Posted on by Nancy Atkinson

Huge Camera to Observe Dark Energy

Discovering the universe is accelerating and not slowing down made it obvious to astronomers there’s a lot we don’t know about the universe; namely, a big chunk of it is missing from our visible observations. Astronomers determined roughly 4% of the universe is made up of ordinary matter and 27% of Dark Matter (inferred from gravitational affects on visible matter), leaving 68% unaccounted for. Dark energy, while still hypothetical, is what is believed to keep the pedal to the metal, so to speak, on the universe’s expansion. But an international group of astronomers believes that dark energy should be detectable, and they are constructing a huge camera, designed to look for it. The camera will consist of five massive lenses, with the largest at one meter in diameter, making it one of the biggest lenses in the world. A milestone was reached in the construction of this camera, as the pieces of glass for these unique lenses, seen in the image here, are ready to be shaped and polished into their final form.

The Dark Energy Survey (DES) camera will map 300 million galaxies using the Blanco 4-meter telescope – a large telescope with new advanced optics at Chile’s Cerro Tololo Inter-American Observatory. This instrument will consist of an extremely red sensitive 500 Megapixel camera, with a 1 meter diameter, 2.2 degree field of view prime focus corrector, and a data acquisition system fast enough to take images in 17 seconds.

Creating this huge map of the galaxy will enable astronomers to measure the dark energy far more precisely than current observations. Professor Ofer Lahav, who leads the United Kingdom DES Consortium said, “Dark Energy is one of the biggest puzzles in the whole of Physics, going back to a concept proposed by Einstein 90 years ago. The DES observations will tell us if Einstein was right or if we need a major shift in our understanding of the universe.”

The glass for the five lenses was manufactured in the US. In France the lenses will be polished to a smoothness level of one millionth of a centimeter.

After, polishing, the lenses will be sent to the telescope in Chile. Observations are scheduled to begin in 2011, continuing until 2016.

The team’s goals are to extract cosmological information on dark energy from counting galaxy clusters and the spatial distribution of clusters, and measuring the redshift of galaxies and supernovae.

The Science and Technology Facilities Council (STFC) is providing support for the Dark Energy Survey (DES) collaboration, which involves over 100 scientists from the US, UK, Spain and Brazil.

Orignal news sources: Science and Technology Facilities Council, Dark Energy Survey

Posted on by Nancy Atkinson

Unusual Galaxies Eat Their Neighbors

Seyfert galaxies appear to be normal spiral galaxies, but they have fluctuating bright centers. And now, their deep-down, hidden nature has been revealed: they are cannibals. While visible-light images didn’t provide much evidence that these galaxies had any interaction with their neighbors, radio-telescope images from the Very Large Array revealed that Seyfert galaxies are snacking on neighboring galaxies, with the “meal” feeding the supermassive black hole at their centers. Astronomers had suspected this was the case, but until now, they didn’t have the evidence to support the idea.

One leading theory said that the fluctuations seen in Seyfert galaxies’ centers were caused by close encounters with neighboring galaxies. The gravitational encounters stirred up gas from the neighboring galaxies and brought it within reach of the black hole. However, when astronomers looked at Seyferts with visible-light telescopes, only a small fraction showed any evidence of such an encounter. Now, new images of hydrogen gas in Seyferts made using the National Science Foundation’s Very Large Array (VLA) radio telescope show the majority of them are, in fact, disturbed by ongoing encounters with neighbor galaxies.

“The VLA lifted the veil on what’s really happening with these galaxies,” said Cheng-Yu Kuo, a graduate student at the University of Virginia. “Looking at the gas in these galaxies clearly showed that they are snacking on their neighbors. This is a dramatic contrast with their appearance in visible starlight,” he added.

The effect of the galactic encounters is to send gas and dust toward the black hole and produce energy as the material ultimately is consumed. Black holes, concentrations of matter so dense that not even light can escape their gravitational pull, reside at the cores of many galaxies. Depending on how rapidly the black hole is eating, the galaxy can show a wide range of energetic activity. Seyfert galaxies have the mildest version of this activity, while quasars and blazars are hundreds of times more powerful.

