The tightly packed system, named Kepler-444, is home to five small planets in very compact orbits. The planets were detected from the dimming that occurs when they transit the disc of their parent star, as shown in this artist's conception. Image Credit: Tiago Campante/Peter Devine
Astronomers
using data from NASA's Kepler mission have discovered a
planetary system of five small planets dating back to when the Milky Way
galaxy was a youthful two billion years old.
The tightly packed system, named Kepler-444, is home to five planets
that range in size, the smallest comparable to the size of Mercury and
the largest to Venus. All five planets orbit their sun-like star in less
than ten days, which makes their orbits much closer than Mercury's
sweltering 88-day orbit around the sun.
"While this star formed a long time ago, in fact before most of the
stars in the Milky Way, we have no indication that any of these planets
have now or ever had life on them," said Steve Howell, Kepler/K2 project
scientist at NASA's Ames Research Center in Moffett Field, California.
"At their current orbital distances, life as we know it could not exist
on these ancient worlds."
Kepler-444 formed 11.2 billion years ago, when the universe was less
than 20 percent its current age. This makes Kepler-444 the oldest known
system of terrestrial-size planets, two and a half times older than the
Earth.
To determine the age of the star and thus its planets, scientists
measured the very small change in brightness of the host star caused by
pressure waves within the star. The boiling motion beneath the surface
of the star generates these pressure waves, affecting the star's
temperature and luminosity. These fluctuations lead to miniscule changes
or variations in a star's brightness. This study of the interior of
stars is called asteroseismology and allows the researchers to measure
the diameter, mass and age of a star.
The Kepler-444 system is approximately 117 light-years away toward the constellation Lyra. A paper reporting this discovery is published in The Astrophysical Journal.
For more information on the discovery, see the University of Birmingham's press release.
Ames is responsible for Kepler's mission operations, ground system
development and science data analysis. NASA's Jet Propulsion Laboratory
in Pasadena, California, managed Kepler mission development. Ball
Aerospace & Technologies Corp. in Boulder, Colorado, developed the
Kepler flight system and supports mission operations with the Laboratory
for Atmospheric and Space Physics at the University of Colorado in
Boulder. The NASA Exoplanet Archive in Pasadena and the Space Telescope
Science Institute in Baltimore archive, host and distribute Kepler
science data. Kepler is NASA's 10th Discovery Mission and was funded by
the agency's Science Mission Directorate in Washington.
Michele Johnson
Ames Research Center, Moffett Field, Calif.
650-604-6982
michele.johnson@nasa.gov
Source: NASA's - Kepler Mission
