- A star cluster is a group of stars that are bound together by gravity and have a shared origin. These clusters move through the galaxy as a single unit, influenced by the gravitational field. Some star clusters also contain clouds of gas and/or dust.
Star clusters can be classified into two main types based on their shape – globular clusters and scattered clusters. However, in June 2011, a new class of clusters was discovered that combines characteristics of both globular and scattered clusters.
Stellar associations refer to groups of stars that are not strongly bound by gravity or are made up of young stars with a common origin.
Similar ideas
A globular cluster is a cluster of stars that contains a significant number of stars, which are closely held together by gravity and revolve around the galactic center as a companion. Unlike scattered star clusters, which are found in the galactic disk, globular clusters are situated in the halo. They are much older, have a larger number of stars, exhibit a symmetrical spherical shape, and are characterized by an increasing density of stars towards the cluster’s center. Spatial aggregations.
An open cluster is a collection of stars that are formed from a single giant molecular cloud and are approximately the same age. There have been over 1100 open clusters discovered in our Galaxy, but it is believed that there are many more yet to be found. The stars within these clusters are held together by relatively weak gravitational forces, and as they orbit around the center of the galaxy, the clusters may be dissolved due to various factors.
The Local Galactic Group is a group of galaxies that are gravitationally connected, including the Milky Way, the Andromeda Galaxy (M31), and the Triangle Galaxy (M33).
A nebula is a distinctive area of interstellar medium that can be easily identified by its emission or absorption of radiation compared to the overall sky. In the past, nebulae were categorized as any large celestial object that appeared stationary in the sky. However, in the 1920s, it was discovered that many of these nebulae were actually galaxies, such as the Andromeda Nebula. As a result, the term “nebula” began to be used more specifically to refer to objects that fit the aforementioned description. Nebulae are comprised of a combination of dust, gas, and plasma.
References in the literary works
This peculiar entity, which bore a striking resemblance to a glistening soap bubble when observed from vast cosmic distances, possessed a remarkable ability to repel anything that ventured near it. Even galaxies, star clusters, and celestial dust associations, all subject to the influence of dark energy, were forcefully pushed away by this enigmatic force, seemingly propelling them to the farthest reaches of the universe. It was through this repulsive effect that the Krestovsky Attractor was initially detected and brought to the attention of astrophysicists on Earth. Calculations suggest that this Attractor emerged approximately six billion years ago, coinciding with the onset of the Universe’s accelerated expansion, and it didn’t just expel a single galaxy, but at least two hundred. Since its discovery, numerous scientists have endeavored to unravel the mysteries behind this phenomenon, presenting numerous ideas and hypotheses, often of a highly exotic nature. It is no wonder, then, that these entities have earned the label of “exotic” within the scientific community.
Nothing happens only once in space (except maybe the Big Bang). The fragments of exploded stars that have scattered throughout outer space have been constantly exposed to gravitational forces. As a result, the remnants of the initial generation of stars inevitably gave birth to new clusters of stars, forming nebulae that consist of massive clouds of interstellar gas and dust that have been left behind from the explosions of previous generations of stars. Each new nebula contained more iron and slightly less hydrogen than the previous one. This process has been occurring for 13.7 billion years: old stars giving rise to new ones, altering the structure of the universe. Countless billions of stars have emerged in countless galaxies.
In the subsequent illustration, Thomas Wright takes a leap forward in the hierarchy and we are presented with multiple configurations of comet-like orbital patterns. It is evident that he comprehended the vastness of the cosmos and recognized the existence of stellar systems resembling our own. In his 1750 publication, he eloquently articulated this insight, as exemplified by the accompanying diagram, which, notably, was the first to propose that the stars visible in the nocturnal expanse are actually constituents of a stellar assemblage referred to as the Milky Way galaxy, possessing distinct form and a central focal point.
It is common knowledge that stars originate from the condensation of gas-dust matter caused by its own gravitational force. All available evidence supports this theory. Proposed alternatives, such as star clusters forming from the decay of unidentified superdense objects, have not been substantiated. Additionally, research has revealed that the current average density of interstellar gas in the Galaxy is approximately 1 atom per cubic centimeter. However, even before the estimation of this average density, it was evident that gas and dust are not uniformly distributed throughout the Galaxy, but instead form clouds or nebulae. The density of gas between these clouds is typically less than 0.1 atoms per cubic centimeter, while within the clouds, it often exceeds 10 atoms per cubic centimeter. It can be demonstrated that the initially relatively homogeneous interstellar medium will inevitably separate into clouds of diffuse matter and the relatively empty space between them.
Other related concepts
The concept of a galactic halo, also known as a stellar halo, refers to an invisible component that exists within a galaxy. This component is the primary part of the galaxy’s spherical subsystem and takes on a spherical shape that extends beyond the visible portion of the galaxy. Comprised mostly of rarefied hot gas, stars, and dark matter, the galactic halo forms the majority of the galaxy’s mass.
