Glory Launch Gets Another Go


NASA will try again to launch its “climate change satellite” on Friday, following an attempt that was scrubbed on Feb. 23 due to technical issues with ground support equipment for the Taurus XL launch vehicle, shown at right.

The March 4 liftoff is targeted for just after 2 a.m. local time at the Vandenberg Air Force Base in California (5:09:43 a.m. eastern).

Two instruments aboard Glory will help address influences on Earth’s climate. The Total Irradiance Monitor led by Greg Kopp at the Boulder, Colorado-based Laboratory for Atmospheric and Space Physics will continue a decades-long measurement of the sun’s energy reaching Earth, and Raytheon’s Aerosol Polarimetry Sensor will track aerosols in Earth’s atmosphere. See a more detailed story about the mission.

NASA will stream coverage of the launch starting at 3:30 a.m. eastern time on March 4. Real-time updates of countdown and launch milestones will also be posted on NASA’s launch blog.

Source: NASA announcement via Eurekalert!

Dusty Neighbor NGC 247 is a Million Light-Years Closer Than Thought


One of our celestial neighbors, the spiral galaxy NGC 247, just moved about a million light-years closer.

Well, not really. But astronomers are retooling estimates of the distance to it, which was overestimated in the past partly because of the nearly edge-on tilt, shown above. The just-released image, from the Wide Field Imager on the MPG/ESO 2.2-metre telescope in Chile, shows large numbers of the galaxy’s component stars and glowing pink clouds of hydrogen, marking regions of active star formation, in the loose and ragged spiral arms. Numerous other galaxies can be seen in the distance.

Through a moderate-sized amateur telescope, the Cetus galaxy appears large but dim, and is seen best in a dark sky. Credit: ESO, IAU and Sky & Telescope

NGC 247 (RA 00h 47′ 14″  – 20deg 52′ 04″) is one of the closest spiral galaxies of the southern sky, now believed to lie about 11 million light-years away in the constellation Cetus (The Whale). It’s part of the Sculptor Group, a collection of galaxies associated with the Sculptor Galaxy (NGC 253, shown in previous releases here and here). This is the nearest group of galaxies to our Local Group, which includes the Milky Way.

To measure the distance from the Earth to a nearby galaxy, astronomers have to rely on a type of variable star called a Cepheid to act as a distance marker. Cepheids are very luminous stars, whose brightness varies at regular intervals. The time taken for the star to brighten and fade can be plugged into a simple mathematical relation that gives its intrinsic brightness. When compared with the measured brightness this gives the distance. However, this method isn’t foolproof, as astronomers think this period–luminosity relationship depends on the composition of the Cepheid.

Another problem arises from the fact that some of the light from a Cepheid may be absorbed by dust en route to Earth, making it appear fainter, and therefore further away than it really is. This is a particular problem for NGC 247 with its highly inclined orientation, as the line of sight to the Cepheids passes through the galaxy’s dusty disc.

However, a team of astronomers is currently looking into the factors that influence these celestial distance markers in a study called the Araucaria Project. The team has already reported that NGC 247 is more than a million light-years closer to the Milky Way than was previously thought, bringing its distance down to just over 11 million light-years.

More information about the lead image: It was created from a large number of monochrome exposures taken through blue, yellow/green and red filters taken over many years. In addition, exposures through a filter that isolates the glow from hydrogen gas have also been included and colored red. The total exposure time per filter was 20 hours, 19 hours, 25 minutes and 35 minutes, respectively.

Source: ESO press release. The paper appears here. See also the website for the Araucaria Project.

Meteorites May Have Delivered First Ammonia for Life on Earth

Researchers have teased ammonia of a carbon-containing meteorite from Antarctica, and propose that meteorites may have delivered that essential ingredient for life to an early Earth.

The results appear today in the Proceedings of the National Academy of Sciences, and add to a growing body of evidence that meteorites may have played a key role in the development of life here. The NASA graphic at left was released just last month, when researchers reported that meteorites may have also delivered Earth’s first left-hand amino acids.

A Renazzo stony meteorite. Credit: NASA

Lead author Sandra Pizzarello, of Arizona State University, and her colleagues note in the new paper that carbonaceous chondrites are asteroidal meteorites known to contain abundant organic materials.

