Posted on 08/01/2017 7:48:11 PM PDT by MtnClimber
Astronomers thought that all Type Ia supernovas shine with the same brightness, making them incredibly useful cosmic yardsticks. But uncertainty over what causes these explosions has led researchers to reconsider their assumptions.
The Type Ia supernova 1994D glows in the lower left of this Hubble Space Telescope image of the spiral galaxy NGC 4526. (photo at link)
Of all the mysteries in astrophysics, supernova explosions may seem to be the best-understood, at least to a lay person. A star runs out of fuel and goes boom.
But most of what we know is based on guesswork. My recent article on supernovas, “Lucky Break Leads to Controversial Supernova Discovery,” focused on the puzzles surrounding just one class of these objects — so-called “Type II core-collapse” supernovas. But another common kind of supernova has recently been subject to scrutiny, and uncertainties over this type of supernova could affect our understanding of larger cosmic questions.
Until a few years ago, astronomers believed that all Type Ia supernovas are like fireworks built on the same assembly line, each one bursting with an identical brightness. Because of this, Type Ia supernovas were used as “standard candles” — calibrated beacons that astronomers could use to deduce cosmic distances.....
More recently, however, scientists have realized that the standard-candle model is flawed. Researchers have known since the 1990s that not all Type Ia supernovas reach the same brightness. Brighter ones appear to dim a little more slowly than fainter ones, so astrophysicists have been able to correct for the difference. But now researchers believe there is a strong relationship between the “metallicity” of a supernova (how many elements it contains that are heavier than helium) and its brightness. And metallicity is not easy to measure.
(Excerpt) Read more at quantamagazine.org ...
A very good article on astronomy.
Astronomy, unlike climate, is a subject of real scientific inquiry where assumptions and models are challenged and theories are tested.
Everything happens all of the time.
most profound..
I’m not an astronomer, but it always seemed wrong to assume that all supernovae of a certain type are the same in intensity.
Nature doesn’t work like that.
I read as far as white dwarfs having a starring role before I groaned ...
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