Mizar is a star in the natal chart. Mizar and Alcor: the story of a sixfold star. Physical characteristics of the stars Mizar and Alcor
Mizar, Miraak
From the Arabic mizar - "the middle [of the tail of the Bear] and al-marakk -" the groin [of the Bear]".
Fixed star, 79 Zeta Ursa Major. Apparent magnitude 2.07m. Mizar is a physically triple star; main components 2.27m class A1 Vp and 3.95m class A1 m white color are located at an angular distance of 14.4" from each other and revolve around a common center of mass with a period of about 20,000 years. Using spectral analysis, it was possible to establish that Mizar A, in turn, consists of two almost touching stars rotating with a period of 20.5 days. In addition, , Mizar together with the star g Ursa Major (Alcor) forms an optical multiple system; Alcor 3.95m is located at an angular distance of 708" from Mizar. The distance from Mizar to the Sun is 27 pc. Astronomical position of the first component for 2000: AR=13 h 23 m 55.5 s; D=+54°55"31"; position of the second component: AR=13 h 23 m 56.4 s; D=+54°55"18". Ecliptic coordinates of the center of the M. system: Long=165°42"00"; Lat=+56°22"44". In the drawing of the constellation, Mizar is in the middle of the tail of the Bear (i.e., in the middle of the ladle handle). Constellation Ursa Major
The multiplicity of Mizar was discovered by the astronomer Riccioli, a contemporary of Galileo.
According to the tradition coming from Ptolemy, Mizar has the influence of Mars. Kefer considers this influence favorable. But according to Ebertin and Hoffmann, this star in conjunction with evil planets does not bode well. Nevertheless, these researchers acknowledge that subtle artistic emanations can also come from Mizar (especially when combined with ASC).
According to Saplin, Arab authors find in Mizar the character of Venus and Mercury.
Rigor points out that in natal astrology this star acts mainly beneficially: Mizar endows the native with ambition, creativity, artistic inclinations, but often also brings disharmony into the life of the native. In mundane astrology, this star influences the masses, it is associated with catastrophes, controversial issues, tragedies.
In the Avestan tradition, the servants of Mizar are Mercury, Venus and Neptune. According to P. Globe, Mizar gives a person the ability to see harmony, a sharp mind, penetration and excellent intuition. Such a person has a lot of friends, supporters. Mizar gives the ability to win over, charm, psychological gift, the ability to recognize dangers. On IC, and also in conjunction with the Moon, Mizar brings the ability to search for treasures.
In the theory of systemic interpretation of stars by D. Kutalev, Mizar, as the zeta of Ursa Major, correlates with the elements of the Earth at the second level of manifestation, and as an A1 class star, it is associated with the Moon and the additional influence of Saturn. According to this theory, Mizar means a good sense of matter, hard work, the desire for comfort and stability. However, the fact that Mizar is a multiple star speaks of opposing aspirations that tear apart a person and that the desired stability is usually not achieved. The problem is that, on the one hand, Mizar requires the native to distance himself from material life and devote himself to the service of higher powers, and on the other hand, he tempts him with all the benefits of this material life.
The angular distance between Mizar and Alcor is close to 12 minutes of arc, which is slightly more than a third of the visible lunar disk. But the apparent proximity of these two stars to each other is caused only by their unimaginable distance from our Earth. In reality, the distance between Mizar and Alcor is at least 17,000 times the distance from the Earth to the Sun, and close to two and a half billion kilometers!
You are, of course, amazed by this monstrous number. But, alas, everything in the world is relative. On the scale of ordinary interstellar distances, Alcor is still close to Mizar - the distance between them is 16 times less than the distance between the Sun and Alpha Centauri. Therefore, it is possible that Mizar and Alcor constitute a physically interconnected system of two stars revolving around a common center of gravity. True, no one has yet noticed this movement. However, it is difficult to count on quick success here, because the period of circulation of Alcor around Mizar should be at least two million years. What is surprising in the fact that over hundreds of years of continuous observations, astronomers have not yet discovered a noticeable shift in Alcor's orbit?