“Given that meteorites and comets have reached the Earth since it formed, it has been proposed that the exogenous influx from these bodies provided the organic inventories necessary for the emergence of life,” they write.

The carbonaceous meteorites of the Renazzo-type family (CR) are known to be especially rich in small soluble organic molecules, such as the amino acids glycine and alanine. To test for the presence of ammonia, the researchers collected powder from the much-studied CR2 Grave Nunataks (GRA) 95229 meteorite and treated it with water at high temperature and pressure. They found that the treated powders emitted ammonia, NH4, an important precursor to complex biological molecules such as amino acids and DNA, into the surrounding water.

Next, the researchers analyzed the nitrogen atoms within the ammonia and determined that the atomic isotope did not match those currently found on Earth, eliminating the possibility that the ammonia resulted from contamination during the experiment. Researchers have struggled to pinpoint the origin of the ammonia responsible for triggering the formation of the first biomolecules on early Earth. The authors suggest that now, they may have found it.

“The findings appear to trace CR2 meteorites’ origin to cosmochemical regimes where ammonia was pervasive, and we speculate that their delivery to the early Earth could have fostered prebiotic molecular evolution,” they write.

Source: Pizzarello et al.Abundant ammonia in primitive asteroids and the case for a possible exobiology.

Meteorites Illuminate Mystery of Chromium in Earth’s Core

It’s generally assumed that the Earth’s overall composition is similar to that of chondritic meteorites, the primitive, undifferentiated building blocks of the solar system. But a new study in Science Express led by Frederic Moynier, of the University of California at Davis, seems to suggest that Earth is a bit of an oddball.



Thin section of a chondritic meteorite. Credit: NASA

Moynier and his colleagues analyzed the isotope signature of chromium in a variety of meteorites, and found that it differed from chromium’s signature in the mantle.

“We show through high-precision measurements of Cr stable isotopes in a range of meteorites, which deviate by up to ~0.4‰ from the bulk silicate Earth, that Cr depletion resulted from its partitioning into Earth’s core with a preferential enrichment in light isotopes,” the authors write. “Ab-initio calculations suggest that the isotopic signature was established at mid-mantle magma ocean depth as Earth accreted planetary embryos and progressively became more oxidized.”

Chromium’s origins. New evidence suggests that, in the early solar nebula (A), chromium isotopes were divided into two components, one containing light isotopes, the other heavy isotopes. In the early Earth (B), these components formed a homogeneous mixture. During core partitioning (C), the core became enriched with lighter chromium isotopes, and the mantle with heavier isotopes. Courtesy of Science/AAAS

The results point to a process known as “core partitioning,” rather than an alternative process involving the volatilization of certain chromium isotopes so that they would have escaped from the Earth’s mantle. Core partitioning took place early on Earth at high temperatures, when the core separated from the silicate earth, leaving the core with a distinct composition that is enriched with lighter chromium isotopes, notes William McDonough, from the University of Maryland at College Park, in an accompanying Perspective piece.

McDonough writes that chromium, Earth’s 10th most abundant element, is named for the Greek word for color and “adds green to emeralds, red to rubies, brilliance to plated metals, and corrosion-proof quality to stainless steels.” It is distributed roughly equally throughout the planet.

He says the new result “adds another investigative tool for understanding and documenting past and present planetary processes. For the cosmochemistry and meteoritics communities, the findings further bolster the view that the solar nebula was a heterogeneous mixture of different components.”

Source: Science. The McDonough paper will be published online today by the journal Science, at the Science Express website.

T Chamaeleon Gets Caught in the Act — Forming Planets, That Is


An international team of astronomers peering at a young star in the constellation Chamaeleon have detected a smaller companion — a dust-shrouded brown dwarf, or perhaps a planet — that appears to be carving out a large gap in the stellar disk. The discovery is a first: Although planets have been spotted before in more mature disks, this is the first detection of a planet-sized object in the disk around a young star.

Planets form from the disks of material around young stars, but the transition from dust disk to planetary system is rapid and few objects are caught during this phase. Astronomers are getting ever closer to glimpsing the births of planets, though — today’s announcement comes on the heels of a discovery last week using the Subaru Telescope in Hawaii, of a stellar disk around the star LkCa 15 similar in size to our own solar system, featuring rings and gaps possibly associated with the formation of giant planets.

