NASA's WISE Catches Aging Star Erupting With Dust

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News release: 2012-118 April 26, 2012

NASA's WISE Catches Aging Star Erupting With Dust

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.cfm?release=2012-118&cid=release_2012-118

PASADENA, Calif. -- Images from NASA's Wide-field Infrared Survey Explorer (WISE) reveal
an old star in the throes of a fiery outburst, spraying the cosmos with dust. The findings offer a
rare, real-time look at the process by which stars like our sun seed the universe with building
blocks for other stars, planets and even life.

The star, catalogued as WISE J180956.27–330500.2, was discovered in images taken during the
WISE survey in 2010, the most detailed infrared survey to date of the entire celestial sky. It
stood out from other objects because it glowed brightly with infrared light. When compared to
images taken more than 20 years ago, astronomers found the star was 100 times brighter.

"We were not searching specifically for this phenomenon, but because WISE scanned the whole
sky, we can find such unique objects," said Poshak Gandhi of the Japan Aerospace Exploration
Agency (JAXA), lead author of a new paper to be published in the Astrophysical Journal Letters.

Results indicate the star recently exploded with copious amounts of fresh dust, equivalent in
mass to our planet Earth. The star is heating the dust and causing it to glow with infrared light.

"Observing this period of explosive change while it is actually ongoing is very rare," said co-
author Issei Yamamura of JAXA. "These dust eruptions probably occur only once every 10,000
years in the lives of old stars, and they are thought to last less than a few hundred years each
time. It's the blink of an eye in cosmological terms."

The aging star is in the "red giant" phase of its life. Our own sun will expand into a red giant in
about 5 billion years. When a star begins to run out of fuel, it cools and expands. As the star
puffs up, it sheds layers of gas that cool and congeal into tiny dust particles. This is one of the
main ways dust is recycled in our universe, making its way from older stars to newborn solar
systems. The other way, in which the heaviest of elements are made, is through the deathly
explosions, or supernovae, of the most massive stars.

"It's an intriguing glimpse into the cosmic recycling program," said Bill Danchi, WISE program
scientist at NASA Headquarters in Washington. "Evolved stars, which this one appears to be,
contribute about 50 percent of the particles that make up humans."

Astronomers know of one other star currently pumping out massive amounts of dust. Called
Sakurai's Object, this star is farther along in the aging process than the one discovered recently
by WISE.

After Poshak and his team discovered the unusual, dusty star with WISE, they went back to look
for it in previous infrared all-sky surveys. The object was not seen at all by the Infrared
Astronomical Satellite (IRAS), which flew in 1983, but shows up brightly in images taken as
part of the Two Micron All-Sky Survey (2MASS) in 1998.

Poshak and his colleagues calculated the star appears to have brightened dramatically since 1983.
The WISE data show the dust has continued to evolve over time, with the star now hidden
behind a very thick veil. The team plans to follow up with space- and ground-based telescopes to
confirm its nature and to better understand how older stars recycle dust back into the cosmos.

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages and operates WISE for NASA's
Science Mission Directorate in Washington. The spacecraft was put into hibernation mode after
it scanned the entire sky twice, completing its main objectives. The principal investigator for
WISE, Edward Wright, is at the University of California, Los Angeles. The mission was selected
competitively under NASA's Explorers Program managed by the agency's Goddard Space Flight
Center in Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory in
Logan, Utah. 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 (Caltech) in Pasadena. Caltech manages JPL for
NASA.

The IRAS mission was a collaborative effort between NASA (JPL), the Netherlands and the
United Kingdom. The 2MASS mission was a joint effort between Caltech, the University of
Massachusetts and NASA (JPL). Data are archived at the Infrared Processing and Analysis
Center at Caltech.

More information about WISE is online at http://www.nasa.gov/wise , http://wise.astro.ucla.edu
and http://jpl.nasa.gov/wise .

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