A distant and dazzling spiral galaxy, Arp 184 (NGC 1961), captured by the Hubble Space Telescope, reveals a stunningly lopsided structure, with one prominent star-strewn arm stretching toward Earth.
This cosmic oddity resides in the constellation Camelopardalis and earns its name from the Atlas of Peculiar Galaxies, a collection of the universe’s strangest-shaped galaxies. Scientists are drawn to Arp 184 not only for its peculiar shape but also for its history of explosive activity, hosting four known supernovae in recent decades, making it a prime target for both beauty and scientific investigation.
A Cosmic Beauty With a Twist
A striking but skewed spiral galaxy takes center stage in the latest Hubble Space Telescope Picture of the Week. Known as Arp 184, or NGC 1961, this galaxy lies approximately 190 million light-years from Earth, nestled in the northern constellation Camelopardalis, also known as The Giraffe.
Cataloging the Strange: Arp’s Atlas
Arp 184 is named after its inclusion in the Atlas of Peculiar Galaxies, a catalog assembled in 1966 by astronomer Halton Arp. This collection features 338 unusual galaxies — most with shapes that don’t fit neatly into typical categories like spiral or elliptical. Many are caught in the act of merging or interacting with other galaxies, while others, known as dwarf galaxies, are small and irregularly formed.
What makes Arp 184 stand out is its asymmetrical design. It boasts a single, wide, star-filled spiral arm that appears to extend in our direction, creating a dramatic, off-kilter appearance. In contrast, the opposite side of the galaxy is much less defined, showing only faint traces of gas and stars without a matching spiral arm.
A Snapshot of the Peculiar
This Hubble image combines data from three Snapshot observing programs, which are composed of short observations that can be slotted into time gaps between other proposals. One of the three programs targeted Arp 184 for its peculiar appearance. This program surveyed galaxies listed in the Atlas of Peculiar Galaxies as well as A Catalogue of Southern Peculiar Galaxies and Associations, a similar catalogue compiled by Halton Arp and Barry Madore.
A Supernova Hotspot
The remaining two programs were designed to check up on the aftermath of fleeting astronomical events like supernovae and tidal disruption events, when a star is ripped apart after wandering too close to a supermassive black hole. Since Arp 184 has hosted four known supernovae in the past three decades, it’s a rich target for a supernova hunt.
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