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Ultra-deep imaging of M33: exploring its stellar halo
Triangulum Galaxy Extended Halo - And450 survey (sample)
Credit: Giuseppe Donatiello
M33 represents a unique opportunity to study spiral galaxies. Dwarf galaxies tend to be irregular mixtures of stars and gas, very different from the beautiful, larger spirals. Large, undisturbed dwarf spirals, like M33, are therefore environments that allow a better understanding of hierarchical formation phenomena.
Strange as it may seem, we still know little about M33. It is unclear whether or not it interacted with the larger Andromeda galaxy (M31).
Both its proximity to M31 and the distorted structure of M33's disk suggest that the galaxies already interacted tidally with each other about 2.5 billion years ago. The effect of this interaction is currently observed as a deformation of the outer part of M33's disk. A close passage between the galaxies would also have increased star formation activity in M33, according to a simulation (Semczuk et al. 2018). According to this scenario, M33 would have already encountered M31 and perhaps lost its satellites and globulars.
In a second scenario, M33 would instead be falling into the Local Group for the first time, thus retaining its entourage of satellites and globulars. According to models, a galaxy like M33 should possess at least a dozen satellite galaxies, but to date only two are suspected: Andromeda XXII (Martin et al. 2013) and Pisces VII, discovered by me (Martinez-Delgado et al. 2021). Triangulum IV remains to be confirmed.
Ultra-deep images, like this one, suggest a past of interaction as documented by two flows to the north and south. However, their formation may not be due to interaction with Andromeda but rather the consequence of the capture and destruction of one of its satellites.
The image was obtained with a telephoto lens array and is a fragment of a larger mosaic in the And450 survey program of the UAI National Deep Sky Research Section (G. Donatiello et al., in progress). The specific processing allows us to highlight the faintest regions of the halo and the associated tidal structures.
Nomenclature is according to the PAndAS survey.
To use this image please first read here: www.flickr.com/people/133259498@N05/
Ultra-deep imaging of M33: exploring its stellar halo
Triangulum Galaxy Extended Halo - And450 survey (sample)
Credit: Giuseppe Donatiello
M33 represents a unique opportunity to study spiral galaxies. Dwarf galaxies tend to be irregular mixtures of stars and gas, very different from the beautiful, larger spirals. Large, undisturbed dwarf spirals, like M33, are therefore environments that allow a better understanding of hierarchical formation phenomena.
Strange as it may seem, we still know little about M33. It is unclear whether or not it interacted with the larger Andromeda galaxy (M31).
Both its proximity to M31 and the distorted structure of M33's disk suggest that the galaxies already interacted tidally with each other about 2.5 billion years ago. The effect of this interaction is currently observed as a deformation of the outer part of M33's disk. A close passage between the galaxies would also have increased star formation activity in M33, according to a simulation (Semczuk et al. 2018). According to this scenario, M33 would have already encountered M31 and perhaps lost its satellites and globulars.
In a second scenario, M33 would instead be falling into the Local Group for the first time, thus retaining its entourage of satellites and globulars. According to models, a galaxy like M33 should possess at least a dozen satellite galaxies, but to date only two are suspected: Andromeda XXII (Martin et al. 2013) and Pisces VII, discovered by me (Martinez-Delgado et al. 2021). Triangulum IV remains to be confirmed.
Ultra-deep images, like this one, suggest a past of interaction as documented by two flows to the north and south. However, their formation may not be due to interaction with Andromeda but rather the consequence of the capture and destruction of one of its satellites.
The image was obtained with a telephoto lens array and is a fragment of a larger mosaic in the And450 survey program of the UAI National Deep Sky Research Section (G. Donatiello et al., in progress). The specific processing allows us to highlight the faintest regions of the halo and the associated tidal structures.
Nomenclature is according to the PAndAS survey.
To use this image please first read here: www.flickr.com/people/133259498@N05/