Even in the smallest telescope, it is easy to see that Mizar consists of two stars that merge to the naked eye into one star. This was first discovered by the astronomer Riccioli, a contemporary of Galileo. Both stars - Mizar A and Mizar B - white hot giant stars. Both of them revolve around a common center of mass with a period of about twenty thousand years!
But that's not all. With the help of spectral analysis, it was possible to establish that Mizar A, in turn, consists of two almost touching stars, circling in a frenzied cosmic waltz - how else to characterize this system, in which the period of revolution is only twenty and a half days!
I repeat, it is impossible to notice this duality in any telescope. Only subtle spectral effects convince us of its reality.
What an amazing system of four suns leading an intricate round dance in space!
There are many double stars in the constellation Ursa Major. But among them, the star, denoted by the letter ξ, is especially remarkable, the distance to which is 25 sv. years. It can be found under the hind “legs” of Ursa Major, close to the constellation Leo Minor.
Two yellow, almost identical stars, with a brightness of 4.4m and 4.9m, very similar to our Sun, revolve around a common center of mass with a period of 60 years. “Xi” Ursa Major is the first binary star for which in 1830 the orbit was calculated (one star relative to the other) and the period of revolution was reliably determined. This showed for the first time that the law gravity manifests itself in the world of stars. Much later it was discovered (again with the help of spectral analysis) that the stars ξ A and ξ B in turn have satellite stars, for one of which the period of revolution is 669, and for the other only 4 days.
Again a system of four suns, and this time already indisputably physically connected with each other!
Careful observations show that many of the stars in Ursa Major - mainly those that can only be studied through a telescope - change their brightness.
Of all the variable stars of Ursa Major, let us pay attention to only one, belonging to the type of so-called eclipsing variable stars. Star W Ursa Major, about which in question, is not common at all. Moreover, it is unique, and not only in Ursa Major, but in general in the starry sky.
Rice. 32. Star type W Ursa Major
The two stars that make up this system are so close to each other that, under the influence of mutual gravitation, they changed their usual spherical shape for stars and turned into elongated melon-shaped ellipsoids (Fig. 32). Circling around a common center of mass, these two melon-shaped luminaries are constantly directed towards each other with their most “sharp” sides. In total, it takes about eight hours for both stars to return to their original position again.
It is easy to figure out that, leading a round dance, the stars that make up the W Ursa Major turn to the earthly observer either with a narrower or with a wider part. It is clear that this also changes the amount of light sent by the stars towards the Earth. They are indistinguishable in any single telescope. All information about Ursa Major W has been gleaned from a careful analysis of its brightness change curve, which varies from 7.8m to 8.6m.
Now imagine how unusual the earthly sky would look if the Sun were replaced by this unique star from the constellation Ursa Major. Instead of a calm, dazzling luminary, two melon-shaped almost touching suns would move across the sky!
In the constellation Ursa Major there are six bright nebulae, listed in the Messier catalog under numbers 81, 82, 97, 101 108 and 109. Five of them are very similar in nature and represent distant star systems - galaxies. The sixth nebula, denoted by the symbol M 97, differs sharply from the rest.
First of all, this is not a star system, but a gigantic spherical cloud of luminous gas. Outwardly, the nebula remotely resembles the disks of planets, and therefore, as already mentioned, formations of this kind have been given the name of planetary nebulae. In powerful telescopes, the planetary nebula from the constellation Ursa Major vaguely resembles the physiognomy of an owl, for which astronomers informally call it the “Owl”.
In the center of the nebula, as usual, a very hot white star is visible. There is reason to believe that the gases that form the nebula were once ejected by the central star in some not entirely clear explosive process. In any case, the nebula is currently expanding in all directions from the star - a clear indication of the source that gave rise to it.
The Owl Nebula is a very distant and difficult object to observe - the distance to it is 2290 parsecs, and the apparent brightness is about 12m. Knowing the apparent angular diameter of the nebula, it is easy to calculate that in fact it is almost 230,000 times the diameter of the earth's orbit. And yet it is an object of our star system, our Galaxy. Only the imperfection of the Messier telescope forced the researcher to mix gaseous nebulae with other star systems in his catalog.
