Blue Snowball Nebula – NGC 7662
The Blue Snowball Nebula (NGC 7662) in Andromeda, image: Judy Schmidt
The Blue Snowball Nebula (or simply Snowball Nebula) is catalogued as NGC 7662 in the New General Catalogue. It is a planetary nebula in Andromeda. It has an apparent magnitude of 8.6 and is located a degree west of magnitude 4 star Kappa Andromedae.
The nebula's distance is uncertain and estimated to be between 2,000 and 6,000 light years. The central star is a bluish dwarf with an estimated temperature of 75,000 K. The nebula's estimated radius is 0.8 light years.
The Blue Snowball Nebula can be seen in a small refractor telescope, but only appears as a star-like object with some nebulosity.
NGC 68 Group
The NGC 68 Group is a cluster of more than 40 galaxies centered on the elliptical galaxy NGC 68. The group is located at an approximate distance of 300 million light years. It was discovered in 1784 by William Herschel, who catalogued the galaxies as a single object. The Danish-Irish astronomer John Louis Emil Dreyer was able to make out some of the individual members of the group and catalogued them as NGC 68, NGC 70 and NGC 71 in the 1880s.
NGC 68 Group, image: Adam Block/Mount Lemmon SkyCenter/University of Arizona
The main members of the NGC 68 Group are the galaxies NGC 68, NGC 67, NGC 67a, NGC 69, NGC 70, NGC 71, NGC 72, NGC 72a, and NGC 74. A smaller cluster can be seen superimposed on the group that includes AGC 102760, UGC 152, and UGC 166.
NGC 68 is classified as an E1-type elliptical galaxy. It has a visual magnitude of 12.9 and is located at an approximate distance of 260 million light years from Earth. It spans 90,000 light years and has an apparent size of 1.288' x 1.202'. It was discovered by William Herschel on September 11, 1784, along with NGC 70.
NGC 67 is an elliptical (E5) galaxy with an apparent magnitude of 14.2, located 275 million light years from Earth. It was discovered by R.J. Mitchell on October 7, 1855, along with NGC 69, NGC 70 and NGC 72. The galaxy is 40,000 light years across and has an apparent size of 24'' x 12''.
NGC 68 Group, image: Donald Pelletier
NGC 67a is also an E5-type elliptical galaxy. It has a visual magnitude of 14.7 and is 287 million light years distant. It occupies an area 0.4' by 0.2' in size, which translates into a real size of 35,000 light years.
NGC 69 is a lenticular (S0) galaxy with an apparent magnitude of 14.7. It is 300 million light years distant and spans 80,000 light years, or 0.9' x 0.8' of the apparent sky.
NGC 70 is a spiral galaxy spanning 180,000 light years. It has a visual magnitude of 13.5 and is about 320 million light years distant. It occupies an area 1.7' x 1.4' in size.
NGC 71 is either an elliptical or lenticular galaxy (E5/S0) about 130,000 light years across, located about 310 million light years from the Sun. It is the second largest galaxy in the group, smaller only than NGC 70. The galaxy has an apparent magnitude of 13.2.
NGC 72 is a barred spiral galaxy with an apparent magnitude of 13.5, located approximately 320 million light years away. It spans about 120,000 light years, which translates to an apparent size of 1.3' x 1.0'.
NGC 72a is another elliptical (E3) galaxy in the group. It is located at a distance of 308 light years and has a visual magnitude of 14.7. It has an apparent size of 0.3' x 0.3', which translates into an actual size of 25,000 light years.
NGC 74 is a spiral galaxy that spans 65,000 light years. It is 315 million light years distant and has an apparent magnitude of 15.3. The galaxy was discovered by the Irish astronomer William Parsons on October 7, 1855.
Arp 65 – NGC 90 and NGC 93
NGC 90 and NGC 93 form a pair of interacting spiral galaxies in Andromeda. NGC 90 is located at a distance of 333.8 million light years and NGC 93 is 259.7 million light years away. The galaxies were discovered by R.J. Mitchell in 1854. NGC 90 has an apparent magnitude of 13.7 and an apparent size of 2.4' x 0.91'. It has two distorted, elongated spiral arms that show evidence of starburst activity, likely caused by the interaction. NGC 93 has a visual magnitude of 14.34 and occupies an area 1.4' x 0.7' in size.
NGC 90 (centre) and NGC 93 (top right). Image: Adam Block/Mount Lemmon SkyCenter/University of Arizona
Ghost of Mirach – NGC 404
NGC 404 is an isolated dwarf lenticular galaxy located just beyond our Local Group. The galaxy has an apparent magnitude of 11.2 and is located at an approximate distance of 10 million light years. It can be seen in small telescopes. The galaxy was discovered by William Herschel in 1784.
NGC 404 has an apparent size of 3.5' x 3.5'. It is located 7 arc minutes from Mirach and is sometimes called the Ghost of Mirach because its proximity to the star makes it difficult to observe and photograph.
Andromeda contains a number of other deep sky objects that were included in the New General Catalogue, including the open cluster NGC 272, the spiral galaxies NGC 11, NGC 13, NGC 21, NGC 228, NGC 48, NGC 214, NGC 218, NGC 226, NGC 260, NGC 280, NGC 39, NGC 27, NGC 19, NGC 169, NGC 184, NGC 140, NGC 109, NGC 160, and NGC 112, lenticular galaxies NGC 81, NGC 149, NGC 20, NGC 76, NGC 69, NGC 229, NGC 243, NGC 304, NGC 43, NGC 80, NGC 393, NGC 389, NGC 94, NGC 258, NGC 96, NGC 108, NGC 86, and NGC 252, and elliptical galaxies NGC 5, NGC 49, NGC 233, NGC 1000, NGC 79, NGC 97, NGC 83, and NGC 183.
[ https://www.constellation-guide.com/constellation-list/andromeda-constellation/ ]
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