Sep 17, 2021 01:18 AM
https://astronomy.com/magazine/news/2021...an-observe
EXCERPTS: The term peculiar galaxies refers to a class of galaxies whose distorted shapes resemble neither classical spiral galaxies nor amorphous elliptical galaxies — and at the time, they were still mysterious. Just 16 years earlier, Halton Arp had published his Atlas of Peculiar Galaxies, a product of his documentation of objects while examining the Palomar Sky Survey. It contained a sampling of some the most unusual galaxies whose warped structures defied explanation.
After the passage of four decades, our understanding of what makes such galaxies peculiar has improved — thanks to the Hubble Space Telescope, giant new telescopes with adaptive optics, and more powerful computers that can model the gravitational dances of interacting galaxies.
[...] As you might expect, the No. 1 cause of peculiarities is collision. An estimated 5 percent of galaxies in the visible universe are interacting. And if we had infrared vision, that number would rise to 25 percent; galaxies that emit mostly infrared light seem to interact at a higher rate. Other causes include bursts of star formation (related to collisions or interactions with intergalactic hydrogen clouds) and exploding cores (due to massive black holes). Some have anomalously large clouds of dust or glowing ionized hydrogen gas (HII regions). A small percentage are still mysterious. Given time and technology, these will become understood.
[...] The good news for amateur observers is that plenty of peculiar galaxies are bright enough to be seen in 4- to 10-inch telescopes. Several can even be picked up in binoculars.
Observing detail, however, is another matter. If you have not dabbled in peculiar galaxies before, it is better to simply find these targets and not worry if you don’t see a peculiar feature.
To bring out the most detail possible, nothing beats a large aperture and dark, unpolluted skies. Another strategy to eke out shreds of detail is to avert your vision slightly to one side of the object, relying on your retina’s more light-sensitive rod cells. Perhaps they will reveal a bit of asymmetry, a faint companion, a bright patch or arm, or a shadowy dark nebula.
[...] My 1981 article featured 12 of my favorite peculiar galaxies. Since then, I’ve observed many other peculiar galaxies with larger optics. Here are 12 of my new favorites... (MORE - missing details)
EXCERPTS: The term peculiar galaxies refers to a class of galaxies whose distorted shapes resemble neither classical spiral galaxies nor amorphous elliptical galaxies — and at the time, they were still mysterious. Just 16 years earlier, Halton Arp had published his Atlas of Peculiar Galaxies, a product of his documentation of objects while examining the Palomar Sky Survey. It contained a sampling of some the most unusual galaxies whose warped structures defied explanation.
After the passage of four decades, our understanding of what makes such galaxies peculiar has improved — thanks to the Hubble Space Telescope, giant new telescopes with adaptive optics, and more powerful computers that can model the gravitational dances of interacting galaxies.
[...] As you might expect, the No. 1 cause of peculiarities is collision. An estimated 5 percent of galaxies in the visible universe are interacting. And if we had infrared vision, that number would rise to 25 percent; galaxies that emit mostly infrared light seem to interact at a higher rate. Other causes include bursts of star formation (related to collisions or interactions with intergalactic hydrogen clouds) and exploding cores (due to massive black holes). Some have anomalously large clouds of dust or glowing ionized hydrogen gas (HII regions). A small percentage are still mysterious. Given time and technology, these will become understood.
[...] The good news for amateur observers is that plenty of peculiar galaxies are bright enough to be seen in 4- to 10-inch telescopes. Several can even be picked up in binoculars.
Observing detail, however, is another matter. If you have not dabbled in peculiar galaxies before, it is better to simply find these targets and not worry if you don’t see a peculiar feature.
To bring out the most detail possible, nothing beats a large aperture and dark, unpolluted skies. Another strategy to eke out shreds of detail is to avert your vision slightly to one side of the object, relying on your retina’s more light-sensitive rod cells. Perhaps they will reveal a bit of asymmetry, a faint companion, a bright patch or arm, or a shadowy dark nebula.
[...] My 1981 article featured 12 of my favorite peculiar galaxies. Since then, I’ve observed many other peculiar galaxies with larger optics. Here are 12 of my new favorites... (MORE - missing details)