Even the most inveterate pragmatist cannot remain indifferent when night falls on the earth, quiet and starry. The constellation map of the northern hemisphere contains several expressive celestial drawings. However, all their beauty can only be appreciated by looking at the sky on such a night. Ursa Major and Ursa Minor, Bootes, Cassiopeia, Cepheus and others fascinate and make you freeze in place, admiring the beauty of the vast space, accessible to the naked eye.
Today our focus is on the constellation Cepheus (photo below), perhaps not the brightest and most impressive, but worthy of detailed study.
Location
Ursa Minor and Cassiopeia coexist with Cepheus in the sky. Finding constellations like these is usually very easy: the stars in these celestial drawings are quite bright and visible. However, the most significant landmark for the search is the Northern Cross asterism, located south of Cepheus in the constellation Cygnus.
All overthe territory of our country, Cepheus is a non-setting constellation. The best time to see it is from July to September. Part of the constellation is located in the Milky Way.
Proximity to the North Pole
The constellation Cepheus, whose scheme includes approximately 150 stars, visible in clear weather without the use of any equipment, is shaped like an irregular pentagon. Interestingly, Cepheus' nearest neighbor, Ursa Minor, will not always contain a polar star. As a result of the precession, the place of today's Polaris will be successively occupied by the luminaries from the constellation Cepheus: Alfirk (beta), Alrai (gamma) and Alderamin (alpha). The first of these will take pride of place around the year 3100. It is these stars, together with Zeta and Iota of Cepheus, that make up the formative asterism of the celestial pattern.
Constellation Cepheus: legend
Scientists believe that the considered group of luminaries appeared simultaneously with neighboring Cassiopeia, Perseus, Pegasus and Andromeda. Constellation myths also speak of their common origin. Involuntarily, you will think about the possible knowledge of the ancients.
Cepheus, according to Greek mythology, was the king of Ethiopia. Among other virtues and riches, he was most famous for the beauty of his wife Cassiopeia and daughter Andromeda. One version of the legend describes the queen as a wayward and obstinate woman. Cassiopeia inadvertently compared the beauty of her daughter with the impeccable appearance of the gods of Olympus, for which they became angry and wished to punish both women.
Another version tells that jealousthe gods did not have to wait for the careless words of Cassiopeia: they themselves noticed the radiant beauty of Andromeda and decided to put an end to such disrespect. Be that as it may, a huge whale appeared off the coast of Ethiopia, every day getting out onto land and devouring the inhabitants of the country. Cepheus tried to save the kingdom. Keith agreed not to ravage the villages, in return he was to be given the most beautiful girl every day.
A miraculous rescue
Sooner or later, the turn came to Andromeda. There was no limit to the grief of the parents, as well as to the joyful anticipation of the envious gods. The girl was tied to a rock. The whale was already approaching the victim, when suddenly Perseus flew on horseback on Pegasus and saved the king's daughter.
The monster was defeated, but the beauty was saved. After a while, each hero was turned into a constellation: Cepheus, Cassiopeia, Andromeda, Perseus, Pegasus and even Kit.
Dim but significant
All named celestial drawings are located close enough to each other in the sky. The constellation Cepheus, like its royal prototype, is inferior to Cassiopeia in beauty. However, the monarch of the times of Antiquity and his heavenly image have something to be proud of. The stars that make up Cepheus have a certain attraction for scientists. Among them there are binary systems, and luminaries, huge even by the standards of the Universe, and a star, which gave its name to a whole type of similar space objects.
Two cows
The brightest star that the constellation Cepheus boasts (the diagram givesidea of differences in the values of elements) - Alderamin (alpha). The name means "right hand". It is located on the elbow of a royal figure. The magnitude of the star is 2.45. The distance that must be overcome from us to Alderamin is estimated at 49 light years. Alpha Cephei is a white subgiant belonging to the spectral class A. A feature of the star is a very fast rotation. It takes only 12 hours for Alderamin to make one revolution, while for the Sun, for example, the same action takes about a month. Scientists' data indicate that Alpha Cephei is now in the process of becoming a red giant.
Beta Cephei has the historical name Alfirk ("flock of sheep"). This is a variable star, the name of which denotes a separate class of similar cosmic bodies. Variables of the Beta Cephei type are characterized by a change in brightness within 0.01-0.3 magnitudes. For Alfirk, the range extends from +3.15 to +3.21. The change period is 0.19 days.
In the Arab countries, ancient scientists combined Alderamin and Alfirk into the asterism "Two Cows". By association with him, the name and scale of Cepheus was given - Alrai ("shepherd").
Dual system
The constellation Cepheus has several stellar "coalitions". Alrai is interesting in that this is the first close couple, one of whose companions was found to have an exoplanet. Gamma Cepheus A is an orange subgiant, exceeding the Sun by 1.6 times in mass and 8.2 times by luminosity. A red dwarf revolves around it. period forwhich the gamma of Cepheus B makes one revolution is 74 years. The Alrai system is 45 light years away from the Sun.
