Capricornus Constellations Astronomy Information

Capricornus is a familiar name for those who are fans of fantasy stories – its name signifies goat horn in Latin, and is among the Zodiac signs. In the zodiac signs, it is referred to as a half-fish, half-goat configuration – much imagination needed here!! Ptolemy entered this constellation in his list of 48 constellations, and it still counts as one of the members of the modern 88 constellations. This constellation is bordered by its other counterparts:  AquilaSagittariusMicroscopiumPiscis Austrinus, and Aquarius. It is sea-related somehow due to its name, and mainly because it is surrounded by other sea-related constellations: Aquarius, Pisces, and Eridanus. Thus the area these constellations are residing in is simply called Sea.

The image credits go to IAU.

The constellation’s alpha star is among the visible stars to naked eye belonging to Capricornus. Generally, this is a very dim constellation. δ Capricorni (Deneb Algedi, or the tail of the goat in Arabic) is the brightest star of this constellation, and it is relatively close to us (only 39 light-years away from Earth). Speaking of its type, it is a Beta Lyrae variable star (a type of eclipsing binary).

There are also multiple stars in this constellation, such as α Capricorni. It is composed of two main stars which are distinguishable by eye and they themselves are multiple stars. β Capricorni is a double star which are distinguishable in binoculars.  γ Capricorni is also visible to naked eye, and is a white-hued giant star located 139 light-years from Earth.

Among the deep-sky objects, there is M30 which is a famous globular cluster, and a group of galaxies called  HCG 87. This is a group of (at least) three galaxies (one elliptical galaxy and two spiral galaxies, one face-on and the other edge-on) lying 400 million light-years from Earth.

HCG 87 containing two spiral galaxies and one elliptical galaxy. The image credits go to NASA.

Cassiopeia Constellations Astronomy Information

Cassiopeia is one of the rare constellations which its name is inspired by the name of someone, and in this case, it is the queen Cassiopeia in Greek mythology. She was arrogant and thought her beauty was unrivalled in the ancient myths. This constellation was also listed in the 48 constellations of Ptolemy, and still makes the list among the 88 modern constellations.

The image credits go to IAU.

Alpha Cassiopeiae (Schedar, derived from the Arabic word Al Sadr which means breast) is the brightest star of Cassiopeia (of magnitude 2.2), but there are occasions during which it is outshone by the variable Gamma Cassiopeiae (of magnitude 1.6). Alpha Cassiopeiae is a multiple stellar system and is composed of four stars. Beta Cassiopeiae (commonly called Caph that means hand) is a white-hued star fairly close to Earth (55 light-years away). Although perhaps not that famous, Cassiopeia contains some of the brightest stars discovered or some generally interesting cases. Among the bright stars, we mention the yellow hypergiants Rho Cassiopeiae and V509 Cassiopeiae and the white hypergiant 6 Cassiopeiae. The famous Tycho Brahe’s supernova which flared in 1572 is also located in Cassiopeia constellation. This is a remarkable supernova because it was among the eight supernovae visible to naked eye historically. A supernova is the energetic explosion of a star which its afterglow can be seen for days (depending on how energetic it would be).

The variable stars of Cassiopeia are: 50 Cassiopeiae,  Zeta Cassiopeiae,  Theta Cassiopeiae,  Iota Cassiopeiae (a triple star system),  Omicron Cassiopeiae (another triple star), Eta Cassiopeiae (which is a spectroscopic binary). The last one is also an RS Canum Venaticorum variable which means the binary components own active chromospheres leading to the emergence of stellar spots.  Kappa Cassiopeiae is another particular star of Cassiopeia which is a runaway star, and a blue supergiant. Due to its strong magnetic field and wind of particles, it is surrounded by a visible bow shock colliding with the interstellar gas and dust (see figure below). This bow shock is relatively huge in dimension, it covers an area of 12 light-years long and 1.8 light-years wide.

 Kappa Cassiopeiae imaged by Spitzer infrared image (NASA/JPL-Caltech).

Cassiopeia A which is the brightest extrasolar radio source in the sky is also located in this constellation and is a supernova remnant. There are fourteen stellar systems that host exoplanets in Cassiopeia constellation. Since a rich section of Milky Way flows through Cassiopeia constellation, it contains several open clusters:  M52 (NGC 7654), NGC 457NGC 457NGC 663, and M103 (NGC 581).

There are also binary stars belonging to Cassiopeia constellation: Sigma Cassiopeiae and AO Cassiopeiae.  Psi Cassiopeiae is a triple star belonging to this constellation, located 193 light-years from Earth. There are also yellow hypergiants which are among the most luminous stars of our galaxy: Rho Cassiopeiae and  V509 Cassiopeiae.  PZ Cassiopeiae which is one of the largest stars known to date also resides in Cassiopeia constellation.

PZ Cassiopeiae (upper right) imaged by WISE infrared.

The irregular galaxy IC 10 is also located in the Cassiopeia constellation, and is a starburst galaxy which means it is a star factory at a high rate.

IC 10, the Local Group dwarf galaxy (PI: Philip Massey, Lowell Observatory).

Heart Nebula and Soul Nebula are neighboring nebulae in Cassiopeia constellation.

Soul Nebula. The image credits go to NASA.
Heart Nebula photographed by ASI2600mc-pro.