Of the treasures of the Big Dipper hidden from the naked human eye, we will mention only three star systems - M101, M81 and M82.
Galaxy M101 can be found in a small telescope in the form of a small luminous hazy speck - 7.9 stars. magnitude - not far from Mizar, “above” the tail of the Big Dipper. On fig. 33 shows her photograph - a magnificent stellar spiral, which, thanks to the play of chance, we see "flat". Billions of suns make up this great star system. Thousands, and maybe even millions of planets in this galaxy are inhabited by creatures who have included our Galaxy in their star catalogs - after all, “from there”, from the M101 nebula, it is clearly visible. If they had "super-telescopes" that allow them to see everything that is being done on our Earth, they would not see people. In their field of view, the Earth would appear as it was about 8 million years ago - so much time is required for a beam of light to overcome the distance between M101 and our Galaxy!
Today we will tell you about the inseparable stellar pair, which since ancient times have pleased the gaze of earthlings in the night sky. For people with good eyesight, they are clearly distinguishable separately from each other even with the naked eye, and for those observing through binoculars or even the most primitive telescope, they are truly a godsend in terms of astronomical aesthetics. Our today's issue will focus on the stars that we used to call Mizar and Alcor, and on the star system where they are included.
You can find this pair in the night sky of the Northern Hemisphere at almost any time of the year, as it is included in the most famous and observed by all the asterism of the Bucket of the circumpolar constellation Ursa Major. Taking the second star from the beginning of the handle of this same Bucket, we, having looked closely at it, will see Mizar and Alcor, which almost merges with it a little to the side.
The conspicuousness in the sky of both Alcor and Mizar has become the reason that both stars are quite often mentioned in folklore, literature, cinema, music and computer games. Their names can be found in Edmond Hamilton's space operas Star Kings and Return to the Stars, in several episodes of the Dorsai cycle by Gordon Dixon, in the novel The Eye of Time by Arthur C. Clarke and Stephen Baxter, in Ivan Efremov's story Starships, in several television episodes of the series "Star Trek", computer games and space simulators "Elite" and "Elite-2", as well as in many other works.
In the US Navy, under the names "Mizar" and "Alcor" there were several military transport ships that were involved in operations during various periods of the Second World War.
In different historical epochs on Earth, increased attention was literally riveted to Mizar and Alcor, since visual acuity was checked by their distinguishability. It was also in the days of the ancient Egyptian pharaohs, in whose personal guard they recruited young men who distinguished two stars, as well as among the Persians and Arabs, where those who saw the duality of the star were considered the owners of the sharpest vision.
In Indian astronomy, Alcor was called Arundhati, and Mizar was Vashistha. In Taoism, both stars were listed under the common name Lu, and in traditional Chinese astronomy they were included in the asterism Bei Du (BEI Dǒu), which means the Northern Dipper, and also had the common name Bei Du Liu, which translates as the Fifth Star of the Northern Dipper. In addition, European researchers of ancient Chinese astronomy note that the couple was also called Kai Yang (Kāi Yáng), that is, the Star of the Discoverer or the Source of Heat. Among the Canadian Indians of the Mikmaw tribe, in the folk epic about the bear and the seven hunters, Mizar was represented as a bear, and Alcor as a pot. AT Kievan Rus and in Ukraine the whole constellation Ursa Major was called a cart, and Alcor and Mizar were called a yoke. However, the stars still owe their generally accepted modern name to the Arabs. Mizar comes from the Arabic word mi'zar, which means "apron", "belt" or "loin", in turn, Alkor comes from the Arabic-Persian words al-kuar or al-hawar, which can be translated as "weak" or "minor". At the same time, the Persian astronomer and mathematician al-Sufi listed Alkor as Al-Sukhya, which means "unnoticed" or "inconspicuous." Apparently, the reason for this name was the fact that Claudius Ptolemy for some reason did not notice this star and did not indicate it in his Almagest. In addition, among all the same Persians and Arabs, this binary asterism was called “Horse and Rider”, where Mizar was a horse, and a rider was seen in Alcor.