Gamma Cephei A possesses an exoplanet theoretically discovered in 1988. In 2003, its existence was confirmed. The planet makes one revolution around the star in 2.5 years. Its mass, according to scientists, should exceed the mass of Jupiter by 1.59 times.
Delta
Another binary system is Alredif or Delta Cepheus. However, it is not known because of its components. Alredif - the luminary that gave the name to the class of variable stars, Cepheids.
Delta Cephei changes its brightness with a period of more than five days. In this case, the increase is faster than its decrease. The peculiarity of a star is that a change in a number of other characteristics is also associated with a change in brightness: the luminary in different periods can be attributed to different spectral classes. At the minimum brightness value, Delta Cephei becomes a representative of the G2 type, to which the Sun also belongs, and at the maximum - F5. These atypical stellar features went unexplained for some time.
The solution, however, was found. It was found that the star pulsates, that is, changes its diameter. On average, this Cepheus delta parameter is equal to 40 diameters of our star. During the pulsation, it changes by 4 corresponding values, which is several million kilometers. During the period of compression, the surface of Alredif warms up, its brilliance increases. The expansion is characterized by some cooling and a decrease in gloss. Similar changes are characteristic of the entire Cepheid class.
Red Supergiants
The constellation Cepheus is famous for the presence of three huge stars in its composition, the sizes of which stand out among all known objects in the Universe. They are red supergiants. The first one is mu Cephei. The star is 350 thousand times greater than the Sun in total luminosity. The second name of the giant is Herschel's Pomegranate Star. It was William Herschel who first noticed the beautiful shade of the star. The mu of Cepheus is 1650 times larger than the Sun. Scientists disagree on how far this red supergiant is from our star. Recently, the figure of 5200 light years is considered the most accurate. Now mu Cephei is at the stage of dying. In the next few million years, an explosion awaits it, after which the collapsed core of the star will most likely turn into a black hole.
Mu Cephei is also a triple star system. Its main pair is made up of less impressive components B and C.
The second red giant is VV Cephei, an eclipsing double star 5000 light-years away from the Sun. Component A of the system is a huge luminary, the third largest among all known and the second in this parameter in the Milky Way galaxy. Its diameter is more than 2.5 billion kilometers, which exceeds that of the Sun by about 1700 times. VV Cephei A shines brighter than our star by 275-575 thousand times. The second component of the system revolves around the first with a period of 20 years. It is 10 times the size of the Sun.
The third red supergiant is HR 8164. The star does not have its own name. Hermagnitude is approximately 5.6.
Close neighbor
All named objects are at a decent distance from the Earth. However, Cepheus also has one star, located only 13 light years from us. This is Kruger 60, a binary star system. Both of its components are red dwarfs, much smaller than the Sun in size. Kruger 60 A is almost four times smaller in mass, its radius is 35% of the radius of the Sun. Component B is even “more modest”: it is about 5.5 times less massive than our luminary. The Kruger diameter of 60 V is equal to 24% of the corresponding parameter of the Sun. The second companion is a flare star. Every eight minutes, its luminosity doubles and then returns to its original value. The components of the system rotate around the same center of mass with a period of 44.6 years.
Fireworks and trunk
The constellation Cepheus boasts not only interesting stars, but also nebulae. The photo of one of them resembles the image of fireworks. Nebula NGC 6946 and the name is appropriate. It is interesting in that nine supernovae have already been discovered within its limits. So far, no other nebula can boast of such a number. Fireworks are located on the border with the constellation Cygnus.
Another similar cosmic formation is connected with Cepheus. IC 1396 is an emission nebula famous for hosting the Elephant's Trunk, a dark cloud of interstellar dust. It got its name due to the visual similarity with the corresponding part.huge animal.
Open Cluster
The constellation Cepheus on its "territory" also keeps one of the most ancient formations of the cosmos, discovered so far. This is the open cluster NGC 188. It includes 120 stars that formed at about the same time from a common molecular cloud. Herschel discovered it in 1831. The very first calculation of the age of the cluster estimated its lifetime at 24 billion years. Subsequent calculations reduced this figure. Today it is generally accepted that NGC 188 is 5 billion years old.
Descriptions of the constellations, even the most detailed, will not help to understand the beauty of celestial drawings. The exact coordinates of the stars, the description of their characteristics do not give that feeling of the infinity of the Universe, which appears when you peer into the night sky. Myths about the constellations partially and in their own way convey the relationship between the earthly and the cosmic, however, they will not replace direct observation. On the other hand, data on the objects included in the celestial pattern help to understand what is hidden even behind the most seemingly inconspicuous stars. A striking example of this is Cepheus, a constellation that is not the most visible, but contains a lot of interesting elements and tells about them to the curious.
