The Pleiades (also Atlantids, Atlantiads, Pleiades, Pigeon, [4] Seven Sisters, Gluckhenne [5] ) are an open star cluster which can be seen with the naked eye. In the Messier catalog it has the designation M45. They are part of our galaxy, the Milky Way.
Observation
Since the Pleiades were already known as an asterism long before the invention of the telescope, traditionally only the brightest main stars are called Pleiades. In some cultures and historical accounts only six stars are counted to the Pleiades. The reason is Pleione, which is a variable star.
Its apparent brightness fluctuates slowly but irregularly between that of Taygeta and Celaeno, so that Pleione is sometimes not seen until Celaeno can also already be detected. Therefore, with the naked eye, depending on the viewing conditions, you can see six to nine stars. The arc of vision is 14.5° to 15.5° in clear sky; 19.5° to 20.5° in cloudy weather. The heliacal rising is observable in good visibility conditions from a horizon altitude of 6° to 7°; the sun is at this time about 9° below the horizon.
| Alkione | 25 | 2,86 | B5 IIIe | 3.5 | 440 |
| Atlas | 27 | 3,62 | B8 III | 4.7 | 430 |
| Electra | 17 | 3,70 | B6 IIIe | ? | 400 |
| Maia | 20 | 3,87 | B8 III | 5 | 400 |
| Merope | 23 | 4,16 | B6 IVe | ? | 360 |
| Taygeta | 19 | 4,29 | B6 IV | 4.5 | 440 |
| Pleione | 28 | 4,8-5,5 | B8 IVpe | 3.4 | 390 |
| Celaeno | 16 | 5,45 | B7 IV | 4 | 430 |
| Asterope | 21 and 22 | 5.76 and 6.43 | ? | ? | 440 |
| 18 Dew | 18 | 5,65 | ? | ? | 440 |
The Pleiades are visible in the northern sky from about the beginning of July until the end of April.
The star cluster is located just under 140 parsecs away in the constellation Taurus, contains at least 1200 stars and is about 125 million years old.
The NGC catalog does not list the Pleiades, but there are several reflection nebulae in the Pleiades area with their own NGC numbers. These include the Maya Nebula NGC 1432 and the Merope Nebula NGC 1435. Only about half a minute of arc or 0.06 light years from Merope is a concentration of interstellar dust known as IC 349 or Barnard’s Merope Nebula is known and kinematically independent of the Pleiades.
The open star cluster appears with an extent of ca. 2° about four times the size of the moon, which was copied to the lower left of the image for comparison. Not considered is the physiological perception to overestimate bright objects in the sky in their size.
Data on the distance of the star cluster
The Pleiades are close enough, at a distance of about 400 light-years, for a measurable annual parallax to occur for individual stars due to the orbit of the Earth around the Sun during the course of a year. Using this method and measurements of other methods, a distance of about 135 parsecs (equivalent to about 440 light-years) was obtained for the Pleiades. Using the trigonometric parallax the distance of the Pleiades was determined in 1999 with the satellite Hipparcos (launched in 1989) to 120 parsecs (equivalent to 390 light-years). In 2009 a publication using the Hipparcos data even gave less than 120 parsecs. The data of the Hipparcos satellite deviated clearly from earlier measurements. However, the distance determined from the Hipparcos data meant that the physical models for young stars had to be corrected: because of the now smaller distance for the same apparent brightness, the stars in the Pleiades would actually have to shine with lower absolute magnitude. In order to take this into account in the physical models, the stars of the Pleiades would have to have a much higher helium fraction, which however has not been detected in such a way. When in 2014 a new trigonometric measurement by Very Long Baseline Interferometry confirmed the original measurements of about 135 parsecs distance, thus substantiating the previous physical models, doubts about the calculations with the Hipparcos data were raised. The follow-up mission Gaia, which is supposed to exceed the accuracy of the Hipparcos measurements and whose mission will end in 2018, was also criticized, because Gaia uses the same methodology as Hipparcos. It is worth mentioning that other distance measurements of Hipparcos are in agreement with other data and the data differ only for those of the Pleiades. [6] [7] Preliminary results from the Gaia mission, published in September 2016, now give the distance of the Pleiades as 134 ± 6 parsecs, [8] thus confirming older distance determinations, as does the 2014 trigonometric measurement by Very Long Baseline Interferometry.
