Universe Today

December 14, 2013December 23, 2015 by Ken Kremer

China Scores Historic Success as Chang’e-3 Rover Lands on the Moon Today

Photo taken on Dec. 14, 2013 shows a picture of the moon surface taken by the on-board camera of lunar probe Chang’e-3 on the screen of the Beijing Aerospace Control Center in Beijing. This marks the first time that China has sent a spacecraft to soft land on the surface of an extraterrestrial body. Credit: Xinhua/CCTV
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China scored a stunning, history making success with the successful touchdown of the ambitious Chang’e-3 probe with the ‘Yutu’ rover on the surface of the Moon today, Dec. 14, on the country’s first ever attempt to conduct a landing on an extraterrestrial body.

The dramatic Chang’e-3 soft landing on the lava filled plains of the Bay of Rainbows occurred at about 8:11 am EST, 9:11 p.m. Beijing local time, 1311 GMT today.

The monumental feat is the first landing on the Moon by any entity in nearly four decades. It was broadcast live on CCTV, China’s state run television network.

Note: Read my related new story with a photo gallery of Yutu’s 6 wheels rolling onto lunar soil – here

This maiden Chinese moon landing marks a milestone achievement for China and clearly demonstrates the country’s technological prowess.

A tidal wave of high fives was unleashed by the huge teams of Chinese space engineers teams controlling the flight from the Beijing Aerospace Control Center (BACC).

There was also a huge sense of relief from the nail biting tension upon confirmation of the successful soft landing following many years of hard work and intense planning.

The Chang’e-3 mission entails the first soft landing on the Moon by anyone since the Soviet Union’s unmanned Luna 24 sample return vehicle touched down back in 1976.

Artists concept of the rocket assisted landing of China’s lunar probe Chang'e-3. — Artists concept of the rocket assisted landing of China’s lunar probe Chang’e-3.

China now joins an elite club of three, including the United States, who have mastered the critical technology required to successfully touch down on Earth’s nearest neighbor.

China’s space vision also stands in total contrast to the utter lack of vision emanating from so called political leaders in Washington, DC who stymie NASA and US science at every opportunity!

‘Yutu’ could very well serve as a forerunner for testing the key technologies required for a Chinese manned lunar landing in the next decade.

In one of its first acts from the surface, the landers life giving solar panels were deployed as planned within minutes of touchdown

The Chang’e-3 mission is comprised of China’s ‘Yutu’ lunar lander riding piggyback atop a much larger four legged landing vehicle.

The Chang’e-3 lander transmitted its first images of the moon in real time during its approach to the lunar surface during the final stages of the ongoing landing operation carried live by CCTV.

A total of 59 images were received instead of the 10 expected, said a CCTV commentator.

The voyage from the Earth to the Moon began 12 days ago with the flawless launch of Chang’e-3 atop China’s Long March 3-B booster at 1:30 a.m. Beijing local time, Dec. 2, 2013 (12:30 p.m. EST, Dec. 1) from the Xichang Satellite Launch Center, in southwest China.

Chang’e-3 made a rocket powered descent to the Moon’s surface today by firing the landing thrusters starting at the altitude of 15 km (9 mi) for a soft landing targeted to a preselected area on the Bay of Rainbows.

The powered descent was autonomous and took about 12 minutes.

The variable thrust engine can continuously vary its thrust power between 1,500 to 7,500 newtons. It was the biggest ever used by China in space said a commentator on CCTV.

The variable thrust engine enabled Chang’e-3 to reduce its deceleration as it approached the moon.

The descent was preprogrammed and controlled by the probe itself, not from the ground.

A descent camera was mounted on the lander’s belly

The 1200 kg lander is equipped with unprecedented terrain recognition equipment and software to hover above the landing site and confirm it was safe. This enabled the craft to avoid rock and boulder fields that could spell catastrophe even in the final seconds before touchdown if the vehicle were to land directly on top of them.

The descent engine fired until the lander was about hovering 100 meters above the lunar surface.

After determining it was safe to proceed, the lander descended further to about 3 meters. The engine then cut off and the lander free fell the remaining distance. The impact was cushioned by shock absorbers.

The solar panels soon unfurled. They are the most efficient Chinese solar panels available, said a CCTV commentator.

