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The Pleiades (), also known as The Seven Sisters, Messier 45 and other names by different cultures, is an asterism and an open star cluster containing middle-aged, hot
B-type stars B type or Type B may refer to: Astronomy * B-type asteroid, a type of relatively uncommon type of carbonaceous asteroid * B-type giant, a type of blue giant star * B-type star, a type of star Biology * B type blood, a type in the ABO blood grou ...
in the north-west of the constellation Taurus. At a distance of about 444 light years, it is among the nearest
star cluster Star clusters are large groups of stars. Two main types of star clusters can be distinguished: globular clusters are tight groups of ten thousand to millions of old stars which are gravitationally bound, while open clusters are more loosely cl ...
s to
Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's sur ...
. It is the nearest Messier object to Earth, and is the most obvious cluster to the
naked eye Naked eye, also called bare eye or unaided eye, is the practice of engaging in visual perception unaided by a magnifying, light-collecting optical instrument, such as a telescope or microscope, or eye protection. Vision corrected to norma ...
in the
night sky The night sky is the nighttime appearance of celestial objects like stars, planets, and the Moon, which are visible in a clear sky between sunset and sunrise, when the Sun is below the horizon. Natural light sources in a night sky in ...
. It is also observed to house the reflection nebula NGC 1432, an HII Ionized region. The cluster is dominated by hot blue luminous stars that have formed within the last 100 million years. Reflection nebulae around the brightest stars were once thought to be left over material from their formation, but are now considered likely to be an unrelated dust cloud in the interstellar medium through which the stars are currently passing. This dust cloud is estimated to be moving at a speed of approximately 18 km/s relative to the stars in the cluster. Computer simulations have shown that the Pleiades were probably formed from a compact configuration that resembled the Orion Nebula. Astronomers estimate that the cluster will survive for about another 250 million years, after which it will disperse due to gravitational interactions with its galactic neighborhood. Together with the open star cluster of the Hyades, the Pleiades form the Golden Gate of the Ecliptic.


Origin of name

The name of the Pleiades comes from grc, Πλειάδες. It probably derives from ''plein'' ("to sail") because of the cluster's importance in delimiting the sailing season in the
Mediterranean Sea The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on ...
: "the season of navigation began with their heliacal rising". However, in mythology the name was used for the Pleiades, seven divine sisters, the name supposedly deriving from that of their mother Pleione and effectively meaning "daughters of Pleione". In reality, the name of the star cluster almost certainly came first, and Pleione was invented to explain it.


