The title explains the questions. I don't find any problem with it. As If the two stars A and B do have equal absolute magnitude for some wavelength $\lambda_0$ then $$M_A=M_B$$ $$-5(\log d_A-1)+m_A=-5(\log d_B-1)+m_B$$ $$m_A-m_B=5\log\left(\frac{d_A}{d_B}\right)$$ I don't find any problem with this. But I'm not sure if this is true. Can any help me with this?

  • $\begingroup$ This is like asking "Is it possible that two people have the same height"... $\endgroup$
    – James K
    Apr 27, 2021 at 4:30
  • 1
    $\begingroup$ This is trivially true, since for two sufficiently cold stars at sufficiently high measured wavelength, the magnitude of both stars will be zero. The non-trivial case, which is a specific wavelength for two stars that is non-zero and the same for both is perhaps more interesting. $\endgroup$
    – Connor Garcia
    Apr 27, 2021 at 5:17
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    $\begingroup$ It can be formulated as how much their spectra depart from the black body one. And as for the previous comment, staying away from the tails.. $\endgroup$
    – Alchimista
    Apr 27, 2021 at 9:35


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