Astronomy problem help?

I'm new to astronomy, can some please help with steps? Thank you!

If the sun’s luminosity is given as 1 L*, what is the luminosity of an A0 type star with twice the radius

of the sun (surface temperature 5800K)?

Comments

  • There's no such thing as an A0 star with a temperature of 5800K.

    For a main sequence star of type A0...

    M = 2.65 solar masses

    R = 1.74 solar radii

    L = 43.6 times the sun's luminosity

    T = 11250 K

    absolute magnitude = +0.642

    B−V color index = −0.1

    λmax = 2576 Å

    time on main sequence = 608 million years

  • There is a nice formula linking L, T with the radius R, derived from Stephen's Law in terms of ratios (of Solar parameters):

    L = R² T⁴,

    = 4 (55 / 29)⁴ = 51.7510 times

    bringing it to an absolute magnitude of +0.545.

    That is, since A0 star has surface temperature of about 11000_K* (peaking at λ=0.263μ in UV).

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