Constellation | |
Abbreviation | Her |
---|---|
Genitive | Herculis [1] |
Pronunciation | /ˈhɜːrkjʊliːz/ , genitive /ˈhɜːrkjʊlɪs/ |
Symbolism | Heracles |
Right ascension | 17h |
Declination | +30° |
Quadrant | NQ3 |
Area | 1225 sq. deg. (5th) |
Main stars | 14, 22 |
Bayer/Flamsteed stars | 106 |
Stars with planets | 15 |
Stars brighter than 3.00m | 2 |
Stars within 10.00 pc (32.62 ly) | 9 |
Brightest star | β Her (Kornephoros) (2.78 m ) |
Messier objects | 2 |
Meteor showers | Tau Herculids |
Bordering constellations | Draco Boötes Corona Borealis Serpens Caput Ophiuchus Aquila Sagitta Vulpecula Lyra [1] |
Visible at latitudes between +90° and −50°. Best visible at 21:00 (9 p.m.) during the month of July . |
Hercules is a constellation named after Hercules, the Roman mythological hero adapted from the Greek hero Heracles. Hercules was one of the 48 constellations listed by the second-century astronomer Ptolemy, and it remains one of the 88 modern constellations today. It is the fifth-largest of the modern constellations and is the largest of the 50 which have no stars brighter than apparent magnitude +2.5.
Hercules is bordered by Draco to the north; Boötes, Corona Borealis, and Serpens Caput to the east; Ophiuchus to the south; Aquila to the southwest; and Sagitta, Vulpecula, and Lyra to the west. Covering 1225.1 square degrees and 2.970% of the night sky, it ranks fifth among the 88 constellations in size. [2] The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is 'Her'. [3] The official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of 32 segments (illustrated in infobox). In the equatorial coordinate system, epoch 2000, the right ascension coordinates of these borders lie between 16h 00m 26.64s and 18h 57m 49.50s, while the declination coordinates are between +3.67° and +51.32°. [4] In mid-northern latitudes, Hercules is best observed from mid-spring until early autumn, culminating at midnight on June 13. [1]
The solar apex is the direction of the Sun's motion with respect to the Local Standard of Rest. This is located within the constellation of Hercules, around coordinates right ascension 18h 00m and declination 30° 00′. [5] The north pole of the supergalactic coordinate system is located within this constellation at right ascension 18h 55m 01s and declination +15° 42′ 32″. [6]
Hercules has no first or second magnitude stars. However, it does have several stars above magnitude 4. Alpha Herculis, traditionally called Rasalgethi, is a triple star system, partly resolvable in small amateur telescopes, 359 light-years from Earth. Its common name means "the kneeler's head". [7] The primary is an irregular variable star; it is a bright giant with a minimum magnitude of 4 and a maximum magnitude of 3. It has a diameter of roughly 400 solar diameters. [8] The secondary, a spectroscopic binary that orbits the primary every 3600 years, is a blue-green hued star of magnitude 5.6. Beta Herculis, also called Kornephoros, is the brightest star in Hercules. It is a yellow giant of magnitude 2.8, 148 light-years from Earth; kornephoros means club-bearer. [9] Delta Herculis A is a double star divisible in small amateur telescopes. The primary is a blue-white star of magnitude 3.1, and is 78 light-years from Earth. The optical companion is of magnitude 8.2. Gamma Herculis is also a double star divisible in small amateur telescopes. The primary is a white giant of magnitude 3.8, 195 light-years from Earth. The optical companion, widely separated, is 10th magnitude. Zeta Herculis is a binary star that is becoming divisible in medium-aperture amateur telescopes, as the components widen to their peak in 2025. The system, 35 light-years from Earth, has a period of 34.5 years. The primary is a yellow-tinged star of magnitude 2.9 and the secondary is an orange star of magnitude 5.7. [10]
