Abstract
The study investigates different aspects of the Mirphak star. The Introductory section explains that the star occurs in the Perseus constellation and is the brightest star in the night sky above the Northern horizon. The paper has a section that describes the various names and myths linked to the star. Moreover, the paper traces a Greek’s mythical story that gave the constellation its name. Under the section on properties and position of the star, the study examines the changing coordinates of Mirphak. As a result, it outlines the star’s coordinates in J2000 and J1900. Other features examined include Mirphak’s surface temperature of 6350 K. In addition, the lifecycle of stars is studied to gain an understanding of Mirphak’s lifecycle. Consequently, the research uses HR diagrams to identify the star as a yellow-white supergiant. Finally, the paper concludes that the Arabic name Mirphak is the proper name for identifying the star.
- Introduction
The topic on Mirphak was chosen because it helps in the study of stars that are visible to the naked eye. In addition, the star is brighter than Algol and; hence, Mirphak is the brightest among the stars of Perseus configuration (Ashland Astronomy Studio (AAS)). Consequently, Mirphak is easy to observe in the northern hemisphere (Figure 1). Mirfak is also significant because it lies at the edge of Cepheid variables’ properties and, hence, is instrumental in determining the nature of such stars (Encyclopedia of Science).
In the constellation Perseus (Figure 3), Mirphak is easier to find than Algol and, hence, serves as a guide to Algol (Constellations of Words). The Perseus constellation was named after a hero in the Greek mythology referred to as Perseus (Constellation Guide). Ptolemy initially cataloged the Perseus constellation in the second century (Top Astronomer). The star-configuration is well known for its Perseid meteor shower that occurs annually (Constellation Guide). Apart from Mirphak and Beta Pesei (Agol), other major stars include Episilon Pesei and Atik, which are the fourth and the third brightest in the constellation, respectively (AAS). In addition, the configuration has famous deep-sky objects, which include the Double Cluster, Messier 34, Little Dumbbell Nebula, and the California Nebula (Constellation Guide).
Perseus is the twenty-fourth largest star-configurations in the sky and occupies a 615-degrees area (Constellation Guide). The constellation occurs in the northern hemisphere’s first quadrant (NQ1) and is seen at the latitudes between -35 and + 90 degrees (Top Astronomer). The Andromeda, Aruga, Camelopardalis, Triangulum, Taurus, Cassiopeia, and Aries are the star configurations that occur near Perseus. Perseus has six stars with confirmed planets and contains two Messier objects: the Messier 76 and the Messier 34. Mirphak, which is also called Alpha Persei, is significantly bright. Scientists have reported that, apparently, Alpha Persei has a 1.79 visual magnitude (Constellation Guide).
Scientists have associated two meteor showers with the star configuration, the September Perseids and the Perseids (Constellation Guide). Moreover, astronomers classify Perseus into the family of Perseus constellations (Constellation Guide). The family includes Triangulum, Lacerta, Cassiopeia, Auriga, Cepheus, Cetus, and Pegasus.
Mirphak’s diameter is 62 times larger than that of the Sun. Moreover, the star is a thousand times brighter than the Sun. Mirphak is also the 35th brightest star in the Earth’s sky at 584 light years from Earth’s surface (AAS). Analysis has revealed that the star is a primary part of a multiple-star system (AAS). According to Ashland Astronomy Studio, the star is currently in motion across the Galaxy at a speed of about 30.1 km/s, in relation to the Sun (AAS). In addition, the star forms a part of the Alpha Perseus moving group. A projection of its galactic orbit shows that its orbit around the galactic center ranges from 20700 to 24600 light years (AAS).
