June 4, 2013
Stars And Planets Are Larger Than Thought, According To Kepler Data
Lee Rannals for redOrbit.com - Your Universe Online
Astronomers writing in the Astrophysical Journal say they have found that many of the stars and planets discovered are larger than previously thought.
The astronomers used the NOAO Kitt Peak National Observatory Mayall 4-meter telescope to observe candidate planets identified by the NASA Kepler Mission and found that most of the stars observed are larger than originally thought, and a quarter of them were 35 percent bigger.
"Therefore, any planets orbiting these stars must be larger and hotter as well. By implication, these new results reduce the number of candidate Earth-size planet analogues detected by Kepler," said Mark Everett, from the National Optical Astronomy Observatory.
The researchers also found that planets larger than Neptune are more likely to be found orbiting stars that contain more heavy metals like iron than stars like the Sun. However, they say that small planets can be discovered around stars both rich and poor in metals.
Scientists knew the approximate sizes of most of the host stars based on the star's colors and brightness. The team acquired spectra using the Mayall telescope in Tucson, Arizona to further improve these observations.
“While Kepler is the discovery machine, it takes both Earth-based and space-based telescopes to truly understand exoplanets and how they relate to the stars they orbit,” says David Silva, NOAO Director and one of the co-investigators of this study.
More than 300 stars identified by Kepler as hosts of potential exoplanets have been observed at the Mayall telescope. The sample used during this study contained more faint stars, with distances ranging from 2,800 to over 7,000 light years. These stars host the majority of high-priority, Earth-sized candidate planets identified by Kepler.
“Determination of accurate stellar sizes allows astronomers to more accurately identify which exoplanets are Earth analogs, fulfilling a key goal of the Kepler mission,” said Steve B. Howell, a Kepler Project Scientist.
The team plans to make more ground-based spectral observations using Kepler.
The Kepler spacecraft behind all these great discoveries is currently inoperable. NASA announced that the spacecraft placed itself in a thruster-controlled safe mode back in May, effectively putting an end to the mission unless scientists figure a way to bring it back to a stabilized position. Kepler already completed its primary three-and-a-half year mission to find Earth-size and small planets, and there is still plenty of data for scientists to go through and make new discoveries.