The Milky Way, which is sometimes referred to as our Galaxy or simply Galaxy with a capital “G,” is a specific galaxy that includes the Earth, the Solar System, and all the individual stars visible to the naked eye. It falls under the category of spiral galaxies and features a distinct junction.
Galaxy clusters are immense structures in the Universe that consist of gravitationally bound systems of galaxies. These clusters are among the largest structures known to exist.
Galaxies that are close enough to each other in space for their mutual gravity to have a significant impact on their shape, the motion of matter and stars, the processes of star formation, and in some cases the exchange of matter between them are known as interacting galaxies. These galaxies are distinguished by the presence of “tails”, “bridges”, and ejections of matter.
Wolf-Rayet stars are a type of star characterized by their extremely high temperature and luminosity. What sets Wolf-Rayet stars apart from other hot stars is the presence of broad hydrogen, helium, oxygen, carbon, and nitrogen bands in their spectrum, each with varying degrees of ionization (N – N, C – C, O – O). The class of stars is named after French astronomers Charles Wolf and Georges Rayet, who first observed these spectral features in 1867.
A spiral galaxy consists of galactic arms, which serve as structural components. These arms are rich in dust, gas, young stars, and star clusters.
One fascinating feature of spiral galaxies is the presence of emission nebulae. These nebulae are made up of ionized gas, or plasma, that emits visible light. The ionization process occurs when high-energy photons from nearby hot stars interact with the gas. Emission nebulae come in various types, including H II regions, where new star formation takes place and young, massive stars serve as the source of ionizing photons. Another type is planetary nebulae, which form when a dying star sheds its outer layers, revealing its core.
Norma, also known as Naugolnik in Latin, is a constellation located in the southern hemisphere of the sky. It can be found southwest of Scorpius and north of the Southern Triangle, with Circulus touching its border. While both branches of the Milky Way can be seen passing through Norma, this particular region of the sky lacks bright stars. In fact, there are no stars in Norma that shine brighter than a visual sidereal magnitude of 4.0. However, there are still 42 stars that can be seen with the naked eye, and the constellation covers a sky area of 165.3 square degrees. The best time to observe Norma is during the months of May and June, and it is partially visible in southern Russia below the latitude of 48 N.
A Supernova Remnant (SNR) is a formation of gas and dust that occurs when a star undergoes a catastrophic explosion and transforms into a supernova, typically occurring many tens or hundreds of years ago. This explosive event causes the supernova shell to burst outwards in all directions, resulting in the formation of a shock wave that expands at an incredibly fast pace, ultimately creating the supernova remnant. The remnants consist of both material that was ejected by the explosion itself and interstellar matter that absorbed the impact of the shock wave.
A galaxy supergroup is a term used to describe numerous groups of galaxies and galaxy clusters that exist within the large-scale structure of the Universe.
A bulge is the primary bright ellipsoidal component of spiral and lenticular galaxies. Its dimensions range from several hundred parsecs to multiple kiloparsecs. The bulge of a galaxy is primarily composed of mature stars that move along elongated orbits. The typical inhabitants of the bulge include red giants, red dwarfs, Type II supernovae, RR Lyrae-type variables, and globular clusters. It makes up the inner, densest portion of the spherical subsystem of a galaxy. The core often holds.
The planetary system is a celestial arrangement consisting of stars and various astronomical objects such as planets, their satellites, dwarf planets, asteroids, meteoroids, comets, and cosmic dust. These objects revolve around a common center of mass. A collection of gravitationally bound stars and their planetary systems form a stellar system. The Solar System, which includes the Earth and the Sun, is a specific example of a planetary system.
A Seyfert galaxy is a type of galaxy that can be classified as either spiral or irregular. It is characterized by having an active nucleus that emits a spectrum with bright and broad bands. These bands indicate the presence of powerful gas emissions with velocities reaching several thousand kilometers per second. The term “Seyfert galaxy” was first introduced by Carl Seyfert in 1943. Approximately 1% of observed spiral galaxies fall into this category.
A diffuse nebula is a term used in astronomy to describe nebulae that emit light. There are three types of diffuse nebulae: reflective nebula, emission nebula, and supernova remnants. Non-diffuse dark nebulae, on the other hand, are nebulae in which the molecules are highly dispersed.
Red shift refers to the shift of spectral lines of chemical elements towards the red (long-wavelength) side. This shift can be caused by weak diffuse scattering, the Doppler effect, gravitational redshift, or a combination of these factors. When spectral lines shift towards the violet (short-wavelength) side, it is called blue shift. The phenomenon of spectral line shift in celestial bodies was first observed by the French physicist Hippolyte Fizeau in 1848, and he proposed that radiation and the Doppler effect could explain this shift.
The Perseus-Pisces Supercluster (SCl 40) represents a conglomerate of galaxies stemming from the Perseus-Pegasus chain, which is in close proximity to the Laniakea supercluster (where the Milky Way, along with the Solar System, is a constituent part). In conjunction with Laniakea, it constitutes a portion of the Pisces-Keith superscope complex.
