The Sextans Constellation does not have any stars brighter than magnitude 3.00, with its brightest star being Alpha Sextantis, with an apparent magnitude of 4.49. It contains five stars located within 10 parsecs (32.6 light years) of Earth and the nearest star is the red dwarf LHS 292, positioned only 14.8 light years from Earth.
Sextans is home to five stars with confirmed exoplanets — HD 86081, HIP 49067, WASP-43, 24 Sextantis and HD 92788 — and one formally named star. The formally named star is HD 86081 and its name, as approved by the International Astronomical Union (IAU), is Bibhā.
There are no Messier objects in Sextans and only one daytime meteor shower associated with the constellation — the Sextantids. It occurs in late October and early November.
History and Mythology of the Sextans Constellation
Johannes Hevelius created the constellation of Sextans in the 17th century and originally named it Sextans Uraniae after the instrument he had used to measure star positions, until it was destroyed in a fire at his observatory in 1679. While telescopes were available to him, Hevelius preferred to use the sextant for naked-eye sightings.
Sextans constellation is not associated with any myths.
Location of the Sextans Constellation
Sextans is the 47th largest constellation and occupies an area of 314 square degrees. It is located in the second quadrant of the southern hemisphere (SQ2) and can be seen at latitudes between +80° and -90°.
Its right ascension is 10h and its declination is 0°. It is best seen at 9pm, during the month of April. It lies near the ecliptic, which causes the Moon and some of the planets to occasionally pass through it for brief periods of time.
Sextans’ neighboring constellations are Crater, Hydra and Leo and it belongs to the Hercules family of constellations, along with Aquila, Ara, Centaurus, Corona Australis, Corvus, Crater, Crux, Cygnus, Hercules, Hydra, Lupus, Lyra, Ophiuchus, Sagitta, Scutum, Serpens, Triangulum Australe and Vulpecula.
Alpha Sextantis is the brightest star in Sextans and has an apparent magnitude of 4.48. It is a white giant star with the stellar classification A0III and is located around 287 light years away from Earth. It is also informally considered to be an “equator star”, as it is currently located less than a quarter of a degree south of the celestial equator. Alpha Sextantis was 7 arc minutes north of the equator in 1900, but crossed over to the southern hemisphere in December 1923.
Alpha Sextantis has a mass that is three times that of the Sun and is 122 times more luminous. It is also thought to be around 300 million years old.
Beta Sextantis is a blue-white main sequence dwarf with the stellar classification B6V. It is also an Alpha-2 Canum Venaticorum type variable star with an apparent magnitude of 5.0 to 5.1 and a period of 15.4 days. It is located around 345 light years away from us.
Delta Sextantis is a blue-white main sequence dwarf with the stellar classification of B9.5V and an apparent magnitude of 5.19. It is located around 300 light years from the Solar System.
Epsilon Sextantis is a yellow-white giant star with the stellar classification of F2 III and an apparent magnitude of 5.25. It is located around 183 light years away from the Sun.
Gamma Sextantis is a triple star system located 262 light years away from us that consists of a close binary star with the stellar classification A1 and a 12th magnitude companion. The components of the binary star are separated by 0.38 arc seconds and orbit each other with a period of 77.6 years. They have visual magnitudes of 5.8 and 6.2, while the whole system has an apparent magnitude of 5.07. The companion orbits the binary star from a distance of 36 arc seconds.
24 Sextantis is a yellow subgiant star with the stellar classification of G5 IV and an apparent magnitude of 6.61. It it located around 253 light years away from us and is around 2.8 billion years old. It also has a mass that is 54 percent more the mass of the Sun.
In 2010, two giant extrasolar planets were discovered orbiting the star; the outer planet has 5/6 the mass of Jupiter and orbits the star every 883 days, while the inner planet has twice the mass of Jupiter and orbits the star every 453 days.
LHS 292 is a red dwarf star with the stellar classification of M6.5 V and an apparent magnitude of 15.73. It is a flare star, meaning its brightness can suddenly increase over short periods of time. It is located around 14.8 light years away from Earth and, although it is close, cannot be seen without a large amateur telescope.
HD 92788 is a class G5 star with a visual magnitude of 4.72. It is slightly smaller than the Sun and more massive and is located 107.1 light years away from us. In 2001, an extrasolar planet with a mass at least 3.67 times that of Jupiter was discovered orbiting the star. It orbits the star with a period of 325.81 days.
HD 86081 is a yellow-white main sequence dwarf star with the stellar classification of F8V and a visual magnitude of 8.74. It has a luminosity 1.75 times that of the Sun and is located 297 light years away from Earth. A planet orbits the star every 2.1375 days. This planet has a mass 1.50 times that of Jupiter.
BD-08°2823 is a an orange main sequence dwarf with the stellar classification of K3V and an apparent magnitude of 9.86. It is smaller, less massive and cooler than the Sun and is located around 137 light years away from Earth. In 2009, two gas giants were discovered orbiting the star; the outer one orbits the star every 237.6 days, while the inner orbits every 5.60 days.
