Making Bright Giants Invisible At The Galactic Centre. (arXiv:1910.04774v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Amaro_Seoane_P/0/1/0/all/0/1">Pau Amaro-Seoane</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chen_X/0/1/0/all/0/1">Xian Chen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Schodel_R/0/1/0/all/0/1">Rainer Schödel</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Casanellas_J/0/1/0/all/0/1">Jordi Casanellas</a>
Current observations of the Galactic Center (GC) seem to display a core-like
distribution of bright stars from $sim 5″$ inwards. On the other hand, we
observe young, massive stars at the GC, with roughly 20-50% of them in a disc,
mostly in the region where the bright giants appear to be lacking. In a
previous publication we put the idea forward that the missing stars are deeply
connected to the presence of this disc. The progenitor of the stellar disc is
very likely to have been a gaseous disc that at some point fragmented and
triggered star formation. This caused the appearance of overdensity regions in
the disc that had high enough densities to ensure stripping large giants of
their atmospheres and thus rendering them very faint. In this paper we use a
stellar evolution code to derive the properties that a red giant would display
in a colour-magnitude diagram, as well as a non-linearity factor required for a
correct estimate of the mass loss. We find that in a very short timescale, the
red giants (RGs) leave their standard evolutionary track. The non-linearity
factor has values that not only depend on the properties of the clumps, but
also on the physical conditions the giant stars, as we predicted analytically.
According to our results, envelope stripping works, moving stars on a short
timescale from the giant branch to the white dwarf stage, thus rendering them
invisible to observations.
Current observations of the Galactic Center (GC) seem to display a core-like
distribution of bright stars from $sim 5″$ inwards. On the other hand, we
observe young, massive stars at the GC, with roughly 20-50% of them in a disc,
mostly in the region where the bright giants appear to be lacking. In a
previous publication we put the idea forward that the missing stars are deeply
connected to the presence of this disc. The progenitor of the stellar disc is
very likely to have been a gaseous disc that at some point fragmented and
triggered star formation. This caused the appearance of overdensity regions in
the disc that had high enough densities to ensure stripping large giants of
their atmospheres and thus rendering them very faint. In this paper we use a
stellar evolution code to derive the properties that a red giant would display
in a colour-magnitude diagram, as well as a non-linearity factor required for a
correct estimate of the mass loss. We find that in a very short timescale, the
red giants (RGs) leave their standard evolutionary track. The non-linearity
factor has values that not only depend on the properties of the clumps, but
also on the physical conditions the giant stars, as we predicted analytically.
According to our results, envelope stripping works, moving stars on a short
timescale from the giant branch to the white dwarf stage, thus rendering them
invisible to observations.
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