A star that is twice as massive as the Sun will burn through its fuel supply in only 800 million years. A star like the Sun has enough fuel in its core to burn at its current brightness for approximately 9 billion years. High mass stars are much brighter than low mass stars thus they rapidly burn through their supply of hydrogen fuel. The life cycle of a star depends upon its mass. If we lived near the center of a globular cluster, there would be several hundred thousand stars closer to us than Alpha Centauri, our current nearest stellar neighbor. The density of stars near the center of a globular cluster is enormous. A globular cluster is a dense collection of close to a million stars, all of which formed at roughly the same time. They estimate the age of the Universe in two ways: (a) by looking for the oldest stars and (b) by measuring the rate of expansion of the Universe and extrapolating back to the Big Bang.Īstronomers can figure out the ages of some of the oldest stars in the Universe by studying globular clusters. (Credit: Jeffrey Newman (UC Berkeley) and NASA)Īstronomers estimate that the Big Bang occurred between 10 and 20 billion years ago. It was the most distant galaxy used in HST's key project to determine the value of the Hubble Constant. Astronomers used nearly 50 Cepheid variables in this galaxy to determine its distance to be 108 million light years. An image of the galaxy NGC 4603, taken by the Hubble Space Telescope in 19.
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