The halo in the galaxy is full of stars

The new map of the halo of stars around our Milky Way galaxy recently revealed the structure of intertwined stars, many of which have never been discovered before.

While most of our galaxy stars are concentrated in relatively flat disk regions and the center of the bulb-shaped center, the halo is the first object that galactic interstellar lines can penetrate with Our galaxy's approach. The halo starts from the edge of the flat disk about 65,000 light-years from the galactic center and can extend outward to 300,000 light-years from the center of the galaxy. It includes constellations, gas clouds, dark matter and some single stars. Some objects belonging to other tiny galaxies are kept by the Milky Way as they pass through.

The largest line of stars in the halo has been mapped over the last decade, but new data from the Sloan Digital Sky Survey (SDSS-II) has discovered many smaller lines before. once known, along with the remnants of dwarf galaxies that are too close and some nearby objects that exist.

The stars are remnants of smaller galaxies that have been destroyed.

New findings are published at the international symposium in Chicago on August 16.

Small scale, small quantity

The survey identified the movement of about 250,000 stars in selected regions of the sky in search of groups moving at the same speed. The survey found 14 distinct structures, of which 11 structures have never been seen before.

Because researchers only search on a small scale in the Milky Way galaxy, 14 lines of stars discovered 'imply a huge number when performing extrapolation to the rest of the galaxy' , Kevin Schlaufman, a graduate student at the University of California in Santa Cruz - said.

There could be up to 1,000 lines of stars in the 75,000 light-years region inside the Milky Way galaxy with the assumption that each of the 14 observed structures is a separate stream of stars. There may be fewer fine lines in different locations.

The hypothetical model of a galaxy like our Milky Way galaxy shows images of stellar lines from broken satellite galaxies merging into the galaxy at the center.The complex structure on the SDSS-II star map supports the prediction of a complex Milky Way.The region on the model is about 1 million light-years away, the sun is in the center of the galaxy with a distance of 25,000 light-years and is located near the center of the image.(Photo: K. Johnston, J. Bullock)

Macaroni fibers

Columbia University researcher Kathryn Johnston described the halo as "a spaghetti" .

She said: 'In the center of the galaxy, the stars gather together so you can observe the flexible combination of stars. But as you look further, you can identify individual strands as well as somewhat similar characteristics like wheat fibers derived from long-drawn dwarfs. '

According to Johnston, dwarf galaxies moving near the Milky Way have been pulled by gravitational forces into spaghetti-like strands that twist around the galaxy as stars move on the same trajectory but with movement. different speeds.

Heidi Newberg of Rensselaer Polytechnic Institute and graduate student Nathan Cole are trying to track some of these noodles as they wind around the galaxy.

Cole said: 'This is a great challenge to assemble all phenomena together due to the stream of stars from a dwarf galaxy that can encircle the Milky Way galaxy and pass through the fine lines from Other dwarf galaxies'.

Newberg and Cole discovered at least two overlapping structures, presumably 3 or more, towards the Virgo constellation where SDSS images reveal a huge amount of stars that cover an area. Great in the sky. Velocity calculations can be used to differentiate overlapping systems, some of which stem from the 'tidal arm' of the Sagittarius dwarf galaxy.

What exists

SDSS data also revealed the Milky Way's 14 'dwarfs' active, including two newly discovered galaxies published at the symposium. These satellite galaxies have orbits in the halo that contain unobservable dark matter with gravity that binds the Milky Way.

The newly discovered dwarf galaxies are somewhat fainter than the galaxies discovered before the survey. Although SDSS can detect extremely dim dwarf galaxies, it can only do so if the galaxy is near. That's why there may be several hundred dwarf galaxies outside the Milky Way's halo or more.

Johnston said: 'SDSS has shown us a lot about the Milky Way and its neighbors. But we are only at the beginning of a comprehensive galaxy mapping. There is much more to discover for the next generation of surveys, including two surveys of the Milky Way galaxy made in SDSS-III '.