Zombie Star Brings Us One Step Closer to Solving the Mystery of Supernovae

I previously touched upon Oppenheimer's scientific achievements regarding research into how stars explode once their mass exceeds a certain threshold.

A pioneer of this, a white dwarf (a type of stellar remnant), has been observed behaving like a zombie. (Title image credit: ESA/ATG medialab/C. Carreau)

In short,
it was discovered that a white dwarf, in the process of resurrecting from death and triggering an explosion, is devouring surrounding stars,
is what this is about.

It certainly sounds like a zombie when written this way.

The aforementioned explosion is called a "Supernova" and is intense enough to be seen with the naked eye.
Some quite interesting research results have been published in recent years, and I will cite the article I introduced in the past.

As mentioned in the article above, understanding is deepened by observing not only with the naked eye (visible light) but also across various electromagnetic wavelength bands.

This time, for the first time in history, we were able to capture evidence of a supernova using "radio waves."

However, it seems this observation would not have been possible with an ordinary white dwarf.

A star that shines alone like the Sun will swell up like a pufferfish when it runs out of energy (in about 5 billion years) and then shrink into a white dwarf.
And when its mass exceeds 1.26 times that of the Sun (called the Chandrasekhar limit, though the cited article says 1.4; there is some variation in the initial definition), the possibility of a supernova explosion arises.

The final "supernova explosion" is merely a potential result, and the mechanism leading up to it remains unexplained.

The white dwarf targeted this time also had not exceeded the Chandrasekhar limit.
However, there was a star in its vicinity (a companion star), and the flow of events was that it absorbed energy from it, exceeded the limit, and triggered a supernova explosion.

Deepening our understanding of supernovae is actually quite important.

For example, supernovae are valued as a "cosmic yardstick."

It is a leading theory that the universe began with inflation and is still expanding today.

Supernovae were used as a means to measure the expansion rate of this universe.

This is because there are several types of supernovae, and the one observed this time is called a Type Ia supernova. (Detailed definitions are omitted.)

It is known that the brightness of these Type Ia supernovae is almost identical, and they were used as a standard to measure the values of other astronomical phenomena.

Then, in 1998, the observation of a certain Type Ia supernova revealed the shocking fact that the universe is expanding at an accelerating rate, faster than previously thought.

This gave rise to the hypothesis of a repulsive force (the opposite of gravity) permeating the entire universe, and created the drama of the "cosmological constant," which Einstein had initially proposed and later retracted, being revived.

This cosmological model has now become the standard and is also known as the "Λ-CDM (Lambda Cold Dark Matter) model".

Supernovae truly play the role of lighthouses illuminating the horizons of our science.