Comet C/2011 L4 Pan-STARRS continues to be visible in the Northern sky and last weekend passed visually close to the Andromeda galaxy, M31. I captured a sequence of twenty, 5 second exposures which were stacked into the photo below (Click on it for a larger version). The short exposure lessens the effect of the stars being drawn out into trails by the earths rotation, and stacking multiple shots creates a brighter image.
On the left is the “fuzzy blob” of the Andromeda Galaxy, 2.2 million light years away. Centre right is Comet Pan-STARRS which came within 100 million miles of the Earth in early March. Arrowed on the right of picture is a red “carbon star” with the grand title of HD1546. It’s in the order of 1825 light years from the solar system and changes brightness in a period of just over 1 year. 3 objects lying at very different distances!
Carbon stars are very red because most of the Hydrogen in them has already being fused into Helium which is in turn is being converted into Carbon. The carbon sits in a “shell” in the upper layers of the star and, just like dust in the earths atmosphere creates a red sunset, filters out the blue region of the spectrum giving these stars an intensely red colour.