Mensa (constellation)
Encyclopedia
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
.
under the name Mons Mensae, the Latin name for Table Mountain in South Africa
, where Lacaille made important early observations of the southern sky.
its brightest star at a barely visible magnitude 5.09, making it the faintest constellation in the entire sky. Alpha Mensae
is a solar-type
star (class G5 V) 33 light-years from Earth, and is considered a good prospect for harboring an Earth
-like planet
. 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.
(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
wavelength
s.
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....
in the southern sky, created in the 18th century. 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 table
Table (furniture)
A table is a form of furniture with a flat and satisfactory horizontal upper surface used to support objects of interest, for storage, show, and/or manipulation...
. It covers a keystone
Keystone (architecture)
A keystone is the wedge-shaped stone piece at the apex of a masonry vault or arch, which is the final piece placed during construction and locks all the stones into position, allowing the arch to bear weight. This makes a keystone very important structurally...
-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
Octans
Octans is a faint constellation the southern sky. Its name is Latin for the eighth part of a circle, but it is named after the octant, a navigational instrument. The constellation was devised by Nicolas Louis de Lacaille in the eighteenth century....
, it is the most southerly of constellations. As a result, it is essentially unobservable from the Northern Hemisphere
Northern Hemisphere
The Northern Hemisphere is the half of a planet that is north of its equator—the word hemisphere literally means “half sphere”. It is also that half of the celestial sphere north of the celestial equator...
. Besides those already mentioned, its other neighbouring constellations are Chamaeleon
Chamaeleon
Chamaeleon is a small constellation in the southern sky. It is named after the chameleon, a form of lizard. It was first defined in the sixteenth century.-History:...
, Dorado
Dorado
Dorado is a constellation in the southern sky. It was created in the late 16th century and is now one of the 88 modern constellations. Its name refers to the dolphinfish , which is known as dorado in Spanish, although it has also been depicted as a swordfish...
, Hydrus
Hydrus
Hydrus is a small constellation in the southern sky, created in the sixteenth century. Its name means "male water snake", and it should not be confused with Hydra, a much larger constellation which represents a female water snake.-History:...
and Volans
Volans
Volans is a constellation in the southern sky. It represents a flying fish; its name is a shortened form of its original name, Piscis Volans...
.
History
Mensa was created by Nicolas Louis de LacailleNicolas Louis de Lacaille
Abbé Nicolas Louis de Lacaille was a French astronomer.He is noted for his catalogue of nearly 10,000 southern stars, including 42 nebulous objects. This catalogue, called Coelum Australe Stelliferum, was published posthumously in 1763. It introduced 14 new constellations which have since become...
under the name Mons Mensae, the Latin name for Table Mountain in South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
, where Lacaille made important early observations of the southern sky.
Stars
Mensa contains no bright stars, with Alpha MensaeAlpha Mensae
Alpha Mensae is the brightest star in the constellation Mensa. At a magnitude of 5.09, it is the dimmest lucida in all the heavens. It is a main sequence dwarf star only slightly smaller and cooler in temperature than the Sun...
its brightest star at a barely visible magnitude 5.09, making it the faintest constellation in the entire sky. Alpha Mensae
Alpha Mensae
Alpha Mensae is the brightest star in the constellation Mensa. At a magnitude of 5.09, it is the dimmest lucida in all the heavens. It is a main sequence dwarf star only slightly smaller and cooler in temperature than the Sun...
is a solar-type
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
star (class G5 V) 33 light-years from Earth, and is considered a good prospect for harboring an Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
-like planet
Planet
A planet is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.The term planet is ancient, with ties to history, science,...
. Pi Mensae
Pi Mensae
Pi Mensae is a yellow subgiant star in the constellation of Mensa. This star has a high proper motion. The apparent magnitude is 5.67, which can be visible to the naked eye in exceptionally dark, clear skies. It is nearly 60 ly away. The star dwarfs the Sun in terms of mass, size, luminosity,...
, on the other hand, while also solar-type (G1) and at 59 light-years, has been found to have a large gas giant
Gas giant
A gas giant is a large planet that is not primarily composed of rock or other solid matter. There are four gas giants in the Solar System: Jupiter, Saturn, Uranus, and Neptune...
in an eccentric
Orbital eccentricity
The orbital eccentricity of an astronomical body is the amount by which its orbit deviates from a perfect circle, where 0 is perfectly circular, and 1.0 is a parabola, and no longer a closed orbit...
orbit
Orbit
In physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet around the center of a star system, such as the Solar System...
crossing the habitable zone
Habitable zone
In astronomy and astrobiology, a habitable zone is an umbrella term for regions that are considered favourable to life. The concept is inferred from the empirical study of conditions favourable for Life on Earth...
, which would effectively rule out the existence of any habitable planets.
Deep sky objects
Mensa contains part of the Large Magellanic CloudLarge Magellanic Cloud
The Large Magellanic Cloud is a nearby irregular galaxy, and is a satellite of the Milky Way. At a distance of slightly less than 50 kiloparsecs , the LMC is the third closest galaxy to the Milky Way, with the Sagittarius Dwarf Spheroidal and Canis Major Dwarf Galaxy lying closer to the center...
(the rest being in Dorado
Dorado
Dorado is a constellation in the southern sky. It was created in the late 16th century and is now one of the 88 modern constellations. Its name refers to the dolphinfish , which is known as dorado in Spanish, although it has also been depicted as a swordfish...
).
The first images taken by the Chandra X-Ray Observatory
Chandra X-ray Observatory
The Chandra X-ray Observatory is a satellite launched on STS-93 by NASA on July 23, 1999. It was named in honor of Indian-American physicist Subrahmanyan Chandrasekhar who is known for determining the maximum mass for white dwarfs. "Chandra" also means "moon" or "luminous" in Sanskrit.Chandra...
were of PKS 0637-752, a quasar
Quasar
A quasi-stellar radio source is a very energetic and distant active galactic nucleus. Quasars are extremely luminous and were first identified as being high redshift sources of electromagnetic energy, including radio waves and visible light, that were point-like, similar to stars, rather than...
in Mensa with a large gas jet visible in both optical and x-ray
X-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...
wavelength
Wavelength
In physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the wave's shape repeats.It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a...
s.