Scientists have discovered that they have been thinking incorrectly about the expansion of the Universe and dark energy for 30 years

About 30 years ago, it was discovered that objects in the Universe were flying apart at an accelerating rate. Something invisible was causing galaxies to fly away from each other when they weren’t bound by gravity. This was determined by studying Type Ia supernova explosions, which were called standard candles because of their predictable brightness. They allow us to accurately determine the distances to exploding stars, but as it turns out, the brightness of the “candles” can be off, and scientists are now fixing that.

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In the Zwicky Transient Facility (ZTF) survey, scientists examined 3,628 exploding white dwarfs. Some of them, under the influence of circumstances and the environment, can turn into type Ia supernovae. A white dwarf itself will not turn into a supernova – it is the core of a dead star that has thrown off its shell. It will smolder until it cools completely, which will take billions of years. However, about 50% of white dwarfs (like other stars in the Universe) are born and die in binary systems. And then there are options.

If both stars in the system are the same age and have roughly equal masses, then after their death the white dwarfs may come together and merge. Depending on the mass of the remains, the swollen white dwarf will either collapse under its own mass into a neutron star or, if the mass of the remains exceeds a certain limit, will explode as a Type Ia supernova. Obviously, this will be a slightly different Type Ia supernova than the one that could explode after the death of one star.

A similar situation arises in the case of a binary system consisting of a white dwarf and a not yet dead red giant or another nearby star. The white dwarf will attract the mass of its neighbor and, if it accumulates enough matter, will flare up as a type Ia supernova. And this, too, will not be quite the same supernova that is considered a standard candle.

Thus, white dwarf explosions introduce a degree of uncertainty into what astronomers actually observe. There can be many scenarios for such explosions, which complicates precise calculations and the search for the mechanism of dark energy. A new review, in which white dwarf explosions over the past five years have undergone a comprehensive analysis and classification, will help scientists take a new look at standard candles – type Ia supernovae. The data is available in the public domain and awaits its researchers.