Fornax constellation was named for the first time by French astronomer Nicolas Louis de Lacaille in 1756, and its name signifies furnace in Latin. Its brightest stars are Alpha, Beta, and Nu Fornacis (Alpha2 Canum Venaticorum variable which indicates the star’s strong magnetic field). Epsilon Fornacis is a binary star (located 104 light-years away from Earth), and Omega Fornacis is another binary star of the constellation (located 470 light-years away from Earth), while Kappa Fornacis is a triple star. There are also stars in this constellation that host planets: Lambda2 Fornacis (Sun-like star), HD 20868 (an orange dwarf), WASP-72 (a main-sequence star), HR 858 (hosts at least three planets), and HD 20781 and HD 20782 which are a Sun-like binary orbiting each other and each has a planet.
The image credits go to IAU.
NGC 1360 (Robin’s Egg Nebula) is a planetary nebula residing in the Fornax constellation. As for the constellation’s other deep-sky objects, there is NGC 1049 which is a globular cluster, NGC 1097 (Caldwell 67) barred spiral galaxy, and Fornax dwarf galaxy. Fornax cluster which is a vast space filled with galaxies is another world of and in itself and encourage the reader to read more about it here.
NGC 1097. The image credits go to ESO.
NGC 1360 (Robin’s Egg Nebula). The image credits go to the Mount Lemmon SkyCenter Schulman Telescope courtesy Adam Block.
Caelum signifies Chisel in Latin and is listed among the 88 modern constellations by Nicolas Louis de Lacaille in 1750s. It was also known as Caelum Sculptorium which means the engraver’s chisel. Sometimes it is mistaken for the word caelum is Latin which means sky, atmosphere, or heaven, but it is only a confusion although it seems to be a more relevant word for a constellation. As the eighth-smallest constellation, it is fairly dim in the night sky and relatively barren due to its distance from the plane of Milky Way. Alpha Caeli and Gamma Caeli are the two stars visible to naked eye with magnitudes brighter than 5. RR Caeli is a binary star hosting a planet lying 65.7 light-years away from the parent star. X Caeli and Delta Scuti variable are two other stars of this constellation that make up for an optical double (they seem close to each other as a double star but they are physically bound).
The image credits go to IAU.
HE0450-2958 is a deep sky object in Caelum constellation, a Seyfert galaxy that is called a naked quasar or even homeless quasar because it is a quasar without a galaxy as its home. It also first appeared as an energetic jet without any galaxy to be associated with. It has been agreed to have a host galaxy after all, but too faint to be detected and perhaps outshone but the quasar.
(Left) HST image of the quasar HE0450-2958. Evidently, there is no host galaxy around the quasar. Only a star-forming companion galaxy is present at the top of the image. (Right) Same image as Left, after applying image sharpening. The quasar is again not at the centre of a host galaxy, but rather placed on the edge of a compact structure composed of gas, ionised by the quasar radiation. The image credits go to ESO.
This is one of the most familiar constellations in the night sky, due to it being a zodiac sign and its name is known to signify crab in Latin – it is actually the second dimmest of the zodiacal constellations. Although it is a zodiac-sign assigned constellation, it is a medium-sized constellation with faint stars. 55 Cancri, is one of its well-known stars hosting five planets: a super-earth and four gas giants. The super-earth planet lies in the habitable zone with a temperature close to that of Earth. Praesepe (Messier 44) is located at the center of this constellation and is one of the closest open clusters to Earth.
The image credits go to IAU.
Cancer constellation enjoys a variety of stars. Beta Cancri (Tarf), is the brightest star of Cancer constellation, lying 300 light-years from earth. It is a binary star with a red dwarf companion. Delta Cancri (Asellus Australis) is an orange-hued giant star. X Cancri is the reddest star in the night sky, and Gamma Cancri a white-hued subgiant (A1IV) with apparent magnitude 4.67. Iota Cancri is located 330 light-years away from earth and is a wide, double star. Alpha Cancri (Acubens) is a multiple star system, the same as Zeta Cancri or Tegmine (the shell). Zeta Cancri is known so far to consist of at least four stars (82 light-years from Earth).
There are also a number of stars that host planets in this constellation. Plus the one we mentioned at the beginning, YBP 1194 hosts three planets and is a sunlike star (located in the open cluster M67 which is an open cluster located in Cancer constellation.
