The Nature of the Stars: Agena - Thesis Example

The Star Agena Luo, Weiyin Dr. Fleming 3/6 This thesis is to give an overview of the star AGENA, also known as AGENA Hadar,but most often referred to as Beta Centauri. The position through right ascension and declination, type, declination, and other technical informative data is also provided. This star is the 10th brightest star in the evening sky and is a B1 III blue-white giant star, about 525 light-years from our solar system. The name Hadar is Arabic for ground, soil and earth (from أل أرض - al ardh) and can also represent civilization (from ألحضارة - al hidaara). AGENA is Latin for “the knee.” AGENA Hadar was identified as a double star in 1935 by Joan Voête, who gave it the identifier VOU 31. Introduction Proper Name AGENA is part of the β Centaurus system Hadar, its second or alternative name, represents the spot at the knee of the centaur in the constellation. AGENA is supposedly derived from the Greek word ‘alpha’ or else the Latin word ‘gena’ which means “the knee.” Hadar means ground, soil, earth and also “The settled land.” “The Horse’s Belly” or Mah Fuh, is the term used by the Chinese (OWL). Reproduced from The New Patterns in the Sky by Julius D. W. Staal AGENA Hadar is most commonly referred to as Beta Centauri. It is the 10th brightest star, Rigil-Kent III, in the overall night sky, and the second brightest in the southern constellation of Centaurus. Beta Centauri, along with Alpha Centauri (Rigil Kentaurus), are the two pointers to the Southern Cross constellation. In location, Rigel Kentaurus, Alpha Centauri, which is closest to the Earth, lies on the left, while Hadar lies between Alpha and the Star (Kaler, 2009). Class Hadar is a blue-white class B1 III giant and very luminous. What this means is when the fuel in the star’s core eventually dissipates, the helium core contracts because of gravitational pull and begins heating up. Hydrogen fusion expands into an outer shell, and expands out, brightening up the star. While expanding, the surface begins to cool and the star becomes a class M red giant. After it heats to 100 million degrees Kelvin, the helium begins fusing into carbon, and at a higher heat, it turns into oxygen. From this point on, the star is stabilized for a time. At this level, the star is a yellow-orange K giant (Kaler, 2011). In reality, Hadar is sometimes considered as three stars but is really two stars, Hadar A, the brightest and the giant, and Hadar B. Both are still considered to be dwarf stars, but in the giant category. Both orbit a centralized mass (the third ‘star’) that lies between the two stars. When looking at it, Hadar A appears to be orbiting around Hadar B, but the mass is the true central focus, and the two stars’ orbit paths meet on in only one spot (Davis, 2005). Properties of the Star AGENA Hadar, as a star in the constellation Beta (β) Centaurus Lupus Crux, had a declination in 1900 of -59.53’ and -60.22’ in 2000. Other important information is the right ascension: 14h 03m. The spectral class is B1 Rigil-Kent III and the magnitude is 0.61 Variable. These are the main technical pieces of knowledge used to confirm the identity of the star against the rest in the nearby area (OWL). Information provided shows a rough temperature of 25,000 Kelvin and using the stellar structure theory gives masses at a calculation close to 14 solar, derived from the binary orbit. Spinning at 140 km/s or more, combined with a radius of 9 solar, gives a calculation of at least one star at under three days. Hadar B takes about 225 years to orbit at a distance of 120 Astronomical Units (AU) (Kalar, 2009). As Hadar, a hydrogen-fusing dwarf star (in two), it is projected to soon meet its 11-million-year lifetime, eventually expanding to become red giants and subsequently, blowing up as supernovae. Some of the calculations of velocity, Doppler shifts and orbit interferometry measures, put up against those of luminosity and temperature do not agree completely. This means there is a possibility Hadar (as both stars) will just become a massive white star, bypassing supernovae (Kaler, 2009). The Hertzsprung-Russell (H-R) Diagram represents the life cycle of a star and AGENA Hadar has currently reached main sequence (Mv-3.5), according to