The Pleiades, often referred to as the Seven Sisters, Messier 45, and other names by other civilizations, is an asterism and an open star cluster in the northwest of the constellation Taurus that is made up of hot, middle-aged B-type stars. It is one of the closest star clusters to Earth at a distance of roughly 444 light-years. It is the most glaring cluster in the night sky that can be seen with the unaided eye, and it is the closest Messier item to Earth. It is also noted to contain the HII area reflection nebula NGC 1432.
Hot blue bright stars that developed during the last 100 million years make up the majority of the cluster. Originally believed to be debris from the stars' formation, reflection nebulae around the brightest stars are now thought to be an unrelated dust cloud in the interstellar medium the stars are now travelling through. According to the stars in the cluster, this dust cloud is thought to be travelling at a speed of about 18 km/s.
According to computer calculations, the Pleiades most likely developed from a compact arrangement that resembled the Orion Nebula. The cluster is predicted to last for another 250 million years before dispersing as a result of gravitational interactions with the nearby galactic region.
The Pleiades make up the Golden Gate of the Ecliptic along with the open star cluster of the Hyades.
The Pleiades make up the Golden Gate of the Ecliptic along with the open star cluster of the Hyades.
The Pleiades' name is derived from Ancient Greek:. Given the cluster's significance in defining the sailing season in the Mediterranean Sea, term is most likely derived from plein ("to sail"): "The season of navigation began with their heliacal rising." However, in mythology, the name was given to the Pleiades, a group of seven celestial sisters. It was said that the Pleiades' mother Pleione gave them the name, hence the phrase "daughters of Pleione" was used to refer to them. In truth, Pleione was created to explain the star cluster's name, which almost definitely originated before.
The Pleiades' name is derived from Ancient Greek: Πλειάδες. Given the cluster's significance in defining the sailing season in the Mediterranean Sea, term is most likely derived from plein ("to sail"): "The season of navigation began with their heliacal rising." However, in mythology, the name was given to the Pleiades, a group of seven celestial sisters. It was said that the Pleiades' mother Pleione gave them the name, hence the phrase "daughters of Pleione" was used to refer to them. In truth, Pleione was created to explain the star cluster's name, which almost definitely originated before.
Observational History.
The Pleiades were first observed through a telescope by Galileo Galilei. Thus, he found that the cluster holds a large number of stars that are too faint to be viewed with the human eye. In March 1610, he published his observations in his book Sidereus Nuncius, which also contained a drawing of the Pleiades that depicted 36 stars.
It has long been recognised that the Pleiades are a group of physically connected stars rather than a coincidental alignment of stars. Since there was only a 1 in 500,000 possibility of such a dense alignment of bright stars, John Michell reasoned in 1767 that the Pleiades and many other star clusters must be physically connected. When the stars' proper movements were initially studied, it was discovered that they were all travelling across the sky at the same speed and in the same direction, further supporting the idea that they were related.
The cluster's location was measured by Charles Messier, who catalogued it as M45 in his 1771 publication of comet-like objects. Messier's inclusion of the Pleiades, along with the Orion Nebula and the Praesepe cluster, has been questioned as most of Messier's objects were much fainter and more readily confused with comets—something that seems improbable for the Pleiades. One explanation is that Messier merely wanted to outnumber his scientific rival Lacaille, whose 1755 catalogue comprised 42 items, so he added some notable, brilliant things to his list to make it longer.
Following his observations in 1779, Edme-Sébastien Jeaurat then created in 1782 a map of 64 Pleiades stars, which he later published in 1786.
The Pleiades were first observed through a telescope by Galileo Galilei. Thus, he found that the cluster holds a large number of stars that are too faint to be viewed with the human eye. In March 1610, he published his observations in his book Sidereus Nuncius, which also contained a drawing of the Pleiades that depicted 36 stars.
It has long been recognised that the Pleiades are a group of physically connected stars rather than a coincidental alignment of stars. Since there was only a 1 in 500,000 possibility of such a dense alignment of bright stars, John Michell reasoned in 1767 that the Pleiades and many other star clusters must be physically connected. When the stars' proper movements were initially studied, it was discovered that they were all travelling across the sky at the same speed and in the same direction, further supporting the idea that they were related.
The cluster's location was measured by Charles Messier, who catalogued it as M45 in his 1771 publication of comet-like objects. Messier's inclusion of the Pleiades, along with the Orion Nebula and the Praesepe cluster, has been questioned as most of Messier's objects were much fainter and more readily confused with comets—something that seems improbable for the Pleiades. One explanation is that Messier merely wanted to outnumber his scientific rival Lacaille, whose 1755 catalogue comprised 42 items, so he added some notable, brilliant things to his list to make it longer.
Following his observations in 1779, Edme-Sébastien Jeaurat then created in 1782 a map of 64 Pleiades stars, which he later published in 1786.
