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Title

A blue tilt in the globular cluster system of the Milky Way-like galaxy NGC 5170

Author(s)

Forbes, Duncan A.;  Spitler, Lee R.;  Harris, W. E.;  Bailin, Jeremy;  Strader, Jay;  Brodie, Jean P.;  Larsen, S. S.

Abstract

Here, we present Hubble Space Telescope/Advanced Camera for Surveys (ACS) imaging, in the B and I bands, of the edge-on Sb/Sc galaxy NGC 5170. Excluding the central disc region, we detect 142 objects with colours and sizes typical of globular clusters (GCs). Our main result is the discovery of a 'blue tilt' (a mass–metallicity relation), at the 3σ level, in the metal-poor GC subpopulation of this Milky Way like galaxy. The tilt is consistent with that seen in massive elliptical galaxies and with the self-enrichment model of Bailin & Harris. For a linear mass–metallicity relation, the tilt has the form Z∼L0.42±0.13 . We derive a total GC system population of 600 ± 100, making it much richer than the Milky Way. However, when this number is normalized by the host galaxy luminosity or stellar mass it is similar to that of M31. Finally, we report the presence of a potential Ultra Compact Dwarf of size ∼6 pc and luminosity MI∼−12.5 , assuming it is physically associated with NGC 5170.

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. 403, no. 1 (Mar 2010), pp. 429-438

Publication year

2010

FOR Code(s)

0201 Astronomical and Space Sciences;  020103 Cosmology and Extragalactic Astronomy

Keyword(s)

Globular clusters;  Milky Way;  NGC 5170;  Star clusters

Publisher

Wiley-Blackwell Publishing

ISSN

0035-8711

Publisher URL

http://dx.doi.org/10.1111/j.1365-2966.2009.16130.x

Copyright

Copyright © 2010 The Authors. Journal compilation copyright © 2010 Royal Astronomical Society. The accepted manuscript of this paper is reproduced here in accordance with the copyright policy of the publisher. The definitive publication is available at www.interscience.wiley.com.

Full text

Peer reviewed