T Chamaeleontis (RA 1h 04m 09.131s dec -76° 27′ 19.30″), T Cha for short, is a faint, young but sun-like star in the small southern constellation of Chamaeleon, about 350 light-years from Earth. T Cha is about seven million years old.

This chart shows the location of the young star T Cha within the constellation of Chamaeleon. The map shows most of the stars visible to the unaided eye under good conditions and the star itself is marked as a red circle. This star is too faint to see with the unaided eye, but is easily seen with a small telescope. Credit: ESO, IAU and Sky & Telescope

“Earlier studies had shown that T Cha was an excellent target for studying how planetary systems form,” said Johan Olofsson of the Max Planck Institute for Astronomy in Heidelberg, Germany, one of the lead authors of two related papers in the journal Astronomy & Astrophysics. “But this star is quite distant and the full power of the Very Large Telescope Interferometer was needed to resolve very fine details and see what is going on in the dust disk.”

The astronomers first observed T Cha using the AMBER instrument and the VLT Interferometer (VLTI). They found that some of the disk material formed a narrow dusty ring only about 20 million kilometers (12.4 million miles) from the star. Beyond this inner disk, they found a region devoid of dust with the outer part of the disk stretching out into regions beyond about 1.1 billion kilometers (683.5 million miles) from the star.

The ESO Very Large Telescope. Credit: ESO/G. Lombardi

“For us the gap in the dust disk around T Cha was a smoking gun,” said Nuria Huélamo, of the Centro de Astrobiología, ESAC in Spain, lead author of the second paper, “and we asked ourselves: could we be witnessing a companion digging a gap inside its protoplanetary disk?”

After further analysis, the team found the clear signature of an object located within the gap in the dust disk, about one billion kilometers, or 621 million miles, from the star — slightly further out than Jupiter is from our own sun.

The astronomers searched for the companion using NACO in two different spectral bands — at around 2.2 microns and 3.8 microns. The companion is only seen at the longer wavelength, which means that the object is either cool, like a planet, or a dust-shrouded brown dwarf.

Huélamo said he hopes future observations will reveal more about the companion and the disk, and explain what fuels the inner dusty disk.

Source: ESO press release. This research is presented in two papers to appear in the journal Astronomy & Astrophysics: Olofsson et al. 2011, “Warm dust resolved in the cold disk around TCha with VLTI/AMBER,” and Huélamo et al. 2011, “A companion candidate in the gap of the T Cha transitional disk.”

Close Look at Cas A Reveals Bizarre ‘Superfluid’


NASA’s Chandra X-ray Observatory has discovered the first direct evidence for a superfluid, a bizarre, friction-free state of matter, at the core of a neutron star.

The image above, released today, shows X-rays from Chandra (red, green, and blue) and optical data from Hubble (gold) of Cassiopeia A, the remains of a massive star that exploded in a supernova. The evidence for superfluid has been found in the dense core of the star left behind, a so-called neutron star. The artist’s illustration in the inset shows a cut-out of the interior of the neutron star, where densities increase from the orange crust to the red core and finally to the inner red ball, the region where the superfluid exists.

Superfluids created in laboratories on Earth exhibit remarkable properties, such as the ability to climb upward and escape airtight containers. When they’re made of charged particles, superfluids are also superconductors, and they allow electric current to flow with no resistance. Such materials on Earth have widespread technological applications like producing the superconducting magnets used for magnetic resonance imaging [MRI].

Two independent research teams have used Chandra data to show that the interior of a neutron star contains superfluid and superconducting matter, a conclusion with important implications for understanding nuclear interactions in matter at the highest known densities. The teams publish their research separately in the journals Monthly Notices of the Royal Astronomical Society Letters and Physical Review Letters.

Cas A (RA 23h 23m 26.7s | Dec +58° 49′ 03.00) lies about 11,000 light-years away. Its star exploded about 330 years ago in Earth’s time-frame. A sequence of Chandra observations of the neutron star shows that the now compact object has cooled by about 4 percent over a ten-year period.

“This drop in temperature, although it sounds small, was really dramatic and surprising to see,” said Dany Page of the National Autonomous University in Mexico, leader of one of the two teams. “This means that something unusual is happening within this neutron star.”

