Colorized Ritter Spectrum

Here is an attempt to represent a Ritter Observatory spectrum of the star Deneb as it would appear if you could see it in color. I have made versions with and without labels. Right click on the thumbnail to download a high-resolution version in JPEG format, or right click on the link below to download a high-resolution PDF version of the labeled picture.

Labeled version, PDF (2.3 MB)

Deneb is the brightest star in the constellation Cygnus, the Swan, also known as the Northern Cross. Deneb is also the northeasternmost star in the asterism known as the Summer Triangle. A first-magnitude star, it is easily visible even in light-polluted city skies or through thin clouds.

It is a supergiant star some 2600 light years distant. Being bright in our sky even at this great distance means that it puts out a lot of light and also that it is large in diameter, about 200 times the Sun's size. Because of its high energy output, it drives its outer atmosphere away to form a stellar wind. In the spectrum, you can see evidence for the stellar wind as a slight excess brightness on the right-hand side of the red hydrogen line. We expect the wind to be fairly steady, but in fact it changes substantially for unknown reasons, and I am following this star over time in order to study these changes.

The colors of the red hydrogen line, the sodium lines, and the blue-green hydrogen line are pretty accurate according to my experience, but the other colors are educated guesses.

Nancy Morrison 7/24/08