Very Small Interacting Galaxies
Posted: Tue Oct 19, 2021 11:57 pm
This text and image were uploaded to Astrobin this afternoon. https://www.astrobin.com/c4nypm/
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NGC 7285 and NGC 7284
Here is a rarely imaged pair of interacting galaxies. NGC 7284 is also known as Arp 93.
This image shows fairly well the very long arm below and to the right. Perhaps the most interesting question in this close pair is whether one of them is a companion of the other, perched on the end of a spiral arm. When Halton Arp published his Atlas of Peculiar Galaxies in 1966 he placed great emphasis on galaxy pairs of this kind. In Arp’s own words, “he postulated that compact bodes were ejected from the nucleus of the parent galaxy. During their passage outwards, these compact bodies formed the spiral arms in the underlying galaxy and then evolved into larger companion-sized galaxies.”
By 1987, when the Catalog of Southern Peculiar Galaxies and Associations was published, Arp had changed his point of view to include the possibility that certain kinds of encounters between galaxies could gravitationally draw out filaments of stars which could connect them. M51 appeared to be the perfect example. Arp and his co-author, Barry Madore, decided to create a new category of peculiar galaxies called “M51 Types” to encompass interacting galaxies formed in this way.
These galaxies meet the definition of a peculiar galaxy because they satisfy three separate categories in the Catalog of Southern Peculiar Galaxies and Associations, by Halton Arp and Barry Madore.
Category 2—Interacting Doubles
Category 9—M51 Types
Category 15—Galaxies with Tails, Loops of Material, or Debris
Tech Notes for ASA 500/3.6:
ASA Newtonian, 500 mm aperture, 1900mm focal length, F3.6
FLI Proline 16803, 9 mm pixel, 4096 X 4096
ASA DDM85 equatorial mount
Processing with PixInsight, StarTools, and Affinity Photo
****************
NGC 7285 and NGC 7284
Here is a rarely imaged pair of interacting galaxies. NGC 7284 is also known as Arp 93.
This image shows fairly well the very long arm below and to the right. Perhaps the most interesting question in this close pair is whether one of them is a companion of the other, perched on the end of a spiral arm. When Halton Arp published his Atlas of Peculiar Galaxies in 1966 he placed great emphasis on galaxy pairs of this kind. In Arp’s own words, “he postulated that compact bodes were ejected from the nucleus of the parent galaxy. During their passage outwards, these compact bodies formed the spiral arms in the underlying galaxy and then evolved into larger companion-sized galaxies.”
By 1987, when the Catalog of Southern Peculiar Galaxies and Associations was published, Arp had changed his point of view to include the possibility that certain kinds of encounters between galaxies could gravitationally draw out filaments of stars which could connect them. M51 appeared to be the perfect example. Arp and his co-author, Barry Madore, decided to create a new category of peculiar galaxies called “M51 Types” to encompass interacting galaxies formed in this way.
These galaxies meet the definition of a peculiar galaxy because they satisfy three separate categories in the Catalog of Southern Peculiar Galaxies and Associations, by Halton Arp and Barry Madore.
Category 2—Interacting Doubles
Category 9—M51 Types
Category 15—Galaxies with Tails, Loops of Material, or Debris
Tech Notes for ASA 500/3.6:
ASA Newtonian, 500 mm aperture, 1900mm focal length, F3.6
FLI Proline 16803, 9 mm pixel, 4096 X 4096
ASA DDM85 equatorial mount
Processing with PixInsight, StarTools, and Affinity Photo