Samsara IV before it became dark

Every shining star in the universe will one day go out, and its "lifespan" is closely related to its mass, the more massive the star, the shorter its "lifespan". For example, the "lifetime" of a Proxima star is about 12.2% of the Sun's mass, and its "lifetime" can be trillions of years, while the Sun's "lifetime" is only about 10 billion years, and the "lifetime" of stars that are much larger than the Sun is even shorter.

For example, Betelgeuse, about 640 light-years away, has a mass of 16.5 to 19 times that of the Sun, which makes the "lifetime" of this star much lower than that of the Sun, and although it was born 8 to 8.5 million years ago, it is already in its "late" age.

According to known patterns of stellar evolution, massive stars like Sensui IV do not die out silently in the universe, but after the "nuclear fuel" in their core is depleted, they undergo a powerful "supernova explosion" that releases enough energy in a short period to rival an entire galaxy. The energy released in a short period is comparable to that of an entire galaxy.

Observations show that the current Sensui IV has evolved into a "red supergiant", which can be up to 700 million times the size of the Sun, and this is the last stage of the life cycle of Sensui IV, which means that shortly, this giant star, which is not too far from us, will undergo a "supernova explosion". That is why astronomers have been keeping an eye on Sensui IV.

The chart above shows the observational record of Sensui IV over the past 20 years (the horizontal axis represents the year, and the vertical axis represents the apparent magnitude), and you can see that the brightness of Sensui IV has been changing since 1996, but usually within a small range.

During this dimming, the brightness of Sensua IV was reduced to about two-thirds of its normal level, leading to speculation that Sensua IV was likely to blow up, but this did not happen, as it gradually returned to its normal brightness in the following time.

The anomalous performance of Sensui IV has undoubtedly attracted strong attention, and astronomers have offered several explanations for the phenomenon in subsequent studies, with the most widely accepted one being that a huge dust cloud may have briefly obscured some of Sensui IV's light, giving us the illusion that the star had dimmed steeply.

Recently, a new study suggests that this dimming of Sensua IV may not be as simple as a dust cloud, as it is suspected to have been pierced by a mysterious force before the dimming of Sensua IV.

The study was led by astronomer Lynn Matthews of the Massachusetts Institute of Technology and astronomer Andrea Dupree of the Smithsonian Astrophysical Center at Harvard University.

In a paper to be published in the Astrophysical Journal, they show that, after careful analysis of detailed observations of Sensui IV, the researchers found that the actual brightness of Sensui IV during this darkening was about 20% fainter than previously announced and that its surface brightness distribution was more complex than the theoretical uniform elliptical disk, but did not have the distinctive feature of being obscured by a dust cloud.

The above figure shows the darkening process of Sensui IV based on the actual observation data. The researchers found that during the darkening of Sensui IV, the electron density in its southern hemisphere showed a significant increase, accompanied by a large amount of material loss.

After linking the above phenomenon with the radio characteristics of Sensui IV, the researchers made bold speculation that Sensui IV may have been pierced by a large-amplitude shock wave before the dimming process, which led to a change in the density structure and surface temperature of Sensui IV, and that the brightness of Sensui IV would be steeply dimmed during the subsequent massive material loss. brightness gradually returns to normal again.

If this is the case, what mysterious force is responsible for such a powerful shock wave?

Astronomers do not have a definite answer to this question, and can only offer reasonable speculation that the shock wave came from the interior of Sensui IV, whose core is usually not very stable when a star like Sensui IV is nearing the end of its life cycle. Of course, this is just a guess, we can also guess that this is a mysterious force from deep space, but this is a bit of science fiction.

It is worth mentioning that, at a distance of 640 light-years, even if a "supernova explosion" occurred in Sensui IV, the material generated by the shock wave is unlikely to affect the Earth, the only thing we need to pay attention to is whether the gamma-ray burst generated by the Sensui IV burst will hit the Earth, fortunately, the direction of the gamma-ray burst is consistent with the rotation axis of the star Fortunately, the direction of the gamma-ray burst is consistent with the rotation axis of the star, and the rotation axis of Sensui IV is not aligned with the Earth, and is at least 20 degrees off, so we do not have to worry about Sensui IV forming a threat to the Earth in the future.