Super-sharp radio 'eye' remeasuring the universe

Feb 19, 2011
Artist's conception of Milky Way, showing locations of star-forming regions whose distances were recently measured. CREDIT: M. Reid, Harvard-Smithsonian CfA; R. Hurt, SSC/JPL/Caltech, NRAO/AUI/NSF

(PhysOrg.com) -- Using the super-sharp radio "vision" of astronomy's most precise telescope, scientists have extended a directly-measured "yardstick" three times farther into the cosmos than ever before, an achievement with important implications for numerous areas of astrophysics, including determining the nature of Dark Energy, which constitutes 70 percent of the Universe. The continent-wide Very Long Baseline Array (VLBA) also is redrawing the map of our home Galaxy and is poised to yield tantalizing new information about extrasolar planets, among many other cutting-edge research projects.

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 -- power equivalent to sitting in New York and reading a newspaper in Los Angeles. This power allows astronomers to make precise cosmic measurements with far-ranging implications for research within our own Galaxy and far beyond.

New measurements with the VLBA have placed a galaxy called NGC 6264 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.

Previously, distances beyond our own Galaxy have been estimated through indirect methods. "Our direct, geometric measurements are independent of the assumptions and complications inherent in other techniques," said James Braatz, of the (NRAO), who worked with Cheng-Yu Kuo, of the University of Virginia and NRAO.

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 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 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.

Redrawing the Map of Our Milky Way

Another ongoing project uses the VLBA to redraw the map of our own home Galaxy. Recent work has added dozens of new measurements to star-forming regions in the Milky Way, The direct VLBA measurements improve on earlier estimates by as much as a factor of two.

This improvement significantly aids in understanding the physics of the young stars and their environments. It also has changed the map of the Milky Way, indicating that our Galaxy has four spiral arms, not two, as previously thought.

"Because we sit inside our Galaxy, it's difficult to actually map it. These precision distance measurements are our most effective tool for learning about the structure of the Milky Way," said Mark Reid, of the Harvard-Smithsonian Center for Astrophysics.

Earlier work by Reid and his colleagues showed that the Milky Way is rotating faster than previous estimates had indicated. That measurement in turn showed our Galaxy to be more massive, equaling our neighbor, the Andromeda Galaxy, in mass.

Reid's team also is 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.

Tiny Wobbles Will Reveal Planets

A long-term, sensitive search of 30 stars seeks to find the subtle gravitational tug that will reveal planets orbiting those stars. The VLBA's precision can reveal a "wobble" in the star's motion through space caused by the planet's gravity. A four-year program, started in 2007, is nearing its completion.

"This study tracks stars smaller than our Sun, seeking evidence of planets the size of Jupiter or smaller," said Geoffrey Bower, of the University of California, Berkeley. "We want to learn how common it is for these low-mass stars to have planets orbiting them at relatively large distances," he added.

The project uses the VLBA along with NRAO's Green Bank Telescope in West Virginia, the largest fully-steerable dish antenna in the world. Together, these telescopes can detect the faint radio emission from the stars to track their motion over time.

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.

The VLBA -- A System of Superlatives

The VLBA, dedicated in 1993, uses ten, 25-meter-diameter dish antennas distributed from Hawaii to St. Croix in the Caribbean. It is operated from the NRAO's Domenici Science Operations Center in Socorro, NM. All ten antennas work together as a single telescope with the greatest resolving power available to astronomy. This unique capability has produced landmark contributions to numerous scientific fields, ranging from Earth tectonics, climate research, and spacecraft navigation to cosmology.

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.

"The VLBA has unmatched capabilities for making unique contributions to many fundamental areas of science. It has a proven track record of enabling transformational research and its new technical enhancements promise a rich harvest of discovery in the coming years," said NRAO Director Fred K.Y. Lo.

Explore further: Astronomer confirms a new "Super-Earth" planet

More information: www.nrao.edu/index.php/about/facilities/vlba

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User comments : 16

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Aliensarethere
not rated yet Feb 19, 2011
How exactly do you measure the distance to NGC 6264 ?
Pratyeka
4.4 / 5 (7) Feb 19, 2011
to Aliensarethere:
"Our direct, geometric measurements", they mean simple triangulation, look it up...
Quantum_Conundrum
2 / 5 (8) Feb 19, 2011
How exactly do you measure the distance to NGC 6264 ?


A direct measurement implies either triangulation, or doppler effect, or a combination of the two.

What I found amusing is that they suddenly discovered twice as much ordinary matter in the Milky Way, no pixie dust required.

There is no such thing as Dark Matter.

