Saturday , October 16 2021

Scientists say that the edge of the galaxy hides large ghost galaxies, British media: there are still unsolved mysteries – International Online



Reference News Network reported on November 24 that British media said that behind the dust and gas disks that are the Milky Way, there were ghost galaxies that looked different from other galaxies that had been seen before. Or at least that's what some astronomers say – but other researchers question their findings.

According to the British "New Scientist" weekly reported on November 16, the newly discovered dwarf galaxy is one-third the size of the Milky Way. Located in the Constellation of Antria, 450 million light years from Earth. This is called "Antelia-2" – or "Ante-2".

Researcher Gabriel Torealva said: "This is similar to some galaxies around the Milky Way. We know they have been around for years. But that's 10 times the size of these galaxies, and brightness is distributed in the sky. The wider area makes it very fragmented and hence more difficult to detect. "

According to reports, he and his team captured "Ante-2" with a bright star called the RR Lyle variable, and bright stars from the RR variable Lyle vibrated, brightened and darkened for a long time. As you know, almost every small galaxy orbiting the Milky Way has at least one flare that goes in harmony with the stars around it.

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Big ghost

According to the report, Torre Yarwa and his collaborators used four stars RR Lyle observed by the Gaia satellite to track the position and movement of nearby stars and map the Milky Way and its surroundings. The team found that a pulsing collection of stars moved together.

The report said that they then measured the light of 100 red giant stars around four RR stars and found that they were moving at the same speed, which meant they belonged to the same galaxy. But these stars also show that the galaxy where they are is strange.

Based on distance, the research team concluded that "Ante-2" was very large, covering around 9,500 light years. But for such large galaxies, it's very gloomy. This is because the diffusion range is even 100 times greater than what is called a hyper-diffusion galaxy. This means that the surface brightness of "Ante-2" is the lowest of the known star system.

Torre Yalva believes that this is probably due to the Milky Way's dark matter. This may be spread evenly in "Ante-2" rather than concentrated in the center as in most galaxies. This allows "Ante-2" to maintain a very large volume in terms of losing mass due to the gravitational influence of the Milky Way.

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Strange galaxy

However, Gisela Clementini of the Italian National Astrophysics Institute said that before we can know exactly how unusual the characteristics of "Ante-2" are, some questions still need to be answered. He studied the RR star observed by the Gaia satellite and stated that there was an error in the formula used by Torreyalava's team to calculate the distance from "Ante-2".

When he realized this, he asked him to collaborate with collaborators in Bologna and Naples, who all thought there was a problem with distance measurement. This is a serious problem, because the characteristics of these galaxies are very unusual only when galaxies are far away from us as Estai's team estimates.

Clementini said he had reminded the team to pay attention to this problem and they agreed that they needed to re-analyze it. He said: "They found something, but at this stage, unless we can confirm the calculation, I can't bet any property from the system."

Clementini said that the RR star Lyle might not belong to a galaxy, but maybe in front of the galaxy. If this is the case, then the research team found "Ante-2" is pure luck. If the distance of the galaxy is far more than we think, then its dimensions will be more extreme. But if it's closer, it's more like an ordinary dwarf galaxy.

Torre Yarwa says that errors in their distance formula make the RR Lair star around 260,000 light years from Earth and not 424,000 light years original. But they use two other methods to confirm the distance of other stars in "Ante-2". He said that galaxies like "Ante-2" should have hundreds of variable stars, and this group is the closest. He also said that the new calculations did not change the unique nature of "Ante-2."

Alan McConaughey from the University of Victoria in Canada said: "To make an extraordinary part of a galaxy look unusual, the 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 that we have long known that "lost" galaxies are hidden behind our Milky Way gas and dust. There are also a small number of galaxies that are as large and scattered – like craters 2 and Andromeda 19. He said: "Are they some extreme objects, or the tip of a new type of iceberg, this is what we really need to know."

The report says that if galaxies are more diverse than previously thought, if galaxies were surrounded by bloated dwarf galaxies, one might need to rewrite understanding of how dark matter spread throughout the universe and the mechanism of collecting stars. (Compilation / Hu Wei)

(Original title: Scientists say that galaxies hide large ghost galaxies on the edge of the Milky Way. British media: there is still no mystery)

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