[http://www.derekscope.co.uk/wp-content/uploads/2013/09/reticulum.jpg]
Reticulum is a small, faint constellation in the southern sky. Its name is Latin for a small net, or reticle- a net of crosshairs at the focus of a telescope eyepiece that is used to measure star positions. The constellation is best viewed between October and December, but cannot be seen from middle to northern latitudes.
Reticulum, shown on Chart XX of Johann Bode’s Uranographia under the name Reticulus.
[http://www.ianridpath.com/startales/reticulum.htm]
A constellation in this area was introduced by Isaac Habrecht II in his celestial globe in 1621, who named it Rhombus. It was replaced with a somewhat different constellation by the French astronomer Nicolas Louis de Lacaille in the eighteenth century; during his stay at the Cape of Good Hope, he named the constellation le Réticule Rhomboide to commemorate the reticle in his telescope eyepiece. The name was later Latinized to Reticulum in his star catalogue Coelum Australe Stelliferum. In 1810, the stars of Reticulum were used by William Croswell to produce the constellation Marmor Sculptile, which represented the bust of Christopher Columbus, but this did not catch on among astronomers.
The constellation Reticulum became officially recognized during the First General Assembly of the International Astronomical Union (IAU) in 1922. The boundary for this and other constellations was drawn up by Belgian astronomer Eugène Delporte along arcs of right ascension and declination for epoch 1875. These were published in 1930 in the Delimination Scientifique des Constellations at the behest of the IAU.
[http://www.dibonsmith.com/ret_con.htm]
[http://www.davidmalin.com/fujii/source/Dor.html]
Only two of the stars in this constellation are brighter than visual magnitude 5: Alpha (α) and Beta (β) reticuli.
Alpha Reticuli is the brightest star in the constellation. It has an apparent visual magnitude of 3.315 and is 161.6 light years distant from the solar system. The star has more than three times the mass of the Sun and almost 13 times the solar radius. It is approximately 240 times more luminous than the Sun. It is believed to be about 330 million years old. Alpha Reticuli is halfway between the giant and bright giant stage of evolution. It has the stellar classification of G8 II-III. It is a known X-ray source. The star has a 12th magnitude companion, CCDM J04144-6228B, at an angular separation of 48 arcseconds. The two stars share a common proper motion.
Beta Reticuli is a triple star system about 100 light years away in Reticulum. It has an apparent magnitude of 3.84. The primary component in the system is an orange giant with the stellar classification K0IV SB.
[http://www.constellation-guide.com/constellation-list/reticulum-constellation/]
The reddish star R Reticuli is a Mira variable. This variable was discovered by C. Ragoonatha Chary at the Madras Observatory in India.
The binary star system Epsilon Reticuli consists of a spectral class K2IV star being orbited by a white dwarf. Based on parallax measurements, this system is located about 50 light years from the Sun. In 2000, a planetary companion was announced, orbiting the star ε Reticuli A.
Zeta Reticuli is a wide binary star system, with both members being similar to the Sun. It is located at a distance of about 39 light years. This system gained some notoriety in ufology when the alleged alien abductees Betty and Barney Hill named it as the home of their abductors.
In 2005, a type 1a supernova was discovered in the spiral galaxy NGC 1559, located in the Reticulum constellation:
NGC 1559 obtained with the multi-mode FORS1 instrument on ESO’s 8.2m VLT. Supernova SN 2005df is visible as the bright star just above the galaxy.
NGC 1559 is a barred spiral galaxy in the constellation Reticulum. It is also a Seyfert galaxy. Although it was originally thought to be a member of the Dorado Group, subsequent observations have shown that it is in fact not a member of any galaxy group or cluster and does not have any nearby companions. NGC 1559 has massive spiral arms and strong star formation. It contains a small bar which is oriented nearly east-west and spans 40″. Its bar and disc are the source of very strong radio emissions.
In 2005, a Type 1a supernova, (SN 2005df) was observed. Two other supernovae discovered in NGC 1559 were SN 1984J and SN 1986L. All three were discovered by Australian amateur astronomer Robert Evans.