The Orion Cloud denotes a group of interstellar material (nebula) situated within the Orion constellation. The Orion Cloud is situated within the Milky Way galaxy, approximately 1600 light-years away from the Sun, and possesses dimensions on the order of several hundred light-years.
A hypergiant is a star that is extremely massive and large, with a luminosity class of 0 on the Hertzsprung-Russell diagram. Hypergiants are known for being the most powerful, heaviest, brightest, and also the rarest and shortest-lived supergiants. Typically, hypergiants are considered to be supergiants that are brighter than -8m. An example of a star that falls on the borderline of being classified as a hypergiant is KY Swan; if it had a lower luminosity, it would no longer be classified as a hypergiant.
Stellar associations are groups of stars that are not bound by gravity or are weakly bound together and are relatively young, typically up to several tens of millions of years old. These stars are united by a common origin.
A peculiar galaxy is a galaxy that does not fit into a specific class in the Hubble sequence due to its unique and distinct features. There is no clear-cut definition for this term, and the categorization of galaxies as peculiar can be subject to debate.
Phoenix (Latin: Pheonix, Phe) is a constellation located in the southern hemisphere of the celestial sphere. It covers an area of 469.3 square degrees and contains 68 stars that can be seen without the aid of a telescope.
A binary system, also known as a double star system, refers to a pair of stars that are observed to be orbiting each other. These systems are typically characterized by large velocity differences between the components and their close proximity, making it difficult to distinguish them individually with modern telescopes. As a result of the stars’ orbital motion around their common center of mass, one star moves towards the observer while the other moves away, causing their radial velocities (in the direction towards the observer) to differ.
Korma (Latin: Puppis, Pup) is a constellation located in the southern part of the celestial sphere. It can be found in the Milky Way and covers an area of 673.4 square degrees. There are a total of 241 stars that can be seen with the naked eye within this constellation. Korma can be observed in various parts of Russia, with the southern regions offering the best visibility. The brightest star in Korma, ζ Korma, becomes visible at a latitude of 50°. In Adler, this star rises at approximately 6°30′, while in the southern region of Dagestan it rises at about 8°30′. The southernmost cities also have the opportunity to observe this constellation.
Ascendant (Latin: Auriga) is a constellation located in the northern hemisphere of the sky. The brightest star in this constellation is Capella, with a visual magnitude of 0.1. The best conditions for visibility occur in December and January. Ascendant can be seen throughout Russia.
A protoplanetary disk, also known as a proplid, is a dense gas disk that surrounds a young star, such as a protostar, Taurus, or Herbig star (Ae/Be). This disk is where planets are formed. It can also be referred to as an accretion disk because the gaseous material within it can fall onto the star’s surface from the inner radius.
Tucan, or Tucana in Latin, is a constellation that can be found in the southern hemisphere of the sky. It covers an area of 294.6 square degrees and is home to 44 stars that can be seen with the naked eye.
Fox, or Vulpecula in Latin, is a faint constellation that can be found in the northern hemisphere. It is located within the Summer Triangle.
The constellation Sculptor (Latin: Sculptor, Scl) is located in the southern hemisphere of the sky and covers an area of 474.8 square degrees. It is home to 55 stars that can be seen with the naked eye. Within the Sculptor constellation, you can find the South Pole of the Galaxy.
Cepheids are a unique group of pulsating variable stars that exhibit a reliable period-luminosity relationship. This relationship was named after the star δ Cepheus. One of the most famous Cepheids is Polaris. Astronomers consider Cepheids as beacons in the universe, as their period-luminosity relationship allows them to serve as luminosity standards for calculating distances to distant celestial objects.
The constellation known as Unicorn, which comes from the Latin term Monoceros and the Greek term μονόκερως, is located along the celestial equator. Covering an area of 481.6 square degrees in the sky, it includes 146 stars that can be seen without the aid of a telescope. While it lies within the Milky Way, it does not contain any particularly bright stars. However, its location inside the winter triangle, which is formed by the prominent stars Sirius, Procyon, and Betelgeuse, makes it relatively easy to locate. Unicorn is one of the 15 constellations that the celestial equator passes through and is visible in the central and southern regions of the sky.
Furnace, or Fornax in Latin, is a constellation that is not well-known and is located in the southern hemisphere. It covers an area of 397.5 square degrees in the sky and includes 57 stars that can be seen without the need for a telescope.
This compilation of stars closest to our planet, arranged in ascending order of distance, encompasses stars located within 5 parsecs (equivalent to 16.308 light years) of Earth. Among these celestial bodies, there are currently 57 recognized stellar systems that potentially exist within this proximity. Altogether, these systems comprise a total of 64 stars and 13 brown dwarfs.
Sails, also known as Vela in Latin, represents a constellation visible in the southern hemisphere of the night sky. Its southern border traverses the most densely populated regions of the Milky Way. Occupying an expanse of 499.6 square degrees in the celestial sphere, it encompasses 195 stars that can be observed with the naked eye.
Dwarf elliptical galaxies, referred to as dE, belong to a category of elliptical galaxies characterized by their diminished luminosity and size. They are typically found within galaxy clusters or serve as satellites to regular galaxies.