Neutron stars contain the densest known matter that is directly observable; one teaspoon of neutron star material weighs six billion tons. The pressure in the star’s core is so high that most of the charged particles, electrons and protons, merge — resulting in a star composed mostly of neutrons.

The new results strongly suggest that the remaining protons in the star’s core are in a superfluid state and, because they carry a charge, also form a superconductor.

Both teams show that the rapid cooling in Cas A is explained by the formation of a neutron superfluid in the core of the neutron star within about the last 100 years as seen from Earth. The rapid cooling is expected to continue for a few decades, and then it should slow down.

“It turns out that Cas A may be a gift from the Universe because we would have to catch a very young neutron star at just the right point in time,” said Page’s co-author Madappa Prakash, from Ohio University. “Sometimes a little good fortune can go a long way in science.”

The onset of superfluidity in materials on Earth occurs at extremely low temperatures near absolute zero, but in neutron stars, it can occur at temperatures near a billion degrees Celsius. Until now there was a very large uncertainty in estimates of this critical temperature. This new research constrains the critical temperature to between one half a billion to just under a billion degrees.

Cas A will allow researchers to test models of how the strong nuclear force, which binds subatomic particles, behaves in ultradense matter. These results are also important for understanding a range of behavior in neutron stars, including “glitches,” neutron star precession and pulsation, magnetar outbursts and the evolution of neutron star magnetic fields.

Sources: Press releases from the Royal Astronomical Society and Harvard. See additional multimedia at NASA’s Chandra page, and the two studies in MNRAS and Phys. Rev. Letters.



Halt, Black Hole! Gemini Captures Explosions That Deprive Black Holes of Mass


Astronomers have long suspected that something must stymie actively growing black holes, because most galaxies in the local universe don’t have them. Now, the Gemini Observatory has captured a galactic check-and-balance — a large-scale quasar outflow in the galaxy Markarian 231 that appears to be depriving a supermassive black hole its diet of gas and dust.

The work is a collaboration between David Rupke of Rhodes College in Tennessee and the University of Maryland’s Sylvain Veilleux. The results are to be published in the March 10 issue of The Astrophysical Journal Letters.

Markarian 231 (12h56’14.23″ +56d52’25.24″) is located about 600 million light-years away in the direction of the constellation of Ursa Major. Although its mass is uncertain, some estimates indicate that Mrk 231 has a mass in stars about three times that of the Milky Way, and its central black hole is estimated to have a mass of at least 10 million solar masses or also about three times that of the supermassive black hole in the Milky Way.

Theoretical modeling specifically points to quasar outflows as the counterbalance to black hole growth. In this negative feedback loop, while the black hole is actively acquiring mass as a quasar, the outflows carry away energy and material, suppressing further growth. Small-scale outflows had been observed before, but none sufficiently powerful to account for this predicted and fundamental aspect of galaxy evolution. The Gemini observations provide the first clear evidence for outflows powerful enough to support the process necessary to starve the galactic black hole and quench star formation by limiting the availability of new material.

This extraction from the data cube shows the large-scale, fast outflow of neutral sodium at the center of the quasar Markarian 231. We are looking down onto the material that moves toward us relative to the galaxy, so the measured velocities are negative. The large black circle marks the location of the black hole, and red lines show the location of a radio jet. In addition to the quasar outflow, the jet pushes the material at the top right, resulting in even greater speeds. Part of the starburst is located at the position of the box at the lower left, and it is likely responsible for the gas motion in this region.

Study author Veilleux says Mrk 231 is an ideal laboratory for studying outflows caused by feedback from supermassive black holes: “This object is arguably the closest and best example that we know of a big galaxy in the final stages of a violent merger and in the process of shedding its cocoon and revealing a very energetic central quasar. This is really a last gasp of this galaxy; the black hole is belching its next meals into oblivion!” As extreme as Mrk 231’s eating habits appear, Veilleux adds that they are probably not unique: “When we look deep into space and back in time, quasars like this one are seen in large numbers, and all of them may have gone through shedding events like the one we are witnessing in Mrk 231.”