The Bay of Rainbows, or Sinus Iridum region, is located in the upper left portion of the moon as seen from Earth. You can see the landing site with your own eyes.

It was imaged in high resolution by China’s prior lunar mission – the Chang’e-2 lunar orbiter – and is shown in graphics herein.

The Yutu rover is also unfurling its solar panels and mast today.

Yutu, which translates as Jade Rabbit, stands 150 centimeters high, or nearly 5 feet – human height.

It weighs approximately 120 kilograms and sports a robotic arm equipped with advanced science instruments.

On Sunday, the six-wheeled ‘Yutu’ rover with a rocker bogie suspension similar to NASA’s Mars rovers will be lowered in stages to the moon’s surface in a complex operation and then drive off a pair of landing ramps to explore the moon’s terrain for at least three months.

In what promises to be a space spectacular, the lander and rover are expected to photograph one another soon after Yutu rolls onto the Bay of Rainbows.

They will work independently.

The rover and lander are equipped with multiple cameras, spectrometers, an optical telescope, ground penetrating radar and other sensors to investigate the lunar surface and composition.

The radar instrument installed at the bottom of the rover can penetrate 100 meters deep below the surface to study the Moon’s structure and composition in unprecedented detail, according to Ouyang Ziyuan, senior advisor of China’s lunar probe project, in an interview on CCTV.

The Chang’e-3 lander is powered by a combination of solar arrays and a nuclear battery said CCTV, in order to survive the two week long lunar nights.

Chinese space officials expect the lander will function a minimum of 1 year.

ESA’s network of tracking stations are providing crucial support to China for Chang’e-3 from launch to landing.

China’s Chang’e-3 probe joins NASA’s newly arrived LADEE lunar probe which entered lunar orbit on Oct. 6 following a spectacular night time blastoff from NASA’s Wallops Flight Facility in Virginia.

Stay tuned here for Ken’s continuing Chang’e-3, LADEE, MAVEN, MOM, Mars rover and more news.

Ken Kremer

December 13, 2013December 23, 2015 by Ken Kremer

China’s Chang’e-3 Moon Rover Descends to Lower Orbit Sets Up Historic Soft Landing

All systems appear to be “GO” for the world’s first attempt to soft land a space probe on the Moon in nearly four decades.

China’s maiden moon landing probe – Chang’e-3 – is slated to attempt the history making landing this weekend on a lava plain in the Bay of Rainbows, or Sinus Iridum region.

Chinese space engineers at the Beijing Aerospace Control Center (BACC) paved the way for the historic touchdown by successfully commanding Chang’e-3 to descend from the 100 km-high lunar circular orbit it reached just one week ago on Dec. 6, to “an elliptical orbit with its nearest point about 15 km away from the moon’s surface”, according to a statement from China’s State Administration of Science, Technology and Industry for National Defense (SASTIND).

UPDATE: CCTV is providing live landing coverage

The first pictures taken from the alien lunar surface in some 37 years are expected to be transmitted within days or hours of touchdown planned as early as Saturday, Dec. 14, at 9:40 p.m. Beijing local time, 8:40 a.m. EST.

CCTV, China’s state run network, carried the launch live. It remains to be seen whether they will have live coverage of the landing since there have been no programming announcements.

SASTIND said the orbit lowering thruster firing was “conducted above the dark side of the moon at 9:20 p.m.” on Dec. 10, Beijing local time.

Confirmation of the Chang’e-3 probes new, lower orbit was received four minutes later.

China's lunar probe Chang'e-3 entered an orbit closer to the moon on Dec. 10, 2013. (Xinhua) — China’s lunar probe Chang’e-3 entered an orbit closer to the moon on Dec. 10, 2013. Credit: Xinhua

If successful, the Chang’e-3 mission will mark the first soft landing on the Moon since the Soviet Union’s unmanned Luna 24 sample return vehicle landed back in 1976.

China would join an elite club of three, including the United States, who have mastered the critical technology to successfully touch down on Earth’s nearest neighbor.

The Chang’e-3 mission is comprised of China’s ‘Yutu’ lunar lander riding piggyback atop a much larger four legged landing probe.

