Everything through a 2.5 meters telescope
Everything presented through a 2.5 meters telescope to the public and put online the twelfth and final release of the SDSS-III. Consulted by anyone using the “Sky Server”, the observations and spectroscopic measurements of the Sloan Digital Sky Survey are one among the richest and most impressive astronomical archives ever made.
Half a billion stars and galaxies for over a hundred terabytes of data were collected over two thousand nights, from 2008 to 2014 and now available to everyone. This is the heritage of the final third observing campaign of the Sloan Digital Sky Survey, the SDSS-III, filed Tuesday in Seattle during 225th meeting of the American Astronomical Society. Six years of spectroscopic measurements converged on Sky Server, a digital oilfield has become legendary among astronomers and beyond – also draws from Google Sky to build its virtual sky.
“The most outstanding feature of this collection,” says the director of SDSS-III, Daniel Eisenstein, the Smithsonian Center for Astrophysics Harvard, “is the range of innovative research that will make it through. We went in search of planets in the nearest stars, we probed the entire history of the Milky Way and measured nine billion years of accelerated expansion in our universe.”
The beginning of the observations of SDSS dates back to 1998, when, after a decade of planning and construction, the Sloan Foundation Telescope – the eye of 2.5 meters with which the SDSS has mapped the entire cosmos – went into operation at the Apache Point observatory in New Mexico. Funded with $ 45 million, the third observing campaign (the SDSS-III, in fact) involving 51 institutions and a thousand scientists from around the world.
Two thousand nights of observations dedicated mostly to spectroscopic measurements of stars and galaxies. “For each object we observe, are carried thousands of measurements at different wavelengths. This allows us to detect the light emission characteristic of specific molecules and atoms,” explains Jon Holtzman of New Mexico State University,” thus enabling us to measure the movements and the chemical composition of stars and galaxies. ”
“Identify elements of a star is like reading his DNA, and what we are doing is to exploit these readings to reconstruct, from the stars that we can see today, the history of the Milky Way,” says Steve Majewski, of the University of Virginia, responsible of APOGEE (Apache Point Observatory Galactic Evolution Experiment), one of the four survey – the others are BOSS, and MARVELS FOLLOWS – the SDSS-III. Observing in the near infrared beyond the opaque dust clouds, APOGEE traced the distribution of 15 chemical elements in over 100 thousand stars, probing all regions of the Milky Way. “It’s a frightening amount of information”, continues Majewski, “every element has its own little story to tell for this script galactic. And sometimes the interactions between the characters are pretty amazing. ”
Another result of the DR12 (the name of the latest release of the SDSS-III) is the set of 3D maps, Baryon Oscillation Spectroscopic Survey produced from (BOSS), the cosmic structure traced by galaxies and intergalactic hydrogen. “Maps that have allowed us to detect the fossil footprints of acoustic waves that passed through the early universe during the first half a million after the Big Bang,” said the head of BOSS David Schlegel, Lawrence Berkeley National Laboratory. Footprints that allow traces the expansion of the universe along nine billion years of cosmic history, and with the analysis that will be completed later this year, promises Schlegel, “constitute the most severe test ever for theories dark energy and the acceleration of the expansion of the universe. ”
The third season is thus completed, but the activities are in full swing with SDSS-IV, which has picked up the baton last July for another six years of observations. “Crossing the finish line of the DR12 was a great result for hundreds of people,” concludes Eisenstein, “but there’s a big universe out there, and is full of other things to observe.”