Hercules hosts further quite bright double stars and binary stars. Kappa Herculis is a double star divisible in small amateur telescopes. The primary is a yellow giant of magnitude 5.0, 388 light-years from Earth; the secondary is an orange giant of magnitude 6.3, 470 light-years from Earth. Rho Herculis is a binary star 402 light-years from Earth, divisible in small amateur telescopes. Both components are blue-green giant stars; the primary is magnitude 4.5 and the secondary is magnitude 5.5. 95 Herculis is a binary star divisible in small telescopes, 470 light-years from Earth. The primary is a silvery giant of magnitude 4.9, and the secondary is an old, reddish giant star of magnitude 5.2. The star HD164669 near the primary may be an optical double. 100 Herculis is a double star easily divisible in small amateur telescopes. Both components are magnitude 5.8 blue-white stars; they are 165 and 230 light-years from Earth. [10]
There are several dimmer variable stars in Hercules. 30 Herculis, also called g Herculis, is a semiregular red giant with a period of 3 months. 361 light-years from Earth, it has a minimum magnitude of 6.3 and a maximum magnitude of 4.3. 68 Herculis, also called u Herculis, is a Beta Lyrae-type eclipsing binary star. 865 light-years from Earth, it has a period of 2 days; its minimum magnitude is 5.4 and its maximum magnitude is 4.7. [10]
Mu Herculis is 27.4 light-years from Earth. The solar apex, i.e., the point on the sky which marks the direction that the Sun is moving in its orbit around the center of the Milky Way, narrowly figures in Hercules, [11] between his more outstretched foot (Omicron Herculis) and Vega (in neighboring Lyra).
Fifteen stars in Hercules are known to be orbited by extrasolar planets.
Hercules contains two bright globular clusters: M13, the brightest globular cluster in the northern hemisphere[ dubious ], and M92. It also contains the nearly spherical planetary nebula Abell 39. M13 lies between the stars η Her and ζ Her; it is dim, but may be detected by the unaided eye on a very clear night.
M13, visible to both the naked eye and binoculars, is a globular cluster of the 6th magnitude that contains more than 300,000 stars and is 25,200 light-years from Earth. It is also very large, with an apparent diameter of over 0.25 degrees, half the size of the full moon; its physical diameter is more than 100 light-years. Individual stars in M13 are resolvable in a small amateur telescope. [10]
M92 is a globular cluster of magnitude 6.4, 26,000 light-years from earth. It is a Shapley class IV cluster, indicating that it is quite concentrated at the center; it has a very clear nucleus. [24] M92 is visible as a fuzzy star in binoculars, like M13; it is denser and smaller than the more celebrated cluster. The oldest globular cluster known at 14 billion years, its stars are resolvable in a medium-aperture amateur telescope. [10]
NGC 6229 is a dimmer globular cluster, with a magnitude of 9.4, it is the third-brightest globular in the constellation. 100,000 light-years from Earth, it is a Shapley class IV cluster, meaning that it is fairly rich in the center and quite concentrated at the nucleus. [25]
NGC 6210 is a planetary nebula of the 9th magnitude, 4000 light-years from Earth visible as a blue-green elliptical disk in amateur telescopes larger than 75 mm in aperture. [10]
AT2018cow, a large astronomical explosion detected on 16 June 2018. [26] [27] As of 22 June 2018, this astronomical event has generated a very large amount of interest among astronomers throughout the world [28] and may be, as of 22 June 2018, considered a supernova tentatively named Supernova 2018cow. [29] [30]
The Hercules Cluster (Abell 2151) is a cluster of galaxies in Hercules.
The brightest radio source in the constellation is Hercules A, an elliptical galaxy located 2.1 billion light years away with a supermassive black hole with a mass of 2.5-billion-solar-mass that has radio jets that extend for one-and-a-half million light-years. [31] Another bright radio source in Hercules is the quasar 3C 345 which has a jet that appears to move faster than the speed of light. [32]
The Hercules–Corona Borealis Great Wall, the largest structure in the universe, is in Hercules.
