The IAC team of researchers, composed of Luis Cicuéndez Y Giuseppina Battaglia, discover the case of galactic cannibalism on a smaller scale observed to date. It is the dwarf galaxy Sextans, 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.
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).
The Víctor M. Blanco Telescope, also known as Blanco 4m, is a 4-meter telescope located at the Cerro Tololo Inter-American Observatory, Chile. Commissioned in 1974 and completed in 1976, the telescope is identical to the 4m Mayall telescope located at Kitt Peak.
The Magellan telescopes are a pair of twin optical telescopes of 6.5 m in diameter located at the Las Campanas Observatory in Chile. The two telescopes are named one in honor of the astronomer Walter Baade opened on September 15, 2000 and the other in honor of the philanthropist Landon Clay, which began operating on September 7, 2002.