Sirius Star
I chose this star because my grandmother used to tell me the story of Orion and Sirius as a bedtime story
General Information:
Names:
Sirius is also called Alpha Canis Majoris or the Dog Star and it is a binary star in the constellation Canis Major. It is defined as a binary star because it is a pair of stars in orbit around their common centre of gravity.
Sirius vs Sun
Brightness and size:
Sirius is one of the nearest known stars to Earth at only 8.6 light years away and not counting the sun is the brightest star in the night sky. It has a mass of 2.063 ± 0.023 M which is two times that of the Sun and a diameter of 1.5 million miles8.611 light years from earth. Astronomers express the brightness of stars in terms of stellar magnitude. The smaller the number, the brighter the star. The visual magnitude of Sirius is -1.44 and the sun has a stellar magnitude of -26.74.
Specific location:
Sirius can be viewed in both the hemispheres and due to its brightness, it is clear in the night sky. It lies just 8.6 light-years away in the constellation Canis Major the Greater Dog which is left to the Orion Belt and with an exact position of RA: 06h 45m 08.9s, dec: -16° 42′ 58″. The position of Sirius is RA: 06h 45m 08.9s, dec: -16° 42′ 58″. Bottom line: Sirius is the brightest star in the night sky as seen from Earth and is visible from both hemispheres. It lies just 8.6 light-years away in the constellation Canis Major the Greater Dog.
Location in regards to the East Coast:
When looking up the Deerfield sky during late summers, it appears east before the sunrise near the sun in the sky. Sirius is behind the sun as seen from Earth in Northern Hemisphere summer.
Culture and History
Greek:
According to Greek mythology, Sirius was the dog of the hunter Orion, and the ancient Romans placed the star in the constellation Canis Major. Canis Major is latin for “Greater Dog”.
Roman:
The Romans thus referred to the sweltering period when the rising of the sun and Sirius converged as the “dies caniculares” or “days of the dog star.” By the 1500s, the English world began to call the same summertime point on the astronomical calendar as the “dog days.”
Egyptian:
Due to a wobble in the Earth’s rotation that shifts the position of the stars in the night sky, the dates of the “dog days” now fall several weeks later on the calendar than they did thousands of years ago. The ancient Egyptians 5,000 years ago noticed Sirius’s heliacal rising, when it was visible just before sunrise, just prior to the annual flooding of the Nile River and the summer solstice.
In approximately 10,000 years, the date of the heliacal rising of Sirius will fall back so late on the calendar that future civilizations in the northern hemisphere will experience the “dog days” of winter.
Classification
Specific Spectra Of Sirius
Sirius is a binary star consisting of a main-sequence star of spectral type A0 or A1, termed Sirius A, and a faint white dwarf companion of spectral type DA2, termed Sirius B. A main sequence star fuses hydrogen atoms to form helium atoms in their cores. About 90 percent of the stars in the universe, including the sun, are main sequence stars. The A0 or A1 and DA2 Classification of the Sirius stars fall under the stellar classification which is a format of stars based on their spectral characteristics. The strengths of the different spectral lines vary mainly due to the temperature of the photosphere.
Morgan- Keenan System
Most stars are currently classified under the Morgan–Keenan (MK) system using the letters O, B, A, F, G, K, and M, a sequence from the hottest (O type) to the coolest (M type). Each letter class is then subdivided using a numeric digit with 0 being hottest and 9 being coolest. To give a comparison to the sun, the sun has a classification of G2V, making Sirius 25 times as luminous as the Sun
H-R Diagram of Sirius
From the x axis, we can see the surface temperature. The more you move to the left the lower the temperature and redder it becomes. On the y-axis, it shows the luminosity. The higher you view the graph, the brighter the star is.
Diving deeper into observing Sirius we can divide it between Sirius A and Sirius B. Like the majority of stars, Sirius A is located in the main sequence. However Sirius B is a lot fainter and smaller than Sirius A, also a white dwarf.
Depending on its initial mass, every star goes through specific evolutionary stages dictated by its internal structure and how it produces energy. Each of these stages corresponds to a change in the temperature and luminosity of the star, which can be seen to move to different regions on the HR diagram as it evolves.
Future of Sirius
Sirius was first reported observed by German astronomer Friedrich Wilhelm Bessel in 1844. Sirius is currently estimated at around 230 million years old and with a star its size, it is believed that its total life will reach 1 billion years. The next phase that Sirius will go through is the Neutron phase. It contracts tremendously into a small, dense mass about ten miles in diameter, 1.4 times the mass of the sun, with an extraordinarily strong magnetic field, and a rapid spin. These are the phases Sirius has to go through, leading to its death.
Life? No chance....
Since Sirius is relatively young in age, combined with the extreme challenges to life development in a Class A star system and the problems presented by Sirius B roaming through the system every 49.9 years makes the probability of even simple life in the Sirius system highly unlikely.
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