In the "Uranometry" of the German astronomer Johann Bayer, both Mizar and Alcor are designated by one symbol, as Zeta Ursa Major, in turn, John Flamsteed divided them into 79 and 80 Ursa Major, respectively. They are separated by the designation and catalog of Henry Draper.
What is the star system that includes the stars we call Mizar and Alcor? As it turned out, this system includes six currently known stellar components that are at a distance of 70 to 82 light years from Earth. Let's try to consider their orbits and each separately.
Most likely, Mizar was the first telescopic binary discovered, according to most historians of astronomy, by the Italian astronomer Benedetto Castelli, who reported this to Galileo Galilei in 1617 and asked to observe the star for this object. After that, Galileo prepared a detailed account of the binary nature of the star. A little later, another Italian astronomer and part-time priest Giovanni Battista Riccioli around 1650 independently described Mizar as a binary star. Thus, we have the main component, designated as Mizar A, and the secondary - Mizar B. They are separated by about 380 astronomical units, and the orbital period relative to the common barycenter is about a thousand years.
With the arrival of spectroscopy to the aid of astronomers, it was possible to establish that both Mizar A and Mizar B are themselves spectroscopically binary stars. The spectroscopic binary of Mizar A was established by the American astronomers Edward Charles Pickering in 1889, and then independently by Antonia Maury in 1890. It has now been established that the two components of the Mizara A system are separated by less than one astronomical unit, and their mutual orbital period is about 20 and a half Earth days. In turn, Mizar B is also a close pair of two stars, whose orbital period relative to the common center of mass is about 175 and a half Earth days, and the distance between them does not exceed one and a half astronomical units.
Alcor has not been considered for a long time as a star gravitationally related to Mizar, many have doubts about this issue even now. However, most astronomers tend to believe that Mizar and Alcor still make up one star system. The exact distance between them is also now the subject of controversy and debate. So, for example, it was previously believed that it is 74 ± 39 thousand astronomical units, and this is from half to one and a half light years. Now the value of 17,800 astronomical units has allegedly been determined, but it is also probably more than arbitrary. As you all understand, with such a scatter of data, it is almost impossible to determine the exact value of the orbital period of systems, and therefore in various sources you can find a variety of values from 350 thousand to 1 million years, while the upper limit looks somewhat overestimated.
At the same time, Alcor is also, as it turned out, a binary star, consisting of the Alcor A and Alcor B components. The distance between them is estimated at 26 astronomical units, and the orbital period is about 90 years.
Two more faint components, probably representing dim red dwarfs, were previously attributed to the Alcor system. In some sources, you can even find their designations as Alcor C and Alcor D, however, later it was determined that they are at least 2 light years away from the main component and have only a common movement with the system as part of a moving group of stars. Thus, their gravitational connection was refuted with a fair degree of certainty.
This concludes the first part of our story, dedicated to the stars and the Mizar-Alcor star system. About what they are in the physical plane, and how astronomers designate them, we will tell you in the second part of our post.
The constellation Ursa Major is one of the most famous constellations located in the northern part of the sky. It belongs to the circumpolar and is visible in the northern hemisphere all year round, although in autumn in the southern regions it can fall very low to the horizon. The Dipper's Dipper is easy to recognize and can usually be easily found by most people.
Constellation Ursa Major in the sky
This constellation is located in the northern part of the sky, and can be found at any time of the year. By winter, it descends to the horizon, then begins to rise higher and higher. During the night, it manages to describe a large arc, thanks to the daily rotation of the Earth. In the spring it is best seen.
Stars of the constellation Ursa Major
The constellation Ursa Major is much larger than many people think, and is not limited to the well-known "bucket" of seven stars. In terms of area, it occupies the 3rd place among all constellations, after Hydra and Virgo. With the naked eye, you can see up to 125 stars in it.
The stars that form the "bucket" of Ursa Major are the brightest in this constellation, but they also have a brightness of about 2 magnitude, except for the delta - its brightness is 3.3m.