The traditional visualization imagines α Herculis as Hercules's head; its name, Rasalgethi, literally means "head of the kneeling one". Hercules's left hand then points toward Lyra from his shoulder (δ Herculis), and β Herculis, or Kornephoros ("club-bearer") forms his other shoulder. His narrow waist is formed by ε Herculis and ζ Herculis. Finally, his left leg (with θ Herculis as the knee and ι Herculis the foot) is stepping on Draco's head, the dragon/snake who Hercules has vanquished and perpetually gloats over for eternities. [33]
A common form found in modern star charts uses the quadrangle formed by π Her, η Her, ζ Her and ε Her (known as the "Keystone" asterism) as Hercules's torso.
H. A. Rey has suggested an alternative visualization in which the "Keystone" becomes Hercules's head. This quadrangle lies between two very bright stars: Vega in the constellation Lyra and α CrB (Alphecca) in the constellation Corona Borealis. The hero's right leg contains two bright stars of the third magnitude: α Her (Rasalgethi) and δ Her (Sarin). The latter is the right knee. The hero's left leg contains dimmer stars of the fourth magnitude which do not have Bayer designations but which do have Flamsteed numbers. The star β Her belongs to the hero's outstretched right hand, and is also called Kornephoros.
According to Gavin White, the Greek constellation of Hercules is a distorted version of the Babylonian constellation known as the "Standing Gods" (MUL.DINGIR.GUB.BA.MESH). White argues that this figure was, like the similarly named "Sitting Gods", depicted as a man with a serpent's body instead of legs (the serpent element now being represented on the Greek star map by the figure of Draco that Hercules crushes beneath his feet). He further argues that the original name of Hercules – the 'Kneeler' (see below) – is a conflation of the two Babylonian constellations of the Sitting and Standing Gods. [34]
The earliest Greek references to the constellation do not refer to it as Hercules. Aratus describes it as follows:
Right there in its [Draco's] orbit wheels a Phantom form, like to a man that strives at a task. That sign no man knows how to read clearly, nor what task he is bent, but men simply call him On His Knees. [Ἐγγόνασιν "the Kneeler"]. [35]
Now that Phantom, that toils on his knees, seems to sit on bended knee, and from both his shoulders his hands are upraised and stretch, one this way, one that, a fathom's length. Over the middle of the head of the crooked Dragon, he has the tip of his right foot. Here too that Crown [Corona], which glorious Dionysus set to be memorial of the dead Ariadne, wheels beneath the back of the toil-spent Phantom. To the Phantom’s back the Crown is near, but by his head mark near at hand the head of Ophiuchus [...] Yonder, too, is the tiny Tortoise, which, while still beside his cradle, Hermes pierced for strings and bade it be called the Lyre [Lyra]: and he brought it into heaven and set it in front of the unknown Phantom. That Croucher on his Knees comes near the Lyre with his left knee, but the top of the Bird’s head wheels on the other side, and between the Bird’s head and the Phantom’s knee is enstarred the Lyre. [36]
The story connecting Hercules with the constellation is recounted by Dionysius of Halicarnassus:
On his way back to Mycenae from Iberia having obtained the Cattle of Geryon as his tenth labour Heracles came to Liguria in North-Western Italy where he engaged in battle with two giants, Albion and Bergion or Dercynus. The opponents were strong; Hercules was in a difficult position so he prayed to his father Zeus for help. With the aegis of Zeus, Heracles won the battle. It was this kneeling position of Heracles when prayed to his father Zeus that gave the name "the Kneeler". [37] and Hyginus [38]
Hercules is also sometimes associated with Gilgamesh, a Sumerian mythological hero. [10]
In Chinese astronomy, the stars that correspond to Hercules are located in two areas: the Purple Forbidden enclosure (紫微垣, Zǐ Wēi Yuán) and the Heavenly Market enclosure (天市垣, Tiān Shì Yuán).
