Galaxy NGC 1097

NGC 1097
NGC 1097: Barred spiral galaxy with tidal streams in Fornax; 16" f/8.3 Hypergraph, SBIG STL-11000M,; 38 x 10 min Luminance, je 5 x 10 min RGB, 2x2 Binning; Farm Tivoli, Namibia; © 2014 Eduard von Bergen, Hansjörg Wälchli


Wilhelm Herschel was the first to encounter this galaxy on October 9, 1790 with his 18.7 inch reflector. He cataloged it as V 48 (class V = very large nebulae). He noted: «Very bright, extended 75°, north preceding, south following, 8' long. A very bright nucleus, confined to a small part, or about 1' diameter.» [465]

Physical Properties

NGC 1097 is a barred spiral galaxy of type SB(s)b and has an exceptionally bright core and therefore belongs to the group of Seyfert galaxies (Type 1), which, together with quasars, are among the most active galaxies. The supermassive black hole in the center is fed by stars, gas and dust, which fall in spirals, are torn apart and heated up, forming an accretion disk around the black hole.

NGC 1097
NGC 1097: Image taken with the 8.2 meter telescope of the VLT in Chile [236]

The distances calculated from the measured heliocentric velocities range from 14 Mpc to 17.7 Mpc (45.6 to 57.7 million light years). [145]

In Fig. 1 and Fig. 2, a noticeable bright ring can be seen around the black hole in the center. There are masses of new stars that are stimulated by the inflow of matter via central bars. The diameter of the ring is estimated to be around 5000 light years and the mass of the black hole to be around 140 million solar masses. For comparison: the black hole in the center of our Milky Way has «only» a few million solar masses. [235, 237]

NGC 1097
NGC 1097: Galaxy NGC 1097 with all four tidal streams, which can be traced to the dwarf galaxy in stream 1; © 2021 Eduard von Bergen

In the image in Fig. 1, four faint rays can be seen, which seem to come radially from the center of the galaxy. These are highlighted in Fig. 3. These were originally interpreted as the remnants of the jets of a currently less active core. A further analysis of the spectral energy distribution from radio to X-rays could rule out such an origin. These «jets» actually consist of individual stars and were created through gravitational interaction with small dwarf galaxies. The main culprit is not the small, elliptical galaxy NGC 1097A, but the remnant of it was discovered in the L-shaped tidal current. [238]

«Catalogue of Principal Galaxies (PGC)», Paturel et al. 1989 [144]
NameRA [hms]Dec [dms]mTypeDim [']Btot [mag]HRV [km/s]PA [°]
NGC 1097A02 46 09.9-30 13 45E M.8 x .513.01337105
NGC 109702 46 18.9-30 16 21SBR9.4 x 6.610.31274130

Finder Chart

The galaxy NGC 1097 is located in constellation Fornax (Furnace) at a declination of -30° and is therefore low in the southern sky. The best time for this is around November, when the constellation is highest above the southern horizon at midnight. Follow the river Eridanus next to Rigel in Orion to the second river bend. Unless the three stars Dalim (α Fornacis, 3.79 mag) - β Fornacis (4.46 mag) - ν Fornacis (4.96 mag) sink into the light dome of Milan or are blocked by a mountain, they show you the way to NGC 1097.

Chart NGC 1097
Chart created using SkySafari 6 Pro and STScI Digitized Sky Survey. [149, 160]

Visual Observation

762 mm aperture: The extremely low and very southerly Seyfert galaxy NGC 1097 with companion PGC 10479 should be planned very well in advance for your successful sighting. In our latitudes and especially in a mountain valley, visibility is only given for three quarters of an hour. Thanks to a right-angled triangle made up of three roughly equally bright stars, NGC 1097 can be clearly found, despite the already bad refraction. The core shows only a slight elongation, whereby it appears at least slightly washed out. The companion galaxy PGC 10479 exceeds expectations in terms of its visibility, it is much easier to spot than expected. — 30" f/3.3 Slipstream Dobsonian, Hasliberg Reuti, 5. 11. 2021, Eduard von Bergen


144Catalogue of Principal Galaxies (PGC); Paturel G., Fouque P., Bottinelli L., Gouguenheim L.; Astron. Astrophys. Suppl. Ser. 80, 299 (1989); (2021-02-18)
145SIMBAD astronomical database;
149SkySafari 6 Pro, Simulation Curriculum;
160The STScI Digitized Sky Survey;
235Astronomers Measure Mass of Supermassive Black Hole in NGC 1097; (2021-01-20)
236Spiral galaxy NGC 1097; (2021-01-20)
237«A Measurement of the Black-Hole Mass in NGC 1097 using ALMA» Kyoko Onishi (1, 2), Satoru Iguchi, Kartik Sheth, Kotaro Kohno ((1) SOKENDAI (The Graduate University for Advanced Studies), (2) National Astronomical Observatory of Japan); DOI:10.1088/0004-637X/806/1/39
238«A dwarf galaxy's transformation and a massive galaxy's edge: autopsy of kill and killer in NGC 1097» N. C. Amorisco, D. Martinez-Delgado, J. Schedler; arXiv:1504.03697
465«Catalogue of 500 new nebulae, nebulous stars, planetary nebula:, and clusters of stars; with remarks on the construction of the heavens» William Herschel, Philosophical Transactions of the Royal Society of London, 1 January 1802; DOI:10.1098/rstl.1802.0021