Research

Astronomers explain unusual waves on the surface of our Milky Way.

Last year, astronomers discovered a dwarf“Ghost galaxy” revolving around our Milky Way and called Antila 2. A new study by scientists from the University of Rochester suggests that this galaxy long ago came across ours and the consequences of this collision are still observed. The galaxy grazed the edge of our Milky Way, having shook it so that our galaxy is still shaking. The results of the study are accepted for publication in the journal Astrophysical Journal Letters.

From our perspective, understand the true dimensions andThe shape of our galaxy is quite difficult. In general terms, scientists know that the Milky Way has the shape of a disk with a convex center (the so-called jumper). If you look at it "from above", you can see its spiral arms, consisting of bright stars and gas, emerging from the center and crossing the galaxy in the middle.

What causes intergalactic collision?

About a decade ago it was found thatthe matter of our galaxy is covered in "waves". Even then, astronomers suggested that these waves are the gravitational consequence of the intergalactic collision of our galaxy and some dwarf satellite galaxy, which could pass along the edge of the Milky Way. Scientists from the University of Rochester believe that they have found a suitable candidate for this role. Experts even calculated its approximate mass and current location.

Detected in Gaia Space Telescope dataEuropean Space Agency Antila 2 was a very unusual dwarf galaxy. It revolves around the Milky Way at a distance of 420,000 light years. It has extremely small size - about 7-8 thousand light years, as well as a record low "star-population density". Finding this "ghost galaxy" was not easy. And not only because of her dullness, but also because she has been hiding behind the bright light of the stars of the jumper of the Milky Way all this time.

Using data from Gaia, astronomers couldcalculate its trajectory and found that it was she several hundred million years ago (by space standards recently) could touch the edge of our galaxy, which caused wave ripples on its surface. Further calculations showed that the size, speed and location of Antlia 2 correspond to those predictions that indicate where the originator of the cosmic collision should have been at the moment.

A team of scientists also modeled the conditions andthe influence she could have on the Milky Way. As it turned out, these models showed similar effects of matter perturbations, which are currently observed in our galaxy.

Simulation showing the movement of the Antlia 2 ghost galaxy (lower cluster) after its collision with the Milky Way (central cluster)

Finalize Your Assumptionsscientists have decided by eliminating other dwarf galaxies, which could also be responsible for the intergalactic catastrophe. For example, scientists found that the Sagittarius dwarf galaxy would not have enough gravitational forces for such effects, and the Large and Small Magellanic clouds are too far away to produce the observed effects.

Of course, the collision of Antlia 2 with the Milky Wayhad a serious impact on her. According to researchers, the gravity of our galaxy, which is much more massive, most likely, has deprived Antlia 2 of most of the matter and stars, making it so dim.

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