NGC 1055 ~ Galaxy on Edge!
Optics:   Ritchey–Chrétien 20" F/8.2 (4166mm FL) Processing:   PixInsight, Photoshop
Camera:   SBIG STXL-11000 with Adaptive Optics Date:   December 2020
11 Megapixel (4008 x 2672 16-bit sensor) Location:   Columbus, Texas
Exposure:   LRGB = 620:120:100:120 minutes Imager:   Kent E. Biggs
This image of Spiral Galaxy NGC 1055 is very rich in extraterrestrial objects, a Field of Dreams so to speak. It contains objects from our solar system, our galaxy, as well as relatively nearby and even more distant clusters of galaxies. The crown jewel of this field is the galaxy itself (center) located over 50 million light years away in the direction of the constellation Cetus, which means the whale or sea monster. Per Hubble's theory of the expansion of the universe, the galaxy's distance from us means it is also traveling about 1000 kilometers per second away from us. NGC 1055 is also about 120,000 light years in diameter, making it slightly larger than our own Milky Way Galaxy. It is part of a small galaxy group that includes M77, NGC 1073 and five other small irregular galaxies. It appears nearly edge-on to us, so that like a dinner plate viewed from the side, we see it appearing more linear or edge-on. In contrast many galaxies appear as a more circular disk as if the same inner plate were facing us.

Why is this edge-on galaxy, NGC 1055, also “on its edge”? Simple answer. There is no law or force on galaxies in our universe that would make them all orient themselves in a particular way. There is no up, down, left or right for galaxies. Most attempts at imaging galaxies, place them in a horizontal or diagonal orientation merely for esthetics. However, in this case there were so few guide stars to use, the only option was to align it vertically for this telescope and camera combination. A guide star is a star that is usually off the edge of the sensor used to create the image. The guide star is placed on another sensor (CMOS, CCD, or eyeball in the old days). It is used to guide the tracking of the telescope to ensure the image stays as stable as possible. Variations in the earth’s rotation, wind, wind gusts, differences in temperature and humidity throughout the atmosphere, and even vibrations in the ground can all create movement of the image that the guide star helps correct. In this image the guide star position required rotating the camera so that the edge-on galaxy was apparently also on its edge!

Seeming to surround NGC 1055 are three other small galaxies in top to bottom order - PGC 1164535, 1164595, and 135658. They can be seen as enlarged inset images by hovering the mouse over the image. These galaxies are actually up to an order of magnitude further away. Click here to see an enlarged view of the above image with the insets and annotations still visible.

Also visible in this Field of Dreams image is the trail (left middle) created by Minor Planet 7583 Rosegger, a main-belt asteroid orbiting between Mars and Jupiter, and discovered recently, on January 17, 1991 by F Borngen at Tautenburg. At 18.1 magnitude, the asteroid is about 70,000 times fainter than the faintest object a human can see with the naked eye. Clicking on and zooming into the asteroid image shows what appears to be a series of dots. The gaps between the dots are caused by small pauses between each of the 30 - 10 minute exposures combined for this image. The larger gap in the middle is likely due to the 5 minute flipping time when the telescope’s German Equatorial mount must flip to reach the other half of the sky.

Finally the three bright stars (right middle) are great examples of the different types of spectral class of stars. Merely from the measured color of a star, one can predict its approximate size, its mass, its temperature, its brightness, and to some extent, its age. This is an amazing about of information from a relatively simple measurement. The bright blueish star is a younger very hot star, probably 1-2 times the mass of the sun. The bright yellow star is similar to our sun in mass and size. It is about 2X fainter than the faintest star a human can observe from a dark site. It is also nearly 100X brighter than the combined light from the hundreds of billions of stars in the spiral galaxy due to their extreme distance. The red star is a cooler, likey smaller star than our sun. Stars have all the colors of the rainbow in them, but there are no green or purple stars due to the way that humans perceive light and how the distribution of light eminates from the star in a curve across the spectrum. For example, what would be a green star, appears white to use since there are relatively equal amounts of red and blue emitted by it as well.