Folklore and mythology

The Pleiades are a prominent sight in winter in the
Northern Hemisphere The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's Nort ...
, and are easily visible out to mid-Southern latitudes. They have been known since antiquity to cultures all around the world, including the
Celts The Celts (, see pronunciation for different usages) or Celtic peoples () are. "CELTS location: Greater Europe time period: Second millennium B.C.E. to present ancestry: Celtic a collection of Indo-European peoples. "The Celts, an ancient ...
( cy, Tŵr Tewdws, ga, Streoillín), Hawaiians (who call them ''Makaliʻi''),
Māori Māori or Maori can refer to: Relating to the Māori people * Māori people of New Zealand, or members of that group * Māori language, the language of the Māori people of New Zealand * Māori culture * Cook Islanders, the Māori people of the Co ...
(who call them '' Matariki''),
Indigenous Australians Indigenous Australians or Australian First Nations are people with familial heritage from, and membership in, the ethnic groups that lived in Australia before British colonisation. They consist of two distinct groups: the Aboriginal peoples ...
(from several traditions), the Achaemenid Empire, whence in
Farsi Persian (), also known by its endonym Farsi (, ', ), is a Western Iranian language belonging to the Iranian branch of the Indo-Iranian subdivision of the Indo-European languages. Persian is a pluricentric language predominantly spoken an ...
(who called them پروین Parvīn or پروی Parvī), the
Arabs The Arabs (singular: Arab; singular ar, عَرَبِيٌّ, DIN 31635: , , plural ar, عَرَب, DIN 31635: , Arabic pronunciation: ), also known as the Arab people, are an ethnic group mainly inhabiting the Arab world in Western Asia, ...
(who call them الثريا ''al-Thurayya''), the Chinese (who called them ''mǎo''), the Quechua (who call them Qullqa or the storehouse), the
Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the n ...
ese (who call them 昴 / スバル Subaru), the Maya, the
Aztec The Aztecs () were a Mesoamerican culture that flourished in central Mexico in the post-classic period from 1300 to 1521. The Aztec people included different ethnic groups of central Mexico, particularly those groups who spoke the Nahuatl ...
, the Sioux, the
Kiowa Kiowa () people are a Native American tribe and an indigenous people of the Great Plains of the United States. They migrated southward from western Montana into the Rocky Mountains in Colorado in the 17th and 18th centuries,Pritzker 326 and e ...
, and the
Cherokee The Cherokee (; chr, ᎠᏂᏴᏫᏯᎢ, translit=Aniyvwiyaʔi or Anigiduwagi, or chr, ᏣᎳᎩ, links=no, translit=Tsalagi) are one of the indigenous peoples of the Southeastern Woodlands of the United States. Prior to the 18th century, th ...
. In
Hinduism Hinduism () is an Indian religion or '' dharma'', a religious and universal order or way of life by which followers abide. As a religion, it is the world's third-largest, with over 1.2–1.35 billion followers, or 15–16% of the global p ...
, the Pleiades are known as Kṛttikā and are scripturally associated with the war-god
Kartikeya Kartikeya ( sa, कार्त्तिकेय, Kārttikeya), also known as Skanda, Subrahmanya, Shanmukha (), and Murugan ( ta, முருகன்), is the Hindu god of war. He is the son of Parvati and Shiva, the brother of Ganesh ...
but the Hindus celebrate the first day (new moon) of the month of Kartik as Diwali, a festival of abundance and lamps. They are also mentioned three times in the
Bible The Bible (from Koine Greek , , 'the books') is a collection of religious texts or scriptures that are held to be sacred in Christianity Christianity is an Abrahamic monotheistic religion based on the life and teachings of Jesus ...
. The earliest-known depiction of the Pleiades is likely a Northern German
Bronze Age The Bronze Age is a historic period, lasting approximately from 3300 BC to 1200 BC, characterized by the use of bronze, the presence of writing in some areas, and other early features of urban civilization. The Bronze Age is the second pri ...
artifact known as the
Nebra sky disk The Nebra sky disc (german: Himmelsscheibe von Nebra) is a bronze disc of around diameter and a weight of , having a blue-green patina and inlaid with gold symbols. These symbols are interpreted generally as the Sun or full moon, a lunar cresc ...
, dated to approximately 1600 BC. The
Babylonian star catalogues Babylonian astronomy collated earlier observations and divinations into sets of Babylonian star catalogues, during and after the Kassite rule over Babylonia. These star catalogues, written in cuneiform script, contained lists of constellations, ...
name the Pleiades (), meaning "stars" (literally "star star"), and they head the list of stars along the ecliptic, reflecting the fact that they were close to the point of vernal equinox around the 23rd century BC. The Ancient Egyptians may have used the names "Followers" and "Ennead" in the prognosis texts of the Calendar of Lucky and Unlucky Days of papyrus Cairo 86637. Some Greek astronomers considered them to be a distinct constellation, and they are mentioned by
Hesiod Hesiod (; grc-gre, Ἡσίοδος ''Hēsíodos'') was an ancient Greek poet generally thought to have been active between 750 and 650 BC, around the same time as Homer. He is generally regarded by western authors as 'the first written poet i ...
's '' Works and Days'',
Homer Homer (; grc, Ὅμηρος , ''Hómēros'') (born ) was a Greek poet who is credited as the author of the ''Iliad'' and the ''Odyssey'', two epic poems that are foundational works of ancient Greek literature. Homer is considered one of the ...
's ''
Iliad The ''Iliad'' (; grc, Ἰλιάς, Iliás, ; "a poem about Ilium") is one of two major ancient Greek epic poems attributed to Homer. It is one of the oldest extant works of literature still widely read by modern audiences. As with the ''Ody ...
'' and ''
Odyssey The ''Odyssey'' (; grc, Ὀδύσσεια, Odýsseia, ) is one of two major ancient Greek epic poems attributed to Homer. It is one of the oldest extant works of literature still widely read by modern audiences. As with the '' Iliad'', ...
'', and the ''
Geoponica The ''Geoponica'' or ''Geoponika'' ( el, Γεωπονικά) is a twenty-book collection of agricultural lore, compiled during the 10th century in Constantinople for the Byzantine emperor Constantine VII Porphyrogenitus. The Greek word ''Geoponica ...
''. The Pleiades was the most well-known star among pre-Islamic Arabs and so often simply referred to as "the Star" (''al Najm''). Some scholars of
Islam Islam (; ar, ۘالِإسلَام, , ) is an Abrahamic monotheistic religion centred primarily around the Quran, a religious text considered by Muslims to be the direct word of God (or '' Allah'') as it was revealed to Muhammad, the ...
suggested that the Pleiades (ath-thurayya) are the "star" mentioned in Surah An-Najm ("The Star") in the
Quran The Quran (, ; Standard Arabic: , Quranic Arabic: , , 'the recitation'), also romanized Qur'an or Koran, is the central religious text of Islam, believed by Muslims to be a revelation from God. It is organized in 114 chapters (pl.: , ...
.