The astronomers picked a number of relatively nearby Seyfert galaxies that had previously been observed with visible-light telescopes. They then carefully studied the Seyferts with the VLA, specifically looking for radio waves emitted by hydrogen atoms. The VLA images showed the vast majority of the Seyferts were disturbed by encounters with neighbor galaxies.

By comparison, similar VLA images of inactive galaxies showed that very few were disturbed. “This comparison clearly shows a connection between close galactic encounters and the black-hole-powered activity in the cores,” said Ya-Wen Tang, who began this work at the Institute of Astronomy & Astrophysics, Academia Sinica (ASIAA), in Taiwan and now is a graduate student at the National Taiwan University.

“This is the best evidence yet for the fueling of Seyfert galaxies. Other mechanisms have been proposed, but they have shown little if any difference between Seyferts and inactive galaxies,” Tang added.

Original News Source: National Radio Astronomy Observatory

Posted on by Nancy Atkinson

Rare Binary Pulsars Provide High Energy Physics Lab

For the first time, a spacecraft has detected signals from both stars of a binary pulsar system in X-rays. XMM-Newton is watching both stars radiate pulsating X-rays, providing scientist with the perfect laboratory for high energy physics and a never-ending source of intriguing physical problems. The binary pulsar PSR J0737-3039 was first spotted by astronomers in 2003 in radio wavelengths, but now X-rays can be used to investigate this system in greater detail.

Binary pulsars are extremely rare. Each star of the closely-packed system is a dense neutron star, spinning extremely fast, radiating X-rays in pulses. One pulsar (B) rotates slowly, what scientists call a ‘lazy’ neutron star, while orbiting a faster and more energetic companion (pulsar A).

Each pulsar or neutron star once existed as a massive star. “These stars are so dense that one cup of neutron star-stuff would outweigh Mt. Everest,” says Alberto Pellizzoni, who has been studying this system. “Add to that the fact that the two stars are orbiting really close to each other, separated by only 3 light-seconds, about three times the distance between Earth and the Moon.”

Pellizzoni added, “One cup of neutron star-stuff would outweigh Mt. Everest. Add to that the fact that they’re orbiting really close, separated by only about three times the distance between Earth and the Moon.”

Pulsar B is an oddity, in that it is very different from a ‘normal’ pulsar. Additionally, the amount of X-rays coming from the system is greater that the scientists predicted. But how the two pulsars work together is still not understood.

“One possible solution for the mystery could be mutual interaction between the two stars, where the lazy star derives energy from the other,” says Pellizzoni.

Watch video of how the two pulsars may interact

The fundamental physical processes involved in these extreme interactions are a matter of debate among theoretical physicists. But now, with XMM-Newton’s observations, scientists have gained new insight, providing a new experimental setting for them. In X-rays, it will be possible to study the subsurface and magnetospheres of the stars as well as the interaction between the two in that close, heated environment.

This system also provides the study of strong-field gravity, given how close and dense the two stars are. Future tests of general relativity by radio observations of this system will supersede the best Solar System tests available. It is also a unique laboratory for studies in several other fields, ranging from the equation of state of super-dense matter to magneto-hydro dynamics.

Original News Source: ESA

Posted on by Nancy Atkinson

Are the Laws of Nature the Same Everywhere in the Universe?

Although we haven’t figured out everything in the universe by a long shot, we’re getting a pretty good a handle on how things work in our world, and how the laws of nature operate here at home. One big question we have is, would laws of nature as we know them function the same at other locations in the universe? A new study says, yes. Research conducted by an international team of astronomers shows that one of the most important numbers in physics theory, the proton-electron mass ratio, is almost exactly the same in a galaxy 6 billion light years away as it is in Earth’s laboratories, approximately 1836.15.

According to Michael Murphy, Swinburne astrophysicist and lead author of the study, it is an important finding, as many scientists debate whether the laws of nature may change at different times and in different places in the Universe. “We have been able to show that the laws of physics are the same in this galaxy half way across the visible Universe as they are here on Earth,” he said.

