The habitable zone (HZ), is the range of orbits around a star within which rocky planets with sufficient atmospheric pressure can support liquid water at their surfaces.

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In astronomy and physical cosmology, the metallicity is the fraction of mass of a star or other kind of astronomical object that is not in hydrogen or helium.

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A supernova is an astronomical event that occurs during the last stellar evolutionary stages of a massive star’s life, whose dramatic and catastrophic destruction is marked by one final titanic explosion.

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The Hertzsprung-Russell diagram (HRD), abbreviated H-R diagram or HRD, is a scatter graph of stars showing the relationship between the stars’ absolute magnitudes or luminosities versus their spectral classifications or effective temperatures.

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A planetary nebula is a kind of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from old red giant stars late in their lives. They are a relatively short-lived phenomenon, lasting a few tens of thousands of years, compared to a typical stellar lifetime of several billion years.

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