Scientists say the edge of the galaxy hides a huge ghost galaxy. British media: there is still no mystery
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Reported on November 24in
The British media said that behind the dust and gas plates that make up the Milky Way, there is a ghost galaxy that looks different from other galaxies that people have seen before. Or at least some astronomers say – but another researcher questioned his findings.
According to the British weekly "New Scientist," published Nov. 16, the newly discovered dwarf galaxies are one-third the size of the Milky Way. It is located in the constellation of Antria, 450 million light years from Earth. It is called "Antelia-2" – or "Ante-2".
Researcher Gabriel Torealva said: "It's similar in brightness to some galaxies around the Milky Way, we know they have been around for many years, but it's 10 times the size of these galaxies, and their brightness is distributed in the sky." The larger area makes it very fragmented and therefore more difficult to detect. "
According to reports, he and his team captured the "Ante-2" with a bright star named variable RR Lyle, and the bright stars of RR Lyle's variable vibrate, brighten and darken for a long time. As you know, almost all the small galaxies that orbit the Milky Way have at least one of these signals in sync with the surrounding stars.
According to the report, Yarwa and his collaborators used the four RR Lyle stars observed by the Gaia satellite to track the position and motion of nearby stars and map the Milky Way and its surroundings. The team discovered that the set of pulsating stars moved together.
The report said that they measured the light of 100 red giants around the four RR stars and found that they moved at the same speed, which means they belonged to the same galaxy. But these stars also indicate that the galaxies in which they are located are strange.
Based on distance, the research team concluded that the "Ante-2" is huge, covering about 9,500 light-years. But for such a galaxy, it is extremely dark. This is because its diffusion range is 100 times larger than the so-called hyper-diffusion galaxy. This means that the surface brightness of "Ante-2" is the lowest of known star systems.
Torre Yalva believes that this may be due to the dark matter of the Milky Way. It can be evenly scattered in the "Ante-2" instead of being concentrated in the center as in most galaxies. This may allow the "Ante-2" to maintain its enormous volume in the event of mass loss due to the gravitational influence of the Milky Way.
However, Gisela Clementini of the National Institute of Astrophysics in Italy said that before we can know exactly how unusual the characteristics of the "Ante-2" are, some questions still need to be answered. She studied the RR stars observed by the Gaia satellite and said there is an error in the formula used by the Torreyalava team to calculate the distance from the "Ante-2".
When she realized this, she asked him to collaborate with employees in Bologna and Naples, who all thought there was a problem with distance measurement. This is a serious problem, because the features of this galaxy are as unusual when the galaxy is as far away from us as Este's esteem team is.
Clementini said he reminded the team to pay attention to this issue and they agreed that they need to re-analyze. She said, "They have found something, but at this stage, unless we can confirm the calculation, I can not bet any property of the system."
Clementini said the RR Lyle star may not belong to the galaxy but may be in front of the galaxy. If this is the case, the research team found that "Ante-2" is pure luck. If the distance of the galaxy is much greater than we think, its dimensions will be more extreme. But if it's closer, it looks more like an ordinary dwarf galaxy.
Yarwa Tower said the error in its distance formula made the RR Lair star about 260,000 light-years away from Earth instead of the original 424,000 light-years. But they used two other methods to confirm the distance from other stars in the "Ante-2". He said that a galaxy like "Ante-2" should have hundreds of variable stars, and that group is the closest. He also said that the new calculations did not change the peculiar nature of "Ante-2".
Alan McConaughey of the University of Victoria in Canada said: "To make the unusual part of the galaxy appear less unusual, its distance must be twice as large.If you change it by 10% or 20%, it is still a very strange type of object ".
He said we have long known that "missing" galaxies are hidden behind the gas and dust of our Milky Way. There are also a small number of equally large and scattered galaxies – such as crater 2 and Andromeda 19. He said: "If they are some extreme objects, or the tip of the iceberg of a new type of galaxies, this is what we urgently need to know . "
According to the report, if the galaxy is more diverse than previously thought, if the galaxy is surrounded by dwarf galaxies, then people need to rewrite the understanding of how dark matter spreads through the universe and its mechanism for collecting stars. (Compile / Hu