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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 660717.0, MPI für Astronomie / Publikationen_mpia
A tidally distorted dwarf galaxy near NGC 4449
Authors:Rich, R. M.; Collins, M. L. M.; Black, C. M.; Longstaff, F. A.; Koch, A.; Benson, A.; Reitzel, D. B.
Date of Publication (YYYY-MM-DD):2012
Journal Abbrev.:Nature
Issue / Number:7384
Start Page:192
End Page:194
Audience:Not Specified
Abstract / Description:NGC 4449 is a nearby Magellanic irregular starburst galaxy with a B-band absolute magnitude of -18 and a prominent, massive, intermediate-age nucleus at a distance from Earth of 3.8megaparsecs (ref. 3). It is wreathed in an extraordinary neutral hydrogen (HI) complex, which includes rings, shells and a counter-rotating core, spanning ~90kiloparsecs (kpc; refs 1, 4). NGC 4449 is relatively isolated, although an interaction with its nearest known companion--the galaxy DDO 125, some 40kpc to the south--has been proposed as being responsible for the complexity of its HI structure. Here we report the presence of a dwarf galaxy companion to NGC 4449, namely NGC 4449B. This companion has a V-band absolute magnitude of -13.4 and a half-light radius of 2.7kpc, with a full extent of around 8kpc. It is in a transient stage of tidal disruption, similar to that of the Sagittarius dwarf near the Milky Way. NGC 4449B exhibits a striking S-shaped morphology that has been predicted for disrupting galaxies but has hitherto been seen only in a dissolving globular cluster. We also detect an additional arc or disk ripple embedded in a two-component stellar halo, including a component extending twice as far as previously known, to about 20kpc from the galaxy's centre.
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
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