Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The Far Side of the Milky Way

13.10.2017

Astronomers from the Max Planck Institute for Radio Astronomy in Bonn, Germany, and the Harvard-Smithsonian Center for Astrophysics have directly measured the distance to a star-forming region on the opposite side of our Milky Way Galaxy from the Sun, using the Very Long Baseline Array. Their achievement reaches deep into the Milky Way’s terra incognita and nearly doubles the previous record for distance measurement within our Galaxy.

Distance measurements are crucial for an understanding of the structure of the Milky Way. Most of our Galaxy's material, consisting principally of stars, gas, and dust, lies within a flattened disk, in which our Solar System is embedded. Because we cannot see our Galaxy face-on, its structure, including the shape of its spiral arms, can only be mapped by measuring distances to objects elsewhere in the Galaxy.


Distance determination by measuring the angle of apparent shift in an object's position, as seen from opposite sides of Earth's orbit around the Sun (trigonometric parallax technique).

Bill Saxton, NRAO/AUI/NSF; Robert Hurt, NASA


Artist’s view of the Milky Way with the location of the Sun and the star forming region (maser source G007.47+00.05) at the opposite side in the Scutum-Centaurus spiral arm.

Bill Saxton, NRAO/AUI/NSF; Robert Hurt, NASA

The astronomers used a technique called trigonometric parallax, first applied by Friedrich Wilhelm Bessel in 1838 to measure the distance to the star 61 Cygni in the constellation of the Swan. This technique measures the apparent shift in the sky position of a celestial object as seen from opposite sides of the Earth's orbit around the Sun. This effect can be demonstrated by holding a finger in front of one's nose and alternately closing each eye -- the finger appears to jump from side to side.

Measuring the angle of an object's apparent shift in position this way allows astronomers to use simple trigonometry to directly calculate the distance to that object. The smaller the measured angle, the greater the distance is. In the framework of the Bar and Spiral Structure Legacy (BeSSeL) Survey, it is now possible to measure parallaxes a thousand times more accurate than Friedrich Bessel.

The Very Long Baseline Array (VLBA), a continent-wide radio telescope system, with ten dish antennas distributed across North America, Hawaii, and the Caribbean, can measure the minuscule angles associated with great distances. In this case, the measurement was roughly equal to the angular size of a baseball on the Moon.

"Using the VLBA, we now can accurately map the whole extent of our Galaxy," says Alberto Sanna, of the Max Planck Institute for Radio Astronomy in Germany (MPIfR).

The new VLBA observations, made in 2014 and 2015, measured a distance of more than 66,000 light-years to the star-forming region G007.47+00.05 on the opposite side of the Milky Way from the Sun, well past the Galaxy's center in a distance of 27,000 light-years. The previous record for a parallax measurement was about 36,000 light-years.

"Most of the stars and gas in our Galaxy are within this newly-measured distance from the Sun. With the VLBA, we now have the capability to measure enough distances to accurately trace the Galaxy's spiral arms and learn their true shapes," Sanna explains.

The VLBA observations measured the distance to a region where new stars are being formed.
Such regions include areas where molecules of water and methanol act as natural amplifiers of radio signals -- masers, the radio-wave equivalent of lasers for light waves. This effect makes the radio signals bright and readily observable with radio telescopes.

The Milky Way has hundreds of such star-forming regions that include masers. "So we have plenty of 'mileposts' to use for our mapping project. But this one is special: Looking all the way through the Milky Way, past its center, way out into the other side", says the MPIfR's Karl Menten.

The astronomers' goal is to finally reveal what our own Galaxy looks like if we could leave it, travel outward perhaps a million light-years, and view it face-on, rather than along the plane of its disk. This task will require many more observations and much painstaking work, but, the scientists say, the tools for the job now are in hand. How long will it take?

"Within the next 10 years, we should have a fairly complete picture," predicts Mark Reid of the Harvard-Smithsonian Center for Astrophysics.

The research team consists of Alberto Sanna of the Max Planck Institute for Radio Astronomy (MPIfR), the first author, along with colleagues Mark Reid and Thomas Dame of the Harvard-Smithsonian Center for Astrophysics and Karl Menten and Andreas Brunthaler, also of the MPIfR. They report their findings in the 13 October issue of the journal Science.

The Long Baseline Observatory (LBO) runs the “Very Long Baseline Array” (VLBA) as a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

The BeSSeL Survey (Bar and Spiral Structure Legacy Survey) is a VLBA Key Science project. The survey is named in honor of Friedrich Wilhelm Bessel (1784-1846) who measured the first stellar parallax in 1838. The goal of the survey is to study the spiral structure and kinematics of the Milky Way.

Original Paper:

Mapping Spiral Structure on the far side of the Milky Way, Alberto Sanna, Mark J. Reid, Thomas M. Dame, Karl M. Menten, Andreas Brunthaler, 2017, Science (October 13 issue)

Contact:

Dr. Alberto Sanna
Max Planck Institute for Radio Astronomy, Bonn.
Fon +49 228 525-304
E-Mail: asanna@mpifr-bonn.mpg.de

Prof. Dr. Karl M. Menten
Director and Head of Research Department Millimeter and Submillimeter Astronomy
Max Planck Institute for Radio Astronomy, Bonn.
Fon +49 228 525-297
E-Mail: kmenten@mpifr-bonn.mpg.de

Dr. Norbert Junkes,
Press and Public Outreach
Max Planck Institute for Radio Astronomy, Bonn.
Fon: +49 228 525-399
E-mail: njunkes@mpifr-bonn.mpg.de

Weitere Informationen:

http://www.mpifr-bonn.mpg.de/pressreleases/2017/9

Norbert Junkes | Max-Planck-Institut für Radioastronomie

Further reports about: Galaxy MPIfR Max Planck Institute Milky Way Radioastronomie Spiral VLBA astronomy

More articles from Physics and Astronomy:

nachricht NASA's James Webb Space Telescope completes final cryogenic testing
21.11.2017 | NASA/Goddard Space Flight Center

nachricht Previous evidence of water on mars now identified as grainflows
21.11.2017 | US Geological Survey

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Previous evidence of water on mars now identified as grainflows

21.11.2017 | Physics and Astronomy

NASA's James Webb Space Telescope completes final cryogenic testing

21.11.2017 | Physics and Astronomy

New catalyst controls activation of a carbon-hydrogen bond

21.11.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>