Recently, the fly-through the Solar system of the inter-stellar object (ISO) `Oumuamua caused quite a stir in the astronomy community. I wonder whether there are reliable estimates for the (local) number density of such objects. Such estimates could be based on the `Oumuamua event (when they are necessarily rather crude owing to very low-number statistics) or on any other constraints. A related question is: how close to Earth must an ISO pass to be detected with today's instruments, or 10, 25, 50 years ago?

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    $\begingroup$ Estimates for LSST (8.4m survey telescope, 6.5m effective area) are ~1 interstellar object detected per year with considerable uncertainty $\endgroup$ Jun 21, 2019 at 16:30
  • $\begingroup$ @astrosnapper That's not at all what I asked, though somewhat related. $\endgroup$
    – Walter
    Jun 21, 2019 at 19:08
  • $\begingroup$ @astrosnapper do you have a reference for that? $\endgroup$
    – Walter
    Jun 21, 2019 at 19:28
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    $\begingroup$ What research did you do? For me, this paper by Do, Tucker and Tonry comes up on the first page of Google search results for "number density of oumuamua" - does it answer your question? $\endgroup$
    – user24157
    Jun 22, 2019 at 18:02
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    $\begingroup$ @mistertribs Though you may also see this ui.adsabs.harvard.edu/abs/2017AJ....153..133E/abstract (quoted from the paper you dug up), which prior to the detection of 'Oumuamua estimated the density 1000 times smaller. $\endgroup$
    – Walter
    Jun 22, 2019 at 21:13


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