Distance to the Large Magellanic Cloud. There was a collision between the Large and Small Magellanic Clouds! We invite you to discuss this publication on our
Magellanic Clouds are satellite galaxies of the Milky Way. Both Clouds - the Large Magellanic Cloud and the Small Magellanic Cloud were previously considered irregular galaxies, but subsequently found features in the structure of barred spiral galaxies. They are located relatively close to each other and form a gravitationally bound (double) system. Visible to the naked eye in the Southern Hemisphere. One of the first descriptions was given by Antonio Pigafetta, a participant in the circumnavigation of Fernando Magellan (-). . Both Clouds float in a common hydrogen shell.
Magellanic clouds are located at high galactic latitudes, so the light from them is little absorbed by our Galaxy, in addition, the plane of the Large Magellanic Cloud is almost perpendicular to the line of sight, so for objects visible nearby it will often be true to say that they are spatially close. These features of the Magellanic clouds made it possible to study, using their example, the patterns of distribution of stars and star clusters.
Magellanic clouds have a number of features that distinguish them from the Galaxy. For example, star clusters with an age of 10 7 -10 8 years have been found there, while clusters of the Galaxy are usually older than 10 9 years. Also, apparently, the content of heavy elements is less in the Magellanic Clouds.
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See what "Magellan clouds" are in other dictionaries:
- (named after the traveler Magellan). Foggy spots in the sky, near the south pole, are visible to the naked eye. Dictionary of foreign words included in the Russian language. Chudinov A.N., 1910. MAGELLANIC CLOUDS named after Magellan two ... ... Dictionary of foreign words of the Russian language
- (Large and Small) two Galaxies close to us, satellites of the Galaxy. Magellanic clouds are visible in the sky in the Southern Hemisphere with the naked eye (respectively in the constellations Dorado and Toucan). In the B. Magellanic Cloud in February 1987 flared up ... ... Big Encyclopedic Dictionary
MAGELLANIC CLOUDS, the two GALAXIES closest to us, visible to the naked eye as separate parts of the Milky Way in the sky in the form of the letter S. The Large Magellanic Cloud is located in the constellations Golden Fish and Table Mountain, the Small Magellanic Cloud ... ... Scientific and technical encyclopedic dictionary
- ... Wikipedia
- (Large and Small) two star systems (Galaxies) of irregular shape, closest to our star system (Galaxy (See Galaxy)), which includes the Sun. Visible in the southern sky with the naked eye in the form of foggy spots (on ... ... Great Soviet Encyclopedia
- (Large and Small), two galaxies close to us, satellites of the Galaxy. Magellanic clouds are visible in the sky in the Southern Hemisphere with the naked eye (respectively in the constellations Dorado and Toucan). Their discovery is attributed to one of the participants ... ... encyclopedic Dictionary
- (Large and Small) two galaxies close to us, satellites of the Galaxy. Magellanic clouds are visible in the sky in the Southern Hemisphere with the naked eye (respectively in the constellations Dorado and Toucan). In the Large Magellanic Cloud in February 1987 flashed ... Astronomical dictionary
- (Nubecula major and N. minor) wonderful foggy spots lying in the southern hemisphere of the sky in the constellations Dorado and Toucan, at a distance of about 20 ° from one another. M. clouds are not solid spots like others; they represent amazing... Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron
- (Large and Small), two galaxies close to us, satellites of the Galaxy. M.O. visible in the sky in South. hemispheres with the naked eye (respectively, in the constellations of the Dorado and Toucan). Their discovery is attributed to one of the participants in the circumnavigation F. ... ... Natural science. encyclopedic Dictionary
Magellanic Clouds- Magellan Clouds a, Magellan Clouds (aster) ... Russian spelling dictionary
The Magellanic Clouds are the closest galaxies to us. They are named so because they were observed and described by the companion and historiographer Magellan Pigafetta. These Cloud-galaxies can only be observed in the southern hemisphere. It was there that the sailors from the expedition of Magellan drew attention to two nebulae shining in the sky. They invariably accompanied the expedition of 1519-1522.
The Magellanic Cloud galaxies are distinguished by a rich and varied composition of stars. Directions to the Large and Small Magellanic Clouds make angles of 33 and 45° with the plane of the Galaxy. This is very good for observations, since the dust in the plane of the Galaxy does not interfere.