Subaru

In
Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the n ...
, the cluster is mentioned under the name Mutsuraboshi ("six stars") in the 8th-century '' Kojiki''. The cluster is now known in Japan as Subaru. It was chosen as the name of the
Subaru Telescope is the telescope of the National Astronomical Observatory of Japan, located at the Mauna Kea Observatory on Hawaii. It is named after the open star cluster known in English as the Pleiades. It had the largest monolithic primary mirror in t ...
which is the flagship telescope of the National Astronomical Observatory of Japan. It is located at the Mauna Kea Observatory on the island of
Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only stat ...
. It had the largest monolithic primary mirror in the world from its commissioning in 1998 until 2005. It was chosen as the brand name of
Subaru ( or ; ) is the automobile manufacturing division of Japanese transportation conglomerate Subaru Corporation (formerly known as Fuji Heavy Industries), the twenty-first largest automaker by production worldwide in 2017. Subaru cars are ...
automobiles to reflect the origins of the firm as the joining of five companies, and is depicted in the firm's six-star logo.


Observational history

Galileo Galilei Galileo di Vincenzo Bonaiuti de' Galilei (15 February 1564 – 8 January 1642) was an Italian astronomer, physicist and engineer, sometimes described as a polymath. Commonly referred to as Galileo, his name was pronounced (, ). He ...
was the first
astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, moons, comets and galaxies – in either ...
to view the Pleiades through a
telescope A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. Originally meaning only an optical instrument using lenses, curved mirrors, or a combination of both to obse ...
. He thereby discovered that the cluster contains many stars too dim to be seen with the naked eye. He published his observations, including a sketch of the Pleiades showing 36 stars, in his treatise '' Sidereus Nuncius'' in March 1610. The Pleiades have long been known to be a physically related group of stars rather than any chance alignment.
John Michell John Michell (; 25 December 1724 – 21 April 1793) was an English natural philosopher and clergyman who provided pioneering insights into a wide range of scientific fields including astronomy, geology, optics, and gravitation. Considered ...
calculated in 1767 that the probability of a chance alignment of so many bright stars was only 1 in 500,000, and so surmised that the Pleiades and many other clusters of stars must be physically related. When studies were first made of the stars' proper motions, it was found that they are all moving in the same direction across the sky, at the same rate, further demonstrating that they were related. Charles Messier measured the position of the cluster and included it as M45 in his catalogue of
comet A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena ...
-like objects, published in 1771. Along with the Orion Nebula and the Praesepe cluster, Messier's inclusion of the Pleiades has been noted as curious, as most of Messier's objects were much fainter and more easily confused with comets—something that seems scarcely possible for the Pleiades. One possibility is that Messier simply wanted to have a larger catalogue than his scientific rival Lacaille, whose 1755 catalogue contained 42 objects, and so he added some bright, well-known objects to boost his list. Edme-Sébastien Jeaurat then drew in 1782 a map of 64 stars of the Pleiades from his observations in 1779, which he published in 1786.