The constellation known as the Goldfish, also referred to as Dorado from the Latin word Doradus, can be found in the southern hemisphere of the sky. It covers an area of approximately 179.2 square degrees and contains a total of 32 stars that can be seen with the naked eye.
Table Mountain, which is referred to as Mensa or Men in Latin, is a relatively faint circumpolar constellation located in the southern hemisphere of the sky. It covers an area of about 153.5 square degrees and includes 24 stars that are visible without the aid of a telescope. None of these stars have a magnitude brighter than 5. Additionally, part of the Large Magellanic Cloud can be found within this constellation.
A supermassive black hole is a type of black hole that has an extremely large mass, typically ranging from 105 to 1010 times the mass of our sun. These black holes have been observed at the center of many galaxies, including our own Milky Way, as of the year 2014.
A dwarf spheroidal galaxy (dSph) is a term used in astronomy to describe small galaxies with a nearly spherical shape and primarily low surface brightness. In the group of galaxies known as the local group, dSph galaxies are often found orbiting our galaxy or M31.
A circumstellar disk refers to a cluster of matter in the shape of a torus or ring that is composed of gas, dust, planetesimals, or asteroids. These disks are typically found in orbit around a star.
Mentions in literature (continuation)
Stozharas, a group of six faintly luminous stars, is mentioned in Russian literature. These stars are easily visible on dark winter nights in the constellation Taurus. Stozharas is classified as one of the closest scattered star clusters, known as Pleiades, in star catalogs. Located approximately 400 light-years away from us, this cluster spans about 22 light-years. Similar to other clusters, the stars of Pleiades move along nearly parallel paths and at nearly the same speed. There are around 100 young stars in Pleiades, estimated to be around 78 million years old. In 1859, a transparent nebula, resembling a blue veil, was discovered. This nebula consists of tiny particles of cosmic dust and does not emit its own light, but instead reflects the light from the Pleiades within it.
With approximately 100,000 stars, along with its small planets and satellites, the Milky Way possesses a distinctive shape resembling a disk launched by a skilled athlete. Situated at the core of the Galaxy, the largest star cluster stands out prominently. Our Galaxy boasts an immense size, with light rays requiring a staggering 100,000 years to traverse from one extremity to the other, even though it is merely one among the countless galaxies scattered throughout the universe.
However, on this particular day, which was celebrated by comedians from all walks of life on various television programs around the world, the anticipated events failed to materialize. The stars scattered throughout the universe refused to explode, quasars remained dim, and asteroids did not make their way past the vector fields of telescopes. Furthermore, no new exotopes were discovered. Despite this lack of excitement, Arthur was content with his responsibilities and directed his focus towards one of the most breathtaking globular star clusters in existence: Omega Centaurus. Situated on the outskirts of the Milky Way, this cluster is comprised of an astounding ten million stars. It formed in the distant past, before the formation of the galactic disk, and the stars within it underwent a unique process of producing carbon from helium rather than the typical transition from hydrogen to helium. As a result, these stars leave behind remnants known as “carbon ash,” which manifest as white and red dwarfs. Omega Centaurus proudly boasts the title of being the first cluster to contain such a substantial accumulation of this “ash.”
If one were to observe the matter cluster closely, they would see that the rest of the molecules also underwent the same process, becoming condensed due to the continuously increasing rotational motion. The end result is a collection of stars orbiting the central luminary, forming what is known as a star cluster or nebula. As of now, there are approximately five thousand nebulae in existence.
Astronomers have always tried to represent the relative brightness of stars in maps of the sky. Traditionally, brighter stars were depicted larger than dimmer ones, which is understandable. However, the appearance of the symbol used to represent a star varied over time. In atlases created before the invention of the telescope, stars were depicted as multibeam stars, reflecting how they appeared to the naked eye (Fig. 1.12). During the era of visual observations through telescopes, the symbol representing a star became more circular, with a faint ray structure inside the circle. With the invention of photographic plates and the beginning of star registration using astrographs, star images in atlases became simple circles of different sizes, similar to those on photographic plates. This can be observed in maps from the late 19th century, such as Messer’s atlas (see Fig. 1.8), where stars of constant brightness are represented by black circles (negative!), with the size of the circle proportional to the star’s brightness. Rings on this map represent variable stars, crossed-out circles indicate double stars, dashed circles represent nebulae, and dotted stars represent star clusters.
3. In order to delve further into the enigma of the stars’ movement, you can navigate using the renowned constellation known as the Big Dipper. By extending the line that connects the two stars in its front section by a segment that is five times longer than this line, you will effortlessly locate Polaris (refer to Figure 5). Commencing your search from the Little Bear, where Polaris is situated at the tip of its tail, proves to be much more challenging. Regrettably, the Little Dipper is a rather inconspicuous constellation and is frequently mistaken for the Pleiades star cluster.
