As well as months connecting planets, planets connecting stars, and dying galactic nuclei, galaxies can be orally displaced by other, less smaller galaxies. The Milky Way has many of these hangers, especially the large and small Magellanic clouds, the only two of our galaxies-satellites visible to the blue eyes.
Well, since Gaia data – always the most complete map of our Heaven ever co-founded – are found astronomers. And it's very great – as big as the Magellanic Cloud, or so one third of the size of # 39; e Milky Way.
In the above, it is the glow in & # 39; the upper left side of the picture, next to the Milky Way (bottom left), with the Magellanic Cloud on the bottom right.
Since it is located in the southern constellation Antlia (De Pomp), it was called Antlia 2.
So, how was Antlia 2 successful to escape long-term discoveries, especially about the world's 964 CE known as the Great Magellanic Cloud?
A few ways. The first is that it is not hidden enough behind the disk of Milky Way. The second is that it has a high low density, which means it does not provide much light. In fact, it is 10,000 times funnier than the Big Magellanic Cloud – its representation in the picture is elevated, so we can see it.
It is, of course, the most encrypted galaxy found there. It's still a lot of drivers – about 100 times – as the unlucky little ultra diffuse galaxies, the star does not form a star-shaped gas, and thus the ability to make new stars.
This could mean Antlia 2 only the remains of a galaxy long dead. Or as astronomer Gabriel Torrealba of Academia Sinica in Taipei set: "This is a spirit of a galaxy."
The team found the galaxies on a hunt for Milky Way satellites based on a type of star named RR Lyrae variables. These stars are very old and metal-arm and are often found in twangling galaxies and globular clusters.
By name they are also variable stars, meaning that their light provides a regular period of time – almost all the earth. This means that they will be used as standard candles to reach the exact distances between the earth and the star, such as Henrietta Leavitt's first in # 39; the 20th century.
The team found a group of stars in Gaia's data, but when they checked the location against known objects, there was nothing else. Thus they continued in the sun and managed to get the spectrum of 100 red gigantic stars just before Antlia's 2-position was found by the Sun, where it was expected for several months to stay.
All the thieves they studied were interconnected, thereby confirms the existence of a great, formerly unknown Antlia 2, which tries outside the Milky Way.
Based on the observations of the team, Antlia 2 or 424,000 light years of & quot; earth and is 11.2 billion years old. Simulations indicate that a lot of their material is included by the Milky Way – the same lot that is waiting for the Magellanic Clouds.
"The simple explanation of why Ant 2 today seems so small is that it is taken off by the Galactic Tides of Milky Way," said Astronomer Sergey Koposov of # 39; the University of Carnegie Mellon.
"What remains, is the growing size of objects. Normally, as galaxies lose massage in 'Milky Way times, they will clean, wait.'
This means that it probably was much larger than it has now begun, although it has not yet been determined. And there is also a question as Antlia 2 size.
As New Scientist reports, according to astronomer and RR Lyrae expert Gisella Clementini of the National Astrophysical Institute in Italy, the calculation used by the team to determine the distance to the RR Lyrae group. By correctly calculated, they are only 260,000 light-years away.
But, according to Torrealba, the musculoskeletal only changes the distance to the RR Lyrae stars, not the red gigants that the team studied, which they confirm with two different methods.
Both RR Lyrae stars for Antlia 2, which means that the discovery of galaxis was the result of a malignant and therefore very lucky, or they are part of. the galaxy, but only the closest edge.
Alderwei, there is no doubt that the team has been exploring in our neighborhood.
"In comparison with the rest of the 60 or so Milky Way satellites, Ant 2 is oddball," said Matthew Walker as astronomer, the University of Carnegie Mellon.
"We want to ask whether this galaxy is just the tip of an ice cream, and the Milky Way is closed by a large population of almost invisible dwarves like this."
The paper from the team was adopted in & # 39; the magazine Monthly Notices of Royal Astronomical Society, and can be read to preprint sources arXiv.