broadcasting on “Galactic TV” has been busy fillling your requests and we’re ready to bring your first photos up on-line for you. We hope you had a chance to follow your object for several hours in the remote telescope today! For Universe Today readers Astrochick and Vino? Come on inside… Your requests have been fulfilled and your images are waiting!

There’s still plenty of time to place more requests, so just add them on at our IYA Remote Telescope Request Page and we’ll get ‘er done! Enjoy!

April 8, 2009December 24, 2015 by Nancy Atkinson

Soyuz Lands Safely in Kazakhstan

Soyuz lands on April 8, 2009. .Photo Credit: (NASA/Bill Ingalls)

Isn’t this a great picture? The Soyuz TMA-13 spacecraft, carrying Expedition 18 Commander Michael Fincke, Flight Engineer Yury V. Lonchakov and American Spaceflight Participant Charles Simonyi, landed safely on Wednesday, April 8, 2009, near Zhezkazgan, Kazakhstan. Fincke and Lonchakov returned after spending six months on the International Space Station, and Simonyi returned from his launch with the Expedition 19 crew members 12 days earlier. Simonyi made history by becoming the first private explorer to complete a second mission to space. He previously flew to the ISS in spring 2007. “With my second mission, I did much more work, but I was also able to rest and relax. I was physically more prepared and more comfortable given the resources that I brought with me,” Simonyi said. “I am very happy to have made the decision to fly again.”

Fincke spent 178 days in orbit and his command of the ISS saw the station go to full power and begin the urine/water supply recycling system. He also became the first American to fly to and from the space station twice aboard a Russian Soyuz. Fincke served almost 188 days as a flight engineer on the Expedition 9 crew in 2004.

This was Lonchakov’s first long-duration spaceflight and his third flight to space.

Sources: NASA, Space Adventures

April 8, 2009December 24, 2015 by Anne Minard

Researchers Propose New Model for the Most Eager Supernova Explosions

2005ke, a Type 1a supernova. Credit: NASA/Swift/S. Immler

Type 1a supernovae like 2005ke, above, are known to go off when one member of a star pair exceeds critical mass and kickstarts a runaway fusion reaction.

Researchers have long puzzled over why some of the explosions happen so fast. Now, a team of Chinese astronomers believes they’ve arrived at a probable cause for the earliest of the blasts.

A team of astronomers, led by Bo Wang from the Yunnan Observatory of the Chinese Academy of Sciences, have shown how the transfer of material from a ‘helium star’ to a compact white dwarf companion causes these cataclysmic events to take place. The new results appear in Monthly Notices of the Royal Astronomical Society.

Most type Ia supernovae are believed to occur when a white dwarf (the superdense remnant that is the end state of stars like the Sun) draws matter from a companion star orbiting close by. Previous theories for the origins of a Type Ia include an explosion of a white dwarf in orbit around another white dwarf, or an explosion of a white dwarf in orbit around a red giant star.

When the white dwarf mass exceeds the so-called Chandrasekhar limit of 1.4 times the mass of the Sun, it eventually collapses and within a few seconds undergoes a runaway nuclear fusion reaction, exploding and releasing a vast amount of energy as a type Ia supernova. Due to their high and remarkably consistent luminosities, astronomers use these events as ‘distance indicators’ to measure the distances to other galaxies and constrain our ideas about the Universe.

Scientists have confirmed more and more type Ia supernovae, and found that about half of them explode less than 100 million years after their host galaxy’s main star formation period. But previous models for these systems did not predict that they could be this young — so Wang and his team set out to solve the mystery.

Employing a stellar evolution computer code, they performed calculations for about 2600 binary systems consisting of a white dwarf and a helium star, a hot blue star which has a spectrum dominated by emission from helium. They found that if the gravitational field of the white dwarf pulls material from a helium star and increases its mass beyond the Chandrasekhar limit, it will explode as a type Ia supernova within 100 million years of its formation.

“Type Ia supernovae are a key tool to determine the scale of the Universe so we need to be sure of their properties,” said research team member Zhanwen Han, also from the Yunnan Observatory. “Our work shows that they can take place early on in the life of the galaxy they reside in.”