Vacuum refers to the airless surroundings that envelop the Earth and all other planets in the Solar System as they orbit the Sun. Additionally, space contains clouds of dust and gas known as nebulae, which possess a slight density, making them a “dirty” vacuum. Pure vacuum exists in the distant regions far from stellar clusters and galaxies, although even in these vast stretches of seemingly empty space, there are bound to be a few atoms of some substance. It is highly probable that these atoms are predominantly composed of hydrogen, which happens to be the most abundant gas in the entirety of the Universe.
The Andromeda constellation contains a nebula which is a separate galaxy that is located close to our own Milky Way galaxy. Similar to our galaxy, the Andromeda galaxy consists of billions of stars, star clusters, gas and dust clouds, as well as extinct stars and planets. It takes a staggering two million, three hundred thousand years for the light from this neighboring galactic entity to reach us, highlighting the immense distance between galaxies. In contrast, the distance between the Earth and the Sun is approximately 150 million kilometers, and it only takes light 8 minutes to travel this distance.
Since ancient times, humans have gazed up at the sky, captivated by the countless star clusters that shine with their unique beauty.
Historical Background
Ancient civilizations observed the stars and imagined them to form various imaginative patterns, giving them epic names. Some of these names include the Andromeda Nebula, the Cassiopeia constellation, the Big Dipper, and Hydra. These names reflect the associations that these sparkling celestial bodies evoked on the dark canvas of the sky. It was believed that people’s destinies were intertwined with the positions of the stars, which could bring wealth, happiness, and good luck, as well as bitterness, misfortune, and disappointment.
Messier 7 star cluster, ESO image
As civilization progressed, the mystical and poetic concepts surrounding the celestial dome underwent significant modifications and systematization, taking on more rational forms, while still retaining their historical names. It was discovered that stars that appear close to each other can actually be quite far apart, and vice versa. This realization led to the need for a stellar hierarchy that aligns with modern understanding of the universe. Thus, the term “star clusters” emerged in astronomical classification, referring to groups of stars that move together within their galaxy as a cohesive unit.
These formations are highly fascinating due to the fact that the celestial bodies that comprise them were created around the same time and are situated at equidistant positions from the observer on Earth, according to cosmic standards. This offers supplementary advantages, enabling the comparison of radiation emitted from various sources within a cluster without the need for extensive adjustments. The signals emanating from these formations are subject to the same distortions, which greatly simplifies the work of astrophysicists who are investigating the structure and evolution of stellar systems and the Universe as a whole, as well as the principles of galaxy formation, star formation and destruction, and numerous other phenomena.
Classification of stellar clusters
The topic of star clusters has long been a subject of interest for astronomers. These celestial formations are typically classified into two main groups: globular and scattered. However, there are instances where certain star clusters do not neatly fit into either category, prompting scientists to consider expanding the classification system.
Globular clusters, which can number more than ten thousand in certain galaxies, are considered ancient even by universal standards, with an age exceeding 10 billion years. Since they are most likely as old as the Universe itself, these clusters possess valuable information that scientists have been able to decipher and interpret.
Collection of globular clusters
Globular clusters are celestial formations that have a nearly spherical or ellipsoidal shape. They are made up of tens of thousands of stars of various sizes, ranging from ancient red dwarfs to young blue giants. These stars are formed through collisions between stars that already exist within the cluster.
Dispersed clusters
Dispersed clusters are significantly younger than globular clusters, with an estimated age of hundreds of millions of years. They are exclusively found in spiral or irregular galaxies, which have a higher tendency to undergo ongoing star formation processes compared to elliptical galaxies, for example.
Scattered Clusters Gallery
The gallery showcases scattered clusters, which contain fewer stars compared to globular clusters. However, what sets them apart is that each individual star can be clearly observed since they are spaced apart and do not blend into the overall sky.
Stellar Associations
Perseus’ h and x dual star cluster
Just like in politics and economics, the celestial bodies have the ability to form temporary alliances, known as “stellar associations” in the field of astronomy.
Resources on the subject
The youngest formations in the Universe are classified as such, having an age of no more than several tens of millions of years. Due to their weak gravitational bonds, these formations lack the necessary stability to endure for an extended period. Consequently, they are destined to disintegrate within a relatively short timeframe.
Scientists believe that these associations could not have formed through the gravitational capture of passing stars. Instead, they suggest that the stars were born together and are approximately the same age. Unlike star clusters, these associations have a relatively small number of “associated members,” typically in the tens, and they are located relatively close to each other, with distances of up to several hundred light-years. This discovery confirms the scientific theory that new stars continue to form in the Universe, not individually, but in groups.
Globular clusters in the halo of the Andromeda galaxy
Up until recently, it was believed that globular clusters, which are the oldest formations of stars and should have lost their internal rotational motion due to their age, could be considered as simple systems. However, in 2014, a team of researchers from the Max Planck Institute for Extraterrestrial Physics, led by Maximilian Fabricius, discovered through long-term observations of 11 globular clusters in the Milky Way that their central regions are still rotating.
Most current theories are unable to explain this phenomenon, which suggests that if the findings are confirmed, there may need to be revisions in both theoretical understanding and mathematical models that describe the motion of globular clusters.
