TY - JOUR
T1 - Inflows and outflows in the dwarf starburst galaxy NGC 5253
T2 - High-resolution H i observations
AU - Kobulnicky, Henry A.
AU - Skillman, Evan D.
N1 - Copyright:
Copyright 2008 Elsevier B.V., All rights reserved.
PY - 2008/2/1
Y1 - 2008/2/1
N2 - Very Large Array and Parkes 64 m radiotelescope 21 cm observations of the starburst dwarf galaxy NGC 5253 reveal a multi-component non-axisymmetric H I distribution. The component associated with the stellar body shows evidence for a small amount of rotational support aligned with the major axis, in agreement with optically measured kinematics and consistent with the small galactic mass. Approximately 20-30% of the H I emission is associated with a second component, an H I "plume" extending along the optical minor axis to the southeast. We consider outflow, inflow, and tidal origins for this feature. Outflow appears improbable, inflow is a possibility, and tidal debris is most consistent with the observations. Thus, kinematics of the H I that include this feature are not indicative of the dynamical mass or the local velocity dispersion of the cold gas. These H I observations also reveal a filamentary third component that includes an 800 pc diameter H I shell or bubble to the west of the nucleus, coinciding with an Hα shell. The mass of H I in the shell may be as large as 4 × 106 M ⊙. This large mass, coupled with the lack of expansion signatures in the neutral and ionized gas (v < 30 km s-1), suggests that this feature may be an example of a starburst-blown bubble stalled by interaction with a massive neutral envelope. Many other H I kinematic features closely resemble those seen in Hα emission from the ionized gas, supporting the interpretation of neutral and ionized gas outflow at velocities of 30 km s-1. Comparison between extinction estimates from the Balmer emission-line decrement and the H I column densities suggests a gas-to-dust ratio 2-3 times the Galactic value in this low-metallicity (Z = 1/4Z ⊙) galaxy.
AB - Very Large Array and Parkes 64 m radiotelescope 21 cm observations of the starburst dwarf galaxy NGC 5253 reveal a multi-component non-axisymmetric H I distribution. The component associated with the stellar body shows evidence for a small amount of rotational support aligned with the major axis, in agreement with optically measured kinematics and consistent with the small galactic mass. Approximately 20-30% of the H I emission is associated with a second component, an H I "plume" extending along the optical minor axis to the southeast. We consider outflow, inflow, and tidal origins for this feature. Outflow appears improbable, inflow is a possibility, and tidal debris is most consistent with the observations. Thus, kinematics of the H I that include this feature are not indicative of the dynamical mass or the local velocity dispersion of the cold gas. These H I observations also reveal a filamentary third component that includes an 800 pc diameter H I shell or bubble to the west of the nucleus, coinciding with an Hα shell. The mass of H I in the shell may be as large as 4 × 106 M ⊙. This large mass, coupled with the lack of expansion signatures in the neutral and ionized gas (v < 30 km s-1), suggests that this feature may be an example of a starburst-blown bubble stalled by interaction with a massive neutral envelope. Many other H I kinematic features closely resemble those seen in Hα emission from the ionized gas, supporting the interpretation of neutral and ionized gas outflow at velocities of 30 km s-1. Comparison between extinction estimates from the Balmer emission-line decrement and the H I column densities suggests a gas-to-dust ratio 2-3 times the Galactic value in this low-metallicity (Z = 1/4Z ⊙) galaxy.
KW - Galaxies: ISM
KW - Galaxies: individual (NGC 5253)
KW - Galaxies: kinematics and dynamics
KW - Galaxies: starburst
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U2 - 10.1088/0004-6256/135/2/527
DO - 10.1088/0004-6256/135/2/527
M3 - Article
AN - SCOPUS:50849120814
SN - 0004-6256
VL - 135
SP - 527
EP - 537
JO - Astronomical Journal
JF - Astronomical Journal
IS - 2
ER -