The astronomers determined this by effectively looking back in time at a distant quasar, labeled B0218+367. The quasar’s light, which took 7.5 billion years to reach us, was partially absorbed by ammonia gas in an intervening galaxy. Not only is ammonia useful in most bathroom cleaning products, it is also an ideal molecule to test our understanding of physics in the distant Universe. Spectroscopic observations of the ammonia molecule were performed with the Effelsberg 100m radio telescope at 2 cm wavelength (red-shifted from the original wavelength of 1.3 cm). The wavelengths at which ammonia absorbs radio energy from the quasar are sensitive to this special nuclear physics number, the proton-electron mass ratio.

“By comparing the ammonia absorption with that of other molecules, we were able to determine the value of the proton-electron mass ratio in this galaxy, and confirm that it is the same as it is on Earth,” says Christian Henkel from the Max Planck Institute for Radio Astronomy in Bonn, Germany, an expert for molecular spectroscopy and co-author of the study.

Their research was published in the journal Science.

Original News Source: Max Planck Institute

Posted on by Nancy Atkinson

Phoenix Press Conference Update: Proof of Water Ice

Phoenix’s scientific team team held a press conference today to officially make their big announcement, which was fairly evident from pictures on the Phoenix website late yesterday: They found what they have been looking for. “It is with great pride and lot of joy that announce today we have found the proof that we have been seeking that show that this hard, white material is water ice,” said the project’s principle investigator Peter Smith. The image here shows a trench dug by Phoenix’s robotic arm scoop that exposed a white area, and left a couple of small chunks of white material, which scientists thought could possibly be ice. A few days later, the ice is gone. “In the course of sitting through the cold and very dry Martian environment for several days, it sublimated,” said Mark Lemmon, co-investigator on the Phoenix’s Surface Stero Imager. “The ice went away into vapor without any melting taking place.” But how do the scientists know for sure this is water ice?

“We can easily and confidently rule out that its carbon dioxide ice,” said Lemmon. “There are certainly times of the year that there would be CO2 ice at this location but with the temperatures we are measuring there, it would be the equivalent of water ice existing on Earth at 140 degrees. It wouldn’t be there very long, and wouldn’t be there long enough for us to take its picture, and it wouldn’t last the night. We’re very confident this is not CO2 ice. We’re ruling out salt, because salt doesn’t react like this. We’re confident now that this is water ice. We’ve hit what we’re looking for. The job now is to find out what is mixed in with the ice, how much salt is there, how many organics are there, and these are the things we’ll need TEGA and MECA to solve.”

TEGA is the Thermal and Evolved Gas Analyzer that “bakes and sniffs” out the chemical composition of the soil, and MECA is Microscopy, Electrochemistry and Conductivity Analyzer, a wet chemistry lab that measures levels of acidity, minerals, and conductivity in dirt samples.

Smith said the landing site was carefully chosen as a place where ice was very likely to exist, based on subsurface hydrogen detected by the orbiting 2001 Mars Odyssey spacecraft.

The team is now going to look for two things associated with the ice. “Does the ice melt, and does the melted ice environment allow a habitable zone on Mars,” said Smith. “That is a place where organic material and energy sources combined with liquid water can be a habitat for Martian life. We don’t have instruments that detect life itself. We’re looking at this stage for habitability, and it will be future missions that will look for life.”

The trick now is to get some of this white material into the TEGA instrument ovens before it sublimates. “The plan for sampling the ice is to gather it up rather quickly using the power tool called the Rasp and deliver it to the TEGA within 30 minutes,” said Ray Arvidson of the Phoenix team. The TEGA ovens do have airtight seal so it’s possible that the ice could go to a liquid stage while being heated. However, because of Mars low surface pressure, the boiling point of water on Mars is 4 Celsius.
Now that they know the ice is there, the scientists want to know more about the soil and why it seems to have a sticky, clumpy consistency. “Knowing that this is ice here, it allows you to speculate there are certain salts that mixed with ice can melt at low temperatures” said Smith. It’s very tempting to get a sample of this into MECA as soon as we can. Right now we have some speculations but no real interpretations available yet. I truly believe we will have answers for you by the end of the summer and hopefully earlier, so stick with us.”