Figure 1. The Mirphak star. The figure shows the bright Mirphak star in the Perseus’ constellation (Encyclopedia of Science)
According to a Greek myth, the star configuration Perseus is a sky representation of Perseus, the Greek hero (Constellation Guide. Consequently, Perseus constellation is among the six star-configurations associated with Perseus’ myth. Perseus’ mother was Danae, King Acrisius’ daughter. After an oracle had informed the king that his grandson would murder him, Acrisius became furious and locked Danae in a dungeon (Constellation Guide). In the cell, Zeus approached and impregnated her. Acrisius got information about the incident but waited until Perseus was born. Subsequently, he locked his daughter and grandson inside a wooden chest before casting them out into the sea. At the sea, Danae prayed to the god Zeus, who heard her prayers (Constellation Guide). Within a few days, the chest washed ashore and landed on Seriphos’ island. Afterward, the angler Dictys rescued Danae and her son from the wooden chase. He then walked home with them where he raised Perseus as his son (Constellation Guide)
However, their ills did not end with the rescue. Dictys’ brother King Polydectes wanted to marry Danae, but Perseus fend off the king’s advances. Polydectes realized that he needed to devise a new strategy for taking Perseus out. Therefore, he made up a story that he was engaged to a foreign woman, Hippodameia. Consequently, he asked everyone in the country to give out horses as wedding presents. Since Perseus could not afford the price of the required present, the king sent him to bring the Gorgon Medusa’s head (Constellation Guide).
Medusa was one of the sea-god Phorcys’ daughters sired with Phorcys’ sister Ceto. The gaze of the three sisters was so horrendous that it turned anyone who saw their faces into a stone. Unlike her sisters, Medusa was mortal due to a curse of ugliness placed on her by the goddess Athena. Because of the spell, she had snakes on her head in the place of hair and, hence, was distinguishable from her sisters. Polydectes expected Perseus to perish, but Athena helped him in the mission. Therefore, Perseus returned home successfully carrying the Gorgon’s head. On his way, he found the princess Andromeda, whose parents Queen Cassiopeia and King Cepheus had chained her to stone and leaving her to die as a calming to Cetus, the sea monster. Perseus rescued her and returned home with her. On arrival, he found both Dictys and his mother hiding inside a temple to avoid Polydectes. The enraged Perseus then used the Medusa’s horrifying head to change Polydectes into stone; thus, fleeing his parents from worry. The Oracle’s prophesy came true, eventually, when Perseus threw a discus, in a contest, which hit Acrisius accidentally and killed him instantly. Later, Perseus and Andromeda married and got numerous children, among them was Perses, the ancestor of the Persian kings (Constellation Guide).
Therefore, Perseus is depicted in the Perseus constellation holding a gemmed blade and the Medusa’s head (Figure 2.). In the sky, Andromeda and Perseus are located next to each other while Cassiopeia and Cepheus lie nearby. The sea monster Cetus and the winged horse Pegasus, which sprung from Medusa’s body after her demise, are also in the vicinity.
The proper name for the shiniest star in the Perseus star configuration is the Arabic name ‘Mirphak.’ The word means the ‘Pleiades Elbow’ (Encyclopedia of Science). Other names attributed to the star include Marfak, Algenib, Mirfak, Alpha Persei, HR1017, HD20902, and HIP15863 (Encyclopedia of Science). Marfak and Algenib are also Arabic names. However, the Bayer name of the star is α Per while the Flamsteed of Mirphak is 33 Persei.
Figure 2: Image of Perseus. The figure shows the Perseus configuration (Constellations of Words)
Figure 3. Perseus in the sky. The figure shows a map of the Perseus Constellation (Top Astronomer)
- Properties and location of the Star
Stars begin their life cycles in clouds of dust and gas called Nebulae (Schools Observatory). Nuclear reactions at the stars’ cores provide energy that allows them to shine brightly for a long duration.
There are various types of nebulae. For example, an Emission Nebula such as the Orion nebula shines brightly because the stars already formed within it energize its gas. In a Reflection Nebula, however, the light from stars reflects on the nebula’s dust grains (Telescope).