Arab translators of Ptolemy named it in Arabic: الرقيس, romanized: al-raqis, lit. 'the player'[ citation needed ] (not to be confused with Arabic: الراقص, romanized: al-rāqiṣ, lit. 'the trotting (camel), the dancing one'), the name for the star Mu Draconis. [39] [40] Hence its Swahili name Rakisi.[ citation needed ]
Aquarius is an equatorial constellation of the zodiac, between Capricornus and Pisces. Its name is Latin for "water-carrier" or "cup-carrier", and its old astronomical symbol is (♒︎), a representation of water. Aquarius is one of the oldest of the recognized constellations along the zodiac. It was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations. It is found in a region often called the Sea due to its profusion of constellations with watery associations such as Cetus the whale, Pisces the fish, and Eridanus the river.
Ara is a southern constellation between Scorpius, Telescopium, Triangulum Australe, and Norma. It was one of the Greek bulk described by the 2nd-century astronomer Ptolemy, and it remains one of the 88 modern constellations designated by the International Astronomical Union.
Corona Borealis is a small constellation in the Northern Celestial Hemisphere. It is one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, and remains one of the 88 modern constellations. Its brightest stars form a semicircular arc. Its Latin name, inspired by its shape, means "northern crown". In classical mythology Corona Borealis generally represented the crown given by the god Dionysus to the Cretan princess Ariadne and set by her in the heavens. Other cultures likened the pattern to a circle of elders, an eagle's nest, a bear's den or a smokehole. Ptolemy also listed a southern counterpart, Corona Australis, with a similar pattern.
Cygnus is a northern constellation on the plane of the Milky Way, deriving its name from the Latinized Greek word for swan. Cygnus is one of the most recognizable constellations of the northern summer and autumn, and it features a prominent asterism known as the Northern Cross. Cygnus was among the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations.
Delphinus is a small constellation in the Northern Celestial Hemisphere, close to the celestial equator. Its name is the Latin version for the Greek word for dolphin (δελφίς). It is one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and remains one of the 88 modern constellations recognized by the International Astronomical Union. It is one of the smaller constellations, ranked 69th in size. Delphinus' five brightest stars form a distinctive asterism symbolizing a dolphin with four stars representing the body and one the tail. It is bordered by Vulpecula, Sagitta, Aquila, Aquarius, Equuleus and Pegasus.
Fornax is a constellation in the southern celestial hemisphere, partly ringed by the celestial river Eridanus. Its name is Latin for furnace. It was named by French astronomer Nicolas Louis de Lacaille in 1756. Fornax is one of the 88 modern constellations.
Hydrus is a small constellation in the deep southern sky. It was one of twelve constellations created by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman and it first appeared on a 35-cm (14 in) diameter celestial globe published in late 1597 in Amsterdam by Plancius and Jodocus Hondius. The first depiction of this constellation in a celestial atlas was in Johann Bayer's Uranometria of 1603. The French explorer and astronomer Nicolas Louis de Lacaille charted the brighter stars and gave their Bayer designations in 1756. Its name means "male water snake", as opposed to Hydra, a much larger constellation that represents a female water snake. It remains below the horizon for most Northern Hemisphere observers.
Ophiuchus is a large constellation straddling the celestial equator. Its name comes from the Ancient Greek ὀφιοῦχος (ophioûkhos), meaning "serpent-bearer", and it is commonly represented as a man grasping a snake. The serpent is represented by the constellation Serpens. Ophiuchus was one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, and it remains one of the 88 modern constellations. An old alternative name for the constellation was Serpentarius.
Pyxis is a small and faint constellation in the southern sky. Abbreviated from Pyxis Nautica, its name is Latin for a mariner's compass. Pyxis was introduced by Nicolas-Louis de Lacaille in the 18th century, and is counted among the 88 modern constellations.
Serpens is a constellation in the northern celestial hemisphere. One of the 48 constellations listed by the 2nd-century astronomer Ptolemy, it remains one of the 88 modern constellations designated by the International Astronomical Union. It is unique among the modern constellations in being split into two non-contiguous parts, Serpens Caput to the west and Serpens Cauda to the east. Between these two halves lies the constellation of Ophiuchus, the "Serpent-Bearer". In figurative representations, the body of the serpent is represented as passing behind Ophiuchus between Mu Serpentis in Serpens Caput and Nu Serpentis in Serpens Cauda.
