Astronomy and Space Science

Biography

Biography: Artur Martirosyan

Abstract

Due to the fact that the brightness of exoplanets in the visible spectral region is about 107-109 times less than that of host stars, indirect methods are usually used to detect them. To date, thousands of exoplanets have been discovered. The main way of detection has become a transit method. The amplitude of relative reduction (transit depth) of stellar light allows evaluating the radius of exoplanet. Kepler Mission uses transit photometry to detect transit depth up to 10-4. Another important tool for exoplanet detection is the Doppler spectroscopy method, also known as radial velocity. The advantage of this method is that it allows us to estimate the mass of an exoplanet if the star oscillates along the earth-star line. If the star rotates in the transverse plane, the method does not work. Gravitational microlensing is a phenomenon predicted by Einstein in General Theory of Relativity. Because microlensing events do not repeat themselves, the detected exoplanets will never be observed again. Accurate prediction of the collision of asteroids and comets with Earth is an important task, which determines the existence of humans, and maybe life, on earth. On the example of Tunguska (1908) and Chelyabinsk (2013) meteorites, we can imagine the degree of threat to the earth, which comes from the space bodies.
Given the importance of the problem, many ground and space based systems are used on this topic. Apparently, the most successful instrument for observing comets and asteroids from the earth orbit is the mission WISE (NEOWISE) which surveyed the sky in 3-12 micrometers band to detect thermal radiation from asteroids. New methods, including synthetic tracking, are applied for finding and tracking small and fast moving near-earth asteroids. Radar provides the ability to study shape and size of asteroids and comets from the ground.