NGC 3169 & 3166

 INTERACTING GALAXIES IN SEXTANS (THE DOLPHINFISH)

AKA THE CAT EYES GALAXIES

(Image centered at: ra 10 h:15 m / dec + 03º 17')

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February 2023, Observatorio Cielos Albertnos, Buenos Aires, Argentina

DATA

TYPE: Interacting Galaxies

APPARENT DIAMETER: 4.8 and 5.2 arc minutes for NGC 3169 and NGC 3166 respectively

APPARENT MAGNITUDE (V): 10.3 and 10.5 for NGC 3169 and NGC 3166 respectively

DISTANCE: 70 to 75 Millions light years

IMAGE INFORMATION

INSTRUMENT: 8" ORION OPTICS UK (Ultra Grade Optics) w/Televue Paracorr working at at f5,75

CAMERA: QSI 583 WS

MOUNT: SKY WATCHER NEQ6, OAG with Starlight Xpress Lodestar

FILTERS: Baader LRGB Set

SKY CONDITIONS: Bortle 2 skies

EXPOSURES: LRGB (180,40,40,40)

OBJECT DESCRIPTION AND IMAGE SESSION

NGC 3169 (left) and NGC 3166 (right) are two interacting spiral galaxies, located some 70 – 75 million light-years away in the constellation of Sextans (the Sextant). The distance between the galaxies is about 160,000 light-years. Combined with NGC 3165, the small and dim spiral galaxy at the below-right of the pair, they form the NGC 3166 group of galaxies within the larger Leo 1 group.

NGC 3169 is an unbarred spiral galaxy with tightly-wound arms, including an asymmetrical one, that are shining bright with big, young, blue stars. It has a small bright nucleus (likely harbours a super massive black hole) and multiple dust lanes that appear in silhouette against the large central bulge. There is an extended halo around the galaxy. NGC 3166 is a barred spiral galaxy with a very small, and bright nucleus in a short smooth bar, and unlike its bluer counterpart, it is not forming many new stars. It shows a large very faint extended envelope.

These adjacent galaxies are demonstrating that each member of the duo is close enough to feel the distorting gravitational influence of the other. As these two galaxies begin to merge, they are starting to be pulled apart. The faint wisps surrounding NGC 3169 are its outer spiral arms being pulled off, and lots of luminous gas has been drawn out from its disk. The three galaxies are embedded within an extended ring of neutral hydrogen that is centered on NGC 3169. Eventually the galaxies will merge to form a single galaxy.

By the 2023 summer Buenos Aires interior is suffering from the "la niña effect" and consequently we had dry fields over the pampas. North winds brought some dust into de atmosphere and also affected the guiding on the NEQ6 loosing a bit of resolution.

NGC 3169 & 3166

 INTERACTING GALAXIES IN SEXTANS (THE DOLPHINFISH)

AKA THE CAT EYES GALAXIES

ANNOTATED IMAGE AT 100% RESOLUTION