Leo Star Constellations Astronomy Information

Leo means lion in Latin and is among the twelve zodiac signs. In Greek mythology, this was the lion killed by the hero Heracles. Leo is one of those rare constellations that hold a zodiac sign under its name and also has many bright stars.  Alpha Leonis is a very bright star in the night sky (1.35 in magnitude) and is a double star divisible even in binoculars. Beta Leonis (Denebola, the lion’s tail in Arabic) is another bright star (2.2 in magnitude) of the constellation. Gamma Leonis is a binary star accompanied by a third optical component. Note that the structure of this star is different from Zeta Leonis which is an optical triple star. Iota Leonis is another binary star in the constellation which is divisible in an amateur telescope. Tau Leonis is a dimmer double star.  R Leonis is a red giant, Mira variable star, and  Wolf 359 (CN Leonis) is a flare star that periodically brightens up in the night sky. CW Leo (IRC +10216) is a carbon star that is the brightest star observed at the infrared N-band (10 μm wavelength).

The image credits go to IAU.

Leo is also home to many bright galaxies:  Messier 65 and Messier 66 make up for the Leo Triplet along with NGC 3628Messier 95Messier 96, and Messier 105. Leo also owns some of the most massive structures in the universe, large quasar groups called Clowes–Campusano LQGU1.11U1.54, and the Huge-LQG.

 NGC 3628, Sarah’s galaxy, or the Hamburger galaxy captured by ESO’s VLT.
M66 captured by ESO’s VLT.
M95 captured by Spitzer.
NGC 3368 captured by ESO’s VLT.
NGC2903 captured by ESA/NASA HST.

Hercules Star Constellations Astronomy Information

Hercules is named after the Roman mythological hero, and it is the fifth-largest constellation among the 88 modern constellations (covers 1225.1 square degrees and 2.970% of the night sky). Although the constellation has no particularly bright stars, it possesses some stars visible to naked eye (above magnitude 4). Alpha Herculis is one of these stars and is a triple star. Beta Herculis (Kornephoros, a yellow giant) is the brightest star in Hercules constellation. Delta Herculis is a double star (separable even in small amateur telescopes, same as Gamma Herculis and  Kappa Herculis). 30 Herculis (g Herculis) and  68 Herculis (u Herculis) are variable stars of Hercules. There are also fifteen stars that host planets in Hercules constellation: 14 Herculis (hosting two planets), HD 149026 (hosts a hot Jupiter), HD 154345 (hosts a long-period planet that takes more than 9 years to complete its orbit), HD 164922 (hosting a long period Saturn-like planet), HD 147506 (hosts a massive planet, of 8.6 Jupiter masses), HD 155358 (hosts two planets), GSC 03089-00929 (hosts one planet), Gliese 649 (owns a saturnian planet), HD 156668 (hosts one plent), HD 164595 (hosts one planet).

The image credits go to IAU.

Among the constellation’s deep-sky objects, we can name its globular clusters (M13, NGC 6229, and M92) and a number of beautiful planetary nebulae (Abell 39 and NGC 6210). As its name suggests, the largest structure in the visible universe, the Hercules–Corona Borealis Great Wall, lies in this constelaltion. By visible univeres we mean the space in which photons have had the time to travel so far from the beginning of time. This space that has been shed light on is observable today. There is also a world (containing many galaxies) located in Hercules cluster called  Hercules Cluster (Abell 2151).  

Abell 39 captured from the Mount Lemmon SkyCenter using the Schulman 32 inch Telescope.
NGC 6210 captured by ESA/NASA HST.

Apus Star Constellations Astronomy Information

A tiny constellation in the southern sky, Apus represents a bird-of-paradise. Its name literally means “without feet”. In the western world at the time of Bayer, who first identified this constellation, the only existing specimen of birds-of-paradise there had their wings and feet removed. French astronomer, Lacaille, gave this constellation’s brighter stars Bayer Designations for the first time in 1756 and also cut the tail of this bird-of-paradise. Alpha Apodis is an orange giant with a diameter 48 times larger than that of the Sun. Beta Apodis is another giant star in this constellation, with a radius 11 times larger than that of the Sun. Gamma Apodis is a yellow giant star of the constellation, and Delta Apodis is a binary stellar system, consisting of an orange giant and a red giant star. No Apodis is the beating heart of the constellation, it’s a variable pulsating star. Its magnitude changes between 5.71 and 5.95, with pulsation periods of 26.2 and 26.6 days respectively. With the help of Doppler spectroscopy, two exoplanets hosted by two stars of these constellations were discovered. This method is being used very frequently these days in astronomy for discovering exoplanets. We encourage the curious readers to visit this Wikipedia page to know more about this powerful method – it contains so many physical concepts involved. Milky Way covers most of this constellation, thus, no galaxies here. But there are two globular clusters, NGC 6101 and IC 4499 namely, in Apus.

Image credits go to

Globular clusters are spherical crowds of stars orbiting a galactic core. They owe their spherical shape to their stars being too strongly bound to each other by gravity. This also gives them a dense core at the center (a beautiful, nice example of this is Messier 80 located in the Scorpius constellation). Globus is Latin means a small sphere. Globular clusters are found in the halo of galaxies. Open clusters, which contain coming stars (loosely gravitationally bound), are found in the disk of galaxies on the other hand.

Messier 80 located in the Scorpius constellation. Image credits go to Hubble space telescope.