The robotic arm is now digging in a new area in the trench called Snow White. They’ve dug a double trench and have hit a hard layer of ice. The team will try other techniques to see how hard the ice is, and how deep it goes, and try to dig down deeper. They will take their time, however, to make sure the sequences they use for the scraper and rasper work correctly (so as not to repeat having delays similar to what happened the first time they tried getting the soil into TEGA.)

Project manager Barry Goldman also said that the problem with Phoenix’s memory is understood, and two software patches being created to solve the problem of that used up all the space on Phoenix’s version of a flash drive.

Source: Phoenix Press Conference

Posted on by Nancy Atkinson

New Satellite Will Monitor Rising Oceans

A Delta 2 rocket blasted off early this morning at 3:46 a.m. EDT bringing the Ocean Surface Topography Mission-Jason 2 into Earth orbit. The satellite will use a radar altimeter to precisely measure the height of ocean surfaces, which have been rising in recent years because of increasing temperatures. The data will be used to monitor effects of climate change on sea level and to improve global weather, climate and ocean forecasts. NASA said the new satellite, which is a cooperative effort between the US and France, will also improve hurricane forecasting.

“Global warming is causing the oceans to rise at a rate of about 3 millimeters per year, and this is a direct result of increasing the temperature of the atmosphere,” said Josh Willis an oceanographer from JPL. “That causes glaciers and ice sheets to melt, raising the levels of the ocean. But also, the ocean itself absorbs heat. And when that happens, again the water expands, stands a little taller, and this causes sea level rise as well, so the altimeter on OSTM, or Jason 2, will see both of these effects at it circles the Earth.”

Similar observations began in 1992 with a spacecraft dubbed TOPEX/Poseidon and have continued with the current Jason 1 satellite. The two Jasons will fly in tandem.

Together with Jason 1, the two spacecraft will double global data coverage. This tandem mission will improve our knowledge of tides in coastal and shallow seas and internal tides in the open ocean, while improving our understanding of ocean currents and eddies.

Jason 2 will map the sea surface highs and lows every 10 days, tracking changes and helping scientists keep tabs on climate, and even weather.

Measurements of sea-surface height, or ocean surface topography, reveal the speed and direction of ocean currents and tell scientists how much of the sun’s energy is stored by the ocean. Combining ocean current and heat storage data is key to understanding global climate variations.

OSTM/Jason 2’s five primary instruments are improved versions of those flying on Jason 1. These technological advances will allow scientists to monitor conditions in ocean coastal regions — home to about half of Earth’s population. Compared with Jason 1 measurements, OSTM/Jason 2 will have substantially increased accuracy and provide data to within 25 kilometers (15 miles) of coastlines, nearly 50 percent closer to shore than in the past. Such improvements will be welcome news for all those making their living on the sea, from sailors and fishermen to workers in offshore industries. NOAA will use the improved data to better predict hurricane intensity, which is directly affected by the amount of heat stored in the upper ocean.

Sources: NASA, JPL

Posted on by Nancy Atkinson

Phoenix: “It Must Be Ice”

Phoenix scientists have been keeping an eye on the white material uncovered in a trench dug by the lander’s scoop. Dice-size nuggets of the bright material have vanished, convincing scientists the material was frozen water that vaporized after digging exposed it. The image here is a “movie” showing the material disappearing after four days. “It must be ice,” said Phoenix Principal Investigator Peter Smith. “These little clumps completely disappearing over the course of a few days, that is perfect evidence that it’s ice. There had been some question whether the bright material was salt. Salt can’t do that.”

The chunks were found at the bottom of a trench informally called “Dodo-Goldilocks” when Phoenix’s Robotic Arm enlarged that trench on June 15, during the 20th Martian day, or sol, since landing. Several were gone when Phoenix looked at the trench early today, on Sol 24.

“We know the ice is H2O but that doesn’t tell us much,” Smith said. “It is the impurities in the ice and the soil above the ice that tell us the history and if it is a habitable environment. We’ll now proceed to get the secrets out of the ice and use our instruments.”

Also on Thursday engineers said while digging in a different trench, the Robotic Arm connected with a hard surface that has scientists excited about the prospect of next uncovering an icy layer. Ray Arvidson, co-investigator for the robotic arm, said the hard layer was at the same depth as the ice layer in our the Dodo-Goldilocks trench.

