AST 101 Lecture Notes - Lecture 11: Harvard College Observatory, Balmer Series, Williamina Fleming
Document Summary
Observe the integrated properties of many stars. Observe the detailed properties of the sun. Spectroscopy of astronomical objects is how we gain the most information about them. Density chemical composition internal dynamics and much else. Let"s consider the issue of temperature a bit more. We have already discussed one method of measuring temperature for stars: fitting their broad-band spectral energy distributions with blackbody curves. In practice this is done by measuring the brightness of stars in a set of standard wavelength regions, defined by standard filters. As an example, one can measure the brightness of a star in blue (or b-band) and yellow (or v-band) light, and compare those measurements. Hot stars are brighter in b than in v. cool stars are brighter in v than in b. Stars have absorption spectra (again, the sun is typical), but can have very different lines than the sun does.
