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Title

Antlia Dwarf Galaxy: distance, quantitative morphology and recent formation history via statistical field correction

Author(s)

Pimbblet, Kevin A.;  Couch, Warrick J.

Abstract

We apply a statistical field correction technique originally designed to determine membership of high redshift galaxy clusters to Hubble Space Telescope (HST) imaging of the Antlia Dwarf Galaxy; a galaxy at the very edge of the Local Group. Using the tip of the red giant branch standard candle method coupled with a simple Sobel edge detection filter we find a new distance to Antlia of 1.31 ± 0.03 Mpc. For the first time for a Local Group member, we compute the concentration, asymmetry and clumpiness quantitative morphology parameters for Antlia from the distribution of resolved stars in the HST/Advanced Camera for Surveys (ACS) field, corrected with a new method for contaminants and complement these parameters with the Gini coefficient (G) and the second-order moment of the brightest 20 per cent of the flux (M20). We show that it is a classic dwarf elliptical (C = 2.0, A = 0.063, S = 0.077, G = 0.39 and M20=−1.17 in the F814W band), but has an appreciable blue stellar population at its core, confirming on-going star formation. The values of asymmetry and clumpiness, as well as Gini and M20 are consistent with an undisturbed galaxy. Although our analysis suggests that Antlia may not be tidally influenced by NGC 3109, it does not necessarily preclude such interaction.

Publication type

Journal article

Research centre

Swinburne University of Technology. Faculty of Information and Communication Technologies. Centre for Astrophysics and Supercomputing

Source

Monthly Notices of the Royal Astronomical Society, Vol. 419, no. 2 (Jan 2012), pp. 1153-1162

Publication year

2012

FOR Code(s)

0201 Astronomical and Space Sciences

Keyword(s)

Antlia Dwarf Galaxy;  Colour magnitude diagrams;  Distances;  Galaxy structure;  Hertzsprung-Russell diagrams;  Local Group;  Redshifts;  Statistics

Publisher

Wiley-Blackwell Publishing

ISSN

0035-8711

Publisher URL

http://dx.doi.org/10.1111/j.1365-2966.2011.19769.x

Copyright

Copyright © 2011 The Authors. Journal copyright © 2011 Royal Astronomical Society. The accepted manuscript is reproduced in accordance with the copyright policy of the publisher. The definitive publication is available at www.interscience.wiley.com.

Full text

Peer reviewed