(a) A pulsating white dwarf has mass and radius . Using the pulsation constant ,…

PHYSICS · Subjective · Fermi University Physics · Astrophysics & Cosmology · Stellar structure, energy generation and evolution · Stellar structure, energy generation and evolution

Stars from the Inside, Ch Pulsating stars: the kappa mechanism, the Leavitt law and asteroseismology

Problem

(a) A pulsating white dwarf has mass M=0.60 M⊙M = 0.60\,M_\odot and radius R=0.0125 R⊙R = 0.0125\,R_\odot. Using the pulsation constant Q=0.040 dQ = 0.040\,\mathrm{d}, estimate its radial fundamental pulsation period, in seconds. (b) A helium-core-burning red giant, observed as a solar-like oscillator, has νmax⁡=25 μHz\nu_{\max} = 25\,\mu\mathrm{Hz}, Δν=3.0 μHz\Delta\nu = 3.0\,\mu\mathrm{Hz} and Teff=4700 KT_{\rm eff} = 4700\,\mathrm{K}. Using the solar calibration Δν⊙=135 μHz\Delta\nu_\odot = 135\,\mu\mathrm{Hz}, νmax⁡,⊙=3090 μHz\nu_{\max,\odot} = 3090\,\mu\mathrm{Hz}, Teff,⊙=5777 KT_{{\rm eff},\odot} = 5777\,\mathrm{K}, find its mass and radius.

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