Distance

The distance to the Pleiades can be used as a key first step to calibrate the
cosmic distance ladder The cosmic distance ladder (also known as the extragalactic distance scale) is the succession of methods by which astronomers determine the distances to celestial objects. A ''direct'' distance measurement of an astronomical object is possible o ...
. As the cluster is relatively close to the Earth, its distance should be relatively easy to measure and has been estimated by many methods. Accurate knowledge of the distance allows astronomers to plot a Hertzsprung–Russell diagram for the cluster, which, when compared to those plotted for clusters whose distance is not known, allows their distances to be estimated. Other methods can then extend the distance scale from open clusters to galaxies and clusters of galaxies, and a cosmic distance ladder can be constructed. Ultimately astronomers' understanding of the age and future evolution of the universe is influenced by their knowledge of the distance to the Pleiades. Yet some authors argue that the controversy over the distance to the Pleiades discussed below is a red herring, since the cosmic distance ladder can (presently) rely on a suite of other nearby clusters where consensus exists regarding the distances as established by the '' Hipparcos'' satellite and independent means (e.g., the Hyades, Coma Berenices cluster, etc.). Measurements of the distance have elicited much controversy. Results prior to the launch of the ''Hipparcos'' satellite generally found that the Pleiades were about 135 parsecs (pc) away from Earth. Data from ''Hipparcos'' yielded a surprising result, namely a distance of only 118 pc by measuring the parallax of stars in the cluster—a technique that should yield the most direct and accurate results. Later work consistently argued that the ''Hipparcos'' distance measurement for the Pleiades was erroneous. In particular, distances derived to the cluster via the
Hubble Space Telescope The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most vers ...
and infrared color-magnitude diagram fitting (so-called " spectroscopic parallax") favor a distance between 135 and 140 pc; a dynamical distance from optical interferometric observations of the Pleiad double Atlas favors a distance of 133 to 137 pc. However, the author of the 2007–2009 catalog of revised ''Hipparcos'' parallaxes reasserted that the distance to the Pleiades is ~120 pc and challenged the dissenting evidence. Recently, Francis and Anderson proposed that a systematic effect on ''Hipparcos'' parallax errors for stars in clusters biases calculation using the weighted mean and gave a ''Hipparcos'' parallax distance of 126 pc and photometric distance 132 pc based on stars in the
AB Doradus AB Doradus is a pre-main-sequence quadruple star system in the constellation Dorado. The primary is a flare star that shows periodic increases in activity. The primary star in this system spins at a rate 50 times that of the Sun, a ...
, Tucana-Horologium, and
Beta Pictoris Beta Pictoris (abbreviated β Pictoris or β Pic) is the second brightest star in the constellation Pictor. It is located from the Solar System, and is 1.75 times as massive and 8.7 times as luminous as the Sun. The Beta Pictoris s ...
moving groups, which are all similar in age and composition to the Pleiades. Those authors note that the difference between these results can be attributed to random error. More recent results using
very-long-baseline interferometry Very-long-baseline interferometry (VLBI) is a type of astronomical interferometry used in radio astronomy. In VLBI a signal from an astronomical radio source, such as a quasar, is collected at multiple radio telescopes on Earth or in space. Th ...
(VLBI) (August 2014) and preliminary solutions using Gaia Data Release 1 (September 2016) and Gaia Data Release 2 (August 2018), determine distances of 136.2 ± 1.2 pc, See also commentary by 134 ± 6 pc and 136.2 ± 5.0 pc, respectively. The Gaia Data Release 1 team was cautious about their result and the VLBI authors assert "that the ''Hipparcos''-measured distance to the Pleiades cluster is in error". For another distance debate see Polaris#Distance, also with a different measurement from '' Hipparcos'', although this time it suggested a greater distance.