Although Mrk 231 is extremely well studied, and known for its collimated jets, the Gemini observations exposed a broad outflow extending in all directions for at least 8,000 light-years around the galaxy’s core. The resulting data reveal gas (characterized by sodium, which absorbs yellow light) streaming away from the galaxy center at speeds of over 1,000 kilometers per second. At this speed, the gas could go from New York to Los Angeles in about 4 seconds. This outflow is removing gas from the nucleus at a prodigious rate — more than 2.5 times the star formation rate. The speeds observed eliminate stars as the possible “engine” fueling the outflow. This leaves the black hole itself as the most likely culprit, and it can easily account for the tremendous energy required.

The energy involved is sufficient to sweep away matter from the galaxy. However, “when we say the galaxy is being blown apart, we are only referring to the gas and dust in the galaxy,” notes Rupke. “The galaxy is mostly stars at this stage in its life, and the outflow has no effect on them. The crucial thing is that the fireworks of new star formation and black hole feeding are coming to an end, most likely as a result of this outflow.”

Source: Gemini press release. The paper appears here. See also some galactic merger animations, courtesy of the Harvard-Smithsonian Center for Astrophysics.

‘Climate Change Satellite’ Gets its Day in the Sun — Finally


NASA is launching an Earth-orbiting satellite called Glory tomorrow that will tackle a highly charged question: How much can the sun contribute to climate change?

The lull in solar activity between solar cycles 23 and 24 lasted for two years, twice as long as expected. By mid-2009, well into the second year, predictions of global cooling — another Little Ice Age — dominated global warming skeptic blogs. Now Solar Cycle 24 is safely underway, but aside from the dramatic flare and rash of sunspots that erupted last week, it’s been wimpy. Tom Woods, a solar physicist at the Boulder, Colo.-based Laboratory for Atmospheric and Space Physics, says he expects a subdued maximum for Solar Cycle 24 (around 2013) and generally, weak solar cycles come in threes. Each known set of sluggish solar cycles in the past has coincided with bitterly cold winters in parts of the globe — especially Europe and North America.

The question is, with the level of greenhouse gases in the atmosphere from the burning of fossil fuels, would we even feel an extended solar minimum? That’s exactly what Glory will aim to find out.

Glory will launch shortly after 2 a.m. local time on Wednesday, Feb. 23 from the Vandenberg Air Force Base north of Santa Barbara, Calif. The six-foot (1.9 meter), 1,100-pound (525 kg) satellite will orbit for at least three years in Earth’s upper atmosphere, where it will monitor both the total solar energy that’s reaching Earth, and the airborne aerosols greeting the energy it when it gets here.

Aerosols include salt, mineral dust, soot, and smoke and come from a variety of sources – such as vehicle exhaust, campfires, volcanoes and even desert winds and sea spray. They can influence climate by absorbing and scattering light, and NASA scientists have said the range of uncertainty about their role in climate change is far greater than any doubt about greenhouse gases from fossil fuels. Raytheon’s Aerosol Polarimetry Sensor, an instrument mounted on the Earth-facing side of the spacecraft, will observe the movement of aerosols through the atmosphere over time, especially on a seasonal scale.

Glory’s sun-facing side will sport the Total Irradiance Monitor, which will measure the intensity of solar radiation at the top of Earth’s atmosphere, adding to a 32-year data set, to record the solar radiation reaching Earth.

Watch a short video on the data: Solar Variability and Total Solar Irradiance (LASP)

Four solar irradiance instruments are currently flying, including VIRGO, launched in 1995, and SORCE, sent into orbit in 2003. Three of those, though, have long exceeded their designed mission lifetimes and are deteriorating. The European PICARD mission, launched in 2010, and NASA’s Glory mission are the new guard.

Greg Kopp, a researcher also at the Laboratory for Atmospheric and Space Physics, is principal investigator on the Glory mission. He says the existing data has already helped researchers understand variations on the scale of the sun’s 11-year activity cycles. But in order to capture longer trends, observations must continue. And solar researchers are increasingly eager to quantify the sun’s role, given the global importance of the question.

“I’m fond of saying we should get closer to the votersphere,” says Daniel Baker, director of Boulder’s Laboratory for Atmospheric and Space Physics. “I can think of no problem that is more significant to humanity than understanding climate change.”

Follow the mission:

On Feb. 23, NASA TV coverage of the countdown will begin at 3:30 a.m. EST (12:30 a.m. PST). Liftoff is targeted for 5:09:43 a.m. EST (2:09:43 a.m. PST). Spacecraft separation from the Taurus occurs 13 minutes after launch. The briefings and launch coverage also will be streamed online.

