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How Would Astronomers Decide If A Planet Was In Star's Habitable Zone (Essay Sample)


TRANSIT METHOD, What is a „habitable zone‟? How would astronomers decide if a planet was in a star‟s habitable zone? How would the speed the star is moving allow astronomers to be able to deduce information about the orbiting planet, Radial- velocity method, DOPPLER EFFECT


An exoplanet is a planet orbiting a host star. These planets exist outside the solar system. The exoplanetary system has thousands of exoplanets with different sizes and orbits that have been discovered over time. Proxima or Alpha Centauri exoplanetary system. It the nearest to the sun. The host star is a red dwarf star with very low mass. It lies in the constellation of Centaurus. This star was first discovered by a Scottish astronomer, Robert Innes in 1915. The star has an apparent magnitude of 11.05 hence it can hardly be seen with naked eyes. Due to its proximity to the earth, its size is measured directly, and it has a diameter of one-seventh that of the earth. It has density 40 times that of the sun with an eighth of the sun's mass. Proxima star has random changes in brightness due to magnetic activity acting on the star despite the fact that it is averagely low luminosity. This kind of glowing is influenced by the star's magnetic field that results from convention throughout the Proxima stellar star. The flare generated creates a total X-ray emission that releases the glare in the same way as the sun. Proxima star will remain a main-sequence star for trillion years. This is explained by the fact that mixing of the fuel at the core of the star through the convention process and that it has a low energy-production rate.
The Proxima Centauri system belongs to the Hertzsprung Russel Diagram's main sequence and a class type of spectral class M6. This kind of class implies that it has low mass and its classified under M-type stars. This star rotates every 83.5 days. It has relatively low mass hence the core of the star is entirely convective, resulting in energy transfer to the exterior parts by plasma movement rather than through radiation processes. The stars chromospheres are generally active, and its emissions radiate a spectrum of ionized magnesium at a wavelength of 280nm. The system's loss mass per unit surface area is eight times that of the sun because the star is a weak stellar body.
The most recently discovered Proxima Centauri b exoplanet that orbits red dwarf Proxima Centauri star which is the closest to the sun. The Proxima Centauri System is in the triple star system. This host star, Proxima Centauri is an M6Ve star type. It has a planetary equilibrium temperature of 234 kelvins and stellar flux of 0.65 R⊕ times relative to that of the earth. It has a radius of 1.1- 1.5- 2.0 comparable to that of the earth. It was discovered in the year 2016 August by astronomers. It lies 4.2light-years from the solar system. The exoplanet system is a rocky world. The exoplanet is 1.3 times massive than the earth. Proxima Centauri b planet receives radiative flux of 65% from Proxima Centauri star.. the radiative flux reaches the planet regarding infrared soectrum.. the planet only receives 2.1% visible spectrum as earth does. The maximum illumination of the planet is 2700 lux with quiet host star. Another characteristic of the exoplanet is that it has a tight orbit that makes it receive about 400 times more X-ray radiation as compared to the earth.
It exists in the habitable zone of the host star, 7.5 million kilometers from the host star. A habitable zone is a region round host star where an exoplanet can maintain liquid water on its surface due to sufficient atmospheric pressure. Proxima Centauri lies in the conservative habitable which is rockier or more likely to keep surface liquid water. The ESO outlines that the presence of water and pressure offers a more hospitable environment.A planet is habitable if the atmospheric pressure that is thick enough to allow the transfer of heat to the side not facing the host star. Astronomers outline that the ability of this planet to retain water can be considered to evaluate the planet's habitability. There also exists planet in the optimistic habitable zone which has lesser rocky composition. The exoplanet is tidally locked and orbits around its host star after every 11.2 earth days. The apparent inclination on its orbit has not yet been obtained. Once the inclination is achieved, the real mass of the exoplanet will be calculable.
The Proxima Centauri discovered in 2016 by the Pale Red Dot team. It was announced by the European Southern Observatory in August 2018. The exoplanet was discovered through the radial velocity method. The orbiting planet was hinted by periodic Doppler shifts of the hist star's spectral lines. This method is also referred to as Doppler spectroscopy or wobble method. This is a procedure of indirectly for finding out new extrasolar planets or orbiting objects from radial-velocity observations through Doppler shifts in the host star CITATION Sea10 \l 1033 (Seager, 2010). About 600 extrasolar planets were found by Doppler Spectroscopy. The method is conducted by collecting a series of observations obtained from the spectrum of light emitted by the host star. The changes in the spectrum are detected by using the wavelength of the specific spectral lines in the spectrum. The variations of increasing and decreasing wavelength over a specified period is considered. Next, the collected information is put is computers and filters to filter out spectrum from other nearby sources. Technical techniques are subjected to the data by astronomers to filter out the tell-tale periodic sine wave which portrays the presence of a planet. Once a planet is detected, the changes in the stars velocity are used to determine the minimum mass of the newly found exoplanet. Then finally, a graph is plotted to determine the minimum mass of the planet. The graph plotted measures the host star radial velocity against time to display a characteristic curve for the planet. A mathematical system called, The Bayesian Kepler periodogram is then applied to detect either single or multiple extrasolar planets. The continuous collected radial-velocity data of the host star they are orbiting are feed into this system. This algorithm uses prior probability distribution criteria to analyze the observations over the specific space. This orbital space is determined by Keplerian orbital parameters. Markov Chain Monte Carlo Method can also be technically applied to translate the radial-velocity observation to detect the exoplanets in that specific place.The planets actual mass is obtained by separating planet's spectral rays from the stars' spectral lines. Once this is done, the planets inclination on the orbit is technically applied to determine the actual planet mass. This radial-velocity method has some challenges. It can only measure the shifting along just the line of sight CITATION Mor03 \l 1033 (Morton, 2003). This means planet's mass it is evaluated from the inclination of

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