The team now plans to model the properties of the companion helium stars at the moment of the supernova explosions, which could be verified by future observations from the Large sky Area Multi-Object fiber Spectral Telescope (LAMOST).

LEAD IMAGE CAPTION: Supernova 2005ke shown in optical, ultraviolet and X-ray wavelengths. When it was captured, this was the first X-ray image of a Type 1a, and it provided observational evidence that Type Ia come from the explosion of a white dwarf orbiting a red giant star. Credit: NASA/Swift/S. Immler

Source: Royal Astronomical Society. The paper is available here.

April 8, 2009December 24, 2015 by Nancy Atkinson

New Array Captures Redoubt Volcano Lightning

Redoubt lightning. Credit: Bretwood Higman

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When Redoubt Volcano in Alaska started rumbling in January, a team of researchers from New Mexico Tech hurried to south central Alaska to deploy a series of radio sensors. When the volcano began erupting overnight on March 22 and 23, the Lightning Mapping Array started returning clear and dramatic information about the electricity created within volcanic plumes and the resulting lightning. This is the first time ever anyone has been able to record data from a volcanic eruption right from the start. “We’re getting all the data we hoped to get and a lot more,” principal investigator Dr. Ron Thomas said. “Absolutely, the quality and quantity of the data will allow us to better understand the electrical charge structure inside a volcanic plume.”

Lightning is a frequent occurance during volcanic eruptions. The Lightning Mapping array allows scientists, meteorologists and storm chasers to pierce the veil of clouds to “see” lightning as it occurs.

“With each lightning flash, we’ll be able to monitor how it moves through the clouds and where it goes,” Thomas said. “If we take all our theories about lightning created in thunderstorms, we can learn about both types of lightning.”

Photo of lightning from Redoubt Volcano during its 11:20 p.m. eruption on March 27, 2009. Photo by Brentwood Higman.

Redoubt erupted explosively about 20 times in the first seven days of activity. Most volcanic eruptions have several distinct stages. In the case of Redoubt, a stage of explosive activity is followed by a second stage that includes dome-building and slow venting of ash, rock and gasses. Within the individual explosive eruptions, different phases of electrical activity are observed.

“First, we see an eruptive or explosive phase,” physics professor Paul Krehbiel said. “Electrical activity is continuous and strong. We see a lot of small electrical discharges as hot gasses come out of the volcano.”
The second phase involves the ash cloud as it drifts away from the volcano with the wind. This phase is punctuated by discrete lightning – or lightning bolts.

“After the explosion is over, there is a subsequent phase of plume lightning,” Krehbiel said. “Full-fledged lightning occurs in the cloud of ash and water both above and downwind of the volcano.”

During a week’s time, Redoubt has had several major eruptions that have produced prolific lightning, Krehbiel said.

“The lightning activity was as strong as or stronger than we have seen in large Midwestern thunderstorms,” Krehbiel said. “The radio frequency noise was so strong and continuous that people living in the area would not have been able to watch broadcast VHF television stations.”

View north into the summit crater of Redoubt volcano where recent eruptions have removed a significant portion of the glacial ice. A remnant shelf of ice remains on the west (right) side of crater, and in this view, fumaroles are rising from near the ice/wall-rock contact. Image Creator: Payne, Allison

The Redoubt eruptions are not over yet. After quieting down and appearing to go into a dome-building phase, just before sunrise Saturday, April 4, the volcano blew its top in the biggest eruption so far.
Thousands of individual segments of a single lightning stroke can be mapped with the Lightning Mapping Array and later analyzed on high-end computers to reveal how lightning initiates and spreads throughout a thunderstorm … or within a volcanic plume.

“We receive radio bursts of noise generated from sparks of lightning, just like the static you hear on your car radio during a thunderstorm,” Thomas said. “We will use our sensing stations to locate the lightning and track its path.”

Source: New Mexico Tech press release

April 8, 2009December 24, 2015 by Anne Minard

Balloon Experiment Solves Mystery of Far Infrared Background

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Scientists have found a way to look past Earth’s atmosphere — and ancient cosmic dust — to glimpse galaxies that were formed in the first 5 billion years of the Universe.

A new study, released today in the journal Nature, reveals first-ever news from star-forming regions both near and far — including some from the edges of the Universe, which are racing away from us the fastest because of the Universe’s expansion.