Those who are a bit familiar with Latin, Italian, or Spanish words know that the name of this constellation signifies hunting dogs in Latin. They are actually attributed to Boötes, and that these are dogs of the patron of farmers, since it is pretty close to this constellation. Canes Venatici has no particularly bright star. Cor Caroli is the brightest star of Canes Venatici constellation. La Superba (Y CVn) is another star belonging to Canes Venatici and is one of the reddest stars visible to naked eye in the dark sky. It is a semiregular variable star, a feature assigned to giants or supergiants that exhibit considerable periodicity in their light changes. Beta Canum Venaticorum (Chara, Joy) is a main-sequence, yellow-hued star. AM Canum Venaticorum is a cataclysmic variable star and it is very blue.
The image credits go to IAU.
One of the particularities of Canes Venatici is the existence of a Giant Voidin its vicinity – voids are empty spaces in outer space, devoid of any celestial bodies. It is currently the second-largest void discovered (second to the Eridanus Supervoid) in size. Eridanus Supervoid is related to the interesting “CMB cold spot” which is much colder than expected based on the regular properties (in particular its temperature distribution) of Cosmic Microwave Background (CMB). Although a cold spot is usually 70 microK (0.00007 K) colder than the average temperature of the CMB (approximately 2.7 K), it still counts and astronomers are investigating the plausible solutions for this temperature deviation.
The quite famous Whirlpool Galaxy (Messier 51a, NGC 5194, , M51a ) is also located in this constellation. This galaxy is particularly interesting as it is a grand design spiral galaxy and was was identified to be a spiral galaxy. Its core contains an active quasar (Seyfert galaxy). M51 has many star-forming regions and on contains so many worlds within it.
Whirpool and NGC 5195 galaxies photographed by Hubble Space telescope.
Canis Major was first cataloged in Ptolemy‘s list of 48 constellations and still makes the list among the modern 88 constellations. Canis Major means ‘Greater Dog’ in Latin. From the major features of this constellation is containing the brightest star in the night sky, Sirius. This star is very bright as it is very close to the solar system, the other stars in Canis Major are more luminous but they are much further. Epsilon Canis Majoris (Adhara) is the second-brightest star of the constellation; the third is a yellow-white supergiant Delta (Wezen); the forth is a blue-white giant called Beta (Mirzam); then there are the blue-white supergiants Eta (Aludra), Omicron2, and the white spectroscopic binary Zeta (Furud). One of the largest known stars so far, red hypergiant VY Canis Majoris is also located in Canis Major. There are also plenty of variable stars in Canis Major. EZ Canis Majoris is a Wolf–Rayet star, and we still do not know the cause of its variability. W Canis Majoris is a variable, carbon star and is a red giant. Tau Canis Majoris contains two stars orbiting each other and blocking one another’s light thus they are categorized as variable stars (their magnitudes differ in different periods). This particular feature qualifies this star as a Beta Lyrae-type eclipsing multiple star system. UW Canis Majoris has the exact same features, it is also a Beta Lyrae-type eclipsing multiple star system. R Canis Majoris can be categorized the same, with a companion lying further from the central binary system.
There are also stars which host planets in this constellation. Nu2 Canis Majoris (an ageing orange giant) is orbited by a planet (2.6 Jupiter masses). HD 47536 is another ageing orange giant orbited by a single planet. HD 45364 (G8 type star, cooler than our Sun with spectral type G0V) hosts two planets. HD 47186 is another sunlike star hosting two planets. HD 43197 is another sunlike star with a Jupiter-size planet orbiting it in eccentric orbits. Z Canis Majoris consists of two pre-main-sequence stars (young stars). This is a particular stellar system as one of its components is a FU Orionis star (stars that change significantly in spectral type and magnitude) and the other is a Herbig Ae/Be star (young stars with ages less than 10 Myr and of spectral type of A or B). The Herbig star is enveloped in a cocoon-like dust shell and its light shines through this cocoon. The in-falling material that formed the whole system is still surrounding the stellar system.
As deep-sky objects, Canis Major contains plenty of open clusters: M41 (NGC 2287), 12 Canis Majoris, NGC 2360, NGC 2362, NGC 2354. NGC 2359 (Thor’s Helmet or the Duck Nebula) is a beautiful emission nebula lying 10,000 light-years from Earth. This nebula is shaped by WR 7 (HD 56925) which is a Wolf–Rayet star and is located at the heart of the nebula. The Canis Major Dwarf galaxy is the closest satellite galaxy to Earth and its name suggests that it is affiliated with Canis Major constellation. The origins of this galaxy are still under debate.
NGC 2207 and IC 2163 are a pair of interacting spiral galaxies lying 125 million light-years from Earth. IC 2163 is the smaller component and it is hypothesized to be merged into NGC 2207 eventually.
