Ch3. Black Body Radiation: properties; estimate temperatures of astro-objects; and what is Teff?

Описание: In this "extended version" lecture we discuss properties of Black-Body radiation. I've included a small part also from an earlier version of intro-course to galaxies & cosmology (on accretion discs). Lecture starts with the spectral shape, the Rayleigh-Jeans and Wien limits, and Wien's displacement law. Then we find frequency-integrated properties, finding values and relations for radiation energy density, flux, and pressure. We also hint toward where "ultra-violet catastrophe" come from (Planck's quantum oscillators treated later during course).

Examples: Wien's Displacement Law and estimating temperatures of stars and basic properties of galaxies. What is the effective temperature "Teff"? Teff of stars and accretion discs (for example around black holes).

0:00 Introduction and basic spectral shape of Planck curve
5:04 Rayleigh-Jeans limit
8:22 Wien limit
10:30 Wien's displacement law
15:10 Estimate temperature of stars
18:55 Estimate basic properties of galaxies
21:05 Integrated radiation energy density
32:55 Integrated radiation flux
36:20 Integrated radiation pressure
39:45 What is effective temperature "Teff" for stars?
54:50 "Teff" and luminosity from accretion disc, contrasted to stars

#astronomy #astrophysics #physics #education

Parts of the video are part of the course: Radiation Processes in Astronomy
Lecturer: Prof. Dr. Jon Sundqvist
Programmes where I teach it: KU Leuven Bachelor Physics & Master Astronomy & Astrophysics, Hasselt University Bachelor Physics (as video course)

I record lectures live and do them on black-board in the hope that it will provide a more authentic feeling of the sort: "we're doing the actual work here and now". So like I keep telling students in the classroom: whenever you discover me doing some error let me know directly; for this channel this means make a comment on the videos. Then we can have a look at it, and thereby learn nicely from each other as we continue to develop our knowledge.

Link to "Radiative Transfer and Radiative Processes in Astrophysics: Extended Version" playlist:
   • Radiative Transfer and Radiative Processes...  

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https://fys.kuleuven.be/ster/research...

Playlist for SUPERSTARS-3D:
   • SUPERSTARS-3D  

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For original non-extended course black-board class lectures (2025 version), see also here:
   • Radiation Processes in Astronomy