An Etymological Dictionary of Astronomy and Astrophysics
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The Lesser Dog. A small → constellation in the equatorial region of the northern sky at approximately R.A. 7h 30m, Dec. +5°. It hosts the bright star → Procyon. Abbreviation CMi, genitive form Canis Minoris.

Canis Minor, from canis "dog" → Canis Major; L. minor "lesser, smaller," from PIE base *min- "small" (cf. Gk. meion "less, lesser," Skt. mi-, minati "to diminish."

Sag "dog," → Canis Major; kucak "small," from Mid.Pers. kok, kotak, kotah "small, short; child."

The second brightest star in the → constellation  → Gemini. This star has the identifier "alpha," but it is fainter than β Geminorum (→ Pollux). Castor was known as a main sequence, blue star of magnitude 1.98 and → spectral type A1. However, it is actually a → gravitationally bound family of six stars. The two brightest of the six, Castor A and Castor B, revolve around one another over a period of about 445 years. Castor A, the brighter of the two, is magnitude 1.9, while its companion is 3.0. Castor A is of spectral type A1 V and Castor B is Am. They are hotter than the Sun and about three times more massive, and lie 51 → light-years from Earth. Castor A and B are orbited by a third star called Castor C. It's a 9th magnitude → red dwarf (dMe1) and lies about one arc minute to the south. Castor C is about 1,000 → astronomical units from the bright pair and takes 14,000 years to orbit around them. Each of the three is a → spectroscopic binary making Castor a → sextuplet. Castor C is a → binary star of red dwarf stars a little more than half the size of the Sun. They revolve around one another evry 19 hours. The companions of Castor A and B are also smaller dwarf stars.

In Gk. mythology, Castor and → Pollux were twin heroes called the Dioscuri. Castor was the son of Leda and Tyndareus, Pollux the son of Leda and Zeus. They were great warriors and were noted for their devotion to each other. After Castor was killed by Lynceus, Pollux implored Zeus to allow his brother to share his immortality with him. Zeus created the constellation Gemini in their honor.

The second brightest star in the constellation → Ursa Minor. It is a reddish, evolved → giant of → spectral type K4 with a visual magnitude of 2.1. It is almost 500 times more luminous than the Sun and lies at a distance of 126 light years. Also called Kocab, Kochah.

Kochab, from Ar. al-Kaukab (الکوکب) "star," shortened from al-Kaukab al-shemali (الکوکب الشمالی) "North Star."

The Lesser Lion. A faint constellation in the northern hemisphere, at 10h 20m right ascension, 35° north declination. Abbreviation: LMi; genitive: Leonis Minoris.

→ Leo; Minor, from L. minor "lesser, smaller, junior," from PIE base *min- "small."

Šir, → Leo; kucak "small," (Mid.Pers. kucak "small"), related to kutâh "short, small, little," kudak "child, infant," kutulé, → dwarf, Mid.Pers. kôtâh "low," kôtak "small, young; baby;" Av. kutaka- "little, small."

Lesser or smaller in amount, extent, or size.

From L. minor "lesser, smaller, junior," from PIE base *mei- "small" (cf. L. minuere "make small;" Gk. meion "less," minuthein "to lessen;" Skt. miyate "diminishes, declines;" O.E. minsian "to diminish").

Kehin comparative and superlative of keh "small, little, slender" (related to kâstan, kâhidan "to decrease, lessen, diminish," kam "little, few; deficient, wanting; scarce," (Mid.Pers. kam "little, small, few," O.Pers./Av. kamna- "small, few;" from Mid.Pers. kâhitan, kâstan, kâhênitan "to decrease, diminish, lessen;" Av. kasu- "small, little;" Proto-Iranian *kas- "to be small, diminish, lessen") + -é nuance suffix.

The axis of an ellipse that is perpendicular to the major axis at a point equidistant from the foci.

→ minor; → axis.

