HI survey of local group dwarf galaxies
type: CreativeWork
description: This thesis investigates the HI properties of 3 dwarf irregular galaxies and one blue compact dwarf galaxy of the Local Group. The data set of each dwarf irregular galaxy was obtained with the Karoo Array Telescope (KAT-7) while the blue compact dwarf was observed with the Dominion Radio Astrophysical Observatory (DRAO) synthesis telescope. While the main purpose of KAT-7 was to test technical solutions for MeerKAT, its capabilities, and that of DRAO, have enabled us to produce interesting Square Kilometer Array (SKA) pathfinder science. The compact configuration of the two telescopes, coupled with low system temperatures (Ts ys) provide a unique HI dataset on nearby dwarf galaxies; sensitivity to extended HI emission while providing intermediate resolution to derive the large scale kinematics. The following properties are investigated in details: i) the HI distribution, ii) kinematics and mass distribution, iii) star formation thresholds, and iv) possible mechanisms for the chaotic HI structure and kinematics in a blue compact dwarf galaxy. The main results of our study are: from the HI distribution, the KAT-7 results have revealed even more neutral gas mass in the outer disk of NGC 6822. We detect 23% more HI mass in NGC 6822 than what was detected with the Australian Telescope Compact Array (ATCA). The KAT-7 results have been able to show an overestimate of the HI extent previously reported for Sextans A using Effelsberg observations. For IC 10, the complex HI features detected with DRAO are by a factor of ∼ 2 more extended than previous interferometric HI studies. Rotation velocities are derived for each galaxy. For NGC 6822, the rotation curve probes the gravitational potential out to 5.8 kpc, ∼ 1 kpc further than existing measurements. The rotation curves of Sextans A and B decline in the outer regions and extends out to 3.5 kpc and 4 kpc respectively. The central region of IC 10 has a regularly rotating disk, and the rotation velocities rise slowly in the inn…
abstract: This thesis investigates the HI properties of 3 dwarf irregular galaxies and one blue compact dwarf galaxy of the Local Group. The data set of each dwarf irregular galaxy was obtained with the Karoo Array Telescope (KAT-7) while the blue compact dwarf was observed with the Dominion Radio Astrophysical Observatory (DRAO) synthesis telescope. While the main purpose of KAT-7 was to test technical solutions for MeerKAT, its capabilities, and that of DRAO, have enabled us to produce interesting Square Kilometer Array (SKA) pathfinder science. The compact configuration of the two telescopes, coupled with low system temperatures (Ts ys) provide a unique HI dataset on nearby dwarf galaxies; sensitivity to extended HI emission while providing intermediate resolution to derive the large scale kinematics. The following properties are investigated in details: i) the HI distribution, ii) kinematics and mass distribution, iii) star formation thresholds, and iv) possible mechanisms for the chaotic HI structure and kinematics in a blue compact dwarf galaxy. The main results of our study are: from the HI distribution, the KAT-7 results have revealed even more neutral gas mass in the outer disk of NGC 6822. We detect 23% more HI mass in NGC 6822 than what was detected with the Australian Telescope Compact Array (ATCA). The KAT-7 results have been able to show an overestimate of the HI extent previously reported for Sextans A using Effelsberg observations. For IC 10, the complex HI features detected with DRAO are by a factor of ∼ 2 more extended than previous interferometric HI studies. Rotation velocities are derived for each galaxy. For NGC 6822, the rotation curve probes the gravitational potential out to 5.8 kpc, ∼ 1 kpc further than existing measurements. The rotation curves of Sextans A and B decline in the outer regions and extends out to 3.5 kpc and 4 kpc respectively. The central region of IC 10 has a regularly rotating disk, and the rotation velocities rise slowly in the inn…
author: Namumba, Brenda
date published: 2019
date modified: 2026-07-22T22:22:46Z
provider: University of Cape Town
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Department of Astronomy

PropertyValue
property ID: Handle
value: http://hdl.handle.net/11427/30109