Composition

The cluster core radius is about 8 light-years and
tidal radius A globular cluster is a spheroidal conglomeration of stars. Globular clusters are bound together by gravity, with a higher concentration of stars towards their centers. They can contain anywhere from tens of thousands to many millions of memb ...
is about 43 light-years. The cluster contains over 1,000 statistically confirmed members, a figure that excludes an unresolved likely further number of binary stars. Its light is dominated by young, hot blue stars, up to 14 of which can be seen with the naked eye depending on local observing conditions and visual acuity of the observer. The arrangement of the brightest stars is somewhat similar to Ursa Major and Ursa Minor. The total mass contained in the cluster is estimated to be about 800 solar masses and is dominated by fainter and redder stars. An estimate of the frequency of binary stars in the Pleiades is about 57%. The cluster contains many
brown dwarf Brown dwarfs (also called failed stars) are substellar objects that are not massive enough to sustain nuclear fusion of ordinary hydrogen ( 1H) into helium in their cores, unlike a main-sequence star. Instead, they have a mass between the most ...
s, which are objects with less than about 8% of the Sun's mass, not heavy enough for nuclear fusion reactions to start in their cores and become proper stars. They may constitute up to 25% of the total population of the cluster, although they contribute less than 2% of the total mass. Astronomers have made great efforts to find and analyse brown dwarfs in the Pleiades and other young clusters, because they are still relatively bright and observable, while brown dwarfs in older clusters have faded and are much more difficult to study.


Brightest stars

The nine brightest stars of the Pleiades are named for the Seven Sisters of
Greek mythology A major branch of classical mythology, Greek mythology is the body of myths originally told by the ancient Greeks, and a genre of Ancient Greek folklore. These stories concern the origin and nature of the world, the lives and activities o ...
:
Sterope Sterope (; Ancient Greek: Στερόπη, , from , ''steropē'', lightning) was the name of several individuals in Greek mythology: * Sterope (or Asterope), one of the Pleiades and the wife of Oenomaus (or his mother by Ares). * Sterope, a Pl ...
, Merope, Electra, Maia, Taygeta,
Celaeno In Greek mythology, Celaeno (; grc, Κελαινώ ''Kelaino'', lit. 'the dark one', also Celeno or Kelaino, sometimes isspelledCalaeno) referred to several different figures. * Celaeno, one of the Pleiades. She was said to be mother of Lycus ...
, and Alcyone, along with their parents
Atlas An atlas is a collection of maps; it is typically a bundle of maps of Earth or of a region of Earth. Atlases have traditionally been bound into book form, but today many atlases are in multimedia formats. In addition to presenting geogra ...
and Pleione. As daughters of Atlas, the Hyades were sisters of the Pleiades. The following table gives details of the brightest stars in the cluster:


Age and future evolution

Ages for star clusters can be estimated by comparing the Hertzsprung–Russell diagram for the cluster with theoretical models of stellar evolution. Using this technique, ages for the Pleiades of between 75 and 150 million years have been estimated. The wide spread in estimated ages is a result of uncertainties in stellar evolution models, which include factors such as
convective overshoot Convective overshoot is a phenomenon of convection carrying material beyond an unstable region of the atmosphere into a stratified, stable region. Overshoot is caused by the momentum of the convecting material, which carries the material beyond th ...
, in which a
convective Convection is single or multiphase fluid flow that occurs spontaneously due to the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoyancy). When the cause of the ...
zone within a star penetrates an otherwise non-convective zone, resulting in higher apparent ages. Another way of estimating the age of the cluster is by looking at the lowest-mass objects. In normal
main-sequence In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar ...
stars,
lithium Lithium (from el, λίθος, lithos, lit=stone) is a chemical element with the symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard conditions, it is the least dense metal and the least dense soli ...
is rapidly destroyed in nuclear fusion reactions.
Brown dwarf Brown dwarfs (also called failed stars) are substellar objects that are not massive enough to sustain nuclear fusion of ordinary hydrogen ( 1H) into helium in their cores, unlike a main-sequence star. Instead, they have a mass between the most ...
s can retain their lithium, however. Due to lithium's very low ignition temperature of 2.5 × 106 K, the highest-mass brown dwarfs will burn it eventually, and so determining the highest mass of brown dwarfs still containing lithium in the cluster can give an idea of its age. Applying this technique to the Pleiades gives an age of about 115 million years. The cluster is slowly moving in the direction of the feet of what is currently the constellation of Orion. Like most open clusters, the Pleiades will not stay gravitationally bound forever. Some component stars will be ejected after close encounters with other stars; others will be stripped by tidal gravitational fields. Calculations suggest that the cluster will take about 250 million years to disperse, with gravitational interactions with giant molecular clouds and the spiral arms of our galaxy also hastening its demise.