The distance to each of the Magellanic Clouds is 46 kpc. This is only one and a half times the size of the Galaxy. Both Clouds are separated from each other by a distance of about 20 kpc. This is much less than the distance between neighboring galaxies. Scientists believe that since our Galaxy and both Magellanic Clouds are so close to each other, they should be considered as one, but a triple galaxy. Both Magellanic Clouds are immersed in a common shell of neutral hydrogen. In addition, they are interconnected by a hydrogen bridge. It is curious that hydrogen, which is located near the main plane of the Galaxy, forms a ledge that is directed towards the Magellanic Clouds. Something similar to a spiral branch stretches from the Big Cloud in the opposite direction from the Galaxy. If this is indeed a spiral branch, then there must be a second one, paired with it and directed towards the Galaxy. Such a second spiral arm may indeed be there, but is difficult to discern from perspective. It is even admitted that the Big Cloud and our Galaxy are interconnected by a gas bridge. The Large Magellanic Cloud, shown in Figure 41, is approximately 10 kpc across. The cloud has a complex and varied structure. An elongated body is clearly visible, which resembles jumpers at crossed spirals. You can see a lot of small details that are formed due to the location of groups of supergiant stars.
The Large Magellanic Cloud is dominated by Type I stellar population. There are almost five thousand supergiants of extremely high luminosity in the Big Cloud. Each of them emits more energy than 10,000 suns. In the Big Cloud is the white star HD 33579. This star is also called S Goldfish. This star shines like a million stars.
The dimensions of the Small Magellanic Cloud (Fig. 42) are about four times smaller than the Large one - 2.2 kpc. And the type I stellar population is not so diverse in it. There are 532 large gaseous nebulae in both Magellanic Clouds. Most of them are in the Big Cloud.
Rice. 41. Large Magellanic Cloud
Rice. 42. Small Magellanic Cloud
There are a lot of star clusters in the Magellanic Clouds. Scientists have registered 1100 open clusters in the Big Cloud and more than 100 in the Small Cloud. 35 globular clusters have been discovered in the Big Cloud, and 5 in the Small Cloud. Globular clusters were found in the Magellanic Clouds, which are not found in our Galaxy. They contain many blue and white giants. That is why they are white. Ordinary globular clusters are composed of red giants, so their color is yellow - orange. It is believed that white globular clusters are very young compared to ordinary ones.
The Magellanic Clouds contain many variable stars of various types. Only in the Magellanic Clouds and in our Galaxy can long-period and short-period Cepheids be observed. New stars have been observed in the Magellanic Clouds. They, in fact, did not differ from the New of our Galaxy.
There is a lot of diffuse matter in the Magellanic Clouds. Hydrogen is distributed throughout the volume of galaxies. The proportion of hydrogen in the Magellanic Clouds is 6%. In our Galaxy, the proportion of hydrogen is only 1–2%.
There is no dust in the Magellanic Clouds. But that doesn't mean it's not there. Indirect facts allow us to conclude that there is more dust in the Magellanic Clouds than in our Galaxy.
> Magellanic Clouds
Magellanic Clouds– Large and Small Magellanic Clouds: description of galaxies and satellites of the Milky Way, distance, size, constellations Dorado and Toucan.
Ancient people did not get tired of admiring the night celestial objects. Of course, due to the lack of knowledge, many of them were mistaken for a divine manifestation or a comet. With the development of technology, each formation received its own designation.
For example, there are the Large and Small Magellanic Clouds. These are large clouds of gas and stars that are available for detection without the use of technology. Removed by 200,000 and 160,000 light years from our galaxy. But, despite the short distance, their features could only be revealed in the last century. However, they still continue to hide mysteries.
Characteristics of the Magellanic Clouds
Large and Small Magellanic Clouds- stellar regions that rotate around and stand out in the form of separate pieces. They are separated by 21 degrees, but their distance is 75,000 light years.
The Large Magellanic Cloud (LMC) is located in. Because of this, it is in third place in terms of proximity. The Small Magellanic Cloud (LMO) lives in.
The Large is twice as large as the Small (14,000 light-years) in diameter, which is why it also becomes the fourth largest galaxy in . 10 billion times more massive, and Small - 7 billion times.
If we talk about the structure, then the Large refers to irregular galaxies, with a prominent bar in the center. Maly also has a bar (it is believed that it was a spiral galaxy, whose structure was disturbed by the Milky Way).
In addition to structure and mass, they differ from our galaxy in two more features. First of all, they have much more gas and a low level of metallicity (stars are less rich in metals). In addition, they have nebulae and young stellar groups.
