Celestial hemisphere:  Northern  ·  Constellation: Ursa Major (UMa)  ·  Contains:  NGC 3769
Arp 280, Gary Imm

Arp 280

Arp 280, Gary Imm

Arp 280

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Description

This object is a pair of galaxies located 55 million light years away in the constellation of Ursa Major at a declination of +48 degrees. In his Arp catalog, Dr. Arp classified this object into the category of Interacting Double Galaxies.

The large galaxy is the magnitude 13 barred spiral NGC 3769. It spans 3.5 arc-minutes in our apparent view, which corresponds to a diameter of 60,000 light years. The galaxy is 10 degrees from edge-on by my calculation. The smaller galaxy is MCG+08-21-077. Assuming it is at the same distance as NGC 3769, it is a dwarf companion galaxy about 20,000 light years in diameter.

The Hubble image of the mouseover is useful in understanding the knot at the top of NGC 3769. The "knot" is a distant spiral galaxy, which makes sense given its orange color in my image.

Although the resolution of the Hubble image wins this comparison hand down, I was happy with the colors which are seen in my image. In particular, the bottom region of the large galaxy closest to the dwarf companion galaxy is bursting with the blue color of star clusters and star formation. I think I also see a reddish tint in this lower region indicating the presence of HII regions. All of this, along with the faint star stream bridge, points to interaction between these 2 distant galaxies.

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