The new trench, called “Snow White 2” trench, is in the middle of a polygon at the “Wonderland” site. While digging, the Robotic Arm came upon a firm layer, and after three attempts to dig further, the arm went into a holding position. Such an action is expected when the Robotic Arm comes upon a hard surface.

The Phoenix science team spent also Thursday analyzing new images and data successfully returned from the lander earlier in the day.

Meanwhile, Phoenix apparently suffered a problem with its flash memory on Tuesday, similar to, but not as serious as the problem that the Spirit Mars Exploration Rover encountered about 20 days after it landed on Mars back in 2004. The spacecraft team at Lockheed Martin Space Systems in Denver is preparing a software patch to send to Phoenix so scientific data can again be saved onboard overnight when needed. Because of a large amount a duplicative file-maintenance data generated by the spacecraft Tuesday, the team is taking the precaution of not storing science data in Phoenix’s flash memory, and instead downlinking it at the end of every day, until the conditions that produced those duplicative data files are corrected.

“We now understand what happened, and we can fix it with a software patch,” said Phoenix Project Manager Barry Goldstein of NASA’s Jet Propulsion Laboratory, Pasadena. “Our three-month schedule has 30 days of margin for contingencies like this, and we have used only one contingency day out of 24 sols. The mission is well ahead of schedule. We are making excellent progress toward full mission success.”

The Phoenix team will hold a press conference today (Friday) at 1:00 pm EST to discuss the latest findings.

Sources: Phoenix News
 The Tucson Citizen

Posted on by Nancy Atkinson

New Instrument Could Reconstruct Planetary and Moon Origins

Image courtesy Joe Tucciarone
One of the leading theories for how our Moon formed is the Giant Impactor Theory, which proposes a small planet about the size of Mars struck Earth early in our solar system’s formation, ejecting large volumes of heated material from the outer layers of both objects. This formed a disk of orbiting material which eventually stuck together to form the Moon. Until now there’s been no way to actually test this theory. But a new instrument that closely examines iron isotopes could possibly shed insight into the origin of the moon, as well as how Earth and the other terrestrial planets formed.

The new instrument, a plasma source mass spectrometer separates ions (charged particles) according to their masses and allows for a close examination of iron isotopes. Looking at the slight variations iron displays at the subatomic level can tell planetary scientists more about the formation of crust than previously thought, according to Nicolas Dauphas from the University of Chicago, Fang-Zhen Teng of the University of Arkansas and Rosalind T. Helz of the U.S. Geological Survey who co-authored a paper that will be published in the journal Science.

Their findings contradicts the widely held view that isotopic variations occur only at relatively low temperatures, and only in lighter elements, such as oxygen. But Dauphas and his associates were able to measure isotopic variations as they occur in magma at temperatures of 1,100 degrees Celsius (2,012 degrees Fahrenheit).

Previous studies of basalt found little or no separation of iron isotopes, but those studies focused on the rock as a whole, rather than its individual minerals. “We analyzed not only the whole rocks, but the separate minerals,” Teng said. In particular, they analyzed olivine crystals.

Inside the instrument, the ions are formed in a plasma of argon gas at a temperature of nearly 14,000 degrees Fahrenheit (8,000 degrees Kelvin, hotter than the sun’s surface).

The instrument was tested on the lava of Kilauea Iki crater in Hawaii.

If applied to a variety of terrestrial and extraterrestrial basalts, including moon rocks, meteorites from Mars and the asteroids, the method could provide more definitive evidence for a the Giant Impactor Theory, and provide clues the formation of Earth’s continents, and could potentially tell us more about how other planetary bodies formed.

“Our work opens up exciting avenues of research,” Dauphas said. “We can now use iron isotopes as fingerprints of magma formation and differentiation, which played a role in the formation of continents.”

