Volume 547, November 2012
|Number of page(s)||4|
|Section||Galactic structure, stellar clusters and populations|
|Published online||19 October 2012|
LUPM – UMR5299, CNRS & Université Montpellier II,
Place Eugène Bataillon,
Montpellier Cedex 05,
2 Max Planck Institute for Extraterrestrial Physics, PO Box 1312, Giessenbachstr., 85741 Garching, Germany
Received: 31 July 2012
Accepted: 14 September 2012
Aims. We study the near-infrared properties of the super star cluster NGC 1750–1 to constrain its spatial extent, its stellar population, and its age.
Methods. We used adaptive-optics assisted integral field spectroscopy with SINFONI on the Very Large Telescope. We estimated the spatial extent of the cluster and extracted its K-band spectrum from which we constrained the age of the dominant stellar population.
Results. Our observations have an angular resolution of about 0.11′′, providing an upper limit on the cluster radius of 2.85 ± 0.50 pc depending on the assumed distance. The K-band spectrum is dominated by strong CO absorption bandheads typical of red supergiants. Its spectral type is equivalent to a K4–5I star. Using evolutionary tracks from the Geneva and Utrecht groups, we determine an age of 12 ± 6 Myr. The large uncertainty is rooted in the large difference between the Geneva and Utrecht tracks in the red supergiants regime. The absence of ionized gas lines in the K-band spectrum is consistent with the absence of O and/or Wolf-Rayet stars in the cluster, as expected for the estimated age.
Key words: galaxies: clusters: individual: NGC 1705 / 1 / stars: massive / stars: late-type
The FITS file of the reduced cluster spectrum is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (184.108.40.206) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/547/A17
© ESO, 2012
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