The Local Volume HI Survey

ESO 223-G009 (HIPASS J1501-48) is a Magellanic irregular galaxy at a TRGB distance of 6.49 ± 0.51 Mpc (Karachentsev et al. 2007). Due to its low Galactic latitude (b = 9.2 degr) it is obscured by dust and foreground stars. While the B-band Galactic extinction in this direction is moderate (A_B = 0.94), the density of Galactic foreground stars is quite high, making it difficult to estimate the galaxy's optical dimensions and orientation. No optical velocity has yet been measured. Using HST ACS images we find that the main stellar body of ESO 223-G009 is best described by an ellipse of size 160 arcsec × 130 arcsec (5 kpc × 4 kpc), PA = 135 degr, centered at α,δ(J2000) = 15:01:08, -48:17:30. ESO 223-G009 appears to be a relativly isolated galaxy, with only one known neighbour, the late-type spiral ESO 274-G001 (HIPASS 1514-46 at D = 3.1 Mpc, i.e. in the foreground), within 3\degr. It may form a loose association with the dwarf irregular galaxies ESO 222-G010, ESO 272-G025 and HIPASS J1526-51 (at projected distances of 266 arcmin, 282 arcmin, and 300 arcmin, respectively), about 2 Mpc behind the Cen A Group. Our ATCA HI maps of ESO 223-G009 reveal a large, nearly circular gas distribution and a very peculiar velocity field (see Koribalski 2010). We measure F_HI = 97.0 Jy km/s, in agreement with HIPASS (Koribalski et al. 2004), and derive M_HI = 9.6 × 10⁸ M_☉. The highly twisted and warped HI velocity field is indicative of a face-on warp where the gaseous disc wobbles in and out of the plane. Using 3D FAT Kamphuis et al. (2015) obtain an HI rotation curve indicating v_rot = 85.6 km/s at R_max = 15.3 kpc (for i = 20.3 degr and PA = 256.1 degr) and M_dyn = 2.6 × 10¹⁰ M_☉. ESO 223-G009 shows similarities to the spiral galaxies NGC 628 (Kamphuis & Briggs 1992), NGC 3642 (Verdes-Montenegro et al. 2002), IC 10 (Manthey & Oosterloo 2008) and the lenticular galaxy ESO 381-G047 (Donovan et al. 2009). The common feature of these rather different galaxies is their warped, nearly face-on HI discs.

Reference: Koribalski et al. 2018 * LVHIS database * LVHIS homepage * next