Artists concept of the Chinese Chang'e 3 lander and rover on the lunar surface. Credit: Beijing Institute of Spacecraft System Engineering — Artists concept of the Chinese Chang’e-3 lander and rover on the lunar surface. Credit: Beijing Institute of Spacecraft System Engineering

Chang’e-3 will make a powered descent to the Moon’s surface on Dec. 14 by firing the landing thrusters at the altitude of 15 km (9 mi) for a soft landing in a preselected area on the Bay of Rainbows.

The powered descent will take about 12 minutes.

The variable thrust engine can continuously vary its thrust power between 1,500 to 7,500 newtons, according to Xinhua.

The Bay of Rainbows is located in the upper left portion of the moon as seen from Earth. It was imaged in high resolution by China’s prior lunar mission – the Chang’e-2 lunar orbiter.

The 1200 kg lander is equipped with terrain recognition equipment and software to avoid rock and boulder fields that could spell catastrophe even in the final seconds before touchdown if the vehicle were to land directly on top of them.

Chang’e-3 is powered by a combination of solar arrays and a nuclear device in order to survive the two week long lunar nights.

The six-wheeled ‘Yutu’ rover, with a rocker bogie suspension, will be lowered in stages to the moon’s surface in a complex operation and then drive off a pair of landing ramps to explore the moon’s terrain.

Yutu measures 150 centimeters high and weighs approximately 120 kilograms and sports a robotic arm equipped with science instruments.

The rover and lander are equipped with multiple cameras, spectrometers, an optical telescope, ground penetrating radar and other sensors to investigate the lunar surface and composition.

The radar instrument installed at the bottom of the rover can penetrate 100 meters deep below the surface to study the Moon’s structure and composition in unprecedented detail.

Stay tuned here for Ken’s continuing Chang’e-3, LADEE, MAVEN, MOM, Mars rover and more news.

Ken Kremer

December 13, 2013December 29, 2015 by Fraser Cain

Weekly Space Hangout – December 13, 2013 – Europa’s Water Jets and Chinese Lunar Lander

Host: Fraser Cain
Guests: David Dickinson, Amy Shira Teitel, Jason Major, Nicole Gugliucci
Continue reading “Weekly Space Hangout – December 13, 2013 – Europa’s Water Jets and Chinese Lunar Lander”

December 13, 2013December 23, 2015 by Jason Major

When Is a Star Not a Star?

Artist's impression of a Y-dwarf, the coldest known type of brown dwarf star. (NASA/JPL-Caltech)

When it’s a brown dwarf — but where do we draw the line?

Often called “failed stars,” brown dwarfs are curious cosmic creatures. They’re kind of like swollen, super-dense Jupiters, containing huge amounts of matter yet not quite enough to begin fusing hydrogen in their cores. Still, there has to be some sort of specific tipping point, and astronomers (being the scientists that they are) would like to know: when does a brown dwarf stop and a star begin?

Researchers from Georgia State University now have the answer.

From a press release issued Dec. 9 from the National Optical Astronomy Observatory (NOAO):

For most of their lives, stars obey a relationship referred to as the main sequence, a relation between luminosity and temperature – which is also a relationship between luminosity and radius. Stars behave like balloons in the sense that adding material to the star causes its radius to increase: in a star the material is the element hydrogen, rather than air which is added to a balloon. Brown dwarfs, on the other hand, are described by different physical laws (referred to as electron degeneracy pressure) than stars and have the opposite behavior. The inner layers of a brown dwarf work much like a spring mattress: adding additional weight on them causes them to shrink. Therefore brown dwarfs actually decrease in size with increasing mass.

As Dr. Sergio Dieterich, the lead author, explained, “In order to distinguish stars from brown dwarfs we measured the light from each object thought to lie close to the stellar/brown dwarf boundary. We also carefully measured the distances to each object. We could then calculate their temperatures and radii using basic physical laws, and found the location of the smallest objects we observed (see the attached illustration, based on a figure in the publication). We see that radius decreases with decreasing temperature, as expected for stars, until we reach a temperature of about 2100K. There we see a gap with no objects, and then the radius starts to increase with decreasing temperature, as we expect for brown dwarfs. “

Dr. Todd Henry, another author, said: “We can now point to a temperature (2100K), radius (8.7% that of our Sun), and luminosity (1/8000 of the Sun) and say ‘the main sequence ends there’ and we can identify a particular star (with the designation 2MASS J0513-1403) as a representative of the smallest stars.”