The findings also clear up the sources of the Far Infrared Background, long shrouded in mystery.

The discoveries hail from the Balloon-borne Large Aperture Submillimetre Telescope (BLAST), which floated 120,000 feet (36,576 meters) above Antarctica in 2006.

The BLAST team chose to map a particular region of the sky called the Great Observatories Origins Deep Survey–South (GOODS-South), which was studied at other wavelengths by NASA’s three “great observatories” — the Hubble, Spitzer, and Chandra space telescopes. In one epic 11-day balloon flight, BLAST found more than 10 times the total number of submillimeter starburst galaxies detected in a decade of ground-based observations.

“We measured everything, from thousands of small clouds in our own galaxy undergoing star formation to galaxies in the Universe when it was only a quarter of its present age,” said lead author Mark Devlin, from the University of Pennsylvania.

In the 1980s and 1990s, certain galaxies called Ultraluminous InfraRed Galaxies were found to be birthing hundreds of times more stars than our own local galaxies. These “starburst” galaxies, 7-10 billion light years away, were thought to make up the Far Infrared Background discovered by the COBE satellite. Since the initial measurement of this background radiation, higher-resolution experiments have tried to detect the individual galaxies that comprise it.

The BLAST study combines telescope survey measurements at wavelengths below 1 millimeter with data at much shorter infrared wavelengths from the Spitzer Space Telescope. The results confirm that all the Far Infrared Background comes from individual distant galaxies, essentially solving a decade-old question of the radiation’s origin.

Star formation takes place in clouds composed of hydrogen gas and a small amount of dust. The dust absorbs the starlight from young, hot stars, heating the clouds to roughly 30 degrees above absolute zero (or 30 Kelvin). The light is re-emitted at much longer infrared and submillimeter wavelengths.

Thus, as much as 50 percent of the Universe’s light energy is infrared light from young, forming galaxies. In fact, there is as much energy in the Far Infrared Background as there is in the total optical light emitted by stars and galaxies in the Universe. Familiar optical images of the night sky are missing half of the picture describing the cosmic history of star formation, the authors say.

“BLAST has given us a new view of the Universe,” said Barth Netterfield of the University of Toronto, the Canadian principal investigator for BLAST, “enabling the BLAST team to make discoveries in topics ranging from the formation of stars to the evolution of distant Galaxies.”

In an accompanying News & Views piece, author Ian Smail, a computational cosmologist from Durham University in the UK, wrote that “the implication of these observations is that the active growth phase of most galaxies that are seen today is well behind them — they are declining into their equivalent of middle age.”

He also pointed out that studies of these extreme star-forming events in the early Universe will be aided by three major advances due over the next year or so: the submillimeter camera on the ESA/NASA Herschel Space Observatory; the development of large-format detectors working at submillimeter wavelengths, including one mounted on the James Clerk Maxwell Telescope; and the first phase of the Atacama Large Millimeter Array (ALMA).

“Such observations will allow astronomers to study the distribution of gas and star formation within these early galaxies,” Smail wrote, “which in turn will help to identify the physical process that triggers these ultraluminous bursts of star formation and their role in the formation of the galaxies we see in the Universe today.”

LEAD IMAGE CAPTION: The BLAST telescope just before launch in Antarctica. BLAST is in the foreground, next the 28 million cubic foot balloon, in the background is the volcano Mount Erebus. Credit: Mark Halpern

Source: Nature and a University of Pennsylvania press release (not yet online). Images, photographs, sky maps and the complete study are available at the BLAST Web site.

April 8, 2009December 24, 2015 by Nancy Atkinson

Kepler Flips Its Lid; Soon Ready for Planet Hunt

Artist concept of the Kepler spacecraft's dust cover coming off. Image credit: NASA/JPL

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Engineers successfully ejected the dust cover from NASA’s Kepler telescope last night and the space observatory will soon begin searching for Earth-like planets. “The cover released and flew away exactly as we designed it to do,” said Kepler Project Manager James Fanson from JPL. “This is a critical step toward answering a question that has come down to us across 100 generations of human history — are there other planets like Earth, or are we alone in the galaxy?”

Click here for an animation of the event.

