Astronomers Find Exoplanets that Orbit Parent Stars in Four Hours

Researchers have now found exoplanets that skim just past the star's surface.  Some of these alien planets have an orbital period of just 4 hours, meaning that by the time a person on earth completes one workday, these star-kissing planets would have completed two years.

The discovery was made by Brian Jackson of the Carnegie Institution for Science's Department of Terrestrial Magnetism and team. Astronomers used data from NASA's Kepler mission and found at least six planets, all with orbital periods of less than 12 hours or half-a-day on earth.

Previously, researchers at Massachusetts Institute of technology had found an exoplanet called Kepler 78b that whizzes around its parent star in a mind-boggling 8.5 hours.

Another exoplanet called KOI 1843.03 was found to have an orbital period of 4 1/4 hours. The discovery of this planet is detailed in the journal Astrophysical Journal Letters. Researchers believe that KOI 1843.03 must be very dense, entirely made of iron to survive so close to a star.

Some of the "super-fast planets" discovered by Jackson and team complete a year in just 4 hours.

Researchers say that gas exoplanets so close to star surface are generally unstable due to their deteriorating orbits. However, for rocky planets, the force of the star's gravity might keep them on track. 

The planets that the team discovered have masses roughly similar to the mass of earth and because they have shorter orbits, they could be studied using ground-based satellites.

NASA is expected to launch a planet-hunter called Transiting Exoplanet Survey Satellite(TESS) somewhere around the end of this decade. Researchers said that TESS could be used in analyzing these alien planets, space.com reported.

"If confirmed, these planets would be among the shortest-period planets ever discovered, and if common, such planets would be particularly amenable to discovery by the planned TESS mission, which will look for, among other things, short-period rocky planets," according to a statement by Carnegie Institution for Science.

Jackson and colleagues recently presented their study at the American Astronomical Society's Division of Planetary Sciences meeting.