NGC 6907 and NGC 6908 (Gary Imm)

NGC 6907 and NGC 6908

This object looks like a single galaxy at first glance, located 120 million light years away in the constellation of Capricornus at a declination of -25 degrees.

NGC 6907 is a beautiful barred spiral which spans 3 arc-minutes in our apparent view, which corresponds to a diameter of 100,000 light years. This grand design spiral galaxy has two distinct spiral arms. The arm extending right from the core appears to be much longer than the arm extending left, but that is only an illusion. The galaxy appears to be face-on to us, but that is an illusion as well. It is actually at about 45 degrees to our view.

Looking more closely at the shorter arm, there is a small object in the foreground, to the left and above the core. This object is the small lenticular galaxy NGC 6908. It is 20,000 light years in diameter. This interacting companion has created a long faint plume in the main galaxy which starts immediately above it and extends to the right, curving downward. The plume extends all of the way down to the pair of 2 bright white stars at lower right.

The two galaxies have been verified to be at the same, or at least a similar, distance. In addition to the plume mentioned above, evidence of some disturbance is seen in the brighter HII regions near the small companion. However, it is surprising to me that neither galaxy looks more disturbed. The relative orientation of each galaxy axis plays an important role in the interaction, and it could be that these two galaxies are oriented in such a way to minimize their interaction. Or perhaps the distance between these two galaxies is greater than estimated.

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Description: Mouseover shown companion and suspected plume

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Status	Advanced success
Started	...
Astrometry.net job	6519039
PixInsight job	PP0JDICAS7GJ2UY2YDJ4QRZE1KKR4U9G
PixInsight queue size	n/a
PixInsight stage	TASK_LOG

RA (center)	20h25m06s.761
RA (top/left)	20h25m51s.892
RA (top/right)	20h24m20s.897
RA (bottom/right)	20h24m21s.447
RA (bottom/left)	20h25m52s.598

Dec (center)	-24°48′32″.82
Dec (top/left)	-24°41′24″.16
Dec (top/right)	-24°41′37″.24
Dec (bottom/right)	-24°55′40″.76
Dec (bottom/left)	-24°55′27″.78

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