Shortperiod

Shortperiod is a term used in astronomy to describe objects or phenomena that have short orbital or rotational periods relative to a reference timescale. The phrase is applied across several subfields, reflecting how the timescale of motion affects formation, dynamics, and observation.

In solar system science, short-period comets are those with orbital periods less than about 200 years. These comets typically originate from the Kuiper Belt or the scattered disk and are dynamically influenced by Jupiter. Their frequent passages through the inner solar system lead to rapid surface evolution and pronounced outgassing, and they are often distinguishable by relatively low-eccentricity, moderate-inclination orbits compared with long-period comets.

In exoplanet research, short-period planets are planets with orbital periods generally less than about 10 days. This category includes many hot Jupiters and super-Earths, which are often detected by transit or radial-velocity methods. Short periods imply strong tidal interactions with their host stars, frequent transits for detection, and frequent opportunities to study atmospheric properties and day–night contrasts, though they can also face atmospheric erosion and inflationary processes.

In stellar astrophysics, short-period binary stars orbit each other in periods from less than a day to several days. Contact and near-contact systems, such as W Ursae Majoris-type binaries, are common examples. The short timescales of these systems yield valuable insights into mass transfer, common envelopes, and stellar evolution in tightly bound pairs.

Shortperiod terminology thus spans comets, planets, and binary stars, united by the shared feature of rapid orbital dynamics compared with longer-period counterparts. See also orbital period, long-period, and tidal locking.