The Local Volume HI Survey

ESO 461-G036 (HIPASS J2003-31) is a dwarf irregular galaxy at a TRGB distance of 7.83 ± 0.63 Mpc (Karachentsev et al. 2006). It appears very isolated, having no known neighbours within at least 5 degr. Our ATCA HI data show a remarkable, regularly rotating HI disc extending well beyond the stellar body. The HIPASS and ATCA HI observations both indicate a total HI flux density of 7.5 Jy km/s, corresponding to an HI mass of 1.1 × 10⁸ M_☉. The velocity field suggests a mild warp of the outer disc, which has a diameter of ~6 arcmin. Our HI maps show a significant swing of the position angle. While the HI emission in the inner most region is aligned with the stellar extent (PA ~ 20 degr), the kinematic major axis suggests rotation along a different axis (PA ~ 340 degr). Begum et al. (2008) observed ESO 461-G036 as part of the FIGGS project. Their estimates of F_HI and D_HI are underestimates due to the limited observed velocity range as evident by the truncated HI spectrum in their Fig. 5. Kreckel et al. (2011) analyse VLA HI data and obtain a rotation curve showing v_rot ~ 51 km/s (for i ~ 65 degr), and R_max = 6.8 kpc. Without the influence of neighbouring galaxies, the kinematics of the large HI disc of ESO 461-G036 reflect its intrinsic evolution. Similar to NGC 2915, the galaxy is dominated by a large dark matter halo.

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