University of Canterbury programs with SALT
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Transcript of University of Canterbury programs with SALT
University of Canterbury programs with SALT
Michael Albrow, Mita Brierley 1,
Peter Cottrell, Jeffrey Simpson, Clare Worley 2
1 now at Astronomy Australia Ltd
2 now at Institute of Astronomy, Cambridge
Other potential users : Jenni Adams, Loretta Dunne, Chris Gordon, John Hearnshaw, Steve Maddox, Karen Pollard, David Wiltshire
Globular Cluster integrated light studies
(Albrow/Brierley)
• Most spectroscopic studies of extragalactic globular clusters at low resolution
metallicity and alpha-element ratios using the Lick index system
• Beyond Milky Way & its satellite galaxies, moderate-to-high resolution spectral studies only on globular cluster system of M31
• Purpose of this research
acquire moderate-to-high resolution integrated light spectra of globular clusters in the Milky Way and Large Magellanic Cloud
these clusters have CMD-derived ages and spectroscopic abundances of individual stars
long slit, integrated-light spectra will be used to help calibrate our new high-resolution theoretical stellar populations spectral models
Young LMC clusters NGC 1831 (red, age 600 Myr) and NGC 1978 (blue, age 1.9 Gyr) in the region around H-beta
Old MW globular clusters NGC 362 (blue) and NGC 6218 (red) in the region around H-delta. Each is overlaid with a 10Gy, [Fe/H] = -1.5 model from
Brierley (2010). The clusters have similar metallicity ([Fe/H] = -1.15 and [Fe/H] = -1.37 on the Caretta & Gratton 1997 scale) but NGC 6218 is older than NGC 362 by a factor of 1.25 according to the main-sequence fitting results of Marin-Franch et al (2009). The two spectra are very similar and
don’t distinguish between the ages of old globular clusters at the 25% level.
Globular Clusters MOS studies
(Simpson/Cottrell/Worley)
• Large samples are the key to understanding stellar evolution processes in globular clusters
• Can medium resolution spectra provide the key signatures of the nulceosynthetic processes?
C, N, Fe, s-process, others
• Purpose of this research
acquire multi-object spectroscopy of a range of globular clusters
Cen, 47 Tuc, NGC 6752, NGC 362
Spectral Matching @ R~1600 in Cen ~200 & 850 stars with 2dF on AAT
Simpson, Cottrell & Worley, 2012, MNRAS, in press ; Simpson & Cottrell, submitted
220 stars
850 stars
SALT MOS
R~3000NGC 362(31 slits)
Future (personal) programs with SALT