Arp 31 & NGC 678 / 680 / 691 (Gary Imm)

Arp 31 & NGC 678 / 680 / 691

This object is a galaxy group located in the constellation of Aries at a declination of +22 degrees. I love fields of view that capture different galaxy types and perspectives, and this one is a great example of that. The 4 galaxies from left to right are Arp 31, NGC 691, NGC 680 and NGC 678. The Arp galaxy is 70 million light years away, while the NGC galaxies are all 130 million light years away.

Arp 31, also known as IC 167, has a strongly barred core, several bright star clusters, and 2 strong arms with Vorontsov-Velyaminov rows. The galaxy spans 3 arc-minutes in our apparent view, which corresponds to a diameter of 60,000 light years.

NGC 691 is an almost face-on spiral with a diameter of 120,000 light years. It lies close to a bright triple star in our apparent view. The galaxy structure is fascinating, with a wide ring in the middle section and star streams on the right side of the outer disk. A curving line of star clusters is seen on the right side of the disk in the middle region.

NGC 680 is an elliptical galaxy with a diameter of 75,000 light years. As with the other galaxies, disturbance is clear here in the form of an asymmetric outer edge to the galaxy region.

NGC 678 is seen edge-on and has a dust lane along its whole length. The galaxy spans 5 arc-minutes in our apparent view, which corresponds to a large diameter of 175,000 years. The dust lane runs above the galaxy disk on the left side and below it on the right, and dips as it crosses our view of the core.

It is amazing to view this image in its inverted view. There, it is easy to see the triple star, the star clusters in Arp 31 and NGC 691, the star stream in NGC 691, the asymmetric shape of NGC 680, and the odd disk of edge-on NGC 678.

Final
Original
C
D

C

Description: Inverted

Uploaded: ...

D

Description: Comparison to Original Arp Image

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ZWO ASI183/QHY183
The refractors!
Cloudy Nights
Arp's Peculiar Galaxies
Texas Astronomy
Takahashi Refractors

Arp Catalog (Complete)
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Status	Advanced success
Started	...
Astrometry.net job	3233147
PixInsight job	337N1E34R0ZBQAV8HY6K5CGWN3IZL5XG
PixInsight queue size	n/a
PixInsight stage	n/a

RA (center)	01h50m12s.775
RA (top/left)	01h51m25s.617
RA (top/right)	01h49m06s.745
RA (bottom/right)	01h49m00s.109
RA (bottom/left)	01h51m18s.576

Dec (center)	+21°53′43″.10
Dec (top/left)	+22°04′20″.78
Dec (top/right)	+22°06′31″.18
Dec (bottom/right)	+21°43′02″.98
Dec (bottom/left)	+21°40′53″.50

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