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A Strange, Solitary Life for Young Stars at the Milky Way’s Center

1 points by raattgift 3y ago

raattgift 3y ago
We are collectively coming to terms with how commonplace multi-star systems are <https://en.wikipedia.org/wiki/Star_system#Multiple_star_systems https://en.wikipedia.org/wiki/Star_system#Multiple_star_syst...> and <https://en.wikipedia.org/wiki/Binary_star#Research_findings https://en.wikipedia.org/wiki/Binary_star#Research_findings> (see the table, and note how heavier stars are much more likely to be binary+). So it's weird that the very centre of the galaxy might be strikingly different. It's not obvious which of several ways the central black hole could matter is the correct way(s). The abstract and discussion section of the open access paper <https://iopscience.iop.org/article/10.3847/1538-4357/acc93e https://iopscience.iop.org/article/10.3847/1538-4357/acc93e> both point out that this extrapolative simulation is evidence supporting an upper limit on the fraction of these young centre-of-the-galaxy stars that are in binaries. That fraction (maximum less than 50%) is much lower than the fraction of similar stars seen elsewhere in the Milky Way (approaching 80% are in binaries). If the results in the paper hold up with further study of our galaxy's central parsec <https://galacticcenter.astro.ucla.edu/index.html https://galacticcenter.astro.ucla.edu/index.html> then the paper raises the obvious question: what happened to all the missing binary partners? Some possibilities: they never formed in the central environment; they did form but they were ejected out of the centre of the galaxy; they did form but they were disrupted ("evaporated" in the paper); the binaries did form but eventually merged together; or some combination of two or more of these. It's also possible that e.g. the central black hole was much noisier (due to feeding and producing a jet) a few million years ago than it is now (it's verrrry quiet), and that the noise back then mattered to this collection of stars. These possible answers require more data.

1 points by raattgift 3y ago

We are collectively coming to terms with how commonplace multi-star systems are <https://en.wikipedia.org/wiki/Star_system#Multiple_star_systems https://en.wikipedia.org/wiki/Star_system#Multiple_star_syst...> and <https://en.wikipedia.org/wiki/Binary_star#Research_findings https://en.wikipedia.org/wiki/Binary_star#Research_findings> (see the table, and note how heavier stars are much more likely to be binary+). So it's weird that the very centre of the galaxy might be strikingly different. It's not obvious which of several ways the central black hole could matter is the correct way(s). The abstract and discussion section of the open access paper <https://iopscience.iop.org/article/10.3847/1538-4357/acc93e https://iopscience.iop.org/article/10.3847/1538-4357/acc93e> both point out that this extrapolative simulation is evidence supporting an upper limit on the fraction of these young centre-of-the-galaxy stars that are in binaries. That fraction (maximum less than 50%) is much lower than the fraction of similar stars seen elsewhere in the Milky Way (approaching 80% are in binaries). If the results in the paper hold up with further study of our galaxy's central parsec <https://galacticcenter.astro.ucla.edu/index.html https://galacticcenter.astro.ucla.edu/index.html> then the paper raises the obvious question: what happened to all the missing binary partners? Some possibilities: they never formed in the central environment; they did form but they were ejected out of the centre of the galaxy; they did form but they were disrupted ("evaporated" in the paper); the binaries did form but eventually merged together; or some combination of two or more of these. It's also possible that e.g. the central black hole was much noisier (due to feeding and producing a jet) a few million years ago than it is now (it's verrrry quiet), and that the noise back then mattered to this collection of stars. These possible answers require more data.