Estimating the luminosity class of an m star is much more important than measuring it for an o star if you are determining the distance to that star. why is that the case?

Acid precipitation chemically weathering a 5.0-kg limestone rock . which coukd be the result ?

What is the technical name for super glue type adhesives?

The two most prominent wavelengths in the light emitted by a hydrogen discharge lamp are 656(red) and 486 (blue). light from a hydrogen lamp illuminates a diffraction grating with 500 lines per mm, and the light is observed on a screen 1.50 behind the grating. what is the distance between the first-order red and blue fringes?