The Neutral Gas Dynamics of the Nearby Magellanic Irregular Galaxy UGCA 105

We present new low-resolution HI spectral line imaging, obtained with the Karl G. Jansky Very Large Array (JVLA), of the star-forming Magellanic irregular galaxy UGCA 105. This nearby (D = 3.39+/-0.25 Mpc), low mass [M_HI=(4.3+/-0.5)x10^8 Solar masses] system harbors a large neutral gas disk (HI rad...

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Bibliographic Details
Published in:arXiv.org 2012-07
Main Authors: Cannon, John M, Bernstein-Cooper, Elijah Z, Cave, Ian M, Harris, Jon B, Marshall, Melissa V, Moen, Jacob M, Moody, Samilee J, O'Leary, Erin M, Pardy, Stephen A, Thomann, Clara M
Format: Article
Language:English
Subjects:
Galaxies
Gas dynamics
Image resolution
Inclination
Irregular galaxies
Line spectra
Neutral gases
Rotation
Star & galaxy formation
Star formation
Stellar mass
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Summary:We present new low-resolution HI spectral line imaging, obtained with the Karl G. Jansky Very Large Array (JVLA), of the star-forming Magellanic irregular galaxy UGCA 105. This nearby (D = 3.39+/-0.25 Mpc), low mass [M_HI=(4.3+/-0.5)x10^8 Solar masses] system harbors a large neutral gas disk (HI radius ~7.2 kpc at the N_HI=10^20 cm^-2 level) that is roughly twice as large as the stellar disk at the B-band R_25 isophote. We explore the neutral gas dynamics of this system, fitting tilted ring models in order to extract a well-sampled rotation curve. The rotation velocity rises in the inner disk, flattens at 72+/-3 km/s, and remains flat to the last measured point of the disk (~7.5 kpc). The dynamical mass of UGCA 105 at this outermost point, (9+/-2)x10^9 Solar masses, is ~10 times as large as the luminous baryonic components (neutral atomic gas and stars). The proximity and favorable inclination (55 degrees) of UGCA 105 make it a promising target for high-resolution studies of both star formation and rotational dynamics in a nearby low-mass galaxy.
ISSN:2331-8422
DOI:10.48550/arxiv.1207.4953