Launch coverage of Glory countdown activities will appear on NASA’s launch blog starting at 3:30 a.m. EST (12:30 a.m. PST). Real-time updates of countdown milestones as well as streaming video clips highlighting launch preparations and liftoff will also be available.

See also NASA’s Glory page and the Laboratory for Atmospheric and Space Physics, at the University of Colorado at Boulder.

Film Review: Nostalgia for the Light (in Atacama)


It’s difficult enough to imagine stark white telescope domes towering over a parched brown landscape made even more arid by the near-constant whistle of high-altitude winds. It’s stranger still to consider that in the desert below those domes, tough and grieving women have been searching in vain for decades for the sun-bleached remains of loved ones stolen from them, killed and dumped in the void by Pinochet’s army.

Acclaimed Chilean film director Patricio Guzmán has woven these stories together into a documentary called Nostalgia de la Luz, or Nostalgia for the Light, that is both touching and stunning, human and other-worldly, emotional — and hopeful.

The film played at the Toronto International Film Festival and at Cannes before lighting up a packed theater at 10 a.m. on a Sunday morning in Boulder, Colorado, a community with a special fondness for space science owing partly to the presence of the Laboratory for Atmospheric and Space Physics, Ball Aerospace, NOAA’s Space Weather Prediction Center and the Southwest Research Institute.

In fact Jason Glenn, an astronomer at the University of Colorado at Boulder, took the podium for a few moments before the start of the film to announce plans for the Cornell-Caltech-Atacama (CCAT) telescope proposed to go atop the Chilean mountain Cerro Chajnantor — and to request donations toward its construction. CCAT, a submillimeter telescope, will be used to probe primeval galaxies, star formation and extra-solar planetary systems.

The film opens with awe-inspiring images of galaxies, close-up views of the pockmarked lunar surface, and eerily beautiful shots of the vast Atacama. The desert lies west of the Andes Mountains in Chile, and is generally regarded as the driest place on Earth. That, plus its high altitude, make it a perfect place for astronomy. The Atacama supports the ESO’s Atacama Large Millimeter/submillimeter Array (ALMA), the Very Large Telescope (VLT) and numerous other instruments. Many Chileans, the film intimates, grow up loving astronomy.

Meanwhile the people of Chile continue to heal from Pinochet’s bloody rule beginning in the early 1970s, when thousands of his political opponents were taken from their families and disappeared. The film captures the perspectives of people on all sides of the tragedy — from the grieving mothers and wives, the archeologists working to decipher both the recent and distant human past, survivors of Pinochet’s concentration camps and even astronomers who, tucked in offices underneath the massive telescope domes, might not seem to have much in common with the grieving women. But they do.

Gaspar Galaz, an astronomer at the Pontifical Catholic University of Chile, says in the film that both he and the women pursue quests to learn history; they’re all chasing rare clues in dauntingly vast spaces. Galaz peers far across the cosmos to study diffuse galaxies, whose origins are unknown, and the women comb the 40,600 square mile (105,000 km2) desert for minute fragments of bone. The difference: At the end of his workday, Galaz says, he can get a good night’s sleep, “but these women must have trouble sleeping after they search for human remains.”

Nostalgia de la Luz is worth seeing for any of its parts — the glimpses through the powerful Atacama telescopes, the desert scenes, the cultural insights or the beautifully human and optimistic ending, which I won’t give away here. Taken together, the film’s elements are an experience not to be missed.

Several trailers for Nostalgia de la Luz are available on YouTube; upcoming showtimes include, according to Facebook, March 8 and 9 at the Wexner Center for the Arts in Columbus, Ohio, March 18 at the IFC Film Center in New York and April 22-28 at Landmark’s Nuart Theater in LA. Today’s showing was at the Boulder International Film Festival.

Continent-Wide Telescope Array Now Seeing 450 Million Light-Years Into Space


Kitt Peak. Los Alamos. St. Croix. Pie Town.

What do these places have in common? They each house one of 10 giant telescopes in the Very Large Baseline Array, a continent-spanning collection of telescopes that’s flexing its optical muscles, reaching farther into space — with more precision — than any other telescope in the world.

