Sextans
Encyclopedia
Sextans is a minor equatorial
constellation
which was introduced in 1687 by Johannes Hevelius
. Its name is Latin
for the astronomical sextant
, an instrument that Hevelius made frequent use of in his observations.
covers a rather dim, sparse region of the sky. It has only one star above the fifth magnitude
, namely α Sextantis
at 4.49m. The constellation contains a few double star
s, including γ
, 35, and 40 Sextantis. There are a few notable variable star
s, including β
, 25, 23 Sextantis, and LHS 292. NGC 3115
, an edge-on lenticular galaxy, is the only noteworthy deep-sky object. It also lies near the ecliptic, which causes the Moon, and some of the planets to occasionally pass through it for brief periods of time.
The constellation is the location of the field studied by the COSMOS project, undertaken by the Hubble Space Telescope
.
Celestial equator
The celestial equator is a great circle on the imaginary celestial sphere, in the same plane as the Earth's equator. In other words, it is a projection of the terrestrial equator out into space...
constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
which was introduced in 1687 by Johannes Hevelius
Johannes Hevelius
Johannes Hevelius Some sources refer to Hevelius as Polish:Some sources refer to Hevelius as German:*Encyplopedia Britannica * of the Royal Society was a councilor and mayor of Danzig , Pomeranian Voivodeship, in the Polish-Lithuanian Commonwealth...
. Its name is Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
for the astronomical sextant
Sextant (astronomical)
Sextants for astronomical observations were used primarily for measuring the positions of stars. They are little used today, having been replaced over time by transit telescopes, astrometry techniques, and satellites such as Hipparcos....
, an instrument that Hevelius made frequent use of in his observations.
Notable features
Sextans as a constellationConstellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
covers a rather dim, sparse region of the sky. It has only one star above the fifth magnitude
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...
, namely α Sextantis
Alpha Sextantis
Alpha Sextantis is the brightest star in the constellation Sextans. It is a white A-type giant with an apparent magnitude of +4.48. It is approximately 287 light years from Earth....
at 4.49m. The constellation contains a few double star
Double star
In observational astronomy, a double star is a pair of stars that appear close to each other in the sky as seen from Earth when viewed through an optical telescope. This can happen either because the pair forms a binary star, i.e...
s, including γ
Gamma Sextantis
Gamma Sextantis is a triple star system in the constellation Sextans. It is approximately 262 light years from Earth. The combined apparent magnitude of the system is +5.07....
, 35, and 40 Sextantis. There are a few notable variable star
Variable star
A star is classified as variable if its apparent magnitude as seen from Earth changes over time, whether the changes are due to variations in the star's actual luminosity, or to variations in the amount of the star's light that is blocked from reaching Earth...
s, including β
Beta Sextantis
Beta Sextantis is a variable star in the constellation Sextans.Beta Sextantis is a blue-white B-type main sequence dwarf. It is approximately 345 light years from Earth. It is classified as an Alpha2 Canum Venaticorum variable and its brightness varies from magnitude +5.00 to +5.10...
, 25, 23 Sextantis, and LHS 292. NGC 3115
NGC 3115
NGC 3115 is a lenticular galaxy in the constellation Sextans. The galaxy was discovered by William Herschel on February 22, 1787. At about 32 million light-years away from us it is several times bigger than our Milky Way...
, an edge-on lenticular galaxy, is the only noteworthy deep-sky object. It also lies near the ecliptic, which causes the Moon, and some of the planets to occasionally pass through it for brief periods of time.
The constellation is the location of the field studied by the COSMOS project, undertaken by the Hubble Space Telescope
Hubble Space Telescope
The Hubble Space Telescope is a space telescope that was carried into orbit by a Space Shuttle in 1990 and remains in operation. A 2.4 meter aperture telescope in low Earth orbit, Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared...
.