The relation between size and temperature at the point where stars end and brown dwarfs begin (based on a figure from the publication) Image credit: P. Marenfeld & NOAO/AURA/NSF.

“We can now point to a temperature (2100K), radius (8.7% that of our Sun), and luminosity (1/8000 of the Sun) and say ‘the main sequence ends there’.”

Dr. Todd Henry, RECONS Director

Aside from answering a fundamental question in stellar astrophysics about the cool end of the main sequence, the discovery has significant implications in the search for life in the universe. Because brown dwarfs cool on a time scale of only millions of years, planets around brown dwarfs are poor candidates for habitability, whereas very low mass stars provide constant warmth and a low ultraviolet radiation environment for billions of years. Knowing the temperature where the stars end and the brown dwarfs begin should help astronomers decide which objects are candidates for hosting habitable planets.

The data came from the SOAR (SOuthern Astrophysical Research) 4.1-m telescope and the SMARTS (Small and Moderate Aperture Research Telescope System) 0.9-m telescope at the Cerro Tololo Inter-American Observatory (CTIO) in Chile.

Why Our Universe is Not a Hologram

Superstrings may exist in 11 dimensions at once. Via National Institute of Technology Tiruchirappalli.

Editor’s note: This article was originally published by Brian Koberlein on G+, and it is republished here with the author’s permission.

There’s a web post from the Nature website going around entitled “Simulations back up theory that Universe is a hologram.” It’s an interesting concept, but suffice it to say, the universe is not a hologram, certainly not in the way people think of holograms. So what is this “holographic universe” thing?

It all has to do with string theory. Although there currently isn’t any experimental evidence to support string theory, and some evidence pointing against it, it still garners a great deal of attention because of its perceived theoretical potential. One of the theoretical challenges of string theory is that it requires all these higher dimensions, which makes it difficult to work with.

In 1993, Gerard t’Hooft proposed what is now known as the holographic principle, which argued that the information contained within a region of space can be determined by the information at the surface that contains it. Mathematically, the space can be represented as a hologram of the surface that contains it.

That idea is not as wild as it sounds. For example, suppose there is a road 10 miles long, and its is “contained” by a start line and a finish line. Suppose the speed limit on this road is 60 mph, and I want to determine if a car has been speeding. One way I could do this is to watch a car the whole length of the road, measuring its speed the whole time. But another way is to simply measure when a car crosses the start line and finish line. At a speed of 60 mph, a car travels a mile a minute, so if the time between start and finish is less than 10 minutes, I know the car was speeding.

A visualization of strings. Image credit: R. Dijkgraaf.

The holographic principle applies that idea to string theory. Just as its much easier to measure the start and finish times than constantly measure the speed of the car, it is much easier to do physics on the surface hologram than it is to do physics in the whole volume. The idea really took off when Juan Martín Maldacena derived what is known as the AdS/CFT correspondence (an arxiv version of his paper is here ), which uses the holographic principle to connect the strings of particle physics string theory with the geometry of general relativity.

While Maldacena made a compelling argument, it was a conjecture, not a formal proof. So there has been a lot of theoretical work trying to find such a proof. Now, two papers have come out (here and here) demonstrating that the conjecture works for a particular theoretical case. Of course the situation they examined was for a hypothetical universe, not a universe like ours. So this new work is really a mathematical test that proves the AdS/CFT correspondence for a particular situation.

From this you get a headline implying that we live in a hologram. On twitter, Ethan Siegel proposed a more sensible headline: “Important idea of string theory shown not to be mathematically inconsistent in one particular way”.

Of course that would probably get less attention.

December 13, 2013December 23, 2015 by Elizabeth Howell

NASA Weighs Spacewalk To Fix Cooling Problem On Station

NASA Television graphic of where spare cooling pumps are located on station as of Dec. 13, 2013. On that day, NASA was weighing whether spacewalks were necessary to deal with a cooling problem caused by a malfunctioning flow control valve inside of a pump. Credit: NASA TV

NASA may allow its first spacewalk since summer to deal with a malfunction that crippled a cooling loop on the International Space Station.

If extravehicular activity is deemed necessary for a fix, it would be the first time NASA spacesuits were used “outside” since Luca Parmitano, an Italian astronaut, experienced a water leak in one that cut short a spacewalk in July. NASA suspended all spacewalks as a precaution while the cause was investigated.