What is the process of star cluster formation? How do star clusters vary and how are they positioned within our Galaxy? Additionally, how is the age of star clusters determined? Dr. Alexei Rastorguev, a Doctor of Physical and Mathematical Sciences, provides insight into these questions.
+7 926 604 54 63
Contemporary space observatories such as the “Hubble” or the brand new James Webb telescope typically focus on exploring not individual stars, but rather objects found in the depths of space. These objects, known as nebulae, star clusters, and entire galaxies, are the subjects of their research. The most easily observable of these objects from Earth are star clusters, which are simply groups of stars that are relatively close by. Many of these star clusters can be seen in the night sky with the naked eye or with the help of binoculars. In this article, we will provide you with information about the most brilliant and expansive star clusters that can be observed in the Earth’s night sky.
Here is a list of the top fifteen star clusters that are visible to the naked eye. The clusters are arranged in descending order of brightness, meaning the brightest ones are mentioned first. Most of these star clusters can be seen from mid-latitudes in the northern hemisphere, although some are best observed during specific seasons. For instance, the clusters in the Taurus constellation, such as the Pleiades and Hyades, are more easily visible during winter nights when they remain in the sky throughout the entire night. However, if you want to observe them during a summer night, you will have to wait until dawn in most northern hemisphere locations.
1. The Hyades (Collinder 50)
Declination: -08°12’06” Right Ascension: 05h 14m 32s, magnitude +0.13 m
The Hyades cluster, which is one of the oldest clusters of its kind, originated approximately 625 million years ago. It is believed to have a common origin with the Beehive cluster (M44), which is also a prominent cluster discussed below. The analysis of the motion parameters and age of both groups of stars suggests this connection. Currently, the Hyades cluster, also known as the “moving Taurus cluster,” is moving away from us at a speed of about 46 km per second. However, a million years ago, it was closest to the Solar System. In the next fifty million years, it is projected to shrink to half a degree in the sky from its current size of 5.5˚. Eventually, it may only be visible through a telescope.
2. Alpha Perseus Cluster (Collinder 39)
Declination: +48° 48′ Right Ascension: 03h 26m 42s magnitude +1.2
3. Pleiades (Messier 45)
Declination: +24° 07′ 00″ Right Ascension: 03h 47m 24s Magnitude: +1.6
The Pleiades in astro-images are surrounded by a nebula that reflects light, a cloud of gas and dust that appears blue and is lit up by a star in its vicinity. Previously, it was believed that the cloud was a leftover from the formation of the cluster. However, it has now been discovered that the cluster and the nebula are separate entities, moving at different velocities through space and coincidentally appearing together in our field of vision.
4. Melotte 111: The Cluster Resembling Veronica’s Hair
Declination: +25° 51′ Right Ascension: 12h 22.5m Magnitude: +1.8
5. The Southern Pleiades (IC 2602)
Declination: -64° 23′ 39″ Right Ascension: 10h 42m 57.5s Magnitude: +1.9
6. Omicron Sails Cluster (IC 2391)
Declination: -53° 02′ Right Ascension: 08h 40.6m magnitude +2.5
7. “The Well of Desire” (NGC 3532)
Declination: -58° 43.8′ Right Ascension: 11h 05m 33s magnitude +3
+7 926 604 54 63
Our narrative about the most luminous star clusters that can be seen in the nocturnal firmament without the need for a telescope or even binoculars carries on. As the inventory of astral formations is arranged in a descending sequence based on brilliance, the latter portion of this composition is not as radiant as the initial half of the record: the manifest stellar magnitudes commence after +3 m, and it will prove more challenging to perceive them relative to the prominent entities from the first section of the list.
8. Messier 7, also known as the Ptolemy cluster
9. Hive (Messier 44)
Declination: 19° 59′ Right Ascension: 08h 40.4m magnitude +3.7
10. Omega Centauri (NGC 5139)
Declination: -47° 28′ 46.1″ Right Ascension: 13h 26m 47.28s magnitude +3.9
Cluster 47 Tucana (NGC 104)
Declination: -72° 04′ 52.6″ Right Ascension: 00h 24m 05.67s Magnitude: +4
12. Butterfly (Messier 6).
Declination: -32° 13′ Right Ascension: 17h 40.1m magnitude +4.2
13. Box (NGC 4755).
Declination: -60° 22′ 00″ Right Ascension: 12h 53m 42.00s magnitude +4.2
The Jewel Box cluster is located in the Southern Cross constellation, near the prominent star Beta Crucis (β Crucis) – situated on the left side of the cross’s “rung”. This cluster contains approximately 100 stars, although only one of them (Kappa Crucis) is visible to the naked eye. The brightest stars in the cluster form a triangular shape or the letter “A”. One of the stars within this triangle stands out due to its distinct red color, contrasting with the surrounding blue giants. This particular star is a red supergiant of the M2 class, and its variable brightness has earned it the designation DU Crucis within the constellation. It is possible that this star’s characteristics inspired Herschel to name the cluster “The Jewel Box”.
