# Is it possible that absolute magnitude for two stars is equal for some wavelength?

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?

• This is like asking "Is it possible that two people have the same height"... Apr 27, 2021 at 4:30
• 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. Apr 27, 2021 at 5:17
• 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.. Apr 27, 2021 at 9:35