NASA'S Wise Mission Discovers Coolest Class of Stars

PASADENA, Calif. Scientists using data from NASA's Wide-field Infrared Survey Explorer (WISE) have discovered the coldest class of star-like bodies, with temperatures as cool as the human body.

Astronomers hunted these dark orbs, termed Y dwarfs, for more than a decade without success. When viewed with a visible-light telescope, they are nearly impossible to see. WISE's infrared vision allowed the telescope to finally spot the faint glow of six Y dwarfs relatively close to our sun, within a distance of about 40 light-years.

"WISE scanned the entire sky for these and other objects, and was able to spot their feeble light with its highly sensitive infrared vision," said Jon Morse, Astrophysics Division director at NASA Headquarters in Washington. "They are 5,000 times brighter at the longer infrared wavelengths WISE observed from space than those observable from the ground."

The Y's are the coldest members of the brown dwarf family. Brown dwarfs are sometimes referred to as "failed" stars. They are too low in mass to fuse atoms at their cores and thus don't burn with the fires that keep stars like our sun shining steadily for billions of years. Instead, these objects cool and fade with time, until what little light they do emit is at infrared wavelengths.

Astronomers study brown dwarfs to better understand how stars form, and to understand the atmospheres of planets beyond our solar system. The atmospheres of brown dwarfs are similar to those of gas-giant planets like Jupiter, but they are easier to observe because they are alone in space, away from the blinding light of a parent star.

So far, WISE data have revealed 100 new brown dwarfs. More discoveries are expected as scientists continue to examine the enormous quantity of data from WISE. The telescope performed the most advanced survey of the sky at infrared wavelengths to date, from Jan. 2010 to Feb. 2011, scanning the entire sky about 1.5 times.

Of the 100 brown dwarfs, six are classified as cool Y's. One of the Y dwarfs, called WISE 1828+2650, is the record holder for the coldest brown dwarf, with an estimated atmospheric temperature cooler than room temperature, or less than about 80 degrees Fahrenheit (25 degrees Celsius).

"The brown dwarfs we were turning up before this discovery were more like the temperature of your oven," said Davy Kirkpatrick, a WISE science team member at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena, Calif. "With the discovery of Y dwarfs, we've moved out of the kitchen and into the cooler parts of the house."

Kirkpatrick is lead author of a paper appearing in the Astrophysical Journal Supplement Series, describing the 100 confirmed brown dwarfs. Michael Cushing, a WISE team member at NASA's Jet Propulsion Laboratory in Pasadena, Calif., is lead author of a paper describing the Y dwarfs in the Astrophysical Journal.

WISE Delivers Millions of Galaxies, Stars, Asteroids

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 (WISE) mission.

"Starting today thousands of new eyes will be looking at WISE data, and I expect many surprises," said Edward (Ned) Wright of UCLA, the mission's principal investigator.

WISE launched into space on Dec. 14, 2009 on a mission to map the entire sky in infrared light with greatly improved sensitivity and resolution over its predecessors. From its polar orbit, it scanned the skies about one-and-a-half times while collecting images taken at four infrared wavelengths of light. It took more than 2.7 million images over the course of its mission, capturing objects ranging from faraway galaxies to asteroids relatively close to Earth.

Like other infrared telescopes, WISE required coolant to chill its heat-sensitive detectors. When this frozen hydrogen coolant ran out, as expected, in early October, 2010, two of its four infrared channels were still operational. The survey was then extended for four more months, with the goal of finishing its sweep for asteroids and comets in the main asteroid belt of our solar system.

The mission's nearby discoveries included 20 comets, more than 33,000 asteroids between Mars and Jupiter, and 133 near-Earth objects (NEOs), which are those asteroids and comets with orbits that come within 28 million miles (about 45 million kilometers) of Earth's path around the sun. The satellite went into hibernation in early February of this year.

Today, WISE is taking the first major step in meeting its primary goal of delivering the mission's trove of objects to astronomers. Data from the first 57 percent of the sky surveyed is accessible through an online public archive. The complete survey, with improved data processing, will be made available in the spring of 2012. A predecessor to WISE, the Infrared Astronomical Satellite, served a similar role about 25 years ago, and those data are still valuable to astronomers today. Likewise, the WISE legacy is expected to endure for decades.

