Fun with spectroscopy

Image Details:

This image is a comparison of a range of spectra taken of 31 naked eye stars visible from the Southern hemisphere. Spectra were taken with a StarAnalyzer diffraction grating mounted in the filter wheel of my CCD camera on a 12.5" Newtonian telescope. Each spectrum was processed using RSpec software and calibrated for instrument response. The resulting spectra show the black body radiation profile of the various stellar types and their typical spectral line features.
The star spectra are ordered according to stellar type, with hot blue stars at the top and cooler red stars towards the bottom. Hot blue stars (O, B, A types) have a light profile heavily skewed towards the left (blue and violet) end of the spectrum given these stars emit the majority of their energy at short wavelengths. They also display the famous Hydrogen Balmer series of absorption lines.
In the centre are the F, G and K type stars with their more even light profiles and numerous but fainter absorption lines.
Towards the bottom are the cooler M type stars with profiles heavily skewed towards the red and infrared end of the spectrum. They show many broad absorption lines from Titanium Oxide molecules suspended in their atmospheres.
At the very bottom are two examples of Wolf-Rayet stars that have unusual spectra with some prominent emission lines.
Also visible are a couple of absorption lines in the red, which appear in every single spectrum regardless of spectral type. These are caused by terrestrial oxygen in the Earth's atmosphere.
The background image is my deep photo of cometary globules CG 30, CG 31 and CG 38 in Puppis.

Date: 29 May, 1 June 2021
Exposure: Luminance 0.03s - 3s @ -25C
Telescope: Homebuilt 12.5" f/4 Serrurier Truss Newtonian
Camera: QSI 683wsg with Lodestar guider
Filters: StarAnalyzer 200 Diffraction Grating
Taken from my observatory in Auckland, New Zealand See Less

Copyright: Rolf Olsen