Cultural significance
The Pleiades were regarded as special stars in many cultures. Thus z. B. a group of six drawn dots in the caves of Lascaux is interpreted as a representation of the Pleiades.
An important object from Central Europe, probably used for astronomy, is the Nebra Sky Disk. A group of seven closely spaced points is identified with the Pleiades. [9]
The Pleiades was first mentioned in writing as a constellation in Sumer (mul.mul) [10] and as Seven gods of the great gods denotes.
In the bible the Pleiades are mentioned in the book of Job ( Hi 38,31 EU): "Canst thou make the bond of the Pleiades, or loose the fetters of Orion??".
In biblical myth the Pleiades are symbolized as a dove, which as a spring star announces the revival of nature.
They were considered Stars of Enki or stars which are located where the east wind comes from. In Astrolabe B, which dates from the 12. Century v. Chr. the Pleiades represent the second sign of the zodiac, Taurus.
As figurative glyptic symbol and representation as Seven deity The beginnings of astronomy can be found with the Assyrians in the period from the 15th to the 14th century. to the 14. Century v.u.Z., the Mitanni time. The Pleiades often adorned Assyrian monuments and were invoked in prophetic texts. In Babylonia the Pleiades played a more subordinate role and were therefore hardly represented pictorially. The Babylonians saw in it the magic number forty, because the Pleiades were covered by the sun for 40 days.
The brightest stars are named after figures of Greek mythology, the Titan Atlas (hence the other name), his wife Pleione, and their seven daughters Alkyone, Asterope, Celaeno, Elektra, Maia, Merope, and Taygete. The Pleiades, who are to be classified as nymphs, raised Dionysus and Zeus. According to mythology, they were pursued by Orion. Zeus moved them to the sky as a constellation, but even there they are still pursued by Orion, whose constellation is located about 30° southeast of the Pleiades.
In Japan the six brightest stars of the Pleiades are seen as the constellation Subaru an, from which the name and trademark of the Japanese automobile brand Subaru is derived.
In Arabic literature, the Pleiades الثريا ath-Thurayya called. The name also became a female given name in Turkish (as Surayya) and in Arabic (z. B. Soraya Obaid). It is also the name of the satellite telephone system Thuraya, which is based in the United Arab Emirates.
Agricultural and hunting calendar star
For the Bedouins, the rising of the Pleiades signals summer, and their setting signals winter: "The Pleiades rise above dry sheaves of grain and set when the valley becomes a stream."This corresponds to the Jewish view: "The world can exist because of the coldness of the Pleiades only because Sirius provides with his heat for compensation."
The Greeks and Romans (lat. Vergiliae) regarded the early setting of the Pleiades at the beginning of November as the sign of the tilling of the fields and the end of navigation. With the early rise around the then 20. May the Pleiades were considered as signal giver for the beginning harvest (see also Gezer calendar).
Flavius Josephus mentions that when the Pleiades set around the time of the Feast of Tabernacles in November, the onset of rain put an end to the water shortage. The Maasai in Africa use the Pleiades in modern times as a Rainy season signal star. The book published by Gladys Dickson Arabian astrology called the 20. May for the early morning and the 17. November for the early sunset (see also: Heliacal); in the old Greek tradition mentions the Geoponica (Cape. 1) the corresponding dates for the 10. June and 4. November.
For the Blackfoot Indians of North America the constellation of the Pleiades was of crucial importance. The Blackfoot were nomadic hunter-gatherers. They lived in small groups in tipis made of bison skins. For hunting expeditions sometimes some groups or even a whole sub-tribe joined together. The position of the Pleiades at the beginning of the dry season was the starting signal for an elaborate drive hunt of the huge herds of bison. If the Pleiades have disappeared from the starry sky at the end of April, the bison have also disappeared. [11]
Pacific New Year
In Pacific cultures the rising of the Pleiades determines the New Year celebration. In New Zealand, Matariki is one of the most important Māori festivals. On the islands of French Polynesia, the Pleiades festival is celebrated once a year. It is a kind of New Year celebration, a festival of abundance and change. [12]