Kepler-37b is an extrasolar planet orbiting Kepler-37 in the constellation Lyra. As of February 2013, it is the smallest planet discovered around a main-sequence star, with a radius slightly greater than the Moon. The measurements do not show its mass, but masses above a few times that of the Moon give unphysically high densities.
Characteristics[]
Mass, Radius, and Temperature[]
Kepler-37b is a "Sub-Earth", which is an exoplanet with a mass and radius smaller than Earth. Its surface temperature is 700 K (427 °C; 800 °F). Because of this, it is not expected to have an atmosphere. Its radius is approximately 0.35 Earth Radii, larger than the Moon, but a little smaller than Mercury. Due to its small size, it is very likely Kepler-37b is a terrestrial planet with a solid surface.
It is too hot to support a stable body of liquid water, however, its possible that water ice could exist near the poles similar to Mercury.
Host Star[]
The planet orbits a G-type main-sequence star similar to the Sun, named Kepler-37. It is orbited by four planets. The star has a mass of 0.80 M☉ and a radius of 0.79 R☉. It has a temperature of 5417 K and is 5.66 billion years old. In comparison, the Sun is 4.6 billion years old and has a temperature of 5778 K.
The star's apparent magnitude, or how bright it appears from Earth's perspective, is 9.71. Therefore, it is too dim to be seen with the naked eye.
Orbit[]
Kepler-37b orbits Kepler-37 at a distance of about 15 million km (0.1 AU) with an orbital period of around 13 days. The outer two planets have orbital periods within one percent of the 8:5 and 3:1 resonances of Kepler-37b’s period.
Discovery[]
Kepler-37b, along with two other planets, Kepler-37c and Kepler-37d, were discovered by the Kepler Space Telescope, which observes stellar Transits. After observing transits of Kepler-37b, astronomers had to compare it with the size of the parent star.
The size of the star was obtained using asteroseismology; Kepler-37 is currently the smallest star to be studied using this process. This allowed the size of Kepler-37b to be determined "with extreme accuracy".
To date, Kepler-37b is the smallest planet discovered around a main-sequence star outside the Solar System. Detection of Kepler-37b was possible due to its short orbital period, relative brightness, and low activity of its host star, allowing brightness data to average out quickly. The discovery of Kepler-37b has led Jack Lissauer, a scientist at NASA's Ames Research Center, to conjecture that "such little planets are common".
See Also[]
- Kepler-37
- Kepler-37c
- Kepler-37d
- Kepler-37e
- List of exoplanet records