The abundance of gas suggests that the Magellanic Clouds can form new stars that can be only a few hundred million years old. This is especially evident in the Bolshoi, where stars form in huge numbers. You can trace this moment on the bright Tarantula Nebula.
It is believed that the Magellanic Clouds appeared 13 billion years ago (like the Milky Way). It used to be thought that they were closer, but everything was explained by the fact that the Milky Way distorts their shape. This reinforces the idea that they don't often get this close. Hubble observations in 2006 showed that their speed may be too high to remain satellites of our galaxy in the long term. Moreover, the eccentric orbits seem to confirm that the approach happened only once in the distant past.
A 2010 study showed that the Clouds may be passing clouds plucked from at some time. The fact that they are in contact with our galaxy is evidenced by the changed structure and flows of neutral hydrogen. Their gravity also affected the Milky Way, which deformed the outer part of the disk.
The history of the discovery of the Magellanic Clouds
The Magellanic Clouds were an object of interest and worship for many tribes, including the Australian Aborigines, the Maori in New Zealand and the Polynesians (used as navigational markers). For serious research in the 1st millennium BC. adopted by the Persian astronomer As-Sufi. He called the Big "sheep" and noted that it could not be seen in northern Arabia or Baghdad.
In the 15th century, Europeans joined the acquaintance. At that moment, trade flourished and ships were sent for goods. Portuguese and Dutch sailors called them "Cape Clouds" as they sailed past the Cape of Good Hope and the Horn.
During the circumnavigation of the world by Ferdinand Magellan, the clouds were described as dim star clusters. Johann Bayer added them to his atlas in 1603 and named the smaller one the "Little Nebula".
John Herschel between 1834-1838 explored the southern skies and described Small as a cloudy mass of light, made in the shape of an oval. In 1891, an observation station appeared in southern Peru with a 24-inch telescope, which was used to observe the Clouds.
One of the scientists was Henrietta Leavitt, who found a variable star in the Small. Her results appeared in print in 1908, "1777 Variables in the Magellanic Clouds", where the relationship between periodic variability and brightness was demonstrated.
The discovery in 2006 (Clouds can move too fast) raised suspicions and thoughts that they formed in another galaxy. Andromeda became a candidate. Given their composition, we can say that they will still create new stars. But millions of years will pass, and they are able to enter the Milky Way. Or they will stay very close, fueled by our hydrogen.
If you ever happen to spend the night south of the Earth's equator, and the southern velvety black sky will spread unusual patterns of constellations in front of you (for some reason, you always want to believe that somewhere there, beyond the seas, there is always good weather), pay attention to two small misty clouds in the sky. These "abnormal" clouds do not move relative to the stars and seem to be "glued" to the sky.
In Europe, mysterious clouds were known as early as the Middle Ages, and the indigenous inhabitants of the equatorial regions and the lands of the southern hemisphere knew about them, apparently, long before that. In the 15th century, sailors called the clouds Cape (the name is akin to the name of the Cape Colony - medieval British possessions in South Africa, located on the territory of the current Republic of South Africa).
The south pole of the world, unlike the north, is more difficult to find in the sky, since there are no such bright and conspicuous stars as the Polar one next to it. The Cape Clouds are located near the south pole of the celestial sphere and form an almost equilateral triangle with it. This property of the Clouds made them well-known objects, and therefore they have long been used in navigation. However, their nature remained a mystery to scientists of that time.
During the round-the-world trip of Ferdinand Magellan in 1518-1520, his companion and chronicler Antonio Pigafetta described the clouds in his travel notes, which made the fact of their existence the property of the general European public. After Magellan died in 1521 in an armed conflict with the local population in the Philippines, Pigafetta suggested calling the clouds Magellanic - Large and Small, according to their size.
Visible to the eye, the size of the Magellanic Clouds in the sky is one of the largest among all astronomical objects. The Large Magellanic Cloud (LMC) has a length of more than 5 degrees, i.e. 10 apparent diameters of the moon. The Small Magellanic Cloud (LMC) is slightly smaller - just over 2 degrees. In the photographs, where it is possible to fix weak outer regions, the sizes of the Clouds are 10 and 6 degrees, respectively. The Small Cloud is located in the constellation Tucan, and the Large Cloud occupies part of the Golden Fish, as well as Table Mountain.
Even at the beginning of our century, scientists did not have a single opinion about the nature of the Clouds. The encyclopedia of Brockhaus and Efron, for example, says that the Clouds are "not solid spots like others; they are the most amazing accumulations of many foggy spots, stellar heaps and individual stars." And only after astronomers measured the distances to some nebulae in the 1920s, and it became clear that there are stellar worlds lying far beyond our Galaxy, the Magellanic Clouds occupied their "niche" among celestial objects.