The nebula that surrounds the Pleiades Cluster is distinctive of a reflection nebula. Moreover, Dark Nebula has been observed in space (Telescope). Dark Nebulae, such as the Horsehead Nebula of the Orion constellation, are dense clouds comprising of molecular hydrogen, which completely or partially absorb the starlight behind them. In contrast, Planetary Nebula is the star’s outer layer that is lost as it changes from a red giant to become a star type called the white dwarf.
A star refers to the luminous globe of gas that produces heat and light through nuclear fusion (Telescope). They emerge from nebulae and consist primarily of helium and hydrogen gas. Their surface temperatures range between 2000 and above 30,000 degrees Celsius, and have the corresponding colors ranging from red to blue-white. Some of the brightest stars have masses that are a hundred times the mass of the Sun and emit an amount of light that would be radiated by millions of Suns (Telescope). Such enormous stars live less than one million years before blowing up as supernovae (Telescope).
Among the different categories of stars, the faintest are the red dwarfs, which emit light that is lower than one-thousandth of the Sun’s brightness. Scientists calculate that the smallest mass required for forming a star is about eight percent of the Sun’s mass or eighty times the mass of Jupiter (Telescope). In the absence of such mass, nuclear reactions cannot occur inside an object’s core. As a result, large objects that possess less than the critical mass glow dimly, and are called large planets or brown dwarfs. As the star’s life ends, a star such as the Sun enlarges into a red giant, before losing its outer layers in the form of a Planetary Nebula. Subsequently, the star shrinks and becomes a white dwarf (Telescope). A white dwarf is viewed as a large bright star that has a cold outer surface. White dwarfs form during the last stages in the evolution of relatively less massive stars such as the Sun. Researchers point out that its formation occurs as it depletes the hydrogen fuel at its core (Telescope). The diameter of Red giants ranges between ten and one-hundred times the Sun’s diameter. Moreover, such stars are exceedingly bright due to their large size. However, their surface temperature is about 2000 to 3000 degrees Celsius, which is lower than Sun’s surface temperature. Gigantic stars or red giants are referred to as Super Giants because their diameters are up to one thousand times the Sun’s diameter. In addition, their luminosities are, usually, one million times greater in comparison to the Sun.
The next stage in the stars’ lifecycles is the formation of dwarf stars. Red dwarfs, for example, are small, extremely cool, and faint stars. They are about one-tenth the diameter and mass of the Sun. Interestingly, they burn slowly, and their lifetimes are approximately 100 billion years (Telescope). Presently, examples of red dwarfs include Barnard's Star and the Proxima Centauri.
Similarly, white dwarfs are small stars, which constitute the final life cycle phase in stars that resemble the Sun. Unlike red dwarfs, the white dwarfs have high surface temperatures. The mass of the white dwarfs is similar to the Sun’s mass, but their diameter is only one percent of the Sun's diameter. Hence, their radius is nearly equivalent to the Earth’s radius. At the surface of white dwarfs, temperatures above 8000 degrees Celsius have been reported (Telescope). Nevertheless, since they are smaller than the Sun, their brightness is one percent of the Sun’s luminosity (Telescope). White dwarfs are the shriveled remains of stars, whose supply of nuclear energy has been exhausted. They comprise of a degraded matter with extremely high density because of gravitational effects. As a result, the mass of one spoonful of the degenerate matter can weigh several tons (Telescope). Eventually, white dwarfs cool and then fade over several billions of years (Telescope).
A spectacular feature observed in the final stages of huge stars is supernova. The phenomenon refers to the explosive ending of a star and, frequently, results in the star acquiring the brightness of a million suns over an extremely short time (Telescope). There are Type Two and Type One supernovas (Telescope). Type One occurs in the binary-star systems, whereby the gas from a star falls on a white dwarf, hence, causing an explosion. In contrast, the Type Two occurs in stars that are ten times as massive as the Sun and that experience internal nuclear reactions as their lives end. Consequently, the runaway reactions result in an explosion. The explosion leaves behind neutron stars, as well as black holes (Telescope). Scientists point out that supernovas are the primary sources of the chemical elements that are more massive than helium and hydrogen (Telescope).
