A project of the Dark Energy Survey collaboration


Star Light, Star Bright


Which star can you see tonight?

Stars live out varied and complicated destinies. From the time of birth, a star’s cores house nuclear fusion reactions that combine lighter elements into heavier ones – e.g., hydrogen into helium, and so on. During fusion, light is emitted. From the core of the Sun, to the pupil of your eye, each ray of light takes a one million-year journey, bouncing off hot plasma on its way out of the star.

This burning can continue for tens of millions to billions of years, depending on the mass of the star. When the burning finally ceases, the light no longer pushes its way out, no longer fights the crushing gravity. For some stars, this disruption results in a massive and violent explosion, a supernova. Stellar material, including the heavier elements, like the calcium in your bones and the silicon in our computer chips, is then blasted into the nearby interstellar medium. In this new enriched region of space, a planet or new star may someday grow.

The pair of images above displays a galaxy, far away from our own, before and after a supernova event. Can you spot the difference? Supernovae often outshine their host galaxies. What’s more they can produce more energy in weeks or months than our own Sun can during its entire lifetime of billions of years.

Supernovae are very well understood. We understand them so well, in fact, that we can use them as buoys in the fabric of space-time: they are precise indicators of how much the universe has expanded at different points in its history.

After a year of commissioning and verifying the telescope and new instrument, the Dark Energy Camera (DECam), we will begin to perform a 5-year census of galaxies, supernovae, and other astrophysical phenomena. Analyzing distances of these objects and recovering patterns, the large-scale structure of the cosmos, we will learn about the nature of dark energy and its impact on the fate of the universe.

Disclaimer: the Sun will not explode. But, in a few billion years, it will grow in size and envelope the inner rocky planets… all except Mars.

Written by: Det. Brian Nord [FNAL], Joe Bernstein [Argonne National Lab]
Image by: Martin Murphy [FNAL] and Andreas Papadopoulos [U. of Portsmouth]

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