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Omicron2 Cancri (ο2 Cnc, ο2 Cancri) is a solitary, yellow-white-hued star in the
zodiac The zodiac is a belt-shaped region of the sky that extends approximately 8° north or south (as measured in celestial latitude) of the ecliptic, the apparent path of the Sun across the celestial sphere over the course of the year. The pat ...
constellation of
Cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...
. With an
apparent visual magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's lig ...
of +5.67, it can be viewed with the naked eye on a dark night. Based upon an annual parallax shift of 21.68  mas as seen from Earth, this star is located around 150  light-years from the
Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
. It most likely forms a co-moving pair with Omicron1 Cancri. With a stellar classification of F0 IV, this is an F-type
subgiant A subgiant is a star that is brighter than a normal main-sequence star of the same spectral class, but not as bright as giant stars. The term subgiant is applied both to a particular spectral luminosity class and to a stage in the evolution ...
star that has left the main sequence and is
evolving Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation t ...
toward the
giant In folklore, giants (from Ancient Greek: ''gigas'', cognate giga-) are beings of human-like appearance, but are at times prodigious in size and strength or bear an otherwise notable appearance. The word ''giant'' is first attested in 1297 fr ...
stage. It is estimated to be roughly 300 million years old with a relatively high rotation rate, as shown by a
projected rotational velocity Stellar rotation is the angular motion of a star about its axis. The rate of rotation can be measured from the spectrum of the star, or by timing the movements of active features on the surface. The rotation of a star produces an equatorial bulg ...
of around 90.5 km/s. With 1.72 times the mass of the Sun and 1.62 times the Sun's radius, it is radiating 10.3 times the
solar luminosity The solar luminosity (), is a unit of radiant flux ( power emitted in the form of photons) conventionally used by astronomers to measure the luminosity of stars, galaxies and other celestial objects in terms of the output of the Sun. One nominal ...
from its photosphere at an effective temperature of . The star has an
infrared excess An infrared excess is a measurement of an astronomical source, typically a star, that in their spectral energy distribution has a greater measured infrared flux than expected by assuming the star is a blackbody radiator. Infrared excesses are oft ...
, suggesting it surrounded by a circumstellar
debris disk A debris disk (American English), or debris disc (Commonwealth English), is a circumstellar disk of dust and debris in orbit around a star. Sometimes these disks contain prominent rings, as seen in the image of Fomalhaut on the right. Debris di ...
. Modelling of this structure indicates there are three distinct components, consisting of belts orbiting at distances of about 20  AU, 80 AU and 270 AU from the central star. They are inclined at an angle of 64° to the line of sight along a
position angle In astronomy, position angle (usually abbreviated PA) is the convention for measuring angles on the sky. The International Astronomical Union defines it as the angle measured relative to the north celestial pole (NCP), turning positive into the ...
of 103°. The gaps between the belts are most likely maintained by orbiting planets.


References

{{DEFAULTSORT:Omicron2 Cancri F-type subgiants Circumstellar disks Cancri, Omicron2 Cancer (constellation) Durchmusterung objects Cancri, 63 076582 044001 3565