mass, and will either remain white stars or move into the red giant category. It will, most likely, move off the H-R line after that. The calculations at present are not accurate for now to predict Hadar’s next step. Once the hydrogen is used up, other sources of the star’s energy are the helium, as well as other complex elements such as iron, neon, oxygen, carbon, magnesium, argon, silicon, sulfur and chlorine (Fraknoi, Morrison and Wolff, 1997, p. 347). AGENA Hadar, as a B1 V in the color index, emits more hot energy in the blue and ultraviolet part of spectrum. Cooler stars project energy in the red and infrared wavelengths. The core of the planets operates the same way as our Sun, where smaller nuclei fuse together to make a larger nuclei. While two smaller nuclei are hydrogen with one proton each, when they fuse together, they make a heavier hydrogen nucleus with one protron and one neutron. This produces a positron and a neutrino emission. In order for fusion to occur, extreme heat over 10 million K must be attained and the speed of the protons must be 1000 km/s, or more. Protons collide and rebound against each other because of electrical forces and it can take millions of years before a proton finally fuses with another. When that happens, then energy is produced and the star utilizes the energy contained in the nuclei of the atoms through nuclear fusion. The ‘proton-proton cycle’ or p-p chain as it is sometimes called, involves four hydrogen atoms that fuse to form a helium atom which has less mass. That lost mass is converted into energy. The reaction processes in the chain are represented through these formulas: 1H + 1H + → 2H + e+ + ν 2H + 1H → 3He + γ 3H + 3H → 4He + 2 1H (Fraknoi, et al., 1997, p. 326). Death of a Star As mentioned previously, AGENA Hadar could possibly remain a white dwarf, or else, turn red and go supernovae. What counts is the star’s mass when it is ready to die and collapse into itself because of gravitational forces. As a white dwarf, at the point when it is without any hydrogen resources left, the only energy source left is in the atomic nuclei in the center which stabilizes. At first, the nuclei will radiate a lot of heat, but over time that lessens, and the nuclei’s movement slows down. It turns into a black dwarf and is mostly carbon and oxygen. As the star cools even more, it solidifies inside and becomes a diamond. An alternative ending would be the supernova where if the star still maintains significant mass, but becomes out of balance when the inner collapse begins. The outer layers remain briefly expanded with nothing to hold them up and then begin to move inwards towards the core. As it does so, the outer layers break into sections and when the center core begins to rebound back out, it meets the layers coming in and an explosion occurs. All the outer layers explode out into space in small masses and the result is a neutron star. Conclusion AGENA Hadar is interesting to watch as we can also watch other stars close by at different points of development to correlate and speculate what will be AGENA’s fate. We are learning new things about stars every day, particularly as we upgrade our instruments and hopefully, make further travels out into space to get closer to other worlds. Appendix A. Interesting Data About AGENA Hadar Downloaded from http://www.statemaster.com/encyclopedia/Beta-Centauri Works Cited Frankoi, Andrew, David Morrison, and Sidney Wolff. Voyages Through the Universe. 2nd ed. Philadelphia: Saunders. 1997. Print. Website Resources: “Beta Centauri.” Abstract. Dbpedia-owl. http://dbpedia.org/page/Beta_Centauri (OWL) Kaler, James B., HADAR: (Beta Centauri) Stars. (Univeristy of Illinois) (Revised 2009) Retrieved 2012-03-07. Crux and Southern Centaurus http://stars.astro.illinois.edu/sow/crux-p.html (Crux) Kaler, James B., HADAR: (Beta Centauri) Stars. (Univeristy of Illinois) (revised 2009) Retrieved 2012-03-07. http://stars.astro.illinois.edu/sow/hadar.html (Kaler, 2009) Kaler, James B. The Nature of the Stars. Stars. (University of Illinois) (2011) Retrieved 2012-03-07. http://stars.astro.illinois.edu/sow/star_intro.html#giants (Kaler, 2011) Encyclopedia:Beta Centauri. 2003-2005. Nation Master.com Online http://www.statemaster.com/encyclopedia/Beta-Centauri Read More