Discovery [1] | |
---|---|
Discovery date | November 5, 2013 |
Transit and reflection/emission modulations (Kepler Mission) | |
Designations | |
KIC 8435766 b | |
Orbital characteristics [2] | |
0.00901+0.00012 −0.00019 AU | |
Eccentricity | 0 |
0.35500745(8) days (8.5 hours) | |
Inclination | 75.2° +2.6° −2.1° |
Star | Kepler-78 |
Physical characteristics [2] | |
1.228+0.018 −0.019 R🜨 [3] | |
Mass | 1.68±0.27 M🜨 |
Mean density | 5.33+0.97 −0.33 g/cm3 |
log g = 3.058+0.069 −0.080 cgs (1.16 g ) | |
Temperature | 2223±32 K (1,950 ºC, 3,542 ºF) |
Kepler-78b (formerly known as KIC 8435766 b) is an exoplanet orbiting around the star Kepler-78. At the time of its discovery, it was the exoplanet most similar to Earth in terms of mass, radius, and mean density.
Kepler-78b is the only planet to be found orbiting the star KIC 8435766, now known as Kepler-78. [4] [5] [6] The planet was discovered in 2013 by analyzing data from the Kepler space telescope. The planet was detected as it passed across the surface of its host star, as viewed from Earth. It was also found by the effects of occultation as it passed behind the star. Reflected light from the parent star due to orbital phases was also detected. It was not at first designated as a Kepler object of interest, as data analysis failed to identify it due to its short orbital period. [4]
At the time of its discovery, Kepler-78b was the exoplanet most similar to Earth in terms of mass, radius, and mean density. [7] The planet is approximately 1.69 times the mass and 1.12 times the radius of Earth. [8] The acceleration due to gravity on the planet's surface is about 11 m/s2 (25 mph/s ), slightly greater than Earth's surface gravity. [8] Two independent teams were involved in pioneering work to estimate the planet's mass. Their estimates were made possible because Kepler-78b's gravity causes a "wobble" in the orbit of the host star. While the method has been used to characterize gas giants, it is difficult to estimate the mass of Earth-sized exoplanets, because their gravity is too weak to produce a visible influence. In this case, the planet's orbit is close enough to its star to produce a detectable effect. [9]
One team, led by Francesco Pepe, used the High Accuracy Radial Velocity Planet Searcher-North (HARPS-N) spectrograph at the Telescopio Nazionale Galileo in the Canary Islands [10] to estimate that the planet has a mass 1.86 times that of the Earth and a radius 1.16 times greater. The other, led by Andrew Howard of the University of Hawaii at Manoa, used data from the High Resolution Eschelle Spectrometer at the W.M. Keck Observatory in Hawaii to estimate the mass as 1.69 times that of the Earth and the radius as 1.12 times larger. Both estimates put the planet's density at about 5.5 grams per cubic centimeter (0.20 pounds per cubic inch ), equivalent to Earth's density. This measurement is possibly indicative of a rock-iron composition like Earth's. [9] [11] The iron core could build up to 40% of the planet mass. [7]
Kepler-78b is most similar to larger high-density, hot exoplanets like Kepler-10b, Kepler-36b and CoRoT-7b. [7]
Kepler-78b orbits around its parent star once every 8.5 hours. It reflects 20% to 60% of the starlight it receives. [12] Due to its extremely close solar orbit, which is about 40 times closer than Mercury is to the Sun, the planet's surface is estimated to be at a temperature of 2,200 K (1,930 °C ; 3,500 °F ). [2] This temperature is high enough to have stripped the planet of any stable atmosphere, but the liquid and solid portions of the planet should be stable. [8] According to Francesco Pepe, the planet may be Earth-sized, but "it can be imagined like a lava planet rather than an Earth-like planet". [9]
According to Harvard–Smithsonian Center for Astrophysics astronomer Dimitar Sasselov, "this lava world is an abomination. There’s no physical way a small world, only 12 percent larger than Earth, could have evolved in that location and there’s no known mechanism that could have transported it there. But one thing that is certain, it can’t stay roasting in that hellish orbit for long; it’s destined to get swallowed by its star very soon". [13] It is estimated that the planet will be swallowed by its parent star in about three billion years. [14] [15]
A Super-Earth or super-terran or super-tellurian is a type of exoplanet with a mass higher than Earth, but substantially below those of the Solar System's ice giants, Uranus and Neptune, which are 14.5 and 17.1 times Earth's, respectively. The term "super-Earth" refers only to the mass of the planet, and so does not imply anything about the surface conditions or habitability. The alternative term "gas dwarfs" may be more accurate for those at the higher end of the mass scale, although "mini-Neptunes" is a more common term.
