We know that when two galaxies are perfectly aligned they form an Einstein Ring by gravitational lensing but can two stars form it? We know gravitational bending by stars, but can two perfectly aligned stars form an Einstein Ring?

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    $\begingroup$ Yup, sure! This effect is usually called microlensing and it is used to detect exoplanets, among other things $\endgroup$
    – Prallax
    Aug 23, 2022 at 18:50
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    $\begingroup$ Resolving an Einstein ring from two stars is another question. The angle is the square root of [typical stellar Schwarzschild radii, divided by typical distances between stars], or $\sqrt{\frac{\sim\mathrm{km}}{\sim\mathrm{pc}}}$, which is very small. $\endgroup$
    – pela
    Aug 23, 2022 at 22:05
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    $\begingroup$ @uhoh Good question, which I'd be happy to look into once I've met a handful of deadlines (unless you find the answer first, using the lens equation above :) ). $\endgroup$
    – pela
    Aug 24, 2022 at 14:57
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    $\begingroup$ Being a non-native English, I'm unsure if that sounded snarky. Definitely didn't mean it that way, but I already spent too much time on this site today 😬 $\endgroup$
    – pela
    Aug 24, 2022 at 14:58
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    $\begingroup$ @pela oh no, it sounded exactly like something I would write; I understand just what you mean. I also find the problem intriguing but in my case am in the middle of an experiment so if someone else wants to try in the mean time that will be great! $\endgroup$
    – uhoh
    Aug 24, 2022 at 22:29


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