All the stars of the "bucket" have their own names - Dubhe, Merak, Fekda, Kaffa, Aliot, Mizar, and Benetnash. Perhaps the most famous of them is Mizar - the middle star in the handle of the "ladle". This star is a double, and with excellent vision, you can find its companion - Alcor.
Stars of the constellation Ursa Major. Merak and Dubhe are called Pointers - if you draw a line through them and continue it further, then it will rest against the North Star. The constellations Ursa Minor and Ursa Major are located nearby, which greatly facilitates the task of finding the North Star.
All the stars of the "bucket" of Ursa Major, due to approximately the same brightness, seem to be equally distant from us. In fact, this is not at all the case. Some of these stars are closer, and some are much further than others. That they form such a figure is simply a matter of chance. Due to the proper motion of the stars in space, the figure of this constellation changes greatly over time. In 10 thousand years, people will not see such a form in the sky at all, as it was not even 10 thousand years ago. However, 5 of these stars fly in the same direction and are similar in their characteristics, which allows us to think about their relationship in terms of a common origin. They are called the moving group of stars Ursa Major.
Ursa Major is a constellation that has a lot of double and even multiple stars, but most of them are either too faint or too close to be observed in most amateur telescopes. There are also many variable stars here, but they are also quite dim and you will need a telescope or good binoculars to study them.
Mizar - sixfold system
Mizar is the middle star in the handle of the "ladle" of the Big Dipper. It is curious in that it is a double star, one of the most famous and easiest to observe. The second component, named Alcor, is a faint star with a magnitude of 4.02m, located at a distance of 12 arc minutes. Only people with excellent eyesight can see Alcor next to Mizar with the naked eye, so this has long been considered a kind of eye test.
Long time there was no evidence of a physical relationship between Mizar and Alcor, because in space the distance between them is a quarter of a light year, and the orbital movement of stars is very slow. In 2009, such evidence was obtained, and now it is known that the Mizar-Alcor system is actually not even double, but six-fold!
Mizar itself, even in a small telescope, is visible as a double star - the distance between its A and B components is 15 arc seconds, and the stars have a brightness of about 4m. However, each of these components is also a close binary system! In total, Mizar is a fourfold star. Component A consists of a pair of hot white stars, each 3.5 times larger and 2.5 times more massive than the Sun. The stars of the B component are also white stars, but somewhat smaller - twice as large, and 1.6 times as massive as the Sun.
Alcor is also not as simple as it seems. This is a binary system consisting of a hot white star twice as massive and larger than the Sun, and a red dwarf, four times lighter than the Sun and three times smaller.
In total, in the Mizar system we can see a curious set of five almost identical hot white stars and one red dwarf. Approximately the same interesting sixfold system is in - this is the star Castor.
Variable stars in Ursa Major
More than 2,800 variable stars are known in this constellation, but most of them can only be seen with a powerful telescope. Three of them are rather curious - W, R and VY Ursa Major, and can be observed with binoculars or a telescope.
W Ursa Major
This is an eclipsing variable star, similar to the famous Algol, but here everything is much more extreme. Here, a pair of white stars, comparable in size and mass to the sun, are located so close to each other that they practically touch. Due to such a close arrangement, under the influence of the gravity of the neighbor, each star took on an elongated egg-shaped shape, and when revolving around a common center of gravity, these stars are always turned to each other with one, convex side. In this place they even exchange matter with each other.
When rotating in orbit, one of the stars in this pair periodically covers (eclipses) the other, and the overall brightness of the system decreases. In addition, the stars are seen either with a wide, elongated side, or with a narrow one. Therefore, the brightness W of Ursa Major is constantly changing from 7.8 to 8.6m. The full period is only 8 hours - so quickly these stars make a revolution around each other. Therefore, the entire cycle can be observed in one night.
R Ursa Major
This is a variable star that belongs to the Mira class. Its brightness varies over a very wide range - at maximum brightness (6.7m) it can be seen with binoculars, and at minimum (13.4m) you will need a fairly powerful telescope. The period of brightness fluctuations is about 300 days.