14. NGC 869 and NGC 884: The Perseus Double Cluster
Right Ascension: 2h 20m, Declination: 57° 08′, Magnitude: +4.3
This particular entity encompasses two distinct dispersed star clusters, which can be observed with the naked eye as a solitary blurred mark adjacent to the recognizable W-shaped configuration of Cassiopeia. Both clusters are situated approximately 7,500 light-years away and consist of numerous youthful and scorching stars. The age of these clusters is merely 14 million years – they are considerably younger in comparison to other cosmic formations of similar youthful nature, such as the Pleiades. The spatial separation between the two assemblages of stars amounts to several hundred light-years, and its dualistic essence was only determined in the 19th century, with the cluster itself being documented in the star catalog of Hipparchus. Furthermore, in close proximity on the celestial sphere lies the radiant point of the most potent meteor shower, known as the Perseids, which reaches its zenith in the middle of August.
Declination: -20° 42′ 58″ Right Ascension: 06h 45h 59.80s magnitude +4.5
The cluster’s apparent magnitude is +4.5 m, which means it can still be observed without the need for binoculars. However, this requires favorable conditions such as no nearby Moon and minimal light pollution from urban areas. This object completes the roster of the first fifteen star clusters in terms of their apparent brightness. Naturally, the night sky harbors numerous other celestial objects that can also be observed under optimal conditions. Additional information about some of these objects can be found in related articles accessible through the links provided below. To conclude, presented here is a summarized map of the celestial sphere, showcasing all fifteen star clusters discussed in this collection.
On a clear night sky, you can observe numerous small luminous objects – stars. In reality, their magnitude can be immense, hundreds or even thousands of times the size of the Earth. They have the ability to exist independently, but occasionally they come together to create a star cluster.
What exactly are these stars?
A star is a massive sphere of gas. It has the ability to remain intact due to the force of its own gravitational pull. Stellar masses are generally larger than planetary masses. Within them, thermonuclear reactions take place, which contribute to the emission of light.
Stars are primarily composed of hydrogen and helium, along with dust. Their internal temperatures can reach millions of Kelvin, while their external temperatures are much lower. The key characteristics for measuring these gas spheres are: mass, radius, and luminosity, which refers to energy.
The human eye is capable of perceiving an estimated total of six thousand stars, with approximately three thousand observable in each hemisphere. However, the Sun, our closest star, can only be seen during daylight hours and is located 150 million kilometers away from Earth. In terms of proximity to our solar system, the nearest star is known as Proxima Centauri.
Dust and gas, which can be found in abundance in the vast expanse of interstellar space, have the ability to undergo compression due to the gravitational forces exerted upon them. As the compression becomes more intense, the temperature within these particles rises significantly. This increase in temperature is directly proportional to the degree of density achieved by the matter. Consequently, as the matter continues to thicken, it also gains mass. If this mass reaches a critical threshold, it becomes possible for a nuclear reaction to take place, resulting in the birth of a star.
It is worth noting that from a single gas-dust cloud, multiple stars can emerge simultaneously. These stars are often drawn to one another by the force of gravity, ultimately leading to the formation of stellar systems. This phenomenon gives rise to a variety of systems, including double and triple star systems, among others. In some cases, clusters containing more than ten stars can even be formed.
A star cluster is a collection of stars that share a common origin and are held together by gravity. They move as a single unit within the galaxy. Star clusters can be classified as either globular or scattered. In addition to stars, clusters may also contain gas and dust. Celestial groups that share a common origin but are not bound by gravity are known as stellar associations.
Discovery’s History
Ancient civilizations have been observing the night sky for centuries. Nonetheless, it was widely believed that the stars in the universe were evenly distributed. In the 18th century, astronomer William Herschel challenged this notion by asserting that certain regions contained a greater concentration of stars.
Prior to Herschel’s observations, his colleague Charles Messier had already documented the presence of nebulae in the sky. Through his telescope, Herschel discovered that nebulae were not always uniform. He observed that some stellar nebulae were actually clusters of stars that appeared as specks to the naked eye. He referred to these discoveries as “clumps,” which later became known as star clusters.
Herschel was able to document approximately two thousand clusters. In the 19th century, astronomers determined that these clusters varied in their shape and size. During this time, they identified two types of clusters – globular and diffuse. However, it wasn’t until the 20th century that a more in-depth study of these phenomena began.
Dispersed clusters
Clusters differ from each other in terms of the number of stars they contain and their shape. A dispersed star cluster can consist of anywhere from ten to several thousand stars. These clusters are relatively young, with ages often measured in just a few million years. They lack well-defined boundaries and are typically found within spiral and irregular galaxies.
There are approximately 1100 clusters within our galaxy. Their lifespan is relatively short since their gravitational bond is fragile and can easily be disrupted by encounters with gas clouds or other clusters. As a result, these clusters disperse and their constituent stars become solitary entities.