This page describes exoplanet orbital and physical parameters.
The Kepler Input Catalog is a publicly searchable database of roughly 13.2 million targets used for the Kepler Spectral Classification Program (SCP) and the Kepler space telescope.
An exoplanet is a planet located outside the Solar System. The first evidence of an exoplanet was noted as early as 1917, but was not recognized as such until 2016; no planet discovery has yet come from that evidence. What turned out to be the first detection of an exoplanet was published among a list of possible candidates in 1988, though not confirmed until 2003. The first confirmed detection came in 1992, with the discovery of terrestrial-mass planets orbiting the pulsar PSR B1257+12. The first confirmation of an exoplanet orbiting a main-sequence star was made in 1995, when a giant planet was found in a four-day orbit around the nearby star 51 Pegasi. Some exoplanets have been imaged directly by telescopes, but the vast majority have been detected through indirect methods, such as the transit method and the radial-velocity method. As of 24 July 2024, there are 7,026 confirmed exoplanets in 4,949 planetary systems, with 1007 systems having more than one planet. This is a list of the most notable discoveries.
Kepler-10b is the first confirmed terrestrial planet to have been discovered outside the Solar System by the Kepler Space Telescope. Discovered after several months of data collection during the course of the NASA-directed Kepler Mission, which aims to discover Earth-like planets crossing in front of their host stars, the planet's discovery was announced on January 10, 2011. Kepler-10b has a mass of 3.72±0.42 Earth masses and a radius of 1.47 Earth radii. However, it lies extremely close to its star, Kepler-10, and as a result is too hot to support life as we know it. Its existence was confirmed using measurements from the W.M. Keck Observatory in Hawaii.
Kepler-10, formerly known as KOI-72, is a Sun-like star in the constellation of Draco that lies 607 light-years from Earth. Kepler-10 was targeted by NASA's Kepler space telescope, as it was seen as the first star identified by the Kepler mission that could be a possible host to a small, transiting exoplanet. The star is slightly less massive, slightly larger, and slightly cooler than the Sun; at an estimated 11.9 billion years in age, Kepler-10 is 2.3 times the age of the Sun.
Kepler-1520 is a K-type main-sequence star located in the constellation Cygnus. The star is particularly important, as measurements taken by the Kepler spacecraft indicate that the variations in the star's light curve cover a range from about 0.2% to 1.3% of the star's light being blocked. This indicates that there may be a rapidly disintegrating planet, a prediction not yet conclusively confirmed, in orbit around the star, losing mass at a rate of 1 Earth mass every billion years. The planet itself is about 0.1 Earth masses, or just twice the mass of Mercury, and is expected to disintegrate in about 100-200 million years. The planet orbits its star in just 15.7 hours, at a distance only two stellar diameters away from the star's surface, and has an estimated effective temperature of about 2255 K. The orbital period of the planet is one of the shortest ever detected in the history of the extrasolar planet search. In 2016, the planet was confirmed as part of a data release by the Kepler spacecraft.
A Mini-Neptune is a planet less massive than Neptune but resembling Neptune in that it has a thick hydrogen-helium atmosphere, probably with deep layers of ice, rock or liquid oceans.
Kepler-47 is a binary star system in the constellation Cygnus located about 3,420 light-years away from Earth. The stars have three exoplanets, all of which orbit both stars at the same time, making this a circumbinary system. The first two planets announced are designated Kepler-47b, and Kepler-47c, and the third, later discovery is Kepler-47d. Kepler-47 is the first circumbinary multi-planet system discovered by the Kepler mission. The outermost of the planets is a gas giant orbiting within the habitable zone of the stars. Because most stars are binary, the discovery that multi-planet systems can form in such a system has impacted previous theories of planetary formation.