Since then, the agency has put in place procedures to protect astronauts from it happening again, opening up a spacewalk or spacewalks as an option to deal with a balky control valve inside a pump on the station.

The valve is an essential part of an S1 (starboard) truss pump that helps maintain the correct temperature for space station electronics. Ammonia circulates through two external cooling loops and is put through radiators to bleed off heat. The valve is required to mix the cool and warm parts of liquid in the ammonia loop.

Expedition 35 Flight Engineers Chris Cassidy (left) and Tom Marshburn completed a the 5-hour, 30-minute spacewalk on May 11 to inspect and replace a pump controller box on the International Space Station’s far port truss (P6) leaking ammonia coolant. Credit: NASA

A pump automatically shut down on Wednesday (Dec. 11) when the loop got too cold. As NASA began troubleshooting the issue, it powered down non-critical systems (including experiments and redundant systems) in the Columbus laboratory, Harmony node and Japanese Kibo laboratory. Primary systems are still online.

The astronauts are safe, NASA said today (Dec. 13), with the biggest impact to their activities being the science they perform. Expedition 38 astronaut Rick Mastracchio did a live media interview this morning (EST) where he similarly assured reporters that everyone on board is fine.

Cooling problems have happened on station before, most recently in May when an emergency spacewalk was needed to replace a pump controller box on the P6 (far port) truss. This particular cooling system experienced an issue in 2010, which required three contingency spacewalks to remove and replace a failed pump on the S1 truss.

Expedition 24 astronaut Douglas Wheelock exits the Quest airlock at the beginning of a spacewalk Aug. 11, 2010 to replace a failed ammonia pump on the International Space Station's S1 truss. Credit: NASA — Expedition 24 astronaut Douglas Wheelock exits the Quest airlock at the beginning of a spacewalk Aug. 11, 2010 to replace a failed ammonia pump on the International Space Station’s S1 truss. Credit: NASA

If a spacewalk is needed this time around, NASA has three spare pumps available on station for astronauts to use. NASA, however, is looking at all options before making a decision — including ways of controlling the errant valve from the ground. The agency is holding multiple meetings to decide what to do next after turning on and off the cooling loop yesterday and seeing the same malfunction.

On Monday, NASA will decide whether to move forward with a launch of a cargo spacecraft expected to head to the station on Dec. 18. The window for Orbital Sciences’ Cygnus spacecraft extends to Dec. 21 or 22, but as of Thursday (Dec. 12), the agency said the lack of redundant systems on station violates certain “commit criteria” for the launch to move forward.

While NASA spacewalks were suspended, activity using the Russian Orlan spacesuits has continued as usual. A spacewalk took place in November with the Olympic torch, amid other duties. Another spacewalk is planned Dec. 27 to install high- and medium-resolution cameras, put in a foot restraint, and remove and replace several external experiment packages.

December 13, 2013December 23, 2015 by Elizabeth Howell

This Picture Symbolizes The Changing Mission Of One Plucky Spacecraft

The Helix nebula is visible in the center of this image, surrounded by tracks of asteroids that are much closer to Earth (yellow dots). Click on the image to see them. The streaks you see are from satellites or cosmic rays. Credit: NASA/JPL-Caltech/UCLA

Besides being a darn pretty picture of the Helix nebula, this snapshot is a bit of symbolism for NASA. The spacecraft that nabbed this view is called the Wide-field Infrared Survey Explorer, or WISE. If you look very carefully — you may have to click on the picture for a closer view — you can see little dots showing the paths of asteroids in the picture. (The streaks are cosmic rays and satellites.)

WISE has an interesting history. It began as a telescope seeking secrets of the universe in infrared light, but ran out of coolant in 2010 and was repurposed for asteroid searching under the NEOWISE mission. It wrapped up its mission, was put into hibernation in February 2011, then reactivated this August to look for asteroids again for at least the next three years. You can see some pictures and data WISE collected during its mission below the jump.

It’s a nice way, NASA said, to celebrate the fourth anniversary of WISE’s launch. “WISE is the spacecraft that keeps on giving,” said Ned Wright of UCLA, who was the principal investigator of WISE before it transitioned into NEOWISE.

