Journal Article

A sub-Mercury-sized exoplanet

Ford, Eric B., Chaplin, William J., Kjeldsen, Hans, Latham, David W., Howell, Steve B., Charbonneau, David, Handberg, Rasmus, Karoff, Christoffer, Agol, Eric, Bedding, Timothy R., Howard, Andrew W., Rowe, Jason F., Still, Martin, Christiansen, Jessie L., Lund, Mikkel N., Fortney, Jonathan J., Horch, Elliott, Stello, Dennis, Lopez, Eric D., Christensen-Dalsgaard, Jørgen, Miglio, Andrea, Henze, Christopher E., Kawaler, Steven D., Everett, Mark, Ragozzine, Darin, Thompson, Susan E., Lillo-Box, Jorge, Dupree, Andrea K., Fressin, François, Barrado, David, Basu, Sarbani, Jenkins, Jon M., Hunter, Roger C., Lissauer, Jack J., Désert, Jean-Michel, Marcy, Geoffrey W., Adams, Elisabeth R., Quintana, Elisa V., Fischer, Debra A., Ciardi, David, Cochran, William D., Geary, John C., Morris, Robert L., Barclay, Thomas, Mullally, Fergal, Elsworth, Yvonne, Isaacson, Howard, Metcalfe, Travis S., Bryson, Stephen T., Lundkvist, Mia, Huber, Daniel, Haas, Michael R., Smith, Jeffrey C., Li, Jie, Buchhave, Lars A., Hekker, Saskia, Torres, Guillermo, Klaus, Todd C.

2013

Overview

Stellar data from the Kepler spacecraft are used to infer the existence of a sub-Mercury-sized exoplanet, the smallest yet discovered, in orbit around a Sun-like star. Mercury-like exoplanets in Kepler's sights When the Kepler spacecraft was launched in 2009 its brief was to search for rocky planets around Sun-like host stars in our Galaxy. Many of the hundreds of known exoplanets are large 'hot Jupiters' close-in to their stars. Last year it became possible to detect Earth-sized exoplanets, and now comes the discovery of a rocky planet significantly smaller than Mercury. Kepler-37b is orbiting the Sun-like star Kepler-37 in a system with at least two other planets. It is similar to our Moon in size and is likely to resemble Mercury: rocky, no atmosphere and no water. Since the discovery of the first exoplanets 1 , 2 , it has been known that other planetary systems can look quite unlike our own 3 . Until fairly recently, we have been able to probe only the upper range of the planet size distribution 4 , 5 , and, since last year, to detect planets that are the size of Earth 6 or somewhat smaller 7 . Hitherto, no planets have been found that are smaller than those we see in the Solar System. Here we report a planet significantly smaller than Mercury 8 . This tiny planet is the innermost of three that orbit the Sun-like host star, which we have designated Kepler-37. Owing to its extremely small size, similar to that of the Moon, and highly irradiated surface, the planet, Kepler-37b, is probably rocky with no atmosphere or water, similar to Mercury.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 639/33/34/862 / Cosmic physics / Design and construction / Discovery and exploration / Dwarf stars / Earth / Extrasolar planets / Humanities and Social Sciences / letter / Mercury / multidisciplinary / Observations / Oscillation / Outer space / Planets / Science / Stars & galaxies / Studies