The University of Arizona's Catalina Sky Survey keeps a watchful eye on asteroids that might cross the Earth's path. A byproduct of that effort is the largest database compiling the brightnesses of 200 million objects in the universe, including supernovae and stars torn up by super-massive black holes.
The night sky is filled with objects such as asteroids that dash across the sky and others such as exploding stars and variable stars that flash, dim, and brighten. Studying such phenomena can help astronomers better understand the evolution of stars, massive black holes in the centers of galaxies, and the structure of the Milky Way.
These types of objects also were essential for the recent discovery of dark energy the mysterious energy that dominates the expansion of the universe that earned last year's Nobel Prize.
Using images obtained by the UA's asteroid-hunting Catalina Sky Survey, the Catalina Real-Time Transient Survey, or CRTS, lets CalTech astronomers systematically scan the heavens for these dynamic objects, resulting in an unprecedented data set that will allow scientists worldwide to pursue new research.
"Exploring variable objects and transient phenomena like stellar explosions is one of the most vibrant and growing research areas in astrophysics," said S. George Djorgovski, professor of astronomy at Caltech and principal investigator on the CRTS. "In many cases, this yields unique information needed to understand these objects."
The new data set is based on observations taken with the 0.7-meter telescope on Mt. Bigelow in Arizona. The observations were part of the Catalina Sky Survey, a search for Near-Earth Objects, or NEOs asteroids that may pose a threat to Earth conducted by astronomers at the UA.
By repeatedly taking pictures of large swaths of the sky and comparing these images to previous ones, the CRTS is able to monitor the brightness of about half-billion objects, allowing it to search for those that dramatically brighten or dim. In this way, the CRTS team identified tens of thousands of variables, maximizing the science that can be gleaned from the original data.The new data set contains the so-called brightness histories of a total of
"This set of objects is an order of magnitude larger than the largest previously available data sets of their kind," said Andrew Drake, a staff scientist at Caltech and lead author on a poster presented at the meeting of the American Astronomical Society in Austin on Jan. 12.
"It will enable many interesting studies by the entire astronomical community."
One of the unique features of the survey, Drake said, is that it emphasizes an open-data philosophy. "We discover transient events and publish them electronically in real time, so that anyone can follow them and make additional discoveries."
"It is a good example of scientific-data sharing and reuse," Djorgovski added. "We hope to set an example of how data-intensive science should be done in the 21st century."
The data set includes more than 1,000 exploding stars called supernovae, including many unusual and novel types, as well as hundreds of so-called cataclysmic variables, pairs of stars in which one spills matter onto another, called a white dwarf; tens of thousands of other variable stars; and dwarf novae, which are binary stars that dramatically change in brightness."We take hundreds of images every night from each of our telescopes as we search for hazardous asteroids," said Edward Beshore, principal investigator of the UA's asteroid-hunting CSS. "As far back as 2005, we were asking if these data could be useful to the community of astronomers.
We are delighted that we could forge this partnership. In my estimation, it has been a great success and is a superb example of finding ways to get greater value from taxpayers' investments in basic science."
The team said it soon plans to release additional data taken with a 1.5-meter telescope on Mt. Lemmon in Arizona and a 0.5-meter telescope in Siding Spring in Australia.
In addition to Djorgovski, Drake and Beshore, the team includes staff scientist Ashish Mahabal, computational scientist Matthew Graham, postdoctoral scholar Ciro Donalek and research scientist Roy Williams from Caltech.
Researchers from other institutions include Steve Larson, Andrea Boattini, Alex Gibbs, Al Grauer, Rik Hill and Richard Kowalski from the UA; Mauricio Catelan from Universidad Catholica in Chile; Eric Christensen from the Gemini Observatory in Hawaii; and Jose Prieto from Princeton University.
The Caltech research is supported by the National Science Foundation. The work done at the UA is supported by NASA.LINKS:
Daniel Stolte | University of Arizona
Climate satellite: Tracking methane with robust laser technology
22.06.2017 | Fraunhofer-Gesellschaft
How reliable are shells as climate archives?
21.06.2017 | Leibniz-Zentrum für Marine Tropenforschung (ZMT)
An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.
Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...
19.06.2017 | Event News
13.06.2017 | Event News
13.06.2017 | Event News
23.06.2017 | Physics and Astronomy
23.06.2017 | Physics and Astronomy
23.06.2017 | Information Technology