Moll, S.L., Mengel, S., de Grijs, R. et al. (2 more authors) (2007) Cluster and nebular properties of the central star-forming region of NGC 1140*. Monthly Notices of the Royal Astronomical Society, 382 (4). pp. 1877-1888. ISSN 0035-8711
Abstract
We present new high spatial resolution Hubble Space Telescope/Advanced Camera for Surveys (ACS) imaging of NGC 1140 and high spectral resolution Very Large Telescope/Ultraviolet and Visual Echelle Spectrograph spectroscopy of its central star-forming region. The central region contains several clusters, the two brightest of which are clusters 1 and 6 from Hunter, O'Connell & Gallagher, located within star-forming knots A and B, respectively. A nebular analysis indicates that the knots have a Large Magellanic Cloud-like metallicity of 12 + log O/H = 8.29 ± 0.09. According to continuum-subtracted Hα ACS imaging, cluster 1 dominates the nebular emission of the brighter knot A. Conversely, negligible nebular emission in knot B originates from cluster 6. Evolutionary synthesis modelling implies an age of 5 ± 1 Myr for cluster 1, from which a photometric mass of (1.1 ± 0.3) × 106 M⊙ is obtained. For this age and photometric mass, the modelling predicts the presence of ∼5900 late O stars within cluster 1. Wolf–Rayet (WR) features are observed in knot A, suggesting 550 late-type nitrogen-rich (WNL) and 200 early-type carbon-rich (WCE) stars. Therefore, N(WR)/N(O) ∼ 0.1, assuming that all the WR stars are located within cluster 1. The velocity dispersions of the clusters were measured from constituent red supergiants as σ∼ 23 ± 1 km s−1 for cluster 1 and σ∼ 26 ± 1 km s−1 for cluster 6. Combining σ with half-light radii of 8 ± 2 and 6.0 ± 0.2 pc measured from the F625W ACS image implies virial masses of (10 ± 3) × 106 and (9.1 ± 0.8) × 106 M⊙ for clusters 1 and 6, respectively. The most likely reason for the difference between the dynamical and photometric masses of cluster 1 is that the velocity dispersion of knot A is not due solely to cluster 1, as assumed, but has an additional component associated with cluster 2.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2007 The Author(s). Reproduced in accordance with the publisher's self-archiving policy. |
Keywords: | stars : Wolf-Rayet; galaxies : individual; NGC 1140; galaxies : starburst; galaxies : star clusters |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Science (Sheffield) > Department of Physics and Astronomy (Sheffield) The University of Sheffield > Sheffield Teaching Hospitals |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 29 Mar 2019 12:16 |
Last Modified: | 31 Mar 2019 12:34 |
Status: | Published |
Publisher: | Oxford University Press |
Refereed: | Yes |
Identification Number: | 10.1111/j.1365-2966.2007.12497.x |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:138894 |