Shulou(Shulou.com)11/24 Report--

Last time we introduced a star that suddenly "disappeared" (N6946-BH1), saying it was "sudden" because it completely disappeared from our view in the visible band in just a few months. A few months is almost an instant for a star, so astronomers call this change in brightness in a short period of time "transient". Although scientists have come up with reasons such as "failed supernova" and "ejection occlusion" for this transient phenomenon, what should scientists do if three "stars" disappear at the same time within an hour?

In the 1950s, when astronomers compared photos of the sky survey, they found that three stars were suddenly missing in one of the photos, and what was even more strange was that the two photos used for comparison were taken less than an hour apart.

Astronomers made a number of observations over the next 71 years, including two deep exposures from the large Canary Telescope in 2023, but failed to capture those three light sources.

Follow-up shooting

To be honest, if one star is missing, to be honest, even three stars we said last time, but it is a bit strange to "disappear" three stars at the same time in such a short time.

There are a variety of sky survey programs today, from the Gaia telescope in space to the Sloan survey based on the ground. Sky survey is a way of scanning the sky, which is equivalent to a "census" of every light source in the sky. Although time-consuming and laborious, the results are very useful, and many celestial bodies and large-scale structures are found in this kind of sky survey.

One of the earliest large-scale Sloan surveys should be the Palomar Observatory Survey I (POSS I), which was funded by the National Geographic Society in the 1950s. From the first photo taken on November 11, 1949 to the last shot on December 10, 1958, Palomar took nearly 2000 sets of photos in nearly 10 years.

In order to record the color information of celestial bodies, at that time, each shot would take a red light, and then a blue light. One day someone found that the red and blue photos of one group did not match. There were three light sources missing in the blue photos, and they were very bright lights. From the characteristics of the light source, the three bright spots show a regular circle, which indicates that their positions are relatively stable. Why? Because if they move obviously relative to the earth, these bright spots should be elongated and deformed during the long exposure of the photo.

So we can first rule out some near-Earth objects, such as asteroids, meteorites, including airplanes. Is it possible that it is a synchronous satellite in geostationary orbit?

Because the synchronous satellite is synchronized with the rotation of the earth, its position is fixed relative to the ground observer. When it reflects sunlight, its brightness in the picture is indeed similar to that of a star. And once it turns the reflection angle, the observer will not see it immediately, which can indeed cause a similar transient phenomenon.

Note, however, that these two photos were taken in 1952, and the first satellite was not launched until 1957, when the first phase of the sky survey was almost completed, so these bright spots could not have been caused by the satellite. Speaking of this, people can't help but think that today's low-Earth orbit in space is already full of all kinds of man-made objects, which makes Palomar's images of the sky survey very precious.

In general, after ruling out the possibility of near-earth, the three light sources are very similar to nearby stars in shape and brightness. And these three bright spots are located in the northeast of Cygnus, less than 1 degree from the surface of the Milky way, almost on the silver plate. Most of the stars in the Milky way are located near the galactic disk, so the possibility that these three bright spots are stars is still relatively high.

A star disappears from the universe, usually because it has reached the end of life. But we know that stars generally evolve in terms of hundreds of millions of years, and even massive stars tend to have a lifespan of tens of millions of years. In short, the extinction of stars is an extremely long process for human beings.

Unless the starlight we see is not emitted by a star under normal conditions, but some kind of explosion. For example, a star in an extragalactic galaxy is so far away that it can't be seen at all, but when it explodes into a supernova, its brightness suddenly increases exponentially. If it is caught by the camera at this time, it may be regarded as an ordinary star in the Milky way. By the time the picture was taken later, the explosion was over, so the star looked as if it had disappeared.

But the problem is that for a supernova explosion, its darkening process lasts at least a few days or even weeks. As can be seen from the time these two photos were taken, one was taken at 08:52 on July 19, and the other was taken at 09:48, less than an hour apart. What's more, these three stars are "flameout" at the same time, so it can be considered that their disappearance is certainly not the reason for the simple end of life.

If the star is not dead, could it be the ejection of one star blocking the three stars? As I said last time, this degree of shielding does not necessarily cover the stars themselves, let alone three stars. And the kind of material ejection caused by the merger of the two stars last time takes about a month, which is also a long process.

Up to now, apart from noise, equipment and other problems, is there any possible performance to explain the disappearance of three light sources at the same time? This time, let's start from the logic and repeat the matter from the beginning.

First of all, the simultaneous dimming of these three light sources is certainly not a coincidence of three separate events. Because it is rare for even a single light source to suddenly disappear in such a short period of time, let alone three, let alone next to each other. No matter what you think, it's hard to believe that they have nothing to do with each other. So we have reason to conclude that the brightness changes of these three light sources are caused by some common cause, is that all right?

Since there is some kind of coordination between the three light sources, the fastest speed of this coordination is the speed of light. The change from bright to dark takes place in about 50 minutes, which means that the actual interval between the three light sources is no more than 50 minutes, which translates to about six astronomical units, which is about the distance between Jupiter and the sun.

Then the upper and lower light sources are about 10 arc seconds apart in the image, from which it can be inferred that the distance between the three light sources is no more than 2 light years. Because if it is more than 2 light years, it means that the angular interval of 10 arc seconds is more than 6 astronomical units, then the causal relationship between the light sources cannot be established.

To sum up, it can be concluded that the three light sources are less than 2 light years from the earth and are within 6 astronomical units apart from each other. But Proxima, our nearest star except the sun, is also more than 4 light-years away. So it can be concluded that these three light sources cannot be three stars.

So far we seem to have come to two opposite conclusions: judging from astronomical phenomena, they are likely to be stars, while logically they cannot be stars. What should we do with such a contradictory result? Astronomers say: maybe both are right.

The researchers offer the possibility that the three bright spots may come from the same light source. They are three images caused by the gravitational lens effect, like the famous Einstein Cross.

If the background light source is located in the Milky way, the light source may be a massive star, and then it is disturbed by some kind of gravity in our line of sight. It may be some kind of celestial body, or it may be some kind of complex mass distribution, in short, the foreground quality causes the background light source to produce the image of three gravitational lenses. After that, once the environment of the foreground quality changes, the image of the gravitational lens disappears.

If the background light source is not in the Milky way, but in the extragalactic galaxy. So such a high brightness means that it is not an ordinary star, but more like some kind of explosion, such as supernova explosions, neutron star merging and gamma ray bursts. In short, light sources are indeed stars, and the image of gravitational lenses makes them look really close to us, which is why they are both right.

Of course, the explanation of this gravitational lens is only speculation, after all, there is no other photo to confirm this statement except the one taken 70 years ago. Even with more advanced devices such as JWST, we can no longer observe them.

The reality is that many phenomena in astronomy are transient phenomena that occur only once. Once you don't grasp it at that time, you miss it. However, this is not the case in our lives. Some things are understood only when we miss them, while some people stop once we miss them.

Reference:

[1] https://en.wikipedia.org/wiki/National_Geographic_Society_%E2%80%93_Palomar_Observatory_Sky_Survey

[2] https://phys.org/news/2023-10-group-stars-vanishedastronomers.html

[3] https://academic.oup.com/mnras/article/515/1/1380/6607509

[4] https://arxiv.org/abs/2310.09035

This article comes from the official account of Wechat: Linvo says ID:linvo001, author: Linvo

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.