A monster star indicates the presence of dark matter

A monster star named Mothra after a giant butterfly from Japanese movies. It is so far away from us that astronomers could see it only thanks to the effect of a gravitational lens. But it is quite possible that this luminary indicates the presence of another mystery.

In this image, the monster star Mothra is designated as LS1. Source: Diego et al., arXiv, 2023

Monster Star and gravitational lens

A group of astronomers led by Jose Diego from the Spanish Research Center discovered an amazing star, which was named Mothra. This is the name of a giant butterfly from Japanese films, which is associated with the famous Godzilla. 

The Mothra star is unusual in its gigantic size and brightness. Such luminaries are extremely rare and are called “Kaiju”. This is the name of the monsters, which include both Godzilla and Mothra.

By the way, a star named after the biggest movie lizard also exists. It was opened a little earlier by the team of the same Diego, and it shone much brighter than Mothra. But despite its gigantic size, under normal conditions, we would never have been able to see any of these objects. After all, they are billions of years away from us.

What does Mothra look like

Scientists were able to see Mothra and Godzilla thanks to the effect of gravitational lensing. Somewhere between them and us are powerful clusters of galaxies, which gravity bends and focuses the light a little. Due to this, the monster star, which is also known as EMO J041608.8-240358 and is located at a distance of 10.4, is still visible as a tiny spot.

In fact, Mothra is a pair of giant luminaries: red and blue, orbiting around a common center of mass. The red star is dimmer. Its surface temperature reaches 5,000 Kelvin, and the luminosity is 50,000 times higher than the solar one. The blue star has a temperature of 14,000 Kelvin and is 125,000 times brighter than the Sun.

Mystery of Dark Matter

Interestingly, when scientists checked the archival images of the Hubble telescope, they found that Mothra was present on them back in 2014. However, then the monster star went unnoticed. But they have allowed scientists to estimate the magnification that the gravitational lens gives it.

It turned out to be equal to 4000. This is too much even for a massive cluster of galaxies. Scientists are convinced that somewhere between it and Mothra there must be another object that creates an additional gravitational lens. And the researchers even estimated its mass — from 10 thousand to 2.5 solar masses.

It should be a dwarf galaxy, but the problem is that James Webb just doesn’t see anything like it there. Scientists explain this mystery by the fact that this star system consists almost entirely of dark matter.

The existence of large systems of dark matter is quite consistent with modern ideas about this type of matter. However, not all theories that explain it permit the formation of compact objects. Scientists hope to learn more about it thanks to the third “Kaiju” — a triple system that has the name Ghidorah.

According to www.sciencealert.com

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