Delta Canis Majoris ( Latinised from δ Canis Majoris, abbreviated Delta CMa, δ CMa), officially named Wezen , is a

star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...

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 origins of the e ...

Canis Major Canis Major is a constellation in the Southern Celestial Hemisphere, southern celestial hemisphere. In the second century, it was included in Ptolemy's 48 constellations, and is counted among the 88 modern constellations. Its name is Latin fo ...

. It is a yellow-white F-type

supergiant Supergiants are among the most massive and most luminous stars. Supergiant stars occupy the top region of the Hertzsprung–Russell diagram with absolute visual magnitudes between about −3 and −8. The temperature range of supergiant stars spa ...

with an

apparent 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 li ...

of +1.83. Since 1943, the

spectrum A spectrum (plural ''spectra'' or ''spectrums'') is a condition that is not limited to a specific set of values but can vary, without gaps, across a continuum. The word was first used scientifically in optics to describe the rainbow of colors i ...

of this star has served as one of the stable anchor points by which other stars are classified.

Observation

Delta Canis Majoris is the third-brightest star in the constellation after

Sirius Sirius is the list of brightest stars, brightest star in the night sky. Its name is derived from the Ancient Greek language, Greek word , or , meaning 'glowing' or 'scorching'. The star is designated α Canis Majoris, Latinisation ...

and ε Canis Majoris (Adhara), with an

of +1.83, and is white or yellow-white in colour. Lying about 10 degrees south southeast of Sirius, it only rises to about 11 degrees above the horizon at the latitude of the United Kingdom. The open cluster NGC 2354 is located only 1.3 degrees east of Delta Canis Majoris. As with the rest of Canis Major, Delta Canis Majoris is most visible in winter skies in the

northern hemisphere The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's Nort ...

, and summer skies in the southern. In Bayer's Uranometria, it is in the Great Dog's hind quarter.

History and naming

''δ Canis Majoris'' (Latinised to ''Delta Canis Majoris'') is the star's

Bayer designation A Bayer designation is a stellar designation in which a specific star is identified by a Greek or Latin letter followed by the genitive form of its parent constellation's Latin name. The original list of Bayer designations contained 1,564 stars. ...

. The traditional name, ''Wezen'' (alternatively ''Wesen'', or ''Wezea''), is derived from the medieval Arabic ''وزن'' ''al-wazn'', which means 'weight' in modern

Arabic Arabic (, ' ; , ' or ) is a Semitic languages, Semitic language spoken primarily across the Arab world.Semitic languages: an international handbook / edited by Stefan Weninger; in collaboration with Geoffrey Khan, Michael P. Streck, Janet C ...

. The name was for one of a pair of stars, the other being ''Hadar'', which has now come to refer to

Beta Centauri Beta Centauri is a triple star system in the southern constellation of Centaurus. It is officially called Hadar (). The Bayer designation of Beta Centauri is Latinised from β Centauri, and abbreviated Beta Cen or β Cen. The sys ...

. It is unclear whether the pair of stars was originally

Alpha Alpha (uppercase , lowercase ; grc, ἄλφα, ''álpha'', or ell, άλφα, álfa) is the first letter of the Greek alphabet. In the system of Greek numerals, it has a value of one. Alpha is derived from the Phoenician letter aleph , whic ...

and Beta Centauri or

and

Beta Columbae Beta Columbae (β Columbae, abbreviated Beta Col, β Col), officially named Wazn , is the second-brightest star in the southern constellation of Columba. It has an apparent visual magnitude of 3.1, which is bright enough to be viewed wi ...

. In any case, the name was somehow applied to both Delta Canis Majoris and Beta Columbae.

Richard Hinckley Allen In astronomy, stars have a variety of different stellar designations and names, including catalogue designations, current and historical proper names, and foreign language names. Only a tiny minority of known stars have proper names; all others ha ...

muses that the name alludes to the difficulty the star has rising above the horizon in the northern hemisphere. Astronomer

Jim Kaler James Bailey "Jim" Kaler (December 29, 1938 — November 26, 2022) was an American astronomer and science writer. After elementary and high-school education in Albany, New York, Kaler earned his A.B. at the University of Michigan in 1960. He atte ...

has noted the aptness of the traditional name given the star's massive nature. In 2016, the

International Astronomical Union The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreac ...

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's first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN; which included ''Wezen'' for this star. In

Chinese Chinese can refer to: * Something related to China * Chinese people, people of Chinese nationality, citizenship, and/or ethnicity **''Zhonghua minzu'', the supra-ethnic concept of the Chinese nation ** List of ethnic groups in China, people of ...

, (), meaning ''

Bow and Arrow The bow and arrow is a ranged weapon system consisting of an elastic launching device (bow) and long-shafted projectiles ( arrows). Humans used bows and arrows for hunting and aggression long before recorded history, and the practice was comm ...

'', refers to an asterism consisting of δ Canis Majoris, ε Canis Majoris, η Canis Majoris, κ Canis Majoris, ο Puppis, π Puppis, χ Puppis,

c Puppis The Bayer designations c Puppis and C Puppis are distinct and refer to two different stars in the constellation Puppis Puppis is a constellation in the southern sky. Puppis, the Latin translation of "poop deck", was originally part of an over-l ...

and k Puppis. Consequently, δ Canis Majoris itself is known as (, en, the First Star of Bow and Arrow.) In the catalogue of stars in the ''Calendarium of Al Achsasi Al Mouakket'', this star was designated ''Thalath al Adzari'' (''تالت ألعذاري'' - ''taalit al-aðārii''), which was translated into

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

as ''Tertia Virginum'', meaning ''the third virgin''. This star, along with ε Canis Majoris (Adhara), η Canis Majoris (Aludra) and ο² Canis Majoris (Thanih al Adzari), were ''Al ʽAdhārā'' (''ألعذاري''), the Virgins.

Physical properties

Delta Canis Majoris is a

class Class or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytical concept used differentl ...

F8 with a radius around 215 times that of the Sun. Its surface temperature is around 5,818 K, and it is 17 times more massive than the Sun. Its absolute magnitude is −6.87, and it lies around 1,600

light-year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

s away. It is rotating at a speed of around 28 km/s, and hence may take a year to rotate fully. Only around 10 million years old, Delta Canis Majoris has stopped fusing

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...

in its core. Its outer envelope is beginning to expand and cool, and in the next 100,000 years it will become a red supergiant as its core fuses heavier and heavier elements. Once it has an

iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in f ...

core, it will collapse and explode as a

supernova A supernova is a powerful and luminous explosion of a star. It has the plural form supernovae or supernovas, and is abbreviated SN or SNe. This transient astronomical event occurs during the last evolutionary stages of a massive star or when ...

. If Delta Canis Majoris were as close to Earth as Sirius is, it would be as bright as a half-full moon.

Modern legacy

Delta Canis Majoris appears on the

flag of Brazil The national flag of Brazil ( pt, bandeira do Brasil), is a blue disc depicting a starry sky (which includes the Southern Cross) spanned by a curved band inscribed with the national motto "''Ordem e Progresso''" ("Order and Progress"), within a y ...

, symbolising the state of

Roraima Roraima (, ) is one of the 26 states of Brazil. Located in the country's North Region, it is the northernmost and most geographically and logistically isolated state in Brazil. It is bordered by the state of Pará to the southeast, Amazonas ...

References

{{DEFAULTSORT:Delta Canis Majoris F-type supergiants Canis Major Canis Majoris, Delta Durchmusterung objects Canis Majoris, 25 054605 034444 2693 TIC objects Wezen