Original News Source: PhysOrg

Posted on by Nancy Atkinson

Another “Where In The Universe” Challenge

Here’s this week’s ‘Where In The Universe’ challenge. I have a soft spot in my heart for craters. And the crater pictured here is one of the most gorgeous examples of a crater you’ll see. But just where in the solar system is this crater? When I worked at a science museum, one of the first activities I ever did with children was to make craters. Just take a small tub, put in a few cups of flour and sprinkle cocoa powder on top. Then let the kids lose with impactors of all sizes and have them drop them (from the same height at first) and let them observe the parts of a crater (the rim, ejecta, rays, and sometimes even the step-like features on the walls). The kids loved this activity (you get to throw things and make a mess), but they also learned a lot about craters and how craters can provide information about the history of a planet or moon. So, back to the image, and “A crater I may contemplate” (see the source of that quote below after you’ve made your guess). Is this crater on a planet or a moon, and which one?

This crater is on Venus, and is named Dickinson Crater. This crater is 69 kilometers (43 miles) in diameter, and located in the northeastern Atalanta Region of Venus at 74.6 degrees north latitude and 177.2 east longitude. This crater is quite complex, characterized by a floor with alternating dark and bright materials. Rough but bright ejecta extend all around the crater, except to the west,which may indicate that the impactor that produced the crater came from the west. Extensive radar-bright flows that emanate from the crater’s eastern walls may represent large volumes of impact melt, or they may be the result of volcanic material released from the subsurface during the cratering event.

The crater was named after Emily Dickinson, an American poet, who wrote a poem about volcanoes and craters:

Volcanoes be in Sicily
And South America,
I judge from my geography.
Volcanoes nearer here,
A lava step, at any time,
Am I inclined to climb,
A crater I may contemplate,
Vesuvius at home.

Emily Dickinson, ‘Volcanoes be in Sicily’, from The Single Hound: Poems of a Lifetime (Boston: Little, Brown, 1914), p. 125.

How’d you do?

Full size image from NASA Photojournal

Posted on by Nancy Atkinson

Identical Twin Stars Not So Identical

I’m lucky enough to have twin sons. They aren’t identical (one looks like me, the other looks like my husband – which is about as different as things get) but they have a lot of similarities. One of my favorite stories about having twins is the time we took the whole family out to a restaurant shortly after the twins were born. The waitress commented that our babies looked the same size, and we said, “Yes, they’re twins.” And she replied, “Oh really? How far apart in age are they?”

I used to think that waitress was a real ditz, but after seeing a press release today from Vanderbilt University, I’m wondering if the waitress was on to something, and maybe she was even an astronomer.

Astronomers recently found a very young pair of identical binary stars that have surprising differences in brightness, surface temperature and size. They also believe one of the stars formed significantly earlier than its twin. Astrophysicists have assumed that binary stars form simultaneously, and so this discovery forces theorists back to the drawing board to determine if their models can produce binaries with stars that form at different times.

The identical twins were discovered in the Orion Nebula, a well-known stellar nursery, 1,500 light years from Earth. The newly formed stars are about 1 million years old. With a full lifespan of about 50 billion years, that makes them equivalent to one-day-old human babies.

“Very young eclipsing binaries like this are the Rosetta stones that tell us about the life history of newly formed stars,” says Keivan Stassun, associate professor of astronomy at Vanderbilt University. He and Robert D. Mathieu from the University of Wisconsin-Madison headed up the project.

The astronomers calculated that these twin stars have nearly identical masses, about 41 percent that of the sun. According to current theories, mass and composition are the two factors that determine a star’s physical characteristics and dictate its entire life cycle. Because the two stars condensed from the same cloud of gas and dust they should have the same composition. And with identical mass and composition, they should be identical in every way. So the astronomers were surprised when they discovered that the twins exhibited significant differences in brightness, surface temperature and possibly size.

“The easiest way to explain these differences is if one star was formed about 500,000 years before its twin,” says Stassun. “That is equivalent to a human birth-order difference of about half of a day.”

Now, I have heard stories of twins being born several hours apart and even in different years (one late on Dec. 31, and the other early on Jan. 1) so, maybe this difference in star formation isn’t such a big deal, and it happens all the time. However, further study is needed.

But this new discovery may cause astronomers to readjust their estimates of the masses and ages of thousands of young stars less than a few million years old, as current estimates are based on models that presumed binary stars formed simultaneously.

Just like having twins causes you to readjust your entire life. But it’s a good readjustment.

Original News Source: Vanderbilt University (this link includes a nice multimedia presentation about the discovery)