Kepler launched on March 6, 2009 and will spend at least three-and-a-half years staring at more than 100,000 stars in our Milky Way galaxy for signs of Earth-size planets. Some of the planets are expected to orbit in a star’s “habitable zone,” a warm region where water could pool on the surface. The mission’s science instrument, called a photometer, contains the largest camera ever flown in space — its 42 charge-coupled devices (CCDs) will detect slight dips in starlight, which occur when planets passing in front of their stars partially block the light from Kepler’s view.

The telescope’s oval-shaped dust cover, measuring 1.7 meters by 1.3 meters (67 inches by 52 inches), protected the photometer from contamination before and after launch. The dust cover also blocked stray light from entering the telescope during launch — light that could have damaged its sensitive detectors. In addition, the cover was important for calibrating the photometer. Images taken in the dark helped characterize noise coming from the instrument’s electronics, and this noise will later be removed from the actual science data.

“Now the photometer can see the stars and will soon start the task of detecting the planets,” said Kepler’s Science Principal Investigator William Borucki at NASA’s Ames Research Center, Moffett Field, Calif. “We have thoroughly measured the background noise so that our photometer can detect minute changes in a star’s brightness caused by planets.”

At 7:13 p.m. PDT on April 7, engineers at Kepler’s mission operations center at the Laboratory for Atmospheric and Space Physics, Boulder, Colo., sent commands to pass an electrical current through a “burn wire” to break the wire and release a latch holding the cover closed. The spring-loaded cover swung open on a fly-away hinge, before drifting away from the spacecraft. The cover is now in its own orbit around the sun, similar to Kepler’s sun-centric orbit.

April 8, 2009December 24, 2015 by Tammy Plotner

Astronomers Are People, Too…

Do you know this face? If you don’t, then you surely know the name – Brother Guy Consolmagno, Vatican Astronomer. Ah, I hear some bells ringing in your head! So why is he important to so many of us? Then sit back and let me tell you a tale about the halcyon days of astronomy…

Once upon a time, there were no computer driven telescopes, no easy access planetarium programs just waiting on our desktops or laptop computer screens for us to find objects in the sky. Telescopes were simply telescopes and astronomy clubs were rare. If you were just learning, you were on your own with what you could find at the library. And, for many of you (like me) Brother Guy’s famous work “Turn Left At Orion” was our teacher. Through its pages I learned what made my telescope work and how to aim at objects in the sky and find them. But even more importantly, he taught me to educate myself about what I was looking at.

Over the years I wore the covers and bindings off of three copies of “Turn Left At Orion”. My original is held together with rubber bands and still holds a place of honor on my bookshelf, for its many grass stains and coffee rings proclaim the nights I’ve spent with it under the stars. Pages have been photocopied and handed out to others who were just beginning and the legend of Brother Guy Consolmagno passed on to the next generation of stargazers. Yet for all of this time I had spent with this book, it never once occurred to me to think of its author as a person…

Until now.

Through the magic of the times that we now live in, we instantly communicate with people around the world – allowing us to make friends in places where we’d never dreamed we could be. One such astronomy friend of mine, Deirdre, is part of the Irish Astronomical Society, and when she told me of her visit with Guy Consolmagno? I just about fainted. He’s real? The man is real? Of course he’s real. You know he’s real. But is he really for real? And the answer is… He’s not only real – but he’s the type of person who would spend a night out under the stars with you.

So often in our hurried, modern world we forget the simple joys of life. Music, friends, starlight… We have conceptions of how we believe things should be, and not what they are. Astronomers can only listen to classical music and have to be stiff scientists, right? Wrong. Stop and visit with one of the most inspirational of all:

The next time you’re out with a telescope, why not unplug the electronics and go manual? Get out your old refractor or reflector and your book of charts. Breathe in the night around you and be curious about the things you look at. Maybe turn on some rock and roll? And when you get to Orion…

Turn left.

Brother Guy Consolmagno is the curator of meteorites at the Vatican Observatory. He has an extensive academic background and has written more than 100 scientific publications alongside numerous books. I would personally like to thank him for being part of the inspiration that made me what I am today. If you, too, owe part of what you are to Brother Guy’s work… why not tell him so here? I’m sure he’s listening.