Module 09 Lab Questions – Balmer Lines

This discussion covers Question 7, “Contrast an A star and an M star. Which has the Balmer lines strong? Which weak?” My choice was “A Balmer strong; M Balmer weak.” The strength of Balmer lines is determined by the temperatures of the star. Balmer lines refer to a group of spectral lines occurring within the visible range of the electromagnetic spectrum, and these lines result from the shifts in energy levels of electrons within hydrogen atoms. They are present in the spectra of many stars, and their relative strengths and positions provide valuable information about a star’s temperature, composition, and other physical properties. A-stars are hotter and more massive main-sequence stars classified as A-type. They emit bluish or white light due to their high temperatures. The temperature of A-stars is around 8500K (Seeds & Backman 2018).

A-stars have stronger Balmer lines because of their medium temperatures, which allow the atoms to be excited out of their ground state and not too excited to other orbits or ionized as in the case for higher temperature stars. M-stars are cooler and less massive main-sequence stars with a spectral class of M. They appear reddish in color due to their lower temperatures. The M stars have temperatures of around 3000K. M stars show weaker Balmer lines because they are cooler. Balmer lines are weak because atoms are not excited out of the ground state due to the low temperatures (Seeds & Backman 2018). A-stars have strong Balmer lines because they have medium temperatures, while M-stars have weak Balmer lines because they have low temperatures.

Regarding interesting remarks about the module, the module covers spectra characteristics and how they are visible and affect the different stars. The module questions help to understand and encourage active participation and grasping of spectra.