Mensa (constellation)

Mensa

Constellation
List of stars in Mensa
Abbreviation	Men
Genitive	Mensae
Pronunciation	/ˈmɛnsə/ genitive: /ˈmɛnsiː/
Symbolism	the Table Mountain
Right ascension	4 ~ 7.5
Declination	−71 ~ −85.5
Family	La Caille
Quadrant	SQ1
Area	153 sq. deg. (75th)
Main stars	4
Bayer/Flamsteed stars	16
Stars with planets	2
Stars brighter than 3.00m	none
Stars within 10.00 pc (32.62 ly)	none
Brightest star	α Men (5.09m)
Nearest star	α Mensae (33.10 ly, 10.15 pc)
Messier objects	none
Meteor showers	none
Bordering constellations	Chamaeleon Dorado Hydrus Octans Volans
Visible at latitudes between +4° and −90°. Best visible at 21:00 (9 p.m.) during the month of January.

The constellation Mensa as it can be seen by the naked eye.

Mensa is a constellation in the southern sky, created in the 18th century. Its name is Latin for table. It covers a keystone-shaped wedge of sky stretching from approximately 4h to 7.5h of right ascension, and −71 to −85.5 degrees of declination. Other than the south polar constellation of Octans, it is the most southerly of constellations. As a result, it is essentially unobservable from the Northern Hemisphere. Besides those already mentioned, its other neighbouring constellations are Chamaeleon, Dorado, Hydrus, and Volans.

History

Initially known as Mons Mensae, Mensa was created by Nicolas Louis de Lacaille out of dim Southern Hemisphere stars in honor of Table Mountain, a South African mountain overlooking Cape Town. He recalled that the Magellanic clouds were sometimes known as Cape clouds, and that Table Mountain was often covered in cloud when a southeasterly stormy wind blew. Hence he made a "table" in the sky under the clouds. Although the stars of Mensa do not feature in any ancient mythology, the mountain it is named after has a rich mythology. Called "Tafelberg" in Dutch and German, the mesa has two neighboring mountains called "Devil's Peak" and "Lion's Head". Table Mountain features in the mythology of the Cape of Good Hope, notorious for its storms—the explorer Bartolomeu Dias saw the mesa as a mythical anvil for storms. Another myth relating to its dangers comes from Sinbad the Sailor, an Arabic folk hero who saw the mountain as a magnet pulling his ships to the bottom of the sea.

Notable features

Stars

Lacaille labelled eleven stars with Bayer designations Alpha through to Lambda (excluding Kappa). Gould later added Kappa, Mu, Nu, Xi and Pi Mensae. Stars as dim as these were not generally given designations; however, Gould felt their closeness to the South Celestial Pole warranted naming. Mensa contains no bright stars, with Alpha Mensae its brightest star with a barely visible apparent magnitude of 5.09, making it the faintest constellation in the entire sky. Alpha Mensae is a solar-type star (class G7V) around 33 light-years from Earth. An infrared excess has been detected around this star, most likely indicating the presence of a circumstellar disk at a radius of over 147 AU. The temperature of this dust is below 22 K. No planetary companions have yet been discovered around it. It has a red dwarf companion star at an angular separation of 3.05 arcseconds; equivalent to a projected separation of roughly 30 AU. Pi Mensae, on the other hand, while also solar-type (G1) and at 59 light-years, has been found to have a large gas giant in an eccentric orbit crossing the habitable zone, which would effectively rule out the existence of any habitable planets.

Deep-sky objects

Mensa contains part of the Large Magellanic Cloud (the rest being in Dorado).

The first images taken by the Chandra X-Ray Observatory were of PKS 0637-752, a quasar in Mensa with a large gas jet visible in both optical and x-ray wavelengths.

References

References

Citations

External links

• The Deep Photographic Guide to the Constellations: Mensa
• Star Tales – Mensa
• Mensa Constellation at Constellation Guide