HiDistribution and Kinematics of UGCA 86

Abstract

We present 21-cm H i line and 408 MHz and 1.4 GHz continuum observations of the Magellanic dwarf galaxy UGCA 86, made with the DRAO synthesis telescope. UGCA 86 is detected in the continuum at both frequencies, with 408 MHz flux density S 408 = 120 ± 30 mJy and 1.4 GHz flux density S 1400 = 79 ± 3 mJy. The H i structure of UGCA 86 is complex, with two separate components: a rotating disk and a highly elongated spur that is kinematically disjunct from the disk. The H i disk is centered on the optical galaxy with similar axial ratio and orientation of the major axis. An area of the disk with a peculiar velocity of ∼ 25 km s −1 relative to the regular rotation of the disk is found on the southern side, where most of the star formation is concentrated. The spur is seen along the minor axis of UGCA 86 and overlaps in part with the disk. Towards the

SAO RAS 6-m telescope spectroscopic observations of globular clusters in nearby galaxies

“…This galaxy is actively forming stars, like IC10. However, this takes place only in two optically bright regions, consistent with the maximum in H i distribution (Stil et al 2005), which extends far from the optical boundaries of the galaxy. UGCA86 covers a larger area than IC10 (3.8 × 2.7 kpc 2 compared to 1.1 × 1.5 kpc 2 ; see Karachentsev et al 2004).…”

“…If we only take into account bright compact GCs, the number of GCs per unit galaxy mass M G = 10 9 M ⊙ , , (Zepf & Ashman 1993) is ∼55 for IC10 and ∼40 for UGCA86. The unusual SC formation activity of both dwarf galaxies was probably induced by the complex H i distribution in them with signatures of interaction with the gas‐rich galaxy M31 in the case of IC10 and of infalling massive gaseous clouds in the case of UGCA86 (Wilcots & Miller 1998; Stil et al 2005).…”

“…In this work, we analyse spectra of 28 GCs in six galaxies of different luminosities situated within ∼4 Mpc in different group environments: (1) the giant spiral neighbour of our Galaxy M 31; (2) the intermediate‐luminosity spiral M 33; (3) IC 10, a starburst dwarf irregular (dIrr) member of the LG; (4) UGCA86, a Magellanic‐type gas‐rich dwarf satellite of IC342, with a complex structure including two bright starburst regions in the visible and a rotating disc as well as a spur in H i (Stil et al 2005 and references therein), and two low surface brightness (LSB) dwarf companions of M81; (5) the spheroidal DDO 71 and (6) the tidal dIrr Holmberg IX (Ho IX) (van den Bergh 1959). Luminosities, heliocentric radial velocities and distances for the galaxies of our study are listed in Table 1.…”

Globular cluster systems in nearby dwarf galaxies - II. Nuclear star clusters and their relation to massive Galactic globular clusters

“…Column (1) gives the cluster ID, in Columns (2), (3) and (4) the distance to the galaxy, D, in Mpc, its absolute magnitude M V ,Gal and the foreground Galactic extinction E (B−V) are listed, Columns (5) and (6) are the absolute magnitude M V ,nGC and V − I colour of the nGCs corrected for foreground extinction, in Columns (7) through (13) are given the cluster mass (M ), ellipticity , half-light radius r h (pc), logarithm of the concentration index c = log 10 (r t /r c ), escape velocity υ esc (km s −1 ) to the tidal radius, projected distance from the galaxy centre R proj in parsecs and R proj normalized to R eff = √ a × b, where a and b are the galaxy semimajor and semiminor axes. Georgiev et al 2009), M H I = 1.6 × 10 8 M , calculated following Roberts & Haynes (1994) from the total flux measured by Stil, Gray & Harnett (2005) and a distance modulus of D = 2.96 Mpc derived by Karachentsev et al (2006). UGCA 86 is at a projected distance of ∼81 kpc (94 arcmin) southeast of the bright (M V = −21.78 mag) Scd galaxy IC 342, thus providing a system similar to the Milky Way and the Magellanic Clouds, although the latter is closer to its dominant host galaxy.…”

OpticalBVIimaging and H I synthesis observations of the dwarf irregular Galaxy ESO 364-G029

“…The H i distribution of several Magellanic dwarfs is known to exhibit further irregularities, such as H i loops surrounding the galaxy (NGC 4618; Bush & Wilcots 2004) and external spurs or blobs (e.g. NGC 5169; Mühle et al 2005;UGCA 98;Stil et al 2005). An S-shaped distortion in the H i velocity field, possibly indicating counterrotation, has been observed in NGC 4449 (Hunter et al 1998) and DDO 43 (Simpson et al 2005).…”