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Tarandus

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Tarandus
Constellations (6)
Aquila, Hercules, Ophiuchus, Sagitta, Sagittarius, Scutum
Nomenclature
Abbreviation Tar
Genitive Tarandi
Pronunciation Name: /'tər•an•dis/
Genitive: /'tər•an•dī/
Symbolism the reindeer
Geometry
Midpoint right ascension Template:RA2
Midpoint declination Template:DEC2
Northernmost border Template:DEC2
Southernmost border Template:DEC2
Westernmost border Template:RA2
Easternmost border Template:RA2
Quadrant NQ4
Segments 74
Bordering caelregios Avis (N)
Hippocampus (E)
Noctua (W/C)
Simianus (SW)
Solarium (SE)
Testudo (E)
Area 3882.439 sq. deg. (7th)
Proportion of the sky 94.113‰
Average constellation area 647.073 sq. deg. (3rd)
Stars
Named stars 41
Main stars 4
Naked eye stars
(m < 6.50)
315
BF stars 396
PH stars 78
Known exoplanets 87
Bright stars
(m < 3.00)
17
Brightest star Altair (0.77m)
Nearby stars
(D < 10.00 pc, 32.62 ly)
25
Nearest star Barnard's Star (1.83 pc, 5.98 ly)
Messier objects 27
Visibility
Full visibility range 44°N–38°S
Partial visibility range 90°N–44°N,
38°S–90°S
Midnight culmination date June 24
Zodiac
Astrological sign 11/23–12/22
Solar sign 11/30–1/18

Tarandus is a caelregio located in the fourth quadrant of the northern hemisphere at its midpoint, but it extends into the southern hemisphere and into the third quadrant. Tarandus is divided into six constellations (listed in the infobox), including Hercules, Ophiuchus, and Sagittarius.

Tarandus is located in the rich star fields because it points near the center of our galaxy. Because of this, this caelregio contains many examples of nebulae, star clusters, and star clouds but very few galaxies. Tarandus also contains the second nearest star system to Earth, which is the red dwarf Barnard's Star, and is also the highest proper motion star known.

Name and symbolism Edit

Tarandus was named after the former constellation Tarandus vel Rangifer, where it was located between Cassiopeia and Camelopardalis in the neighboring caelregio Testudo.

Tarandus is named after the Latin word for reindeer. This caelregio can also be called Rangifer since it also means reindeer in Latin. It is imagined that reindeer, although a holiday creature, does share little relationship with eagle (Aquila). Reindeer wears the shield (Scutum) for protection as worn by Heracle (Hercules), especially from arrows (Sagitta).

Notable stars Edit

Bright stars Edit

An A-type main sequence Altair is the Tarandus' brightest star at a magnitude of 0.77, located in Aquila. Altair is one of the stars that make up the Summer Triangle, the other two are Vega and Deneb, both located in the neighboring caelregio Avis.

The other notable bright stars in Tarandus are Kaus Australis (a 1.80m B-type giant located in Sagittarius), Rasalhague (a 2.08m A-type giant located in Ophiuchus), and Kaus Borealis (a 2.83m K-type subgiant located in Sagittarius).

Nearby stars Edit

Barnard's Star is the Tarandus' nearest star at a distance of 5.98 light-years (1.83 parsecs), located in Ophiuchus. It is also the second nearest star system overall after the Alpha Centauri system in Simianus. Barnard's Star is a red dwarf with the highest known proper motion, moving at 10.3 arcsec/year. Barnard's Star can sometimes be referred as Proxima Ophiuchi. This star was discovered by the American astronomer E.E. Barnard in 1916. Barnard's Star was claimed to have planets but further observations find no evidence for planets. However, Barnard's Star is speculated to have three sub-Earth planets all orbiting within 0.105 AU. The innermost planet orbits only 0.008 AU from the star, taking 17 hours to orbit. Yet the planet's temperature is just 664 K (735°F, 390°C), cooler than Mercury and Venus and it is a lava planet caused by the intense tidal forces from its parent star.

Another notable nearby star is 70 Ophiuchi, which was claimed to have the first ever extrasolar planet discovered in 1855, but subsequent observations gradually ruled out the planet's existence. However, 70 Oph is speculated to have eight planets, four orbit component A and four orbit component B. 70 Oph is a K-type main sequence star located 16.58 light-years away. Yet another nearby star speculated to have planets is 12 Ophiuchi, which is a K-type star speculated to contain nine planets, one more than in our solar system.

Variable stars Edit

The notable variable star in Tarandus is Ras Algethi (Alpha Herculis). This red supergiant varies in brightness with a period between 50–150 days that is the result of irregular pulsations.

