An Etymological Dictionary of Astronomy and Astrophysics
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A binary star, in the constellation → Canis Major, 470 → light-years distant from Earth. The main star possesses an apparent magnitude of +1.5 and belongs to the spectral classification B2 II. The +7.5 magnitude companion star is 7''.5 apart from the main star.

Adhara, from Ar. adhârâ "virgins," plural of adhrâ' "virgin".

Azârâ, from Ar. Adhara.

The Greater Dog. A → constellation in the southern hemisphere which contains → Sirius, the brightest star of the whole sky. Approximate position: R.A. 7 h, Dec. -20°; abbreviation CMa; genitive form Canis Majoris.

L. Canis Major, from canis "dog" (cf. Gk. kuon, Skt. svâ-, Av. spâ-, Pers. sag; PIE *kwon-) + Maior "larger," from L. major, irregular comp. of magnus "large, great" (cf. Gk. megas, Av. maz-, masan-, mazant- "great, important," Skt. mah-, mahant-, Mod.Pers. meh; PIE *meg- "great").
Canis Major is usually seen as one of the two hunting dogs of the hunter Orion. The other dog is Canis Minor, the Little Dog.

Sag-e Bozorg, from sag, see the above paragraph, + bozorg "large, great," Mid.Pers. vuzurg, O.Pers. vazarka- "great," Av. vazra- "club," Skt. vajati, vaja- "strength," vajra- "Indira's thunderbolt," L. vegere "to be lively," PIE *weg- "to be strong, be lively."

The fourth brightest star in the constellation → Canis Major. It is a B1 → giant of magnitude 2.0 lying about 500 → light-years away. Mirzam is one of the brightest of the → Beta Cephei variable stars.

From Ar. al-Mirzam (المرزم) "subordinate," which according to the Persian astronomer Biruni (A.D. 973-1048) was a general name for a relatively fainter star lying beside a much brighter one, in this case → Sirius. Some sources have related the name of this star to Ar. al-Murzim (المرزم) "the roarer." They claim that this name refers to the fact that the star is situated to the east of Sirius and thus "announces, heralds" imminent rising of Sirius. However, this interpretation does not seem tenable since the meaning "announcing" is far-fetched, and moreover the angular distance between Sirius and Mirzam being small, they actually rise together.

A → red supergiant star which is one of the largest and most intrinsically luminous stars in the sky. It has a radius of about 1,420 solar radii (→ solar radius) and a luminosity of 3 × 10⁵ Lsun (→ solar luminosity). It is about 3,900 → light-years from the Earth. Excluding solar system bodies, VY CMa is the third brightest object in the sky at 10 µm. It has a large optical → reflection nebula, visible through even small telescopes, created by its prodigious mass loss (> 10^-4 Msun per year). Its initial mass is estimated to be about 25 Msun and its current mass 17 Msun. Recent observations have shown the presence of submicron → dust grains, with an average radius of ~ 0.5 μm, in the ejecta. These grains are 50 times larger than those found in the diffuse → interstellar medium (P. Scicluna et al., 2015, A&A, 584L, 10S).

V and Y, following the → variable star designation scheme; → Canis Major.

A luminous → FU Orionis object consisting of two young stars in a → binary system, a → Herbig Be star embedded in a dust cocoon and a less massive component located 0.1 arcsecond south-east. It is associated with a very large-scale and high-velocity → bipolar outflow extending in total 3.6 pc (for a distance of 1150 pc) with radial velocities up to -620 km/sec. The outflow is traced by a → jet and at least 15 → Herbig-Haro objects. In 2008 Z CMa showed the largest "outburst" ever reported in the past 90 years.

→ Canis Major.