Pair of Galaxies NGC 3395/6 (Arp 270)
History
The galaxy pair NGC 3395/6 was discovered on 7 December 1785 by the German-British astronomer William Herschel with his homemade 18.7 inch f/12.8 reflecting telescope in Slough, England. He listed them under the designations I 116 and I 117. The same night he also encountered NGC 3413 (II 439), NGC 3424 (II 494), and NGC 3430 (I 118). [196, 277, 313] He classified his discoveries based on purely visual impressions, with I = bright nebulae and II = faint nebulae. [269]
The French astronomer Stephane Javelle searched this area of the sky on 17 May 1896 with the 76 cm refractor telescope of the Observatoire de Nice and recorded four other nebulae: IC 2604, IC 2605, IC 2608 and IC 2612, with IC 2605 being a bright node in the galaxy NGC 3995. [196, 277, 315]
Halton Arp divided his «Atlas of Peculiar Galaxies», published in 1966, into groups based on purely morphological criteria. The pair of galaxies here received the designation Arp 270 as a pair of interacting galaxies. [199]
Physical Properties
The interacting galaxy pair NGC 3395/6 is at a distance of 15 to 30 Mpc. [145] According to HyperLEDA [134] they together form the NGC 3430 galaxy group with a total of 15 members, which also includes NGC 3381, NGC 3424, NGC 3430, NGC 3442, IC 2604 and IC 2608. IC 2612 (PGC 32704) has a much higher redshift of z = 0.04452, which corresponds to a heliocentric velocity of about 13400 km/s. This galaxy is far in the background.
| Name | RA [hms] | Dec [dms] | mType | Dim ['] | Btot [mag] | HRV [km/s] | PA [°] |
|---|---|---|---|---|---|---|---|
| PGC 32390, IC 2604 | 10 49 25.7 | +32 46 29 | SB | 1.2 x .9 | 14.8 | 1680 | 40 |
| PGC 32424, NGC 3395 | 10 49 49.4 | +32 58 51 | SB M | 1.7 x .9 | 12.5 | 1621 | 50 |
| PGC 32434, NGC 3396 | 10 49 56.1 | +32 59 22 | IB M | 2.9 x 1.2 | 12.6 | 1633 | 100 |
| PGC 32464, IC 2608 | 10 50 15.4 | +32 46 06 | S | .9 x .3 | 15.6 | ||
| PGC 32543, NGC 3413 | 10 51 21.1 | +32 46 04 | L | 1.8 x .8 | 13.1 | 645 | 178 |
| PGC 32584, NGC 3424 | 10 51 46.5 | +32 54 02 | SB | 2.7 x .8 | 13.2 | 1497 | 112 |
| PGC 32614, NGC 3430, IC 2613 | 10 52 10.9 | +32 57 09 | SB | 4.1 x 2.2 | 12.2 | 1585 | 30 |
| PGC 32704 | 10 53 34.3 | +32 45 01 | E | x |
Finder Chart
The interacting galaxy pair NGC 3395/6 is located in the constellation Leo Minor. The best viewing time is October to June.
Visual Observation
762 mm Aperture: Both galaxies are slightly more elongated than wide and are at right angles to each other, one of which is slightly wider compared to the second. The nuclei are each perceptible as points. — 30" SlipStream-Dobson f/3.3, Hasliberg, 14. 2. 2023, Eduard von Bergen