Zeta Cassiopeiae, Latinized from ζ Cassiopeiae, and officially named Fulu , is a

variable star A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes systematically with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are ...

in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The first constellati ...

Cassiopeia Cassiopeia or Cassiopea may refer to: Greek mythology * Cassiopeia (mother of Andromeda), queen of Aethiopia and mother of Andromeda * Cassiopeia (wife of Phoenix), wife of Phoenix, king of Phoenicia * Cassiopeia, wife of Epaphus, king of Egy ...

. It has a blue-white hue and is classified as a B-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 ...

with a variable

apparent magnitude Apparent magnitude () is a measure of the Irradiance, brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction (astronomy), ...

of about +3.6, making it visible to the

naked eye Naked eye, also called bare eye or unaided eye, is the practice of engaging in visual perception unaided by a magnification, magnifying, Optical telescope#Light-gathering power, light-collecting optical instrument, such as a telescope or microsc ...

. Based upon

parallax Parallax is a displacement or difference in the apparent position of an object viewed along two different sightline, lines of sight and is measured by the angle or half-angle of inclination between those two lines. Due to perspective (graphica ...

measurements, it is approximately 590

light-year A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by the International Astr ...

s from the

Sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

Nomenclature

''ζ Cassiopeiae'' ( Latinised to ''Zeta Cassiopeiae'') is the star's

Bayer designation A Bayer designation is a stellar designation in which a specific star is identified by a Greek alphabet, Greek or Latin letter followed by the genitive case, genitive form of its parent constellation's Latin name. The original list of Bayer design ...

. In

Chinese astronomy Astronomy in China has a long history stretching from the Shang dynasty, being refined over a period of more than 3,000 years. The Ancient China, ancient Chinese people have identified stars from 1300 BCE, as Chinese star names later categori ...

, Zeta Cassiopeiae is called 附路,

Pinyin Hanyu Pinyin, or simply pinyin, officially the Chinese Phonetic Alphabet, is the most common romanization system for Standard Chinese. ''Hanyu'' () literally means 'Han Chinese, Han language'—that is, the Chinese language—while ''pinyin' ...

: Fùlù, meaning '' Auxiliary Road'', because this star is marking itself and standing alone in the ''Auxiliary Road'' asterism, ''

Legs A leg is a weight-bearing and locomotive anatomical structure, usually having a columnar shape. During locomotion, legs function as "extensible struts". The combination of movements at all joints can be modeled as a single, linear element cap ...

'' (mansion) (see

Chinese constellation Traditional Chinese astronomy has a system of dividing the celestial sphere into asterisms or constellations, known as "officials" ( Chinese ''xīng guān''). The Chinese asterisms are generally smaller than the constellations of Hellenisti ...

). 附路 (Fùlù) was westernized into ''Foo Loo'', but that name was also designated for

Eta Cassiopeiae Eta Cassiopeiae (η Cassiopeiae, abbreviated Eta Cas, η Cas) is a binary star system in the Northern celestial hemisphere, northern constellation of Cassiopeia (constellation), Cassiopeia. Its binary nature was first discovered by Will ...

by R.H. Allen, with the meaning of "a by-path" Richard Hinckley Allen: Star Names — Their Lore and Meaning: Cassiopeia
/ref> In 2016, the IAU organized a

Working Group on Star Names The International Astronomical Union (IAU) established a Working Group on Star Names (WGSN) in May 2016 to catalog and standardize proper names for stars for the international astronomical community. It operates under Division C – Education ...

(WGSN) to catalog and standardize proper names for stars. The WGSN approved the name ''Fulu'' for Zeta Cassiopeiae on 30 June 2017 and it is now so included in the List of IAU-approved Star Names.

Properties

Zeta Cassiopeiae is a B2

, indicating that it has exhausted its core hydrogen and started to

evolve Evolve may refer to: * Evolution, change in heritable characteristics of biological populations over time Music * ''Evolve'' (Ani DiFranco album) or the title song, 2003 * ''Evolve'' (Coldrain album), 2014 * ''Evolve'' (Endo album), 2001 * '' ...

away from the

main sequence In astronomy, the main sequence is a classification of stars which appear on plots of stellar color index, color versus absolute magnitude, brightness as a continuous and distinctive band. Stars on this band are known as main-sequence stars or d ...

. It has a temperature of over 20,000 K, is about eight times the mass of the sun, and is 7,200 times as luminous.

Variability

Zeta Cassiopeiae is a probable member of an unusual group of variable stars known as " Slowly Pulsating B" (SPB) stars. It shows a pulsation frequency of 0.64 per day (or once every 1.56 days) and displays a weak

magnetic field A magnetic field (sometimes called B-field) is a physical 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 ...

with a strength of roughly , which varies with a period of 5.37 days. This likely matches the rotation rate of the star, which, when combined with the low

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 bu ...

, indicates the star may be seen nearly pole-on. Zeta Cassiopeiae is a candidate magnetic Bp star that shows an overabundance of helium. The star contains a randomly oriented fossil magnetic field, which impacts the outflow of the stellar wind. Collisions between streams from this stellar wind creates a shock front, with cooling particles settling toward a co-rotating disk.

References

{{Stars of Cassiopeia Cassiopeiae, Zeta Cassiopeiae, 17 B-type subgiants Cassiopeia (constellation) Slowly pulsating B-type stars 0153 003360 002920 BD+53 0105

Fulu () are Asemic writing, asemic Daoist, Taoist magic symbols and incantations, translatable into English as 'talismanic script', which are written or painted on talismans by Taoist practitioners. These practitioners are called , an informal gr ...