New results from NASA's NEOWISE survey find that more potentially hazardous asteroids, or PHAs, are closely aligned with the plane of our solar system than previous models suggested. Image credit: NASA/JPL-Caltech — Results from NASA’s NEOWISE survey find that more potentially hazardous asteroids, or PHAs, are closely aligned with the plane of our solar system than previous models suggested. Image credit: NASA/JPL-Caltech

This enormous section of the Milky Way galaxy is a mosaic of images from NASA's Wide-field Infrared Survey Explorer, or WISE. The constellations Cassiopeia and Cepheus are featured in this 1,000-square degree expanse. Image credit: NASA/JPL-Caltech/UCLA — This enormous section of the Milky Way galaxy is a mosaic of images from NASA’s Wide-field Infrared Survey Explorer, or WISE. The constellations Cassiopeia and Cepheus are featured in this 1,000-square degree expanse. Image credit: NASA/JPL-Caltech/UCLA

This oddly colorful nebula is the supernova remnant IC 443 as seen by WISE. Image credit: NASA/JPL-Caltech/UCLA

December 13, 2013December 23, 2015 by Elizabeth Howell

Why Exoplanet-Hunting Is ‘Like Seeing A Flea In A Lightbulb’

Artist's conception of the Kepler Space Telescope. Credit: NASA/JPL-Caltech

Exoplanets are really tiny compared to their host star, and it’s hard to imagine sometimes how astronomers can even find one of these worlds — let alone thousands of them. This nifty two-part series from PBS explains how it’s possible in an easy-to-understand and hilarious way. As an example, this is how they describe the Kepler space telescope’s capabilities:

“It can’t actually see those exoplanets because the stars that they surround are so big and bright. Instead, it looks for the tiny shadow of the planet as it passes in front of its parent star. If that sounds hard, that’s because it is. It’s like seeing a flea in a lightbulb in Los Angeles from New York City,” said host Joe Hanson in the video.

Near the end, he provides an interesting segway into the question of life beyond Earth: “The question we’re really interested in is not how common are planets, but how common are we.” That gets tackled in part 2 of the video, which you can see below the jump.

Remember that 2014 will be an interesting year for Kepler as NASA figures out what to do next with the observatory. It isn’t able to perform its primary mission (seeking exoplanets in Cygnus) because two of its four reaction wheels or pointing devices are malfunctioning. NASA, however, has an innovative fix on the books that could allow it to swing different fields of view during the year — check out this infographic for more details.

December 13, 2013December 23, 2015 by Shannon Hall

Fast Radio Bursts May Originate Closer to Home Than Previously Thought

Fast radio bursts — eruptions of extreme energy that occur only once and last a thousandth of a second — are continuing to defy astronomers. At first observations suggested they came from billions of light years away. A new study, however, points to sources much closer to home: nearby flaring stars.

“We have argued that fast radio burst sources need not be exotic events at cosmological distances, but rather could be due to extreme magnetic activity in nearby Galactic stars,” said Harvard professor Abraham Loeb in the study.

All radio bursts show a dispersion measure — a frequency dependent time delay — as the long-wavelength component arrives a fraction of a second after the short-wavelength component. When the burst travels through a medium, the long-wavelength component moves slightly slower than short-wavelength component.

This dispersion may easily be created when light travels through intergalactic space. The farther the light travels, the more electrons it will have to travel through, and the greater time delay between the arriving wavelength components.

With this assumption, fast radio bursts are likely to have originated anywhere from five to 10 billion light years away. Universe Today covered an extra-galactic origin a few months ago (read it here).

However, Loeb and his colleagues turned their eyes instead to electrons in stellar corona. These electrons are tightly packed, more so than diffuse intergalactic electrons, and would create the same observable effect.

Flaring stars — variable stars that can undergo unpredictable increases in brightness — are a likely source of fast radio bursts. Two circumstances may create flaring stars: young, low mass stars and solar-mass contact binaries, which orbit so close to one another that they share a common envelope.

In order to test this theory, Loeb and his colleagues searched the vicinities of three of the six known fast radio bursts for flaring stars.

“We were surprised that, apparently, no one had done this before,” said graduate student Yossi Shvartzvald in a press release. Shvartzvald led the observations at Tel-Aviv University’s Wise Observatory in Mitspe Ramon, Israel.

The team discovered a contact binary system in one location. Two sun-like stars orbit one another every 7.8 hours. They calculate a five percent chance that the contact binary is there by coincidence.

