Whale and Hockey Stick Galaxies
- Optic: TS APO 115/800
- Mount: NEQ6
- Guide Optic: TS APO 65Q
- Acquisition Camera: Qsi 683 Ws
- Guide Camera: Magzero Mz5m
- Accessories: TS 2
- Resolution: 3279x2427 pixel
- Exposure Details: LRGB => 160:50:50:50 (colors Bin 2x2)
- Total Exposure Time: 5,2 Hours
- Dark: 9
- Flat: 11
- DarkFlat: 0
- Bias: 50
- Cooling Detail: -20 °C
- Ambient Temperature: 5p °C
- Observation Site: Pian dell'Armà (PV) Italy
- Date: 20/4/2015
- NGC 4631 (also known as the Whale Galaxy or Caldwell 32) is an edge-on spiral galaxy in the constellation Canes Venatici. This galaxy's slightly distorted wedge shape gives it the appearance of a herring or a whale, hence its nickname. Because this nearby galaxy is seen edge-on from Earth, professional astronomers observe this galaxy to better understand the gas and stars located outside the plane of the galaxy.NGC 4631 contains a central starburst, which is a region of intense star formation. The strong star formation is evident in the emission from ionized hydrogen and interstellar dust heated by the stars formed in the starburst. The most massive stars that form in star formation regions only burn hydrogen gas through fusion for a short period of time, after which they explode as supernovae. So many supernovae have exploded in the center of NGC 4631 that they are blowing gas out of the plane of the galaxy. This superwind can be seen in X-rays[6] and in spectral line emission. The gas from this superwind has produced a giant, diffuse corona of hot, X-ray emitting gas around the whole galaxy.
NGC 4656/57 is a galaxy is sometimes informally called the Hockey Stick Galaxies or the Crowbar Galaxy. A Luminous Blue Variable in "super-outburst" was discovered in NGC 4656/57 by Doug Rich on March 21, 2005. (text adapted from Wikipedia)