WASP-43 is an orange dwarf with the stellar classification of K7V and an apparent magnitude of 12.4. It has a mass that is half that of the Sun and a radius that is 0.598 times that of the Sun.
In April 2011, a planet, a Hot Jupiter named WASP-43b, was discovered orbiting the star. At the time, it was the most closely orbiting Hot Jupiter discovered. It completes an orbit around the star every 0.813475 days and has a mass 1.78 times that of Jupiter and a radius 0.93 times that of Jupiter.
Deep Sky Objects
The Spindle Galaxy, also known as NGC 3115 or Caldwell 53, is a lenticular galaxy which appears almost exactly edge-on. It has an apparent magnitude of 9.9 with a supermassive black hole at its center, and is several times bigger than the Milky Way. It is the nearest galaxy with a billion-solar-mass black hole to Earth and is located approximately 31.6 million light years away from Earth.
NGC 3115 was first discovered by William Herschel on February 22, 1787. It should not be confused with with Messier 102 (NGC 5866) in Draco constellation, which is also called the Spindle Galaxy.
NGC 3169 is a spiral galaxy with an apparent magnitude of 10.3. It is located around 70 million light years away from us, just under the bright star Regulus in the constellation of Leo.
NGC 3169 was discovered by William Herschel in 1783, along with NGC 3166. NGC 3169 has a Sdistorted shape as a result of gravitational interaction withNGC 3166 that is located close by.
In 2003, a supernova, SN 2003cg, was discovered in NGC 3169.
NGC 3166 is a spiral galaxy that is located around 50,000 light years from NGC 3169. Eventually, the two galaxies will merge into one larger galaxy.
Sextans A, also known as UGCA 205, is a small dwarf irregular galaxy with a visual magnitude of 11.9. It is located around 4.31 million light years away from Earth, within the Local Group of galaxies, and is about 5,000 light years across.
Sextans B, also known as UGC 5373, is an irregular galaxy with an apparent magnitude of 11.9. It is located approximately 4.44 million light years away from us and is is either within the Local Group or just beyond it.
There have been five planetary nebulae discovered in Sextans B, making it one of the smallest galaxies in which planetary nebulae have been found. It also forms a pair with its neighbour Sextans A.
UGC 5797 is an emission line galaxy that is currently undergoing active star formation. It has an apparent magnitude of 14.4 and is located 34 million light years away from us.
Cosmos Redshift 7
Cosmos Redshift 7, also known as (CR7), is one of the oldest and most distant galaxies known. It is located about 12.9 billion light years away from the Solar System.
CR7 is a high-redshift Lyman-alpha emitter galaxy which contains Population III (first generation) stars, formed not long after the Big Bang. It also contains old, metal-poor Population II stars and is three times brighter than other extremely distant galaxies.
Sextans Dwarf Spheroidal Galaxy
The Sextans Dwarf Spheroidal galaxy, also known as Sextans I, is one of the satellites of our own galaxy, the Milky Way, and has an apparent magnitude of 10.4. It is located only 290,000 light years away from the Sun and is receding from us at 224 km/s.
It was first discovered in 1990 by Michael Irwin, director of the Cambridge Astronomical Survey Unit, who was one of the discoverers of the Sagittarius Dwarf Elliptical Galaxy and the Cetus Dwarf.
CL J1001+0220 is located 11.1 billion light years away from Earth and is the most distant known galaxy cluster, as of 2016. It contains 17 galaxies, 9 of which are showing evidence of new stars forming at a very high rate in the cluster’s central region.
CL J1001+0220 is the first cluster observed in the stage of evolving from a proto-cluster to a mature cluster.
CID-42, also known as CXOC J100043.1+020637, is a galaxy quasar that is believed to be the result of a collision between two smaller galaxies and contain a supermassive black hole at its core. The supermassive black hole was created when the two smaller galaxies collided and their black holes also collided to form a single supermassive black hole.
CID-42 is located around 3.9 billion light years away from us and has an extended trail of stars.
- Some Images created with the NightVision app – https://www.nvastro.com/nvj.html
- Some Images created with the Stelvision Sky Map https://www.stelvision.com/en/sky-map/
- Sextans 1 – https://starregistration.net/constellations/sextans-constellation.html
- Alpha Sextantis – https://theskylive.com/sky/stars/alpha-sextantis-star
- Beta Sextantis – https://theskylive.com/sky/stars/beta-sextantis-star
- Gamma Sextantis – https://theskylive.com/sky/stars/gamma-sextantis-star
- Spindle Galaxy (NGC 3115) – http://annesastronomynews.com/photo-gallery-ii/galaxies-clusters/the-spindle-galaxy-ngc-5866-m102/
- NGC 3169 – https://en.wikipedia.org/wiki/NGC_3169
- Sextans Dwarf Spheroidal – https://en.wikipedia.org/wiki/Sextans_A