It is now known that the Magellanic Clouds are the closest neighbors of our Galaxy in the entire Local Group of galaxies. Light from the LMC takes 230 thousand years to reach us, and even less from the MMO - "only" 170 thousand years. For comparison, the nearest giant spiral galaxy, the Andromeda Nebula, is almost 10 times further away than the LMC. The linear dimensions of the Clouds are relatively small. Their diameters are 30 and 10 thousand light years (recall that our Galaxy has more than 100 thousand light years across).
The clouds have a shape and structure typical of irregular galaxies: irregularly distributed areas of increased brightness stand out against the background of a ragged structure. And yet there is order in the structure of these galaxies. In the LMC, for example, there is an orderly movement of stars around the center, which makes this Cloud look like "regular" spiral galaxies, the stars in the galaxy are concentrated to a plane called the plane of the galaxy.
By the motion of the matter of the Clouds, one can find out how their galactic planes are located. It turned out that the LMC lies almost "flat" on the celestial sphere (the inclination is less than 30 degrees). This means that all the complex "stuffing" of the Big Cloud - stars, clouds of gas, clusters - are located almost at the same distance from us, and the observed difference in the brightness of various stars is true and is not distorted due to different distances to them. In our Galaxy, only stars in clusters have this property.
The successful orientation of the LMC, its "openness", as well as the proximity of the Magellanic Clouds to us, made them a real astronomical laboratory, "object number 1" for the physics of stars, star clusters and many other interesting objects.
The Magellanic Clouds have brought some surprises to astronomers. One of them was star clusters. They have been found in the Magellanic Clouds, as well as in our Galaxy. About 2000 of them were found in the MMC, more than 6000 in the LMC, of which about a hundred are globular clusters. There are several hundred globular clusters in our Galaxy, and all of them contain anomalously few chemical elements heavier than helium. In turn, the content of metals clearly depends on the age of the object - after all, the longer the stars live, the longer they enrich the "environment" with chemical elements heavier than helium. The low content of metals in the stars of globular clusters of our star system indicates that their age is very advanced - 10-18 billion years. These are the oldest objects in our galaxy.
A surprise awaited astronomers who measured the "metallicity" of clusters in the Clouds. More than 20 globular clusters have been discovered in the LMC, which have the same metal content as stars that are not yet very old. This means that, by the standards of astronomical objects, the clusters were born not so long ago. There are no such objects in our Galaxy! Consequently, in the Magellanic Clouds the formation of globular clusters continues, while in the Galaxy this process ceased many billions of years ago. Most likely, gigantic tidal forces in our stellar system have time to "pull apart" the unborn globular clusters. In the Magellanic Clouds, small in size and mass, in a more "polite" environment, there are all conditions for the formation of globular star clusters.
The Clouds themselves do not stand out in the world of galaxies because of their modest size and luminosity. However, there is an object in the Large Magellanic Cloud that is a prominent figure among its own kind. We are talking about a huge, hot and bright cloud of gas, which is clearly visible in the photographs of the LMC. It's called the Tarantula Nebula, or, more formally, 30 Dorado. The name Tarantula was given to the nebula because of its appearance, in which a person with a rich imagination can see the resemblance to a large spider. The length of the nebula is about a thousand light years, and the total mass of gas is 5 million times the mass of the Sun. The Tarantula glows like several thousand stars combined. This is because massive hot stars are born inside the nebula, emitting much more energy than stars like our Sun. They heat up the gas around them and make it glow. There are only a few nebulae of similar size in our galaxy, but they are all hidden from us by a dense veil of galactic dust. If not for the dust, they would also be visible and bright celestial objects.
Inside the Tarantula Nebula are many star birth centers where stars are born "in bulk". Young massive stars, whose age does not exceed several million years, show us those regions where the formation of stars from gas clumps is still ongoing.
Inside the Tarantula, supernovas have also repeatedly exploded. Such explosions of stars at the final stage of their evolution lead to the fact that most of the star is scattered across space at speeds of several thousand kilometers per second. Supernova explosions have made the structure of the nebula confusing, chaotic, filled with intersecting gaseous filaments and shells. The Tarantula Nebula serves as a good testing ground for theories of the birth and death of stars.