Clusters are commonly found along spiral arms and in close proximity to the galactic plane, where the concentration of gas is higher. They exhibit irregular, amorphous boundaries and possess a dense, well-defined core. Dispersed clusters are categorized based on their density, variations in the brightness of the central stars, and their distinctiveness from the surrounding environment.
Spherical Clusters of Stars
Globular star clusters, in contrast to scattered clusters, possess a unique spherical form. The stars within these clusters are held together by a much stronger gravitational force and orbit around the center of the galaxy as satellites. These clusters are significantly older than their scattered counterparts, with ages exceeding 10 billion years. However, they are much less abundant, with only approximately 160 globular clusters identified within our galaxy to date.
Globular star clusters are stellar agglomerations that consist of a varying number of stars, ranging from tens of thousands to millions. The concentration of stars within these clusters increases as you move towards the center. One distinguishing characteristic of globular star clusters is the absence of gas and dust, which suggests that they formed a long time ago. Additionally, all stars within these clusters are typically at a similar stage of development, indicating that they formed around the same time as well.
The clustering of stars frequently leads to collisions, which can give rise to the creation of unique types of celestial bodies. One example is the emergence of a blue laggard star when two stars from a binary system combine. This star stands out due to its higher temperature compared to other blue stars within the cluster. Additionally, collisions can generate other extraordinary phenomena in outer space, including low-mass X-ray binary stars and millisecond pulsars.
Star associations, in contrast to clusters, are not held together by a shared gravitational force; occasionally, there is some presence of it, but its magnitude is insufficient. These associations emerged simultaneously and possess a relatively young age, spanning tens of millions of years.
Galactic star clusters, known as stellar associations, are characterized by their larger size compared to young scattered clusters. These associations are sparsely distributed throughout outer space and typically consist of up to a hundred stars. Among these stars, around a dozen are massive hot giants.
Due to the weak gravitational field within stellar associations, the stars are unable to maintain their association for an extended period of time. Typically, these associations decay within a range of a few hundred thousand to a million years, which is considered insignificant in astronomical terms. Consequently, stellar associations are often referred to as temporary formations.
Clusters that are already known
There have been numerous discoveries of star clusters, totaling in the thousands, with some being observable without the aid of a telescope. Among the closest to Earth are the Pleiades (also known as the Seven Sisters) and the Hyades, which can be found in the Taurus constellation. The Pleiades cluster consists of approximately 500 stars, only seven of which are visible to the naked eye. The Hyades, situated near Aldebaran, is made up of around 130 bright stars and 300 dimly burning members.
A dispersed star cluster situated in the Cancer constellation is also among the nearest ones. It goes by the name of the Nursery and encompasses more than two hundred members. The Yasli and the Hyades share many similarities in terms of characteristics, which suggests the possibility that they were formed from the same gas-dust cloud.
An easily observable star cluster in the northern hemisphere’s Veronica’s Hair constellation is visible through binoculars. It is referred to as M 53 and is a globular cluster that was first discovered in 1775. It is located over 60,000 light years away from us. Despite being one of the farthest clusters from Earth, it can be easily seen through binoculars. A vast number of globular clusters can be found in the Sagittarius constellation.
Summary
Star clusters, which consist of a varying number of stars, are connected by gravitational forces and have a shared origin. These clusters can be classified as either globular or diffuse, with differences in shape, composition, size, number of members, and age. Additionally, there are stellar associations, which are temporary clusters with weaker gravitational coupling that eventually collapse and form individual stars.
It is common knowledge that the universe consists of planets, stars, and galaxies, all governed by physical laws and constants. A fascinating topic of discussion is the nature of intergalactic space and its role in the expansion of the universe.
The Triangle constellation is a compact constellation situated in the sky’s Northern Hemisphere. It encompasses a sum of 25 stars detectable to the naked eye, occupying a relatively modest area of approximately 131.8 square degrees.
In ancient times, our ancestors on planet Earth believed that it was the largest entity in the entire cosmos. However, contemporary scientists have a different perspective on the matter – what is now considered the biggest celestial body?
The constellation Lizard is of a small size and relatively young. It can be observed in the night sky using a telescope, even a beginner’s one. This constellation represents clusters of stars rather than a single galaxy.
Ever since Hubble’s groundbreaking scientific discoveries, the concept of the Milky Way being the sole galaxy in the Universe has been shattered. Numerous similar systems have been discovered and classified by scientists. Nowadays, astronomers worldwide actively study the primary types of galaxies.
What does our Galaxy resemble and where is the Solar System positioned within it? What are the characteristics of a bulge and a galactic bar? What does the future hold for the Milky Way and what is the reason behind the name of our star system? Find out all the answers in our comprehensive article.
Kiel is a star group that covers a 494.2 square degree portion of the sky in the southern hemisphere. It cannot be observed from Russian territory because its full visibility is limited to latitudes south of 15 ° north. The constellation is known as Carinae (abbreviated Car) in Latin, which means the keel of a ship.
Andromeda, also referred to as M31 and NGC224, is a spiral galaxy situated approximately 780 kiloparsecs (2.5 million light-years) away from our planet.