And today, at the 177th annual meeting of the American Association for the Advancement of Science in Washington, DC, VLBA researchers announced an amazing feat: They’ve used the VLBA to peer, with stunning accuracy, three times as far into the universe as they had just two years ago. New measurements with the VLBA have placed a galaxy called NGC 6264 (coordinates below) at a distance of 450 million light-years from Earth, with an uncertainty of no more than 9 percent. This is the farthest distance ever directly measured, surpassing a measurement of 160 million light-years to another galaxy in 2009.

VLBA telescope locations, courtesy of NRAO/AUI

Previously, distances beyond our own Galaxy have been estimated through indirect methods. But the direct seeing power of the VLBA scraps the need for assumptions, noted James Braatz, of the National Radio Astronomy Observatory.

The VLBA provides the greatest ability to see fine detail, called resolving power, of any telescope in the world. It can produce images hundreds of times more detailed than those from the Hubble Space Telescope, at a power equivalent to sitting in New York and reading a newspaper in Los Angeles. VLBA sites include Kitt Peak, Arizona; Los Alamos and Pie Town, New Mexico; St. Croix in the Virgin Islands, Mauna Kea, Hawaii; Brewster, Washington; Fort Davis, Texas; Hancock, New Hampshire; North Liberty, Iowa; and Owens Valley in California. Sure, I could include pictures of the scopes in Hawaii or the Virgin Islands. But Pie Town, besides hosting the Very Large Array, also has two fun restaurants (the Daily Pie and the Pie-O-Neer) with really amazing pie. And an annual pie-eating festival. So it wins:

The VLBA site at Pie Town, N.M., courtesy of NRAO/AUI.

Tripling the visible “yardstick” into space bears favorably on numerous areas of astrophysics, including determining the nature of dark energy, which constitutes 70 percent of the Universe. The VLBA is also redrawing the map of the Milky Way and is poised to yield tantalizing new information about extrasolar planets, the NRAO points out.

Fine-tuning the measurement of ever-greater distances is vital to determining the expansion rate of the Universe, which helps theorists narrow down possible explanations for the nature of dark energy. Different models of Dark Energy predict different values for the expansion rate, known as the Hubble Constant.

“Solving the Dark Energy problem requires advancing the precision of cosmic distance measurements, and we are working to refine our observations and extend our methods to more galaxies,” Braatz said. Measuring more-distant galaxies is vital, because the farther a galaxy is, the more of its motion is due to the expansion of the Universe rather than to random motions.

As for the map of our own galaxy, the direct VLBA measurements are improving on earlier estimates by as much as a factor of two. The clearer observations have already revealed the Milky Way has four spiral arms, not two as previously thought.

Mark Reid, of the Harvard-Smithsonian Center for Astrophysics led an earlier VLBA study revealing that the Milky Way is also rotating faster than previously believed — and that it’s as massive as Andromeda.

Reid’s team is now observing the Andromeda Galaxy in a long-term project to determine the direction and speed of its movement through space. “The standard prediction is that the Milky Way and Andromeda will collide in a few billion years. By measuring Andromeda’s actual motion, we can determine with much greater accuracy if and when that will happen,” Reid said.

The VLBA is also being used for a long-term, sensitive search of 30 stars to find the subtle gravitational tug that will reveal orbiting planets. That four-year program, started in 2007, is nearing its completion. The project uses the VLBA along with NRAO’s Green Bank Telescope in West Virginia, the largest fully-steerable dish antenna in the world. Early results have ruled out any companions the size of brown dwarfs for three of the stars, and the astronomers are analyzing their data as the observations continue.

Ongoing upgrades in electronics and computing have enhanced the VLBA’s capabilities. With improvements now nearing completion, the VLBA will be as much as 5,000 times more powerful as a scientific tool than the original VLBA of 1993.

NGC 6264 Coordinates, from DOCdb: 16<sup>h</sup> 57<sup>m</sup> 16.08<sup>s</sup>; +27° 50′ 58.9″

Source: A press release from the National Radio Astronomy Observatory, via the American Astronomical Society (AAS). Not to be confused with the American Association for the Advancement of Science (AAAS), which now conducting its annual meeting in Washington, DC — and where the VLBA results were presented.