Distance and location
One important initial step in calibrating the cosmic distance ladder is the distance to the Pleiades. Since the cluster is quite close to the Earth, it should be simple to measure and has been approximated using a variety of techniques. Astronomers can plot a Hertzsprung-Russell diagram for the cluster if the distance is known with accuracy, and by comparing it to diagrams for clusters whose distances are unknown, their distances can be approximated. A cosmic distance ladder can then be created by using additional techniques to increase the distance scale from open clusters to galaxies and clusters of galaxies. Astronomers' knowledge of the Pleiades' distance ultimately affects how old the universe is and how it will continue to evolve. However, some authors contend that the debate over the Pleiades' distance, which is covered in the section below, is a red herring because the cosmic distance ladder can currently rely on a number of other nearby clusters, including the Hyades and Coma Berenices cluster, where there is agreement on the distances determined by the Hipparcos satellite and other independent methods. |
The tidal radius is around 43 light-years, while the cluster core radius is roughly 8 light-years. Including an unresolved likely additional number of binary stars, the cluster has over 1,000 statistically confirmed members. Up to 14 of the young, blazing blue stars that make up its brightness can be seen with the unaided eye, depending on local observing conditions and the observer's visual acuity. The arrangement of the brightest stars resembles Ursa Major and Ursa Minor to some extent. The cluster is made up primarily of fainter and redder stars, with an estimated total mass of 800 solar masses. In the Pleiades, binary stars are thought to occur roughly 57% of the time.
Many of the brown dwarfs in the cluster are too light for nuclear fusion to begin in their cores and form proper stars; brown dwarfs are objects with less mass than 8% of the Sun. Despite contributing less than 2% of the cluster's overall mass, they may make up as much as 25% of its entire population. Brown dwarfs in the Pleiades and other young clusters have attracted a lot of attention from astronomers because they are still quite bright and viewable, but brown dwarfs in older clusters have faded and are considerably more challenging to examine.
Many of the brown dwarfs in the cluster are too light for nuclear fusion to begin in their cores and form proper stars; brown dwarfs are objects with less mass than 8% of the Sun. Despite contributing less than 2% of the cluster's overall mass, they may make up as much as 25% of its entire population. Brown dwarfs in the Pleiades and other young clusters have attracted a lot of attention from astronomers because they are still quite bright and viewable, but brown dwarfs in older clusters have faded and are considerably more challenging to examine.
Possible Planets
Researchers found that one of the stars in the cluster, HD 23514, which has a mass and brightness slightly larger than that of the Sun, is surrounded by an unprecedented quantity of hot dust particles by analysing deep-infrared photos taken by the Gemini North telescope and the Spitzer Space Telescope. This might be proof that planets are forming near HD 23514.
Researchers found that one of the stars in the cluster, HD 23514, which has a mass and brightness slightly larger than that of the Sun, is surrounded by an unprecedented quantity of hot dust particles by analysing deep-infrared photos taken by the Gemini North telescope and the Spitzer Space Telescope. This might be proof that planets are forming near HD 23514.
Data collection
The night data collection and setup details:
Scope – Sharpstar EDPH 61 III
Mount - Skywatcher EQ6 R Pro
Guide scope – ZWO 30mm
Guide Camera – ZWO ASI 120mm mini
Main Camera – ZWO Asi 533mc Pro
Control box – ZWO ASIAIR Pro
Filter – UV/IR filter
Starizona Filter drawer next to the camera sensor
Fox Halo 96k power bank
A dew heater with its own power bank on the guide scope
Main scope Celestron ring dew heater powered through Celestron control box/ ASIAir
The total exposure was 2 hours and 30 mins with 60-sec sub-exposures, stacked in Deep Sky Stacker and processed in Pixinsight.
Currently, these are the V1 pictures and they will be updated as time goes on.
The night data collection and setup details:
Scope – Sharpstar EDPH 61 III
Mount - Skywatcher EQ6 R Pro
Guide scope – ZWO 30mm
Guide Camera – ZWO ASI 120mm mini
Main Camera – ZWO Asi 533mc Pro
Control box – ZWO ASIAIR Pro
Filter – UV/IR filter
Starizona Filter drawer next to the camera sensor
Fox Halo 96k power bank
A dew heater with its own power bank on the guide scope
Main scope Celestron ring dew heater powered through Celestron control box/ ASIAir
The total exposure was 2 hours and 30 mins with 60-sec sub-exposures, stacked in Deep Sky Stacker and processed in Pixinsight.
Currently, these are the V1 pictures and they will be updated as time goes on.
This target starts to come up in the early hours of September and as the winter months start to roll in, this target rises earlier in the night and is in the night sky all night until March time.
This is an easy target to capture, but you do need to be careful of the stars in this target as they are large and bright! They will oversaturate very easily, even with a UV/IR filter. Keep the exposure times low to avoid over-bloating the stars. Since the Nebula is reflective in this target, a narrowband filter is not needed and is generally one of the brighter reflection nebulas in the sky.
The colour variation between the dust and the stars makes this a unique target and capturing it either by a wide-field camera or a mosaic-style picture will capture a lot of the details in the surrounding areas which you can start to see in the bottom part of the picture above.
I encourage you to try this target, it is an amazing target to capture and the results are worth the wait but is only around for a set time during the year.