Astronomy: Milky Way almost killed neighboring galaxy
If the Large Magellanic Cloud were not quite so massive, the Milky Way would have robbed it of any opportunity to form new stars. But it was close.
Artist's impression of the dwarf galaxy and the pushed away gas
(Image: NASA, ESA, Ralf Crawford (STScI))
One of the closest galaxies to us has not lost too much gas for the formation of stars through "catastrophic interaction" with the Milky Way only because it is comparatively large. This is suggested by a new analysis of the so-called halo of the Large Magellanic Cloud (GMW), which has now been presented. According to the study, this structure of gas surrounding the dwarf galaxy is only a tenth of the size of comparable galaxies. Most of it has apparently been pushed away by our Milky Way, which has made it almost impossible for its neighbor to form more stars. "The GMW is a survivor," says study leader Andrew Fox from the European Space Agency ESA.
Narrowly escaped death
The Large Magellanic Cloud has about 10 percent of the mass of our Milky Way, which puts it above most other dwarf galaxies. Whether it orbits the Milky Way or merely passes through it is still controversial among researchers, writes the research group. However, their work now shows that our home galaxy is pushing gas away from the GMW like a gigantic hairdryer. If the dwarf galaxy were not so massive, it would probably have lost almost everything and have no material left from which stars could form. Then it would have remained merely "a collection of ageing red stars", the team writes.
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The astronomers determined the extent of the GMW's halo using the Hubble Space Telescope. Only this is capable of doing this. They focused on quasars behind the dwarf galaxy, whose light provided information about the gas that passed through it. Quasars are so-called active galactic nuclei, supermassive black holes around which matter is racing, which is strongly heated and therefore shines immensely brightly. The analysis once again underlines how valuable the ageing space telescope still is for research.
The study, which has now been presented in the scientific journal The Astrophysical Journal Letters, should not only help to better understand the interaction between the Milky Way and the Large Magellanic Cloud. As a unique laboratory of astrophysics, the two galaxies could also help to better understand processes in the early universe. At that time, the galaxies in the cosmos were much closer to each other than they are today. The study underlines how "chaotic and complicated the process of galaxy interaction is". Next, the research group is eager to explore the area where the halos of the Milky Way and the GMW meet.
(mho)