The → merging in which one of the galaxies is significantly larger than the other (mass ratios above 10). The larger galaxy will often "swallow" the smaller satellite galaxy. The swallowed galaxy can trigger disk and nuclear star formation or activate a central core with shells that surround the predator.

→ minor; → merger.

An obsolete name used to describe an → asteroid.

→ minor; → planet.

Logic: In a → categorical syllogism, the premise containing the → minor term.

→ major; → premisse.

Logic: In a → syllogism, the → subject of the → conclusion.

→ minor; → term.

For a function f defined on the interval I, the point m such that for each x on I, f(x)≥ m. See also → majorant.

From Fr. minorant, from minorer "to reduce, cut," from L. → minor.

Kehân, from kehidan, from keh "small, little," → minor.

The smaller number, part, or quantity of a whole.

→ minor; → -ity.

A blue → giant star in the constellation → Ursa Minor, also known as HR 5735, HD 137422, HIP 75097, BD+72°79, and SAO 8220. It has an → apparent visual magnitude of +3.0, → color indices of B -V = +0.09, U - B = +0.08, and a → spectral type of A2 III. Pherkad has a → luminosity of 1,100 Lsun, a radius of 15 Rsun, and a → surface temperature of 8,200 K. It lies 487 → light-years away from Earth.

From Ar. Al-Farqad (الفرقد) "calf."

The brightest star in the constellation → Gemini despite its designation as β. Also known as HR 2990 and HD 62509. Pollux lies about 4 degrees apart from the blue star → Castor with which it has no physical connection. Pollux is an orange-red star with a → visual magnitude 1.14 (B - V = +1.00) located about 34 → light-years away. It is a → giant star of → spectral type K0 III, with a mass of 2 Msun, a radius of about 10Rsun, a luminosity of 43 Lsun, and an → effective temperature of 4666 K. Pollux has a large planet, → Pollux b, with a mass of at least 2.3 times the mass of Jupiter.

Pollux, Gk. Polydeucus is one of the "Heavenly Twins," brother to → Castor, sons of Leda and Zeus.

Pollux, loan from L., as above. It has a too long Ar. name: Al-Ra's-at-Tau'am-al-Mo'akhkhar (الرأس‌التوأم‌المؤخر) "the head of the posterior twin," translating the Gk. mythological figure.

The prototypical and first discovered → cataclysmic variable. It is a → dwarf nova system with a relatively long → orbital period of 4 hr 17 minutes. U Gem undergoes → outbursts on time-scales between 30 and 250 days and shows → grazing occultations. The → accretion disk is partially eclipsed, but the → white dwarf remains visible during mideclipse. The mass of the white dwarf → primary is estimated to be 1.24 Msun, about two times higher than the mass of the → secondary; the → angle of inclination is 69°.7 (P. J. Groot 2001, ApJ 551, L89).

→ variable star designation; → Gemini.

The Lesser Bear. A constellation situated in the northern hemisphere, at about 15h right ascension, +79° declination. Its two brightest stars, both of 2nd magnitude, are → Polaris, the present pole star, and → Kochab. Abbreviation: UMi, Genitive: Ursae Minoris.

Ursa,from L. ursus "bear," cognate with Pers. xers, as below; Minor "smaller, less," from minus related to L. minuere "make small;" cf. Gk. meion "less," minuthein "to lessen;" Skt. miyate "diminishes, declines;" O.E. minsian "to diminish;" PIE base *mei- "small."

Xers "bear," dialectal Tabari aš; Mid.Pers. xirs, Av. arša- "bear;" cf. Skt. rksa- "bear;" Gk. arktos; L. ursus; PIE base *rtko- "bear;" kucak "small;" Mid.Pers. kucak "small," related to kutâh "short, small, little," kudak "child, infant," kutulé, → dwarf; Mid.Pers. kôtâh "low," kôtak "small, young; baby;" Av. kutaka- "little, small."

A dwarf spheroidal galaxy of faint luminosity that is a member of the Local Group.

→ Ursa Minor; → system.