In astronomy, a disrupted planet is a planet or exoplanet or, perhaps on a somewhat smaller scale, a planetesimal, moon, exomoon or asteroid that has been disrupted or destroyed by a nearby or passing astronomical body or object such as a star. Necroplanetology is the related study of such a process. Nonetheless, the result of such a disruption may be the production of excessive amounts of related gas, dust and debris, 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. Excessive amounts of infrared radiation may be detected from such stars, suggestive evidence in itself that dust and debris may be orbiting the stars.
Examples of planets, or their related remnants, considered to have been a disrupted planet, or part of such a planet, include: 'Oumuamua and WD 1145+017 b, as well as asteroids, hot Jupiters and those that are hypothetical planets, like Fifth planet, Phaeton, Planet V and Theia.
Tabby's Star (KIC 8462852) is an F-type main-sequence star exhibiting unusual light fluctuations, including up to a 22% dimming in brightness. 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. 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.
All light curve data − December 2009 to May 2013, scan days 0066 to 1587 (Kepler)
5 March 2011 − day 792
15% max dip (Kepler)
28 February 2013 − day 1519
22% max dip (Kepler)
17 April 2013 − day 1568
8% max dip (Kepler)
Light curve between 10 October 2019 and 11 January 2020 (HAO)
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 (as described by Rappaport et al, 2017 link); 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).