A large tidal stream observed in the Sombrero galaxy — ScienceDaily

Maria J. Danford

In accordance to the latest cosmological types, large spiral galaxies these kinds of as the Milky Way grew by absorbing scaled-down galaxies, by a form of galactic cannibalism. Evidence for this is specified by quite large constructions, the tidal stellar streams, which are noticed all over them, which are the continues to be of these satellite galaxies. But the comprehensive histories of the the vast majority of these circumstances are difficult to study, simply because these flows of stars are quite faint, and only the continues to be of the most the latest mergers have been detected.

A study led by the Instituto de Astrofísica de Andalucía (IAA-CSIC), with the participation of the Instituto de Astrofísica de Canarias (IAC), has made in-depth observations of a large tidal stream all over the Sombrero galaxy, whose peculiar morphology has continue to not been definitively explained. The outcomes are revealed today in the journal Every month Notices of the Royal Astronomical Society (MNRAS).

The Sombrero galaxy (Messier 104) is a galaxy some 30 million gentle decades absent, which is portion of the Nearby Supercluster (a team of galaxies which consists of the Virgo cluster and the Nearby Group containing the Milky Way). It has around one particular 3rd of the diameter of the Milky Way, and exhibits features of both of those of the dominant types of galaxies in the Universe, the spirals and the ellipticals. It has spiral arms, and a quite large vibrant central bulge, which would make it appear like a hybrid of the two types.

“Our motive for obtaining these quite deep photos of the Sombrero galaxy (Messier 104) was to appear for the continues to be of its merger with a quite substantial galaxy. This achievable collision was not too long ago instructed on the foundation of scientific tests of the stellar population of its peculiar halo obtained with the Hubble Place Telescope,” says David Martínez-Delgado, a researcher at the IAA-CSIC and first author of the paper reporting the get the job done.

The observations with the Hubble, in 2020, confirmed that the halo, an intensive and faint region surrounding the Sombrero galaxy, exhibits many stars rich in metals, components heavier than hydrogen and helium. This is a attribute to normal of new generations of stars, which are usually identified in the discs of galaxies, and are quite abnormal in galactic halos, which are populated by aged stars. To describe their presence astronomers instructed what is recognized as “a soaked merger,” a situation in which a large elliptical galaxy is rejuvenated by large quantities of gasoline and dust from a different substantial galaxy, which went into the development of the disc which we now observe.

“In our photos we have not identified any evidence to support this hypothesis, although we simply cannot rule out that it could have transpired several thousand million decades ago, and the debris is wholly dissipated by now -describes David Martínez-Delgado-. In our research we have in reality been in a position to trace for the first time the finish tidal stream which surrounds the disc of this galaxy, and our theoretical simulations have allow us reconstruct its development in the very last 3 thousand million decades, by cannibalism of a satellite dwarf galaxy.”

“Observational procedures in current working day Astrophysics will need superior impression processing. Our modelling of the vibrant stars all over the Sombrero galaxy, and at the exact same time of the halo gentle of the galaxy itself has enabled us to unveil the nature of this tidal stream. It is extraordinary that thanks to these superior photometric procedures we have been in a position to do entrance line science with a Messier object employing only an eighteen cm (diameter) telescope,” describes Javier Román, a postdoctoral researcher at the IAC and a co-author of the study.

The investigate workforce rejects the plan that the large stellar tidal stream, recognized for far more than 3 decades, could be relevant to the event which developed the peculiar morphology of the Sombrero galaxy which, if it was induced by a soaked merger, would will need the interaction of two galaxies with large masses.

The get the job done has been achievable thanks to the collaboration between skilled and beginner astronomers. “We have collaborated with the Spanish astrophotographer Manuel Jiménez, who took the photos with a robotic telescope of eighteen centimetre diameter, and the effectively-recognized australian astrophotographer David Malin, who found this tidal stream on photographic plates taken in the 90’s of the very last century. This collaboration exhibits the opportunity of beginner telescopes to consider deep photos of close by galaxies which give essential clues about the approach of their assembly which is continuing till the current epoch,” concludes Martínez-Delgado.

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