Sextans: the smallest cannibal galaxy discovered to date
Sextans: the smallest cannibal galaxy discovered to date
The team of researchers from the IAC (Spain), composed by Luis Cicuéndez and Giuseppina Battaglia, discovers the case of galactic cannibalism on a smaller scale observed to date. It is the dwarf galaxy Sextans that, with a mass 100,000 times smaller than the Milky Way, has devoured an even smaller companion.
Using data from the Víctor M. Blanco Telescope (4 m in diameter), installed at the Cerro Tololo Inter-American Observatory, and the Landon Clay Telescope (6 m), also known as Magallanes 2, from the Las Campanas Observatory, both in Chile, In Sextans they observed clear signs of having absorbed another system of smaller size.
When analyzing the dwarf galaxy, they observed that the spatial distribution of the blue stars (poor in metals) becomes round and regular, while that of the red stars (rich in metals) is much more elliptical and irregular, with the presence of a stellar overdensity on its northeast side. "The most reasonable explanation for this phenomenon is that, originally, the merged galaxies had different metallicities," explains Luis Cicuéndez, a researcher at the IAC and the University of La Laguna.
Several examples of massive galaxies fusing with each other. (Credits: NASA, ESA, the Hubble Heritage and Collaboration, and A. Evans.)
In the same way, both velocity analysis and indicators of the chemical composition of the stars reveal the presence of a ring-shaped spatial substructure. This substructure presents a considerably higher speed and chemical composition different from the rest of stars in the galaxy.
"This finding would prove that the hierarchical model of galaxy formation, by which these would merge to form the larger galaxies, can continue to explain the formation of the smallest galaxies known so far, the so-called dwarf galaxies," says the researcher. of the IAC and co-author of the work, Giuseppina Battaglia.
The details of this new discovery are published in the new volume of the Monthly Notices of the Royal Astronomical Society (MNRAS). (Source: IAC)
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