Another variable star is AM Herculis. AM Her is the prototype cataclysmic variable star also called polar. AM Her is a red dwarf varying between 12.3 and 15.7 magnitudes.

Multiple stars Edit

36 Ophiuchi is a triple star system, all are K-type stars. Star C is separated from the A-B pair by about 700 arcseconds, which itself separated by 4.6 arcseconds at minimum. 36 Ophiuchi speculatively contains eight planets, two around Star A, one around Star B, and five around Star C.

Double stars Edit

The two stars of Xi Sagittarii are separated by 0.46° which is more easily resolvable with the naked eye. ξ2 is nearly 523 times further away from the observer than ξ1, 2069 vs. 365 light-years.

Planetary systems Edit

As of February 8, 2014, there are 87 exoplanets identified in 78 planetary systems in Tarandus. A notable example is HD 154345 (P12 Tar) in Hercules, which has a Jupiter-twin Alpheus (P170). HD 154345 also contains six speculative planets, four of them are terrestrials. Also in Hercules, HD 164922 (P15 Tar) has a long-period saturnian planet named Diomedes (P182) along with two speculative smaller planets closer to the star.

14 Herculis (P1 Tar) has two long-period planets: Cerenytis (14 Her b, P20) and Eurystheus (14 Her c, P163). 14 Her also has two speculative planets orbiting closer than the two known planets: 14 Herculis d and 14 Herculis e. 14 Her e is in a 1:4 resonance with Cerenytis while Cerenytis is in a 1:4 resonance with Eurystheus. So this puts three outer planets in a 1:4:16 laplacian resonance, which would dynamically make 14 Her a very interesting planetary system.

But the most famous example of a planetary system in Tarandus is GJ 1214 (P35 Tar) in Ophiuchus, which has a super-Earth exoplanet detected by transit. This planet, named Shesha (P385), is a mini-Neptune with a hydrogen-helium atmosphere. Despite this planet has a relatively cool temperature of 516 K compared with all other transiting exoplanets, it has one of the closest orbits to the star than any other exoplanets. The planet's distance from the star is only 170 the Earth–Sun distance and takes just 38 hours to orbit the star. The reason why this planet is so cool is because the parent star's radiation is only about 1300 as strong as the Sun.

Another star with a transiting planet is HD 149026 (P9 Tar, in Hercules), which has a planet named Augean (P151). Based on its density, the core makes up merely 70% the mass of this planet. The mass of this planet is 0.36 MJ and the density 0.81 g/cm3.

Notable deep sky objects Edit

Tarandus contains a lot of notable deep sky objects. The Lagoon Nebula (M8, NGC 6523), which is an interstellar cloud, and Trifid Nebula, which is an HII region, are located in Sagittarius. The Omega Nebula (also known as the Swan Nebula, Horseshoe Nebula, Checkmark Nebula or the Lobster Nebula) (M17, NGC 6618) is an HII region also located in Sagittarius. Also in this constellation, there is Sagittarius A, which is a supermassive black hole at the center of our galaxy.

There is the Sagittarius Star Cloud (M24, IC 4715). This star cloud does contain the open cluster NGC 6603. Sagittarius also contains the nearest barred irregular galaxy Barnard's Galaxy (NGC 6822, C57) located just 1.6 million light-years from the Milky Way. This galaxy is similar in structure and composition to the Small Magellanic Cloud (SMC).

The Twin Jet Nebula (M2-9) is a planetary nebula located in Ophiuchus. Also in this constellation, there is the Little Ghost Nebula (NGC 6369). There is the Hercules Globular Cluster (M13, NGC 6205), which is a bright globular cluster visible to the naked eye in Hercules. Sagitta contains the Necklace Nebula, which is a planetary nebula dotted with dense, bright knots of gas that resemble diamonds in a necklace.

Ophiuchus contains two notable dark nebulae: the Snake Nebula (B72) and B68. The Snake Nebula is a part of the much larger Dark Horse Nebula. B68 is also an absorption nebula and Bok globule.

The Rho Ophiuchi cloud complex is a group of objects in Ophiuchus south of the star Rho Ophiuchi. It contains two globular clusters in the upper right, one reflection nebula from above to the upper left, and one dark nebula to the upper left in the image.

This caelregio contains the Hercules Cluster (Abell 2151) of galaxies. This cluster contains about 100 galaxies, many are spirals and interacting galaxies.

