Sumários

Stellar atmospheres (part IV)

23 Março 2020, 13:00 • Israel Matute

Spectral line profiles

  • Line depth, Equivalent width (EW) & FWHM.

Origin of spectral line broadening:

  • Natural broadening (Lorentz profile).

  • Doppler broadening (Gaussian profile).

  • Pressure broadening (Lorenz profile.

Curve of growth.

Abundances.

Exercises related to Series #2 - Spectral lines

19 Março 2020, 15:00 • Israel Matute

Discussion and solving together the questions and problems posted in the second series of lab exercises.

Stellar atmospheres (part III)

19 Março 2020, 14:00 • Israel Matute

The lecture was dedicated to concepts and equations of radiative transfer when applied to stellar atmospheres.

  • Radiative transfer

    • Random Walk

    • Limb darkening 

    • Radiative Transfer Equation and approximations to solve it: Plane-parallel atm., Grey atmosphere, and the Eddington approximation

Stellar atmospheres (part II)

17 Março 2020, 13:00 • Israel Matute


The lecture was dedicated to defining stellar opacity and its sources

  • Opacity

    • Absorption: the absorption coefficient.

    • Optical Depth and its extremes: optically think and optically thin.

    • Processes that contribute to total opacity:

      • Bound-bound;

      • Bound-free; 

      • Free-free;

      • Electron Scattering;

      • The H- ion.


Stellar atmosphere

16 Março 2020, 13:00 • Israel Matute

The following topics were introduced and discussed during this lecture

  • Basic stellar structure

  • Radiation field

    • Specific intensity

    • Mean intensity

    • Specific radiative flux

    • Radiation pressure

  • Stellar Opacity

    • Different temperature definitions 

    • Local Thermodynamic Equilibrium (LTE)

      • Example of LTE