[https://en.wikipedia.org/wiki/NGC_1559]
The Topsy Turvy Galaxy, NGC 1313, is another barred spiral galaxy in Reticulum, which is also a starburst galaxy:
[http://www.constellation-guide.com/constellation-list/reticulum-constellation/]
Unusual Starburst Galaxy NGC 1313
Why is this galaxy so discombobulated? Usually, galaxies this topsy-turvy result from a recent collision with a neighboring galaxy. Spiral galaxy NGC 1313, however, appears to be alone. Brightly lit with new and blue massive stars, star formation appears so rampant in NGC 1313 that it has been labeled a starburst galaxy. Strange features of NGC 1313 include that its spiral arms are lopsided and its rotational axis is not at the center of the nuclear bar. Pictured above, NGC 1313 spans about 50,000 light years and lies only about 15 million light years away toward the constellation of the Reticle (Reticulum). Continued numerical modeling of galaxies like NGC 1313 might shed some light on its unusual nature.
[http://apod.nasa.gov/apod/ap100330.html]
The dwarf galaxy Reticulum II is an old dwarf galaxy in the Local Group:
The Magellanic Clouds and the Auxiliary Telescopes at the Paranal Observatory in the Atacama Desert in Chile are shown. Only 6 of the 9 newly discovered satellites are present in this image.
A team of astronomers from the University of Cambridge have identified nine new dwarf satellites orbiting the Milky Way, the largest number ever discovered at once. The findings, from newly-released imaging data taken from the Dark Energy Survey, may help unravel the mysteries behind dark matter, the invisible substance holding galaxies together.
The new results also mark the first discovery of dwarf galaxies- small celestial objects that orbit larger galaxies- in a decade, after dozens were found in 2005 and 2006 in the skies above the northern hemisphere. The new satellites were found in the southern hemisphere near the Large and Small Magellanic Cloud, the largest and most well-known dwarf galaxies in the Milky Way’s orbit.
The newly discovered objects are a billion times dimmer than the Milky Way, and a million times less massive. The closest is about 95,000 light years away, while the most distant is more than a million light years away.
According to the Cambridge team, three of the discovered objects are definite dwarf galaxies, while others could be either dwarf galaxies or globular clusters- objects with similar visible properties to dwarf galaxies, but not held together with dark matter.
Dwarf galaxies are the smallest galaxy structures observed, the faintest of which contain just 5,000 stars- the Milky Way, in contrast, contains hundreds of billions of stars. Standard cosmological models of the universe predict the existence of hundreds of dwarf galaxies in orbit around the Milky Way, but their dimness and small size makes them incredibly difficult to find, even in our own ‘backyard’.
Since they contain up to 99 percent dark matter and just one percent observable matter, dwarf galaxies are ideal for testing whether existing dark matter models are correct. Dark matter- which makes up 25 percent of all matter and energy in our universe- is invisible, and only makes its presence known through its gravitational pull.
“Dwarf satellites are the final frontier for testing our theories of dark matter,” said Dr Vasily Belokurov of the Institute of Astronomy, one of the study’s co-authors. “We need to find them to determine whether our cosmological picture makes sense. Finding such a large group of satellites near the Magellanic Clouds was surprising, though, as earlier surveys of the southern sky found very little, so we were not expecting to stumble on such treasure.”
The closest of these pieces of ‘treasure’ is 97,000 light years away, about halfway to the Magellanic Clouds, and is located in the constellation of Reticulum, or the Reticle. Due to the massive tidal forces of the Milky Way, it is in the process of being torn apart.
The most distant and most luminous of these objects is 1.2 million light years away in the constellation of Eridanus, or the River. It is right on the fringes of the Milky Way, and is about to get pulled in.
[https://futurism.com/hunt-for-dwarf-galaxies-uncovers-9-new-members-of-milky-way-family/]
[https://en.wikipedia.org/wiki/Reticulum]
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