On January 27, Zhang Xiang, an assistant researcher at the Shanghai Astronomical Observatory, and scientists at the International Radio Astronomy Research Center at Curtin University in Australia released a research result online in Nature, and two scientific teams found a radio transient source with unusually slow periodic radiation by analyzing the sky survey observation data of the SKA pilot telescope.
So how exactly was this uncommon object discovered?
In fact, the signal was discovered as early as early 2018, when the telescope recorded a mysterious object that lit up at least 70 times, and then it was silent until today. Three years later, an undergraduate intern taught by Dr. Hurley Walker was the first to discover an anomalous data while collating the data.
In February 2021, while collating past data, the intern discovered this magical "light" and reported to his supervisor, Dr. Hurley Walker. Hurley Walker immediately analyzed and processed this data and thought that this unusual "light" was a polarization source, and Dr. Hurley Walker also found Zhang Xiang, a researcher at the Shanghai Observatory who was engaged in this aspect of research on the mainland, to conduct in-depth analysis, re-observe and modeling reasoning and finally concluded that this temporary source is in our Milky Way, and even the specific location is on the edge of the Milky Way, and it is only 4200 light-years away from the earth.
It can be speculated that at the time of its outbreak is 150 megahertz band, the burst period is about 18 minutes, each burst lasts about 30-60 seconds, this burst cycle is 9 times longer than the longest known white dwarf burst cycle found by scientists today, we can imagine the scene at that time, its burst if we find it in time is like a night pearl hanging in the sky, the luminosity is softer.
Speaking of which, you may be curious, what exactly is a white dwarf?
We all know that everything in nature has a lifespan, even for seemingly eternal objects like stars, which are combined by clouds of dust and gas gravitationally at the beginning of their life cycle, and then throughout their long life cycles, they are emitted by activating nuclear fusion at the original extremely high temperatures to consume fuel. Massive stars end their long lives in the form of explosions after consuming the last bit of fuel.
But this is only the case with massive stars, smaller stars in the late stage of their own life volume will continue to expand and become red giant, red giant is not the final form of the sun, when the temperature inside the red giant can not reach the conditions of nuclear fusion, its outer layer of the body will gradually fall off, only the core part remains, leaving the core of the sun is the white dwarf, which can also be said to be the last fuel in the life of the sun, this core is bright and hot, far higher than the temperature of the sun, but you may not believe it, This white dwarf, although it is glowing and hot, does not burn, it is small in size and low in brightness, but it is massive and dense.
For example, the earliest discovered white dwarf Star Sirius Companion Star, which is the same size as the Earth, but the mass is not much different from the Sun, which can be said to be quite exaggerated, which is due to gravity pushing electrons as far as possible to crowd in the smallest space, and then making the white dwarf become very dense. Once the white dwarf has burned up the little fuel left, it will be extinguished forever.
So the question is, will our sun eventually become a white dwarf?
Scientists have long believed that white dwarfs are the final destination of stars such as the sun, but as the research progresses, scientists have found that the end of the sun may not be like this.
White dwarfs have extremely high surface temperatures, usually above 10,000 degrees, and the core temperature is even as high as 100 million degrees, so high temperatures are doomed to have no nuclear fusion reaction inside white dwarfs, but as the temperature drops, eventually the white dwarf will cool down, and finally it is likely to become a non-luminous dark star, which scientists call black dwarfs.
So black dwarfs may be the ultimate destination of stars like the Sun, and if scientists' speculation holds, then black dwarfs, like black holes, are almost impossible to observe. But so far, black dwarfs are still only at the forefront of science theory, this is because the current age of the universe is not old enough or the universe is not vast enough we have not yet discovered, scientists currently observe the oldest white dwarf with its surface temperature of thousands of degrees Celsius, that is to say, we have not yet observed the cooling to the black dwarf sun.