Sagitta is a dim but distinctive constellation in the northern sky. Its name is Latin for 'arrow', not to be confused with the significantly larger constellation Sagittarius 'the archer'. It was included among the 48 constellations listed by the 2nd-century astronomer Ptolemy, and it remains one of the 88 modern constellations defined by the International Astronomical Union. Although it dates to antiquity, Sagitta has no star brighter than 3rd magnitude and has the third-smallest area of any constellation.
Tucana is a constellation of stars in the southern sky, named after the toucan, a South American bird. It is one of twelve constellations conceived in the late sixteenth century by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman. Tucana first appeared on a 35-centimetre-diameter (14 in) celestial globe published in 1598 in Amsterdam by Plancius and Jodocus Hondius and was depicted in Johann Bayer's star atlas Uranometria of 1603. French explorer and astronomer Nicolas Louis de Lacaille gave its stars Bayer designations in 1756. The constellations Tucana, Grus, Phoenix and Pavo are collectively known as the "Southern Birds".
Alpha Herculis, also designated 64 Herculis, is a multiple star system in the constellation of Hercules. Appearing as a single point of light to the naked eye, it is resolvable into a number of components through a telescope. It has a combined apparent magnitude of 3.08, although the brightest component is variable in brightness. Based on parallax measurements obtained during the Hipparcos mission, it is approximately 360 light-years (110 parsecs) distant from the Sun. It is also close to another bright star Rasalhague in the vicinity.
Lynx is a constellation named after the animal, usually observed in the Northern Celestial Hemisphere. The constellation was introduced in the late 17th century by Johannes Hevelius. It is a faint constellation, with its brightest stars forming a zigzag line. The orange giant Alpha Lyncis is the brightest star in the constellation, and the semiregular variable star Y Lyncis is a target for amateur astronomers. Six star systems have been found to contain planets. Those of 6 Lyncis and HD 75898 were discovered by the Doppler method; those of XO-2, XO-4, XO-5 and WASP-13 were observed as they passed in front of the host star.
Pictor is a constellation in the Southern Celestial Hemisphere, located between the star Canopus and the Large Magellanic Cloud. Its name is Latin for painter, and is an abbreviation of the older name Equuleus Pictoris. Normally represented as an easel, Pictor was named by Abbé Nicolas-Louis de Lacaille in the 18th century. The constellation's brightest star is Alpha Pictoris, a white main-sequence star around 97 light-years away from Earth. Pictor also hosts RR Pictoris, a cataclysmic variable star system that flared up as a nova, reaching apparent (visual) magnitude 1.2 in 1925 before fading into obscurity.
Hydra is the largest of the 88 modern constellations, measuring 1303 square degrees, and also the longest at over 100 degrees. Its southern end borders Libra and Centaurus and its northern end borders Cancer. It was included among the 48 constellations listed by the 2nd century astronomer Ptolemy. Commonly represented as a water snake, it straddles the celestial equator.
Messier 13 or M13, is a globular cluster of several hundred thousand stars in the constellation of Hercules.
Messier 92 is a globular cluster of stars in the northern constellation of Hercules.
14 Herculis or 14 Her is a K-type main-sequence star 58.4 light-years away in the constellation Hercules. It is also known as HD 145675. Because of its apparent magnitude, of 6.61 the star can be very faintly seen with the naked eye. As of 2021, 14 Herculis is known to host two exoplanets in orbit around the star.
Theta Herculis is a single, variable star in the northern constellation of Hercules. This object is visible to the naked eye as a faint, orange-hued star with an apparent visual magnitude of 3.851. Based upon parallax measurements, it is located around 750 light years away from the Sun. The star is advancing toward the Earth with a heliocentric radial velocity of –28 km/s.