Kepler-69 is a G-type main-sequence star similar to the Sun in the constellation Cygnus, located about 2,390 ly (730 pc) from Earth. On April 18, 2013 it was announced that the star has two planets. Although initial estimates indicated that the terrestrial planet Kepler-69c might be within the star's habitable zone, further analysis showed that the planet very likely is interior to the habitable zone and is far more analogous to Venus than to Earth and thus completely inhospitable.
Kepler-90g is a super-puff exoplanet orbiting the early G-type main sequence star Kepler-90, one of eight planets around this star discovered using NASA's Kepler space telescope. It is located about 2,840 light-years (870 pc) from Earth, in the constellation Draco. The exoplanet was found by using the transit method, in which the dimming effect that a planet causes as it crosses in front of its star is measured. It orbits its parent star about every 210.5 days at a distance of 0.71 astronomical units.
Kepler-78 is a 12th magnitude star 407 light-years away in the constellation Cygnus. Initially classified as an eclipsing binary with orbital period 0.710015 days, it was later re-classified as a single star with significant interaction between star magnetosphere and close-in planet. The radius of the star is of about 74% of the Sun, and the effective temperature is about 5100 K. Yıldız çekim kuvveti 523,6758338802 Newton yıldızdan ayrılma hızı738.011,05009176 metre saniye
Kepler-138, also known as KOI-314, is a red dwarf located in the constellation Lyra, 219 light years from Earth. It is located within the field of vision of the Kepler spacecraft, the satellite that NASA's Kepler Mission used to detect planets transiting their stars.
Kepler-186f is an Earth-sized exoplanet orbiting within the habitable zone of the red dwarf star Kepler-186, the outermost of five such planets discovered around the star by NASA's Kepler space telescope. It is located about 580 light-years from Earth in the constellation of Cygnus.
Kepler-296e is a confirmed super-Earth exoplanet orbiting within the habitable zone of Kepler-296. The planet was discovered by NASA's Kepler spacecraft using the transit method, in which the dimming effect that a planet causes as it crosses in front of its star is measured. NASA announced the discovery of the exoplanet on 26 February 2014.
Kepler-444 is a triple star system, estimated to be 11.2 billion years old, approximately 119 light-years (36 pc) away from Earth in the constellation Lyra. On 27 January 2015, the Kepler spacecraft is reported to have confirmed the detection of five sub-Earth-sized rocky exoplanets orbiting the main star. The star is a K-type main sequence star. All of the planets are far too close to their star to harbour life forms.
Kepler-186e is a confirmed exoplanet orbiting the red dwarf star Kepler-186, approximately 582 light years away from Earth in the constellation of Cygnus. It is near the optimistic habitable zone but probably not in it, possibly making it have a runaway greenhouse effect, like Venus. The exoplanet was found by using the transit method, in which the dimming effect that a planet causes as it crosses in front of its star is measured. Four additional planets orbiting the star were also discovered.
Kepler-1520b, is a confirmed exoplanet orbiting the K-type main sequence star Kepler-1520. It is located about 2,020 light-years away from Earth in the constellation of Cygnus. The exoplanet was found by using the transit method, in which the dimming effect that a planet causes as it crosses in front of its star is measured. The planet was previously proposed in 2012 when reports of its host star recorded drops in its luminosity varying from 0.2% to 1.3%, which indicated a possible planetary companion rapidly disintegrating. In 2015, the planetary nature of the cause of the dips was finally verified. It is expected to disintegrate in about 40–400 million years.
KOI-2700b is a confirmed exoplanet that orbits the K-type main-sequence star KIC 8639908, located about 1,608 light-years distant. It orbits the star very rapidly, with an orbital period of 0.91 days, at a distance of just 0.0150 AU (2,240,000 km). This, along with its small mass, is causing it to evaporate and lose material, which leaves a comet-like tail of dust stretching from the planet.