There is only un-discovered ordinary matter.
Skeptic_Heretic
4.4 / 5 (8) Feb 19, 2011
What I found amusing is that they suddenly discovered twice as much ordinary matter in the Milky Way, no pixie dust required.
The research paper I read wasn't a discovery of more matter, it was a determination of what the structure of the know baryonic matter was arranged in. Like putting a face to a name so to speak.

There is no such thing as Dark Matter.
Biold statement.
There is only un-discovered ordinary matter.
Even bolder.
soulman
5 / 5 (3) Feb 19, 2011
I'd be very interested to know the degree of inaccuracy of the previous indirect methods compared with this direct method. Were the previous estimates off significantly?
Quantum_Conundrum
1.7 / 5 (12) Feb 19, 2011
I'd be very interested to know the degree of inaccuracy of the previous indirect methods compared with this direct method. Were the previous estimates off significantly?


I wouldn't put too much stock in this crap anyway.

"Astronomers" can't even nail down the distance or size of Betelgeuse, and are off by as much as plus or minus a half, and that is in our "back yard," as it were, in the constellation Orion.

So, they are off by as much as 50% on Betelgeuse, but would like us to believe they are within 9% on an object at least 750,000 to one million times farther away.

Wow, just wow.

It would be somewhat more believable if these people had alleged to have nailed down betelgeuse to within a percent or two before making the bold claims of this article, but they haven't.

What we have here is a bunch of crackpots masquerading as cosmologists.
soulman
3.9 / 5 (7) Feb 19, 2011
What we have here is a bunch of crackpots masquerading as cosmologists.

Wow, just wow.

Indeed.
omatumr
1.3 / 5 (12) Feb 19, 2011
The sketch certainly looks like fragmentation from neutron repulsion in the core of the Milky Way. See:

"Attraction and repulsion of nucleons: Sources of stellar energy", Journal of Fusion Energy 19, 93-98 (2001)

omatumr.com/abstracts/jfeinterbetnuc.pdf

youtube.com/watch?v=sXNyLYSiPO0

With kind regards,
Oliver K. Manuel
Former NASA Principal
Investigator for Apollo
bluehigh
3 / 5 (2) Feb 19, 2011
The parallax angle at distances to another galaxy are not generally resolvable from earth. With the exception of a few stars close enough to allow a direct measure of distance the accepted measurement technique is based on comparative brightness with Cepheid variable stars .. a kind of best guess.
Pyle
5 / 5 (1) Feb 20, 2011
There is no such thing as Dark Matter.

There is only un-discovered ordinary matter.

QC, it won't work with Einstein's model. What are you suggesting?

Manuel, where does your theory sit within MOG?
Aliensarethere
5 / 5 (1) Feb 20, 2011
to Aliensarethere:
"Our direct, geometric measurements", they mean simple triangulation, look it up...


It's not possible to do triangulation at those distances. I miss a description of how they did it in an otherwise excellent article.
Ethelred
5 / 5 (3) Feb 20, 2011
Triangulation at those distances is done with measurement of parallax versus other, farther out, objects. The greater the resolution the better the measurement of parallax can be. They are claiming they have good enough resolution for a 9 percent error.

Ethelred
yyz
5 / 5 (11) Feb 20, 2011
The method employed for the distance measurements involves observations of water-vapor maser complexes that reside in circumnuclear disks very close (sub-parsec scales) to the nucleus of many AGN galaxies.

Assuming a Keplerian orbit, measuring the centripetal acceleration and velocity of water maser complexes yields the physical diameter subtended by the maser spots. By then comparing the physical radius to the angular diameter measured on the sky, the distance to the maser may be determined.

This technique was first employed in 1999 through study of NGC 4258 using VLBI. These new measurements are the first to explore galaxies well into the Hubble flow (~50-200 Mpc) and are part of a project to determine the value of the Hubble constant without the use of standard candles.

An outline of the Megamaser Cosmology Project and description of the technique can be found here:

htp://www.nrao.edu/A2010/whitepapers/rac/Braatz_maser_cosmology_CFP.pdf
Aliensarethere
5 / 5 (2) Feb 20, 2011
yyz: Thanks for the detailed description.
crackerhead
not rated yet Feb 23, 2011
NY,NY to Los Angles: 2827 miles. Sounds like Big Brother not space exploration. doubled the arms in our Milky Way , How could we have missed that ? We know so little yet we are very quick to judge, To dismiss out of hand without empirical evidence any theory not our own. So much with so little, sure wish u could stretch a buck as far!
Ethelred
5 / 5 (2) Feb 24, 2011
How could we have missed that ? We know so little yet we are very quick to judge,
Somehow that seems like accidental irony.
To dismiss out of hand without empirical evidence any theory not our own.
So quit doing it.

Show us your photo of the Milky Way from 100 million light years away than you can tell people that they should have known there were four arms. Or three or however many it turns out to be.

Ethelred

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