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Post Info TOPIC: KOI-961
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Title: Characterising the Cool KOIs III. KOI-961: A Small Star with Large Proper Motion and Three Small Planets
Authors: Philip S. Muirhead, John Asher Johnson, Kevin Apps, Joshua A. Carter, Timothy D. Morton, Daniel C. Fabrycky, J. Sebastian Pineda, Michael Bottom, Barbara Rojas-Ayala, Everett Schlawin, Katherine Hamren, Kevin R. Covey, Justin R. Crepp, Keivan G. Stassun, Joshua Pepper, Leslie Hebb, Evan N. Kirby, Andrew W. Howard, Howard T. Isaacson, Geoffrey W. Marcy, David Levitan, Tanio Diaz-Santos, Lee Armus, James P. Lloyd

We present the characterisation of the star KOI 961, an M dwarf with transit signals indicative of three short-period exoplanets, originally discovered by the Kepler Mission. We proceed by comparing KOI 961 to Barnard's Star, a nearby, well-characterized mid-M dwarf. By comparing colours, optical and near-infrared spectra, we find remarkable agreement between the two, implying similar effective temperatures and metallicities. Both are metal-poor compared to the Solar neighbourhood, have low projected rotational velocity, high absolute radial velocity, large proper motion and no quiescent H-alpha emission--all of which is consistent with being old M dwarfs. We combine empirical measurements of Barnard's Star and expectations from evolutionary isochrones to estimate KOI 961's mass (0.13 ±0.05 Solar masses), radius (0.17 ±0.04 Solar radii) and luminosity (2.40 x 10^(-3.0 ±0.3) Solar luminosity). We calculate KOI 961's distance (38.7 ±6.3 pc) and space motions, which, like Barnard's Star, are consistent with a high scale-height population in the Milky Way. We perform an independent multi-transit fit to the public Kepler light curve and significantly revise the transit parameters for the three planets. We calculate the false-positive probability for each planet-candidate, and find a less than 1% chance that any one of the transiting signals is due to a background or hierarchical eclipsing binary, validating the planetary nature of the transits. The best-fitting radii for all three planets are less than 1 Earth radii, with KOI 961.03 being Mars-sized (Rp = 0.57 ±0.18 Earth radii), and they represent some of the smallest exoplanets detected to date.

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Blobrana


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Smallest exoplanet is the size of Mars

The smallest exoplanet yet found around a sun-like star is a rocky world half the size of Earth and almost identical in size to Mars. Although it is too hot for life, researchers say its discovery boosts the chances of finding other, more life-friendly planets.
The newly discovered planet, called KOI-961.03, periodically passes in front of its parent star, causing a slight dip in its brightness detected by NASA's Kepler space telescope.
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Blobrana


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Keck telescope helps discover 3 small planets outside Milky Way

Astronomers at the Keck Observatory at the summit of Mauna Kea have helped to determine the size of three planets smaller than Earth that orbit a star outside the Milky Way galaxy.
The three planets orbit a star called KOI-961, according to W.M. Keck Observatory scientists. Their radii are calculated to be 78, 73 and 57 percent that of Earth, according to a news release.
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Blobrana


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NASA's Kepler Mission Finds Three Smallest Exoplanets

Astronomers using data from NASA's Kepler mission have discovered the three smallest planets yet detected orbiting a star beyond our sun. The planets orbit a single star, called KOI-961, and are 0.78, 0.73 and 0.57 times the radius of Earth. The smallest is about the size of Mars.
All three planets are thought to be rocky like Earth but orbit close to their star, making them too hot to be in the habitable zone, which is the region where liquid water could exist. Of the more than 700 planets confirmed to orbit other stars, called exoplanets, only a handful are known to be rocky.
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Astronomers Find Three Smallest Planets Outside Solar System

A team of astronomers led by scientists at the California Institute of Technology (Caltech) has discovered the three smallest confirmed planets ever detected outside our solar system. The three planets, which all orbit a single star, are smaller than Earth and appear to be rocky with a solid surface. Until now, astronomers have found at most only four other rocky planets, also called terrestrial planets, around other stars.
The trio of new planets is too close to the central star to be in its habitable zone - the ring-shaped region around a star where the temperature is mild enough for liquid water, and possibly life, to exist. But the planets are the first rocky ones to be found orbiting a type of dim, small star called a red dwarf, the most common kind in the Milky Way. Their existence suggests that the galaxy could be teeming with similarly rocky planets - and that there's a good chance that many are in the habitable zone.
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