This artist's concept shows the immediate
aftermath of a large asteroid impact around NGC 2547-ID8, a
35-million-year-old sun-like star thought to be forming rocky planets.
Image credit: NASA/JPL-Caltech. Full image and caption
Astronomers were surprised to see these data
from NASA's Spitzer Space Telescope in January 2013, showing a huge
eruption of dust around a star called NGC 2547-ID8. Image credit:
NASA/JPL-Caltech/University of Arizona. Full image and caption - enlarge image
NASA's Spitzer Space Telescope has spotted an eruption of dust around a young star, possibly the result of a smashup between large asteroids. This type of collision can eventually lead to the formation of planets.
NASA's Spitzer Space Telescope has spotted an eruption of dust around a young star, possibly the result of a smashup between large asteroids. This type of collision can eventually lead to the formation of planets.
Scientists had been regularly tracking the star, called NGC 2547-ID8,
when it surged with a huge amount of fresh dust between August 2012 and
January 2013.
"We think two big asteroids crashed into each other, creating a huge
cloud of grains the size of very fine sand, which are now smashing
themselves into smithereens and slowly leaking away from the star," said
lead author and graduate student Huan Meng of the University of
Arizona, Tucson.
While dusty aftermaths of suspected asteroid collisions have been
observed by Spitzer before, this is the first time scientists have
collected data before and after a planetary system smashup. The viewing
offers a glimpse into the violent process of making rocky planets like
ours.
Rocky planets begin life as dusty material circling around young stars.
The material clumps together to form asteroids that ram into each other.
Although the asteroids often are destroyed, some grow over time and
transform into proto-planets. After about 100 million years, the objects
mature into full-grown, terrestrial planets. Our moon is thought to
have formed from a giant impact between proto-Earth and a Mars-size
object.
In the new study, Spitzer set its heat-seeking infrared eyes on the
dusty star NGC 2547-ID8, which is about 35 million years old and lies
1,200 light-years away in the Vela constellation. Previous observations
had already recorded variations in the amount of dust around the star,
hinting at possible ongoing asteroid collisions. In hope of witnessing
an even larger impact, which is a key step in the birth of a terrestrial
planet, the astronomers turned to Spitzer to observe the star
regularly. Beginning in May 2012, the telescope began watching the star,
sometimes daily.
A dramatic change in the star came during a time when Spitzer had to
point away from NGC 2547-ID8 because our sun was in the way. When
Spitzer started observing the star again five months later, the team was
shocked by the data they received.
"We not only witnessed what appears to be the wreckage of a huge
smashup, but have been able to track how it is changing -- the signal is
fading as the cloud destroys itself by grinding its grains down so they
escape from the star," said Kate Su of the University of Arizona and
co-author on the study. "Spitzer is the best telescope for monitoring
stars regularly and precisely for small changes in infrared light over
months and even years."
A very thick cloud of dusty debris now orbits the star in the zone where
rocky planets form. As the scientists observe the star system, the
infrared signal from this cloud varies based on what is visible from
Earth. For example, when the elongated cloud is facing us, more of its
surface area is exposed and the signal is greater. When the head or the
tail of the cloud is in view, less infrared light is observed. By
studying the infrared oscillations, the team is gathering
first-of-its-kind data on the detailed process and outcome of collisions
that create rocky planets like Earth.
"We are watching rocky planet formation happen right in front of us,"
said George Rieke, a University of Arizona co-author of the new study.
"This is a unique chance to study this process in near real-time."
The team is continuing to keep an eye on the star with Spitzer. They
will see how long the elevated dust levels persist, which will help them
calculate how often such events happen around this and other stars. And
they might see another smashup while Spitzer looks on.
The results of this study are posted online Thursday in the journal Science.
NASA's Jet Propulsion Laboratory in Pasadena, California, manages the
Spitzer Space Telescope mission for NASA's Science Mission Directorate
in Washington. Science operations are conducted at the Spitzer Science
Center at the California Institute of Technology in Pasadena. Spacecraft
operations are based at Lockheed Martin Space Systems Company in
Littleton, Colorado. Data are archived at the Infrared Science Archive
housed at the Infrared Processing and Analysis Center at Caltech.
Caltech manages JPL for NASA.
For more information about Spitzer, visit: http://www.nasa.gov/spitzer
Whitney Clavin
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-4673
whitney.clavin@jpl.nasa.gov
Felicia Chou
NASA Headquarters, Washington
202-358-0257
felicia.chou@nasa.gov