There is a globular cluster in Sagittarius: M22 (also known as the Sagittarius Cluster) (NGC 6656), which is the first known globular cluster discovered in 1665 (possibly earlier). This globular cluster is the third brightest in the sky after Omega Centauri and 47 Tucanae and before M13 just mentioned. This cluster is even more notable because it contains a planetary nebula. Sagittarius contains another globular cluster: M55 (NGC 6809). This cluster appears more grainy than nebulous, which is more akin to an open cluster than a globular cluster. Sagittarius contains yet another globular cluster: M70 (NGC 6681). This globular cluster is located close to the center of our galaxy and is visible through a small telescope. This constellation contains yet another globular cluster: M54 (NGC 6715), which was the first globular cluster found outside of our galaxy belonging to the Sagittarius Dwarf Elliptical Galaxy. However this cluster was previously thought to belong to our galaxy until 1994 after it was discovered by Charles Messier in 1778.

In Scutum, there is the Wild Duck Cluster (M11, NGC 6705), which is one of the densest open clusters containing at least 3000 stars within a 23 light-year diameter.

Ophiuchus contains Kepler's Supernova Remnant SN 1604 located in our galaxy after the progenitor star exploded in 1604. This supernova was seen by Johannes Kepler. It was the first naked-eye supernova since 1572 and the next naked-eye supernova would not take place until 1987.

In Sagittarius, there is a rare example of triple merger of galaxies appearing like a bird: the Tinker Bell Triplet (also dubbed 'The Bird'). This triplet is composed of two massive spiral galaxies and an irregular galaxy. In Ophiuchus, there is the Starfish Galaxy (NGC 6240), which is a remnant of a merger between two smaller galaxies and is a nearby ultraluminous infrared galaxy.

Gallery Edit

Lagoon Nebula
The Lagoon Nebula (M8, NGC 6523)
PlanetStarAdded by PlanetStar
Twin Jet Nebula
The Twin Jet Nebula (M2-9)
PlanetStarAdded by PlanetStar
M13
The Hercules Globular Cluster (M13, NGC 6205)
PlanetStarAdded by PlanetStar
Wild Duck Cluster
The Wild Duck Cluster (M11, NGC 6705)
PlanetStarAdded by PlanetStar
Sagittarius Star Cloud
The Sagittarius Star Cloud (M24, IC 4715)
PlanetStarAdded by PlanetStar
Trifid Nebula
The Trifid Nebula
PlanetStarAdded by PlanetStar
Omega Nebula
The Omega Nebula (also known as the Swan Nebula, Horseshoe Nebula, Checkmark Nebula or the Lobster Nebula) (M17, NGC 6618)
PlanetStarAdded by PlanetStar
Barnard's Galaxy
Barnard's Galaxy (NGC 6822, C57)
PlanetStarAdded by PlanetStar
M22
The globular cluster M22 (also known as the Sagittarius Cluster) (NGC 6656)
PlanetStarAdded by PlanetStar
M55
The globular cluster M55 (NGC 6809)
PlanetStarAdded by PlanetStar
Snake Nebula
The Snake Nebula (B72)
PlanetStarAdded by PlanetStar
Little Ghost Nebula
The Little Ghost Nebula (NGC 6369)
PlanetStarAdded by PlanetStar
B68
The dark nebula B68
PlanetStarAdded by PlanetStar
Rho Ophiuchi cloud complex
The Rho Ophiuchi cloud complex
PlanetStarAdded by PlanetStar
Hercules Cluster
The Hercules Cluster (Abell 2151)
PlanetStarAdded by PlanetStar
Necklace Nebula
The Necklace Nebula
PlanetStarAdded by PlanetStar
Tinker Bell Triplet
The Tinker Bell Triplet (also dubbed 'The Bird')
PlanetStarAdded by PlanetStar
Starfish Galaxy
The Starfish Galaxy (NGC 6240)
PlanetStarAdded by PlanetStar
SN 1604
Kepler's Supernova Remnant SN 1604
PlanetStarAdded by PlanetStar
M54
The globular cluster M54 (NGC 6715)
PlanetStarAdded by PlanetStar

Visibility Edit

In the northern hemisphere, Tarandus can be visible from late fall till mid winter. Since the area of Tarandus is extremely similar between northern and southern hemispheres, observers at the north pole and south pole would see about equal proportions of Tarandus. The north pole observer would find that the northern half of Tarandus appears to circumnavigate clockwise along the horizon, and the southern half would never rise. The south pole observer would see that the southern half of Tarandus appears to circumnavigate counterclockwise along the horizon, and the northern half would never rise.

Sagittarius contains the "Teapot" asterism which the main stars make up the prominent arrow we see in the sky.

Zodiac Edit

The Sun appears to cross Tarandus from November 30 till February 15: it crosses the constellations Ophiuchus (November 30 till December 17), Sagittarius (December 18 till January 18), and then Capricornus (January 19 till February 15). This zodiacal caelregio is located between Simianus to the west and Hippocampus to the east.

Tarandus was formerly in the sign of zodiac from November 23 till January 20.


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