How do astronomers make conclusions about the life of a star?

..from its birth to its death, taking into consideration that it is impossible to observe a star's evolution through its entire lifetime?How do astronomers make conclusions about the life of a star?there are several types of stars, such as red giant, red dwarf, brown dwarf, neutron star, supernova, quasar, balck hole, only to name a few of them. all of these stars are defined in relative to the size of our Sun. like to describe a star as supernova its mass has to exceed at least 10X the mass of Sun.



then there are evolution of stars as much as humans and other beings evolve. a red giant might evolve into a depending on how much fuel it has(helium) and how much it has been affected by gravitional forces around it. the ultimate evolution of all stars are into a supernova which is a bright star, which later tears apart by tremendous gravitional force to become a black hole.



now that the evolution of stars are said, scientists have figured out how much does each classification of stars survive. like a brown dwarf can survive a certain period of time before it evolves into a supernova.



also from the spectrometric analysis of the wavelengths emitted from stars show at what speed the star is approaching or receding. now if you use the Hubble's formula which is velocity=(Hubble's constant)X(Distance) you could find how far the star is from us. now that you know velocity and distance, use the classical formula, which is speed=(velocity)X(time), and find time. BINGO!!! you get the time, hence the age of that star.



hope that helps :)How do astronomers make conclusions about the life of a star?Its size, color, and sometimes the way objects move around it(its gravity)How do astronomers make conclusions about the life of a star?measuring the changes in the Doppler shift of an emission line.



"We detect spectroscopic binary systems by observing Doppler shifts in the spectral lines. If one star is orbiting another, it periodically moves toward us and away from us in its orbit, and its spectral lines show blueshifts and redshifts as a result of this motion. Each of the two stars we see when we view Mizar through a telescope is a spectroscopic binary.



We measure the orbital period of a spectroscopic binary by noting the time it takes the spectral lines to shift back and forth. Except in rare cases, we can calculate the separation of a binary only if we know the actual orbital speeds of the stars. The primary technique for measuring stellar speeds relies on the Doppler effect, but Doppler shifts tell us only the portion of a star's velocity that is directly toward us or away from us. Orbiting stars generally do not move directly along our line of sight, so their actual velocities can be significantly greater than those we measure through the Doppler effect. The orbits of eclipsing binaries are particularly important to the study of stellar masses because we know the inclination of the system and thus can calculate the actual orbital speeds of the stars."