Since Cepheid variables are a relatively short evolutionary stage in the lifecycle of stars, and knowing the mass of the star allows for the star to be tracked in its evolutionary path, one can estimate the age of the Cepheid variable.Įxceptional stellar properties which allow for an estimation of age are not confined to advanced evolutionary stages. For example, Cepheid variables have a characteristic pattern in their lightcurves, the rate of repetition of which is dependent on the luminosity of the star. Īs well as the scenarios of supermassive stars violently casting off their outer layers before their deaths, other examples can be found of the properties of stars which illustrate their age. Betelgeuse in particular is expected to die in a supernova explosion within the next million years. Very large stars like VY Canis Majoris, one of the largest stars known, together with NML Cygni, VX Sagittarii and Trumpler 27-1 all have radii larger than that of the average orbital radius of Jupiter in the Solar System, thus showing that they are in extremely late evolutionary stages. These enormous outbursts can be used to infer that the star system is nearing the end of its life, and will explode as a supernova within a relatively short period of astronomical time. For example, the Eta Carinae system is emitting large quantities of gas and dust. Various properties of stars can also be used to determine their age. As the star spends only about 1% of its total lifetime as a red giant, this is an accurate method of determining age.Įta Carinae, a star system that is violently ejecting gas. However, when one can observe a red giant star with a known mass, one can calculate the main-sequence lifetime, and thus the minimum age of star is known given that it is in an advanced stage of its evolution.

This method only works for calculating stellar age on the main sequence, because in advanced evolutionary stages of the star, such as the red giant stage, the standard relationship for the determination of age no longer holds. Given the mass of the star, one can use this rate of increase in luminosity in order to determine the age of the star.

Luminosity increase and the Hertzsprung–Russell diagram Īs stars grow older, their luminosity increases at an appreciable rate.

No individual method can provide accurate results for all types of stars. Nearly all of the methods of determining age require knowledge of the mass of the star, which can be known through various methods.

These methods include stellar evolutionary models, membership in a given star cluster or system, fitting the star with the standard spectral and luminosity classification system, and the presence of a protoplanetary disk, among others. Various methods and tools are involved in stellar age estimation, an attempt to identify within reasonable degrees of confidence what the age of a star is. Young star ejecting two jets of energised gas.

Calculating the stars