"We are excited that the preliminary data contain millions of newfound objects," said Fengchuan Liu, the project manager for WISE at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "But the mission is not yet over -- the real treasure is the final catalog available a year from now, which will have twice as many sources, covering the entire sky and reaching even deeper into the universe than today's release."

Astronomers will use WISE's infrared data to hunt for hidden oddities, and to study trends in large populations of known objects. Survey missions often result in the unexpected discoveries too, because they are looking everywhere in the sky rather than at known targets. Data from the mission are also critical for finding the best candidates for follow-up studies with other telescopes, including the European Space Agency's Herschel observatory, which has important NASA contributions.

"WISE is providing the newest-generation 'address book' of the infrared universe with the precise location and brightness of hundreds of millions of celestial objects," said Roc Cutri, lead scientist for WISE data processing at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena, Calif. "WISE continues the long tradition of infrared sky surveys supported by Caltech, stretching back to the 1969 Two Micron Sky Survey."

So far, the WISE mission has released dozens of colorful images of the cosmos, in which infrared light has been assigned colors we see with our eyes.


JPL manages and operates the Wide-field Infrared Survey Explorer for NASA's Science Mission Directorate, Washington. The principal investigator, Edward Wright, is at UCLA. The mission was competitively selected under NASA's Explorers Program managed by the Goddard Space Flight Center, Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory, Logan, Utah, and the spacecraft was built by Ball Aerospace & Technologies Corp., Boulder, Colo. Science operations and data processing take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA.

NASA's WISE Mission Warms up but Keeps Chugging Along

PASADENA, Calif. -- After completing its primary mission to map the infrared sky, NASA's Wide-field Infrared Survey Explorer, or WISE, has reached the expected end of its onboard supply of frozen coolant. Although WISE has 'warmed up,' NASA has decided the mission will still continue. WISE will now focus on our nearest neighbors -- the asteroids and comets traveling together with our solar system's planets around the sun.

"Two of our four infrared detectors still work even at warmer temperatures, so we can use those bands to continue our hunt for asteroids and comets," said Amy Mainzer of NASA's Jet Propulsion Laboratory in Pasadena, Calif. Mainzer is the principal investigator of the new phase of the mission, now known as the NEOWISE Post-Cryogenic Mission. It takes its name from the acronym for a near-Earth object, NEO, and WISE. A cryogen is a coolant used to make the detectors more sensitive. In the case of WISE, the cryogen was frozen hydrogen.

WISE launched Dec. 14, 2009, from Vandenberg Air Force Station in California aboard a Delta II launch vehicle. Its 40-centimeter (16-inch) infrared telescope scans the skies from an Earth-circling orbit crossing the poles. It has already snapped more than 1.8 million pictures at four infrared wavelengths. Currently, the survey has covered the sky about one-and-one-half times, producing a vast catalogue containing hundreds of millions of objects, from near-Earth asteroids to cool stars called "brown dwarfs," to distant, luminous galaxies.

To date, WISE has discovered 19 comets and more than 33,500 asteroids, including 120 near-Earth objects, which are those bodies with orbits that pass relatively close to Earth's path around the sun. More discoveries regarding objects outside our solar system, such as the brown dwarfs and luminous galaxies, are expected.

"The science data collected by WISE will be used by the scientific community for decades," said Jaya Bajpayee, the WISE program executive in the Astrophysics Division of NASA's Science Mission Directorate, at the agency's headquarters in Washington. "It will also provide a sky map for future observatories like NASA's James Webb Space Telescope."

The NEOWISE Post-Cryogenic Mission is designed to complete the survey of the solar system and finish the second survey of the rest of the sky at its new warmer temperature of about minus 203 degrees Celsius (minus 334 degrees Fahrenheit) using its two shortest-wavelength detectors. The survey extension will last one to four months, depending on early results.

