variable star
A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as e ...
in the northern
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 p ...
Aries
Aries may refer to:
*Aries (astrology), an astrological sign
*Aries (constellation), a constellation of stars in the zodiac
Arts, entertainment and media
* ''Aries'' (album), by Luis Miguel, 1993
* ''Aries'' (EP), by Alice Chater, 2020
* "Aries" ...
. It has the
variable star designation
In astronomy, a variable star designation is a unique identifier given to variable stars. It uses a variation on the Bayer designation format, with an identifying label (as described below) preceding the Latin genitive of the name of the constel ...
SX Arietis, while ''56 Arietis'' is the
Flamsteed designation
A Flamsteed designation is a combination of a number and constellation name that uniquely identifies most naked eye stars in the modern constellations visible from southern England. They are named for John Flamsteed who first used them while c ...
. This object is visible to the naked eye as a faint, blue-white hued point of light with a baseline
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 5.79. The estimated distance to this star is approximately , based on
parallax
Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight and is measured by the angle or semi-angle of inclination between those two lines. Due to foreshortening, nearby object ...
, and it is drifting further away with a
radial velocity
The radial velocity or line-of-sight velocity, also known as radial speed or range rate, of a target with respect to an observer is the rate of change of the distance or range between the two points. It is equivalent to the vector projection ...
of +18 km/s.
This is a magnetic,
chemically peculiar star
In astrophysics, chemically peculiar stars (CP stars) are stars with distinctly unusual metal abundances, at least in their surface layers.
Classification
Chemically peculiar stars are common among hot main-sequence (hydrogen-burning) stars. Thes ...
of the
silicon
Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic ...
type with a
stellar classification
In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting t ...
of B9pSi, and it has a rapid rotation period of 17.5 hours. This period is increasing by about two seconds every hundred years. The star displays evidence of a five year period for procession of its axis. 56 Arietis is the prototype of a class of
variable star
A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as e ...
s known as SX Arietis variables, which are rotationally variable stars with strong
magnetic field
A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and t ...
s. It ranges in brightness from 5.75 down to 5.81 with a cyclical period matching its rotation rate.