Reflection nebulosity

With larger amateur telescopes, the nebulosity around some of the stars can be easily seen; especially when long-exposure photographs are taken. Under ideal observing conditions, some hint of nebulosity around the cluster may even be seen with small telescopes or average binoculars. It is a reflection nebula, caused by dust reflecting the blue light of the hot, young stars. It was formerly thought that the dust was left over from the
formation Formation may refer to: Linguistics * Back-formation, the process of creating a new lexeme by removing or affixes * Word formation, the creation of a new word by adding affixes Mathematics and science * Cave formation or speleothem, a secondar ...
of the cluster, but at the age of about 100 million years generally accepted for the cluster, almost all the dust originally present would have been dispersed by radiation pressure. Instead, it seems that the cluster is simply passing through a particularly dusty region of the interstellar medium. Studies show that the dust responsible for the nebulosity is not uniformly distributed, but is concentrated mainly in two layers along the line of sight to the cluster. These layers may have been formed by deceleration due to radiation pressure as the dust has moved towards the stars.


Possible planets

Analyzing deep-infrared images obtained by the Spitzer Space Telescope and Gemini North telescope, astronomers discovered that one of the cluster's stars, HD 23514, which has a mass and luminosity a bit greater than that of the Sun, is surrounded by an extraordinary number of hot dust particles. This could be evidence for planet formation around HD 23514.


Gallery

File:Pleiades.png, A starchart of the Pleiades and their nebulae File:LocalSpur.png, The approximate location of the Pleiades just above the Local Bubble in the middle of this map of the
Orion Arm The Orion Arm is a minor spiral arm of the Milky Way Galaxy that is across and approximately in length, containing the Solar System, including Earth. It is also referred to by its full name, the Orion–Cygnus Arm, as well as Local Arm, Orion ...
(yellow: major stellar associations; red: nebulae; grey: dark nebulae.


See also

* List of Messier objects * Pleiades in folklore and literature * *
Stozhary Festival ''Stozhary'' is an international actors film festival which takes place in Kyiv, Ukraine. The name of the festival is an Old Slavonic counterpart for the asterism of Pleiades. In the mythology of ancient Greece Pleiads were the 7 beautiful ...
* Matariki


References


External links

*
The Pleiades (M45) At the astro-photography site of T. Yoshida.

Photos and information on the Pleiades from the University of Calgary




* ttp://www.nightskyinfo.com/archive/pleiades/ NightSkyInfo.com: The Pleiades
Maya Astronomy


first Doppler image of a Pleiades solar-type G dwarf – HII314, Strassmeier & Rice 2001, A&A 377, 264
Dark Atmospheres Photography (deep nebulosity exposure)

WEBDA open cluster database webpage on Pleiades cluster
– E. Pauzen (Univ. Vienna) *
The Pleiades (M45) at Constellation Guide

Warburg Institute Iconographic Database (medieval and early modern images of the Pleiades)
{{DEFAULTSORT:Pleiades (Star Cluster) Astronomical objects known since antiquity Messier objects NGC objects Orion–Cygnus Arm * Taurus (constellation)