Neutron stars are composed primarily of neutrons produced when a supernova bursts, forcing the electrons and protons to combine, hence, producing a neutron star. The stars are extremely dense and their mass almost three times the Sun’s mass, but their diameter is only twenty kilometers. However, if the neutron stars exceed the Sun’s mass, then its gravity becomes stronger, and it shrinks further to form a black hole (Telescope). Neutron stars that spin very rapidly are referred to as Pulsars (Telescope).
Black holes are generated by the death of massive stars. A black hole’s gravitational pull is so intense that nothing can break loose from its influence (Telescope), not even light. Scientists have observed that there is no known way of measuring the density of matter contained in a black hole (Telescope). Black holes alter the space that surrounds them and, hence, can suck nearby matter into them (Telescope). Black holes also suck objects as massive as the stars.
Therefore, the lifecycle of a star is affected by its size. As a result, the lifecycles of some massive stars end in supernovas while stars that are more massive form black holes at the end of their lives. In contrast, relatively less massive stars such as the Sun become red giants and, eventually, form white dwarfs. However, every star has a different life cycle.
The study of stars’ lifecycles can help in identifying the present phase of the Mirphak star. The Bayer name of Mirphak is α Per (Frosty Drew Observatory & Sky Theatre) and the luminosity class is F5 (McClure). Moreover, the absolute magnitude is -5.1. According to the chart in Figure 4, therefore, the Mirphak is a supergiant. In Figure 5, the star Mirphak, circled in red, lies inside the HR Diagram. Therefore, the star is a yellow-white supergiant that does generate energy.
Figure 4. Composition and Structure of various stars. The diagram shows that Mirphak is in the region of yellow-white super-giants (Wikipedia)
Figure 5. HR diagram (Kaler). The Hertzsprung-Russell (HR) Diagram shows the location of Mirphak or α Per (circled in red)
- Conclusion
Mirphak is the brightest among the stars of the Perseus constellation. However, the star is 35th among the brightest stars and is a primary component of a multiple-star system. The star has many different names, such as, Marfak, Algenib, Mirfak, Alpha Persei, HR1017, and HD20902. However, the Arabic name Mirphak is its proper name. The present study has also observed that Mirphak is moving through the Galaxy at the speed of 30.1 km/s in relation to the Sun. In addition, Mirphak is part of the Alpha Perseus moving group. The star, therefore, is significant in the study of bright stars as well as the star configurations such as the Perseus constellation.
Works Cited
Alcyone. Mirphak. Alcyone, n. d. Web. 16 Nov. 2014.
Ashland Astronomy Studio. Mirphak. Ashland Astronomy Studio, n. d. Web. 16 Nov. 2014
Constellations of Words. The history of the star: Algol. Constellations of Words, n. d. Web. 16 Nov. 2014.
Encyclopedia of Science. Mirfak (Alpha Persei).Worlds of David Darling, n.d. Web 16 Nov. 2014
Frosty Drew Observatory & Sky Theatre. Mirphak. Frosty Drew, n. d. Web. 16 Nov. 2014
Kaler, James B. The Hertzsprung-Russell (Hr) Diagram, Illinois University, n. d. Web. 15 Nov. 2014
McClure, Bruce. Mirfak is Perseus’ brightest star. Earth Sky, 26 Dec. 2013. Web. 16 Nov. 2014
Schools Observatory. Life Cycle of a Star. National Schools Observatory, n. d. Web 16 Nov. 2014
Telescope. The Life Cycle of a Star. Bradford University, n. d. Web 16 Nov. 2014
Top Astronomer. Perseus. Top Astronomer, n. d. Web 16 Nov. 2014
Wikipedia. White Dwarf. N. d. Web. 15 Nov. 2014
