Astronomers release unprecedented data set on celestial objects that brighten and dim

Jan 12, 2012
This is an image of a dwarf nova, which is a star system where material flows from a red giant star to a dense, compact star called a white dwarf. The flowing material triggers explosions that cause the system to flare up as seen from Earth. The graph shows the change in brightness of this system over a period of seven years. The images at the top show the nova at its brightest and dimmest, as indicated in the plot. Such systems are important for understanding stellar evolution, and the CRTS team has discovered nearly a thousand of them‑‑more than any other survey. Credit: The CRTS Survey Team, Caltech

Astronomers from the California Institute of Technology (Caltech) and the University of Arizona have released the largest data set ever collected that documents the brightening and dimming of stars and other celestial objects—two hundred million in total.

The night sky is filled with objects like asteroids that dash across the sky and others—like 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 were also essential for the recent discovery of dark energy—the mysterious energy that dominates the expansion of the universe—which earned last year's Nobel Prize.

Using the Catalina Real-Time Transient Survey (CRTS), a project led by Caltech, the astronomers systematically scanned the heavens for these dynamic objects, producing 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," says 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 (CSS), a search for Near-Earth Objects (NEOs)—asteroids that may pose a threat to Earth—conducted by astronomers at the University of Arizona. 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 a 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 two hundred million stars and other objects, incorporating over 20 billion independent measurements. "This set of objects is an order of magnitude larger than the largest previously available data sets of their kind," says Andrew Drake, a staff scientist at Caltech and lead author on a poster to be presented at the meeting of the American Astronomical Society in Austin on January 12. "It will enable many interesting studies by the entire astronomical community."

One of the unique features of the survey, Drake says, 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," he explains.

"It is a good example of scientific-data sharing and reuse," Djorgovski says. "We hope to set an example of how data-intensive science should be done in the 21st century."

The data set includes over a thousand exploding stars called supernovae, including many unusual and novel types, as well as hundreds of so-called cataclysmic variables, which are 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 that dramatically change in brightness.

"We take hundreds of images every night from each of our telescopes as we search for hazardous asteroids," adds Edward Beshore, principal investigator of the University of Arizona's asteroid-hunting CSS. "As far back as 2005, we were asking if this 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 says they soon plan 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.

Explore further: Computers beat brainpower when it comes to counting stars

Related Stories

Peek Into the Depths of the Universe - With Your iPhone

Apr 15, 2010

(PhysOrg.com) -- Transient Events, a new iPhone application for amateur and professional astronomers and anyone interested in the universe, highlights cosmic events such as exploding supernovae, comets traveling ...

Unique sky survey brings new objects into focus

Jun 15, 2009

An innovative sky survey has begun returning images that will be used to detect unprecedented numbers of powerful cosmic explosions-called supernovae-in distant galaxies, and variable brightness stars in our ...

Astronomers eager to add to Sky in Google Earth

Sep 07, 2007

Since Sky in Google Earth debuted two weeks ago to let the public explore the heavens from their computers, two University of California, Berkeley, astronomers have jumped in to populate Google's sky with ...

WISE delivers millions of galaxies, stars, asteroids

Apr 15, 2011

(PhysOrg.com) -- Astronomers across the globe can now sift through hundreds of millions of galaxies, stars and asteroids collected in the first bundle of data from NASA's Wide-field Infrared Survey Explorer ...

A New Class of Variable Stars Revealed

Feb 26, 2010

(PhysOrg.com) -- Modern astronomy sometimes makes discoveries by looking in new places, the distant universe for example, using telescopes and instruments that extend the previous limits of detection.

Recommended for you

ESO image: A study in scarlet

12 hours ago

This new image from ESO's La Silla Observatory in Chile reveals a cloud of hydrogen called Gum 41. In the middle of this little-known nebula, brilliant hot young stars are giving off energetic radiation that ...

Astronomers: 'Tilt-a-worlds' could harbor life

Apr 15, 2014

A fluctuating tilt in a planet's orbit does not preclude the possibility of life, according to new research by astronomers at the University of Washington, Utah's Weber State University and NASA. In fact, ...

Pushy neighbors force stellar twins to diverge

Apr 15, 2014

(Phys.org) —Much like an environment influences people, so too do cosmic communities affect even giant dazzling stars: Peering deep into the Milky Way galaxy's center from a high-flying observatory, Cornell ...

Image: Multiple protostars within IRAS 20324+4057

Apr 14, 2014

(Phys.org) —A bright blue tadpole appears to swim through the inky blackness of space. Known as IRAS 20324+4057 but dubbed "the Tadpole", this clump of gas and dust has given birth to a bright protostar, ...

User comments : 0

More news stories

Meteorites yield clues to Martian early atmosphere

(Phys.org) —Geologists who analyzed 40 meteorites that fell to Earth from Mars unlocked secrets of the Martian atmosphere hidden in the chemical signatures of these ancient rocks. Their study, published ...

Red moon at night; stargazer's delight

Monday night's lunar eclipse proved just as delightful as expected to those able to view it. On the East Coast, cloudy skies may have gotten in the way, but at the National Science Foundation's National Optical ...

Down's chromosome cause genome-wide disruption

The extra copy of Chromosome 21 that causes Down's syndrome throws a spanner into the workings of all the other chromosomes as well, said a study published Wednesday that surprised its authors.

Researchers see hospitalization records as additional tool

Comparing hospitalization records with data reported to local boards of health presents a more accurate way to monitor how well communities track disease outbreaks, according to a paper published April 16 in the journal PLOS ON ...

Ebola virus in Africa outbreak is a new strain

The Ebola virus that has killed scores of people in Guinea this year is a new strain—evidence that the disease did not spread there from outbreaks in some other African nations, scientists report.