The Magellanic Clouds also played an important role in the construction of the intergalactic distance scale. Over 2000 variable stars have been found in the Clouds, most of which are Cepheids. The period of change in the brightness of Cepheids is closely related to their luminosity, which makes these stars one of the most reliable indicators of the distance to galaxies. Using the Clouds as an example, it is very convenient to compare various distance indicators, according to which the intergalactic "ladder" of distances is built.
If the human eye were capable of perceiving radio waves with a wavelength of 21 cm (atomic hydrogen emits at this wavelength), then it would see an amazing picture in the sky. He would have seen dense clouds of gas in the plane of our Galaxy - the Milky Way, and individual clouds at different latitudes - nearby gas nebulae and clouds "wandering" at high latitudes. The Magellanic Clouds would change amazingly. Instead of two separated objects, a "longwave" person would see one large cloud with two bright condensations where we are used to seeing the Large and Small Magellanic Clouds.
Back in the 1950s, it was found that clouds are immersed in a common gas envelope. The shell gas circulates continuously: cooling in intergalactic space, it falls on the Clouds under the action of gravity and is pushed back by supernova "pistons", as a result of which an expanding shell of hot gas with excess pressure inside appears (this process resembles the movement of water in a saucepan heated from below gas burner).
Recently it has also become clear that the Clouds are connected by a common gas bridge not only with each other. A filament of gas has been found - a thin band of gas starting in the Clouds and going across the entire sky. It links the Magellanic Clouds to our Galaxy and several other galaxies in the Local Group. It was called the "Magellan Stream". How did this stream come about? Most likely, several billion years ago, the Magellanic Clouds approached our Galaxy. Our giant star system "pulled out" some of the gas from the Clouds with its gravitational pull, like a vacuum cleaner. This gas partially enriched our star system. The rest of it "splashed" in intergalactic space, forming the Magellanic Stream.
The proximity of the Magellanic Clouds to our massive Galaxy is not in vain for them. It is possible that the convergence of the Clouds and the Milky Way, causing the exchange of gas and stars, occurred more than once in the past. If the nearest of the clouds - Small, comes to our Galaxy 3 times closer than it is now, tidal forces will completely destroy it. In the distant future, similar collisions may occur, and the Magellanic Clouds will be completely absorbed by our Milky Way. They will not soon be "digested" in the huge belly of our Galaxy, and activate the birth of stars in the places of their fall, as is observed in a stronger form during the merger of large galaxies.
NASA and Pennsylvania State University researchers have completed the most detailed ultraviolet survey ever made of the Large and Small Magellanic Clouds using the Swift spacecraft. The resulting 160-megapixel mosaic of the Large Magellanic Cloud (LMC) and the 57-megapixel Small Magellanic Cloud (LMC) were presented on June 3, 2013 at the 222nd Congress of the American Astronomical Society.
The new images show approximately one million sources in the LMC and about 250,000 in the MMC, ranging from 1600 to 3300 angstroms (angstrom is an international unit of wavelength, equal to one ten-millionth of a millimeter), which corresponds to the ultraviolet wavelength range, most of which is completely blocked the earth's atmosphere.
To obtain a 160-megapixel LMO mosaic, it took 2,200 images of this object, and their addition took about five and a half days. The MMO image is somewhat simpler and consists of 656 parts; the processing time was about two days. Both obtained images have an angular resolution of 2.5 arcseconds, which is the maximum possible for this telescope.
Says Michael Siegel, lead researcher for Swift's Ultraviolet/Optical Telescope (UVOT) program:
“Until now, there have been very few ultraviolet observations of these galaxies, and there has not been a single study with such unprecedented resolution. Thus, this review closes many questions about the current state of the Large and Small Clouds. With the resulting mosaics, we can observe in one image how the stars go through all the stages of their lives, which is very difficult to understand when studying our Galaxy, since we are inside it. ”
LMC and MMO are located at a distance of 163 thousand and 200 thousand light years from us, respectively, and revolve around each other, as well as around the Milky Way. The LMC is about one-tenth the size of our galaxy and contains only one percent of its mass. MMO is half the size of LMO and contains two-thirds of its mass.
Studying galaxies in the ultraviolet allows astronomers to study in detail the stars that make up them. In the ultraviolet range, light from dim stars is suppressed, revealing the structure of hot clusters, gas clouds, and star-forming regions. To date, there are no analogs to the ultraviolet telescope installed on the Swift apparatus in terms of resolution and field of view.
General view of the Large and Small Magellanic Clouds. Source: Axel Mellinger, Central Michigan Univ.
Ultraviolet image of the Large Magellanic Cloud.