VY Ursa Major
Compared to the previous one, this is a rather bright star - its brightness varies within 5.9 - 6.5m. So it can be easily observed with 8-10x binoculars. This is a semi-correct variable - it has a period of 180 days, but incorrect fluctuations are superimposed on it.
We advise you to even just look at this star, even if you are not going to observe changes in its brightness. The fact is that this is one of the carbon stars, that is, it is a giant in whose atmosphere there is a lot of carbon. Because of this, the star has a rich red color, which sharply distinguishes it from the background of ordinary stars.
There are a lot of other interesting objects in the constellation Ursa Major, mostly galaxies. Some of them can be found even with binoculars, but they will be discussed in.
To study the starry sky more productively, we recommend using.
:: Mizar and Alcor: the story of a sixfold star:: In the constellation Ursa Major, in the handle of the Big Dipper, there is the most famous double star in the sky - Mizar and Alcor. This couple occupies an important place not only in astronomical folklore, but in the entire history of the science of the sky. On a dark moonless night, far from city lights, several thousand stars are visible in the sky. Most of them are scattered across the sky quite randomly, but in some places we meet strange star "heaps" like the Pleiades and Hyades, as well as absolutely amazing celestial drawings, such as the Big Dipper. Are they random??? And when we look at two stars close to each other, does this mean that they are actually close, or just happened to be on the same line of sight, but are actually at different distances from the Earth??? Mizar and Alcor through a telescope
If you have a telescope, be sure to look through it at Mizar and Alcor: together with the neighboring stars, they form one of the most beautiful objects in the sky! A small instrument will do for observation; you need to look at the minimum magnification. The color of the stars is diamond white, or, as Allen, the famous researcher of heavenly names, said, “light emerald”. The angular distance between Mizar and Alcor is 708.55″ or 11.8′. In the same field of view with Mizar and Alcor, you will find several more stars that complement the picture, as if shading a bright couple. Particularly noteworthy is the asterisk of the 7th magnitude, located between them: this is the “star of Ludwig”, so named by one German astronomer of the 18th century. It is not included in the Mizar and Alcor systems, being a vivid example of just an optical satellite! Now take a closer look! The bright star Mizar in a telescope breaks up into two stars very close to each other! It turns out that besides Alcor, Mizar has one more satellite, and the double star is actually a triple! Mizar and Alcor are about 80 light years away from Earth. Photo: DSS2
The distance between the stars Mizar A and Mizar B is 14.4″; the main star has a brightness of 2.27m, its companion is the same white star - 3.95m. The brightness of the satellite is almost equal to that of Alcor (4.01m). It is often mistakenly written that Riccioli first saw Mizar's companion in 1650, but in fact the duality of the star was discovered by a friend and student of Galileo, mathematician Benedetto Castelli, on January 7, 1617, which he mentioned in one of his letters to the great scientist. And on January 15, 1617, Mizar A and Mizar B were already observed by Galileo himself. And here Mizar and Alcor for the first time appear on the stage of science as an important double star Mizar and Alcor - the six-fold system Star Alcor and its companion (circled). The picture was taken in infrared. The radiance of bright Alcor is leveled by a protective hood. Source: Neil Zimmerman et al., 2010
The point in this dispute, it seems, was put in 2010, when a team of astronomers led by Eric Mamajec discovered ... a satellite around the star Alcor! Alcor B turned out to be a typical red dwarf, which is located only 1 arc second from the main star. It is so dim that it drowns in the rays of Alcor. To detect it, I had to use the infrared camera of the 6.5-meter MMT telescope in Arizona, equipped with adaptive optics. An amazing discovery made it possible to increase the mass of Alcor by 0.3 solar masses (alcor B approximately “weighs”), and this brought the total mass of the Mizar-Alcor system to 9 solar masses! Accurate measurements of the speeds and directions of movement of the two luminaries showed that Alcor and Mizar are most likely gravitationally connected, which means that we are dealing with a sixfold star system! Such star systems are very rare. It is believed that there are only two such stars within a radius of 130 light years from the Sun - Castor in the constellation Gemini and Mizar with Alcor. What an amazing star is in the handle of the Big Dipper!