NEOWISE will also keep observing other targets, such as the closest brown dwarfs to the sun. In addition, data from the second sky scan will help identify objects that have moved in the sky since they were first detected by WISE. This allows astronomers to pick out the brown dwarfs closest to our sun. The closer the object is, the more it will appear to move from our point of view.

The WISE science team now is analyzing millions of objects captured in the images, including many never seen before. A first batch of WISE data, covering more than half the sky, will be released to the astronomical community in spring 2011, with the rest to follow about one year later.

"WISE has provided a guidebook to the universe with thousands of targets worth viewing with a large telescope," said Edward (Ned) Wright, WISE principal investigator from UCLA. "We're working on figuring out just how far away the brown dwarfs are, and how luminous the galaxies are."

NASA's WISE Mission to Complete Extensive Sky Survey

PASADENA, Calif. -- NASA's Wide-field Infrared Survey Explorer, or WISE, will complete its first survey of the entire sky on July 17, 2010. The mission has generated more than one million images so far, of everything from asteroids to distant galaxies.

"Like a globe-trotting shutterbug, WISE has completed a world tour with 1.3 million slides covering the whole sky," said Edward Wright, the principal investigator of the mission at the University of California, Los Angeles.

Some of these images have been processed and stitched together into a new picture being released today. It shows the Pleiades cluster of stars, also known as the Seven Sisters, resting in a tangled bed of wispy dust. The pictured region covers seven square degrees, or an area equivalent to 35 full moons, highlighting the telescope's ability to take wide shots of vast regions of space.

The new picture was taken in February. It shows infrared light from WISE's four detectors in a range of wavelengths. This infrared view highlights the region's expansive dust cloud, through which the Seven Sisters and other stars in the cluster are passing. Infrared light also reveals the smaller and cooler stars of the family.

"The WISE all-sky survey is helping us sift through the immense and diverse population of celestial objects," said Hashima Hasan, WISE Program scientist at NASA Headquarters in Washington. "It's a great example of the high impact science that's possible from NASA's Explorer Program."

The first release of WISE data, covering about 80 percent of the sky, will be delivered to the astronomical community in May of next year. The mission scanned strips of the sky as it orbited around the Earth's poles since its launch last December. WISE always stays over the Earth's day-night line. As the Earth moves around the sun, new slices of sky come into the telescope's field of view. It has taken six months, or the amount of time for Earth to travel halfway around the sun, for the mission to complete one full scan of the entire sky.

For the next three months, the mission will map half of the sky again. This will enhance the telescope's data, revealing more hidden asteroids, stars and galaxies. The mapping will give astronomers a look at what's changed in the sky. The mission will end when the instrument's block of solid hydrogen coolant, needed to chill its infrared detectors, runs out.

"The eyes of WISE have not blinked since launch," said William Irace, the mission's project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Both our telescope and spacecraft have performed flawlessly and have imaged every corner of our universe, just as we planned."

So far, WISE has observed more than 100,000 asteroids, both known and previously unseen. Most of these space rocks are in the main belt between Mars and Jupiter. However, some are near-Earth objects, asteroids and comets with orbits that pass relatively close to Earth. WISE has discovered more than 90 of these new near-Earth objects. The infrared telescope is also good at spotting comets that orbit far from Earth and has discovered more than a dozen of these so far.

WISE's infrared vision also gives it a unique ability to pick up the glow of cool stars, called brown dwarfs, in addition to distant galaxies bursting with light and energy. These galaxies are called ultra-luminous infrared galaxies. WISE can see the brightest of them.

"WISE is filling in the blanks on the infrared properties of everything in the universe from nearby asteroids to distant quasars," said Peter Eisenhardt of JPL, project scientist for WISE. "But the most exciting discoveries may well be objects we haven't yet imagined exist."

JPL manages the Wide-field Infrared Survey Explorer for NASA's Science Mission Directorate in Washington. The mission was selected under NASA's Explorers Program managed by the Goddard Space Flight Center in Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory in Logan, Utah, and the spacecraft was built by Ball Aerospace & Technologies Corp., in Boulder, Colo. Science operations and data processing take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA.