Supernova differences could change our understanding of dark energy

Science Focus

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Measuring distance in the Universe is very challenging—you can't simply run a tape measure out to the Cosmic Microwave Background. What astronomers have done instead is find classes of objects that have a consistent brightness. By measuring how much dimmer than the expected value an object is, you can infer its distance. These objects have been termed "standard candles."

The most useful object for measuring great distances is the type Ia supernova. These supernovae are created when a white dwarf star reaches a specific mass, which triggers a thermonuclear explosion. Since the explosions always happen through the same process, it's thought that the light output is always more or less the same. Type Ia supernova have thus been used to measure the expansion of the Universe out to great distances. They're what were used to spot the apparent acceleration of the expansion, which led to the recognition that much of the Universe is composed of dark energy, a feature we know extremely little about.

Recently, however, a paper was published that suggests that these distance estimates may not be entirely reliable. The supernovae, it seems, are not quite as standard as we thought.

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