In astronomy, a disrupted planet [1] [2] is a planet or exoplanet or, perhaps on a somewhat smaller scale, a planetary-mass object, planetesimal, moon, exomoon or asteroid that has been disrupted or destroyed by a nearby or passing astronomical body or object such as a star. [1] [2] Necroplanetology is the related study of such a process. [3] [4]
The result of such a disruption may be the production of excessive amounts of related gas, dust and debris, [5] which may eventually surround the parent star in the form of a circumstellar disk or debris disk. As a consequence, the orbiting debris field may be an "uneven ring of dust", causing erratic light fluctuations in the apparent luminosity of the parent star, as may have been responsible for the oddly flickering light curves associated with the starlight observed from certain variable stars, such as that from Tabby's Star (KIC 8462852), RZ Piscium and WD 1145+017. [3] [4] Excessive amounts of infrared radiation may be detected from such stars, [6] suggestive evidence in itself that dust and debris may be orbiting the stars. [5] [7] [8] [9]
Examples of planets, or their related remnants, considered to have been a disrupted planet, or part of such a planet, include: ‘Oumuamua [10] and WD 1145+017 b, as well as asteroids, [11] hot Jupiters [12] and those that are hypothetical planets, like Fifth planet, Phaeton, Planet V and Theia. Planets can also be disrupted by black holes; one example involves a "Jupiter-like object" being subject to a tidal disruption event by the supermassive black hole IGR J12580+0134, at the center of the galaxy NGC 4845. [13]
Examples of parent stars considered to have disrupted a planet include: EPIC 204278916, Tabby's Star (KIC 8462852), PDS 110, RZ Piscium, WD 1145+017 and 47 Ursae Majoris.[ citation needed ]
Tabby's Star (KIC 8462852) is an F-type main-sequence star exhibiting unusual light fluctuations, including up to a 22% dimming in brightness. [14] Several hypotheses have been proposed to explain these irregular changes, but none to date fully explain all aspects of the curve. One explanation is that an "uneven ring of dust" orbits Tabby's Star. [15] [16] However, in September 2019, astronomers reported that the observed dimmings of Tabby's Star may have been produced by fragments resulting from the disruption of an orphaned exomoon. [17] [18]
An exomoon or extrasolar moon is a natural satellite that orbits an exoplanet or other non-stellar extrasolar body.
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.
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.
Planet Hunters is a citizen science project to find exoplanets using human eyes. It does this by having users analyze data from the NASA Kepler space telescope and the NASA Transiting Exoplanet Survey Satellite. It was launched by a team led by Debra Fischer at Yale University, as part of the Zooniverse project.
An exocomet, or extrasolar comet, is a comet outside the Solar System, which includes rogue comets and comets that orbit stars other than the Sun. The first exocomets were detected in 1987 around Beta Pictoris, a very young A-type main-sequence star. There are now a total of 27 stars around which exocomets have been observed or suspected.
Kepler-90, also designated 2MASS J18574403+4918185, is a F-type star located about 2,790 light-years (855 pc) from Earth in the constellation of Draco. It is notable for possessing a planetary system that has the same number of observed planets as the Solar System.
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-186 is a main-sequence M1-type dwarf star, located 177.5 parsecs away in the constellation of Cygnus. The star is slightly cooler than the sun, with roughly half its metallicity. It is known to have five planets, including the first Earth-sized world discovered in the habitable zone: Kepler-186f. The star hosts four other planets discovered so far, though they all orbit interior to the habitable zone.
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.
Tabby's Star (designated as KIC 8462852 in the Kepler Input Catalog and also known by the names Boyajian's Star and WTFStar, is a binary star in the constellation Cygnus approximately 1,470 light-years from Earth. The system is composed of an F-type main-sequence star and a red dwarf companion.
Tabetha "Tabby" Suzanne Boyajian is an American astronomer and associate professor at Louisiana State University. She works in the fields of stellar interferometry, stellar spectroscopy, exoplanet research, and high angular resolution astronomy, all particularly at optical and infrared wavelengths. Boyajian was the lead author of the September 2015 paper "Where's the Flux?", which investigated the highly unusual light curve of KIC 8462852; the star is colloquially known as Tabby's Star in her honor.
WD 1145+017 is a white dwarf approximately 476 light-years from Earth in the constellation of Virgo. It is the first white dwarf to be observed with a transiting minor planet orbiting it.
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.
Hereford Arizona Observatory (HAO), IAU-code G95, is an astronomical observatory, owned and operated by amateur astronomer Bruce L. Gary. Observational studies of unusual starlight fluctuations in Tabby's Star and WD 1145+017 are recent interests.
RZ Piscium is a UX Orionis type variable star 608 light-years (186 pc) away, in the constellation Pisces. Over the years, the star has been found to brighten and dim erratically, dimming by as much as a tenth of its usual luminosity. RZ Piscium has been found to emit large amounts of infrared radiation, suggesting the presence of a substantial mass of gas and dust orbiting the star, possibly from a "disrupted planet".
Kepler-21, also known as HD 179070, is a star with a closely orbiting exoplanet in the northern constellation of Lyra. At an apparent visual magnitude of 8.25 this was the brightest star observed by the Kepler spacecraft to host a validated planet until the discovery of an exoplanet orbiting HD 212657 in 2018. This system is located at a distance of 354 light-years from the Sun based on parallax measurements, but is drifting closer with a radial velocity of −18.2 km/s.
WD 0145+234 is a white dwarf star approximately 95 ly (29 pc) from Earth in the constellation of Aries that has been associated with studies suggesting that a very large exoasteroid near the star was substantially disrupted, resulting in a considerable amount of dust and debris around the star. Alternatively, the outburst around WD 0145+234 is explained with ongoing collisions between planetesimals inside the dusty debris disk around the white dwarf.
Kepler-429 is a variable subdwarf B star in the constellation Lyra, about 5,900 light years away.
Note: g'-band and r'-band dip depths (and shapes) may differ, with g'-band being more sensitive to dust cloud scattering due to its shorter wavelength (0.47 vs. 0.62 micron). For a reasonable particle size distribution (e.g., Hanson, 0.2 micron) the extinction cross section ratio would produce a depth at r'-band that is 0.57 x depth at g'-band. If g'-band depth is 0.3 %, for example, depth at r'-band could be 0.17 %. The "Tabby Team" measurements (Fig. 3) at r'-band are compatible with that small dip depth. Incidentally, none of these shapes resemble exo-comet tail transits; so the mystery of what's producing these week-timescale dips continues! Actually, long oval shapes are known to produce V-shaped dips (think of rings with a high inclination).– (as described by Rappaport et al, 2017 link)