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 SwRI-led team discovers lull in Mars' giant impact history
26.04.2017 | Southwest Research Institute

nachricht New survey hints at exotic origin for the Cold Spot
26.04.2017 | Royal Astronomical Society

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: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

From volcano's slope, NASA instrument looks sky high and to the future

27.04.2017 | Earth Sciences

Control of molecular motion by metal-plated 3-D printed plastic pieces

27.04.2017 | Materials Sciences

Move over, Superman! NIST method sees through concrete to detect early-stage corrosion

27.04.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>