Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Dark Energy, The Milky Way galaxy, and Giant Planets

11.01.2008
The Sloan Digital Sky Survey Continues

Building on eight years of extraordinary discoveries by the Sloan Digital Sky Survey (SDSS and SDSS-II), a new program of four coordinated surveys will revolutionize the study of the distant universe, the Milky Way galaxy, and giant planets orbiting other stars. The largest of these surveys will use a novel and powerful technique to study dark energy, one of the biggest mysteries in contemporary science.

The new programme was announced today at the American Astronomical Society meeting in Austin, Texas.

"The cosmological measurements in SDSS-III could rewrite fundamental physics, either pinning down the properties of an exotic form of energy that fills the universe or showing that Einstein's theory of gravity fails at cosmological distances," explains Daniel Eisenstein of the University of Arizona and director of the newly formed collaboration.

The largest of the four surveys, the Baryon Oscillation Spectroscopic Survey (BOSS), will measure the expansion of the universe with unprecedented precision.

"BOSS will measure the distance across the local universe to an accuracy of better than one centrimeter for every meter measured: it’s the ultimate cosmic tape measure!” says Bob Nichol of the University of Portsmouth’s Institute of Cosmology and Gravitation.

"Once we have done BOSS, there may not be much more of the local Universe we need to study.”

The University of Portsmouth was the first British university to become a member of the Sloan Digital Sky Survey, the most ambitious survey of the sky ever undertaken, involving over 300 astronomers and engineers at 25 institutions around the world.

A decade ago, Daniel Eisenstein explains, astronomers made the startling discovery that the expansion of the universe is speeding up. "It's like tossing a ball in the air, waiting for it to fall, and instead seeing it accelerate upwards and disappear from sight."

Cosmologists attribute this acceleration to so-called "dark energy," which pervades otherwise empty space and exerts repulsive gravitational force. Dark energy could be the cosmological constant proposed by Albert Einstein in 1917, or it could be a new form of energy whose properties evolve with time. Distinguishing these possibilities, or determining whether the theory of gravity itself is at fault, requires measuring the history of cosmic expansion with very high precision, explains David Schlegel of Lawrence Berkeley National Laboratory, principal investigator of BOSS.

In 2005, the SDSS achieved one of the first clear detections of "baryon acoustic oscillations," a feature imprinted on the clustering of galaxies by sound waves that traveled in the early universe. BOSS will use this feature as a "yardstick in the sky" to measure cosmic distances, says Schlegel. "Our measurements should reach one-percent accuracy and extend to distances of ten billion light years, giving us strong tests of dark energy theories."

While new, more sensitive instruments are being constructed for BOSS, SDSS-III will carry out a one-year extension of SEGUE, an SDSS-II survey mapping the outer Milky Way. "The Galaxy's stellar halo is much more complex than anyone realized a decade ago, and we want to understand what that is telling us about the formation of the Milky Way," explains Constance Rockosi of the University of California at Santa Cruz, the principal investigator of SEGUE-2.

Interstellar dust blocks visible light coming from stars in the inner Milky Way. Infrared light penetrates this dust, revealing stars even from heavily obscured regions near the Galactic centre. The new APOGEE survey will employ a unique new instrument that observes infrared light from 300 stars simultaneously, enabling a survey of 100,000 stars across the entire Galaxy. "When stars die, the chemical elements forged by nuclear reactions in their cores are released into space," explains Steven Majewski of the University of Virginia, principal investigator of APOGEE.

"The APOGEE measurements will provide detailed chemical 'fingerprints' for each target star, which in turn reveal the properties of the stars that preceded them. It's the ultimate exercise in forensic archeology."

And what about planets orbiting those stars? Of the 200 or so planetary systems currently known, most are very different from our own solar system, notes Jian Ge of the University of Florida. The majority of known planets are gaseous giants, like Jupiter, but they follow elongated (instead of circular) trajectories and orbit much closer to their parent stars. Ge is the principal investigator of MARVELS, which will search more than 10,000 stars for orbiting giant planets, a three-fold increase on the number searched by all other telescopes to date.

"By systematically monitoring such a large number of stars," says Ge, "MARVELS will address two of the biggest questions in planetary science: how do giant planets form, and why are so many in such unusual orbits?"

Jim Gunn of Princeton University, who has led nearly two decades of construction and operation of the Sloan Digital Sky Survey, is excited about its new ventures. "It's amazing to see that the SDSS can transform scientific fields we hadn't even conceived of 20 years ago."

The Alfred P. Sloan Foundation of New York has approved a $7 million grant in support of SDSSIII, conditional on raising the additional funds from collaboration members and federal agencies needed to complete the project.

SDSS-III is due to run from mid-2008 to mid-2014. Its four component surveys will all operate from the 2.5-meter telescope at Apache Point Observatory in New Mexico, using optical fibres to capture the light of hundreds of objects simultaneously. This technique allowed the SDSS and SDSS-II to create the largest three-dimensional map of the present-day universe.

Lisa Egan | alfa
Further information:
http://www.port.ac.uk
http://www.astronomy.ohiostate.edu/~dhw/SDSS3/sdss3pr.html

More articles from Physics and Astronomy:

nachricht Tracing aromatic molecules in the early universe
23.03.2017 | University of California - Riverside

nachricht New study maps space dust in 3-D
23.03.2017 | DOE/Lawrence Berkeley National Laboratory

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: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

When Air is in Short Supply - Shedding light on plant stress reactions when oxygen runs short

23.03.2017 | Life Sciences

Researchers use light to remotely control curvature of plastics

23.03.2017 | Power and Electrical Engineering

Sea ice extent sinks to record lows at both poles

23.03.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>