The explosion marked the death of the white dwarf, the most common star in the galaxy. Unusually, however, the death of this white dwarf was accompanied by ultraviolet flash. This rare flash shows that there are some extremely hot substances in this star, although white dwarfs are notoriously cold. Astronomers are not sure what caused this light, but further observation of this rare event will help them better understand what caused the white dwarf to explode into a supernova. The findings, published in the Journal of Astrophysics on Thursday, may give scientists a deeper understanding of the elusive dark energy that dominates the universe.
When a star reaches the end of its life, it will run out of fuel and collapse under its own gravity. The death of this giant star will lead to a huge explosion of the whole galaxy, which is a supernova. Each supernova is unique, which stems from the characteristics of the star itself. However, astronomers know white dwarfs very well. These common star types will gradually cool down with age and get colder and colder as time goes by. So the ultraviolet flash mentioned above is easy to be confused. Ultraviolet flash is produced under the condition of overheating, and the temperature is three to four times higher than that of the sun. Most supernovae cannot produce so much heat.
Adam miller, an astrophysicist at Northwestern University and the first author of this new study, believes that this ultraviolet flash shows something special about the explosion of this special white dwarf. Miller said in a report: "The explosion of these white dwarfs is the most common explosion in the universe, but especially its ultraviolet flash. For many years, astronomers have been looking for the reason behind this, but they still haven't found it.
This supernova appears as a blue light spot in its entire galaxy, 65438+400 million light years away from the Earth (Zwicky transient facility/Adam Miller (Northwestern University) and D goldstein (California Institute of Technology)).
The team that conducted this new study suggested four possible situations that could lead to this flash:
A white dwarf star may have swallowed a companion star and become so huge and unstable that it exploded.
Extremely hot radioactive material from the core of a star mixes with the outer material, causing the temperature to rise.
Helium in the outer layer reacts with carbon in the star, causing a double explosion.
Or is this flash an explosion made up of two white dwarfs?
As time goes on, clues about how supernovae are produced will be further revealed. "As time goes on, this explosive substance gradually moves away from the source, and with the decrease of this substance, we can see deeper and deeper places," Miller said. "After a year, this substance will become very rare, and we can see the whole picture of the explosion center." Further study of supernova explosion can provide astronomers with clues about dark energy. Although dark energy accounts for 68% of the energy in the universe, it has never been directly observed because it is very dark. However, astronomers believe that this explosion is the force of dark energy, which is contrary to gravity and accelerates the probability of cosmic explosion, but astronomers are not sure about the reason behind it.
Therefore, astronomers use supernovae formed by the explosion of white dwarfs as cosmic candles in the dark to measure the distance of the universe.
abstract:
The observation results of early type Ia supernovae provide important clues for understanding the ancestral system that led to the final thermonuclear explosion. We show the abnormal observation results of supernova 20 19yvq, which is the second type Ia supernova observed after IPTF 14 ATG. It shows the early ultraviolet light and optical flash. We think that supernova 20 19yvq is unusual. Even if its initial flash is ignored, it is moderately dim for type Ia supernovae (magnitude peak), but its absorption speed is very high (km s 1, with a peak value of Si iiλ6355).
We found that we can explain many features of supernova 20 19yvq except flash, provided that the radioactive 56Ni equivalent contained in the explosion is relatively low (measured by us), and it and other iron group elements are concentrated in the inner layer of the jet. In order to explain the ultraviolet/optical flash and peak characteristics of supernova 20 19yvq, we propose four different models: the interaction between supernova ejecta and nondegenerate companion stars, the 56Ni mass in external ejecta, a double explosion and the fierce merger of two white dwarfs.
There is a gap between each model and the observed results. Obviously, extra adjustment is needed to better match supernova 20 19yvq. Finally, if the ejecta collide with the companion star, strong ejection of Ca ii, double explosion, a small amount of O i, or violent merger, we predict that the nebula spectrum of supernova 20 19yvq will be characterized by the emission of H or he.