No flaring stars, however, were detected in the two other fields.

“Whenever we find a new class of sources, we debate whether they are close or far away,” Loeb said in a press release. Initially we thought gamma-ray bursts were faint stars within the Milky Way. Today we know they are bright explosions in distant galaxies.

It seems the distance debate for fast radio bursts has only begun.

The paper has been accepted for publication in the Monthly Notices of the Royal Astronomical Society and is available for download here. The original press release may be found here.

December 12, 2013December 23, 2015 by Tammy Plotner

Argon – The First Noble Gas Molecules Discovered In Space

Messier 1 Hubble Image: Credit - NASA, ESA, J. Hester and A. Loll (Arizona State University)

There are only six of them: radon, helium, neon, krypton, xenon and the first molecules to be discovered in space – argon. They are all odorless, colorless, monatomic gases with very low chemical reactivity. So where did a team of astronomers using ESA’s Herschel Space Observatory make their rather unusual discovery? Try Messier 1… The “Crab” Nebula!

In a study led by Professor Mike Barlow (UCL Department of Physics & Astronomy), a UCL research team was taking measurements of cold gas and dust regions of this famous supernova remnant in infrared light when they stumbled upon the chemical signature of argon hydrogen ions. By observing in longer wavelengths of light than can be detected by the human eye, the scientists gave credence to current theories of how argon occurs naturally.

“We were doing a survey of the dust in several bright supernova remnants using Herschel, one of which was the Crab Nebula. Discovering argon hydride ions here was unexpected because you don’t expect an atom like argon, a noble gas, to form molecules, and you wouldn’t expect to find them in the harsh environment of a supernova remnant,” said Barlow.

When it comes to a star, they are hot and ignite the visible spectrum. Cold objects like nebular dust are better seen in infrared, but there’s only one problem – Earth’s atmosphere interferes with the detection of that end of the electromagnetic spectrum. Even though we can see nebulae in visible light, what shows is the product of hot, excited gases, not the cold and dusty regions. These invisible regions are the specialty of Herschel’s SPIRE instruments. They map the dust in far-infrared with their spectroscopic observations. In this instance, the researchers were somewhat astounded when they found some very unusual data which required time to fully understand.

“Looking at infrared spectra is useful as it gives us the signatures of molecules, in particular their rotational signatures,” Barlow said. “Where you have, for instance, two atoms joined together, they rotate around their shared center of mass. The speed at which they can spin comes out at very specific, quantized, frequencies, which we can detect in the form of infrared light with our telescope.”

According to the news release, elements can exist in varying forms known as isotopes. These have different numbers of neutrons in the atomic nuclei. When it comes to properties, isotopes can be somewhat alike to each other, but they have different masses. Because of this, the rotational speed is dependent on which isotopes are present in a molecule. “The light coming from certain regions of the Crab Nebula showed extremely strong and unexplained peaks in intensity around 618 gigahertz and 1235 GHz.” By comparing data of known properties of different molecules, the science team came to the conclusion the mystery emission was the product of spinning molecular ions of argon hydride. What’s more, it could be isolated. The only argon isotope which could spin like that was argon-36! It would appear the energy released from the central neutron star in the Crab Nebula ionized the argon, which then combined with hydrogen molecules to form the molecular ion ArH+.

Professor Bruce Swinyard (UCL Department of Physics & Astronomy and Rutherford Appleton Laboratory), a member of the team, added: “Our discovery was unexpected in another way — because normally when you find a new molecule in space, its signature is weak and you have to work hard to find it. In this case it just jumped out of our spectra.”

Is this instance of argon-36 in a supernova remnant natural? You bet. Even though the discovery was the first of its kind, it is doubtless not the last time it will be detected. Now astronomers can solidify their theories of how argon forms. Current predictions allow for argon-36 and no argon-40 to also be part of supernova structure. However, here on Earth, argon-40 is a dominant isotope, one which is created through the radioactive decay of potassium in rocks.

Noble gas research will continue to be a focus of scientists at UCL. As an amazing coincidence, argon, along with other noble gases, was discovered at UCL by William Ramsay at the end of the 19th century! I wonder what he would have thought had he known just how very far those discoveries would take us?

Original Story Source: University College London (UCL) Press Release