Research investigating the surroundings of the globular cluster NGC 6355
Interstellar extinction (E(B − V )) map across the observed NGC 6355 field. The black circle represents the cluster radius. Credit: Piatti et al., 2024.
Argentine astronomers used the Dark Energy Camera (DECam) to study the surroundings of a globular galaxy cluster called NGC 6355. The study, published in a paper published May 2 on the preprint server arXiv, found that star clusters have some additional features: tidal characteristics. House nanotechnology Physics earth astronomy and space chemistry biology Other science Research investigating the surroundings of the globular cluster NGC 6355 0 May 9, 2024 0 astronomy and space astronomy Editor’s note Research investigating the surroundings of the globular cluster NGC 6355 Written by Tomasz Nowakowski, Phys.org report Research investigating the surroundings of the globular cluster NGC 6355 Interstellar annihilation map (E(B – V )) across the observed NGC 6355 field. The black circle represents the radius of the cluster. Image credit: Piatti et al., 2024. Argentine astronomers used the Dark Energy Camera (DECam) to study the surroundings of a globular galaxy cluster called NGC 6355. The study, published in a paper published May 2 on the preprint server arXiv, found that star clusters have some additional features: tidal characteristics. Globular clusters (GCs) are collections of closely connected stars orbiting a galaxy. Astronomers consider them natural laboratories that allow them to study the evolution of stars and galaxies. In particular, because the origin of GCs appears to be closely linked to periods of intense star formation, GCs could help researchers better understand the formation history and evolution of early-type galaxies. Located about 27,800 light-years away in the galactic bulge, NGC 6355 is a 13.2 billion-year-old GC with a chaotic orbit. The absolute magnitude is -8.07 mag, and the average metallicity is estimated to be -1.39 Dex. Recently, a team of astronomers led by Andres E. Piatti of the National University of Cuyo in Mendoza, Argentina, observed NGC 6355 and its surroundings in search of extratidal structures. For this purpose, they used his DECam attached to his 4m Blanco telescope at the Cerro Tororo Inter-American Observatory (CTIO). “We analyzed wide-field DECam-g,i images around the bulge globular cluster NGC 6355 in the Milky Way Galaxy, with the aim of exploring extratidal structures. -627924 was observed as part of the program observations, resulting in relatively deep photometry outside the cluster,” the researchers wrote in their paper. DECam observations revealed the existence of extratidal overcrowding that exceeds the average density of the star field. These excess densities appear to be 4 to 6 times larger than the density spread of the stellar field.
The identified overdensities turned out to consist of an extra-tidal extended envelope azimuthally not symmetric, a tidal tail, and scattered stellar debris alongside the tidal tail. It was noted that the tidal tail points toward the Milky Way center.
The astronomers noted that their discovery makes NGC 6355 the first Milky Way bulge GC with detected extra-tidal structures. However, they added that this finding is somehow surprising according to the theoretically expected scenario.
“These results contrast with previous theoretical speculations about the possibility to detect tidal tails of globular clusters with chaotic orbits because they would be washed out after they were generated,” the authors of the paper explained.
Therefore, based on their discovery, the astronomers concluded that tidal tails among bulge GCs seem to be a more common phenomenon than previously thought. However, more observations of the outskirts of such GCs are required in order to confirm this assumption.
source: https://dx.doi.org/10.48550/arxiv.2405.01485