| 1. |
- Cirasuolo, M., et al.
(författare)
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MOONS: the Multi-Object Optical and Near-infrared Spectrograph for the VLT
- 2014
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Ingår i: Ground-based and Airborne Instrumentation for Astronomy V. - : SPIE. - 0277-786X .- 1996-756X. ; 9147, s. 91470-91470
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Konferensbidrag (refereegranskat)abstract
- MOONS (the Multi-Object Optical and Near-infrared Spectrograph) has been selected by ESO as a third-generation instrument for the Very Large Telescope (VLT). The light grasp of the large collecting area offered by the VLT (8.2m diameter), combined with the large multiplex and wavelength coverage (optical to near-IR: 0.8 -1.8 mu m) of MOONS will provide the European astronomical community with a powerful, unique instrument able to pioneer a wide range of Galactic, extragalactic and cosmological studies, and it will provide crucial follow-up for major facilities such as Gaia, VISTA, Euclid and LSST. MOONS has the observational power needed to unveil galaxy formation and evolution over the entire history of the Universe, from stars in our Milky Way, through the redshift desert, and up to the epoch of very first galaxies and reionization of the Universe at redshifts of z > 8-9, just a few million years after the Big Bang. From five years of observations MOONS will provide high-quality spectra for > 3M stars in our Galaxy and the Local Group, and for 1-2M galaxies at z > 1 (for an SDSS-like survey), promising to revolutionize our understanding of the Universe. The baseline design consists of similar to 1000 fibres, deployable over a field-of-view of similar to 500 arcmin(2), the largest patrol field offered by the Nasmyth focus at the VLT. The total wavelength coverage is 0.8 -1.8 mu m with two spectral resolving powers: in the medium-resolution mode (R similar to 4,000-6,000) the entire wavelength range is observed simultaneously, while the high-resolution mode will cover three selected sub-regions simultaneously: one region with R similar to 8,000 near the Ca II triplet to measure stellar radial velocities, and two regions at R similar to 20,000 (one in each of the J- and H-bands), for precision measurements of chemical abundances.
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| 2. |
- Feltzing, Sofia, et al.
(författare)
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The Low-Mass IMF - Deep Star Counts in the DSph Galaxy Ursa Minor
- 2002
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Ingår i: Modes of Star Formation and the Origin of Field Populations, ASP Conference Proceedings. - 1583811281 ; 285, s. 223-229
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Konferensbidrag (refereegranskat)abstract
- We present a new study of deep star counts in the Local Group dwarf spheroidal (dSph) in Ursa Minor. Both the luminosity function (LF) and the color-magnitude diagram (CMD) of the unevolved stars are compared with the LF and CMD of the old, metal-poor globular cluster M92. The main sequence locations and turn-offs are identical within the errors. Since we. know from the brighter evolved stars that the metallicities for these two disparate systems are the same this implies that they also have equal ages. A direct comparison of faint LFs is then equivalent to a comparison of the low-mass stellar initial mass functions (IMF). We find that the LFs are identical within the mass range covered (similar to 0.35 - 0.8 M-circle dot). The Ursa Minor dSph has one of the highest apparent M/L ratios known in the Local Group, and is an extremely low surface brightness external galaxy. M92 is a typical high surface brightness globular cluster, with no apparent dark matter. Our findings lead to the conclusion that the low-mass stellar IMF in systems that formed at high redshift is independent of environment. Indeed, it is consistent with the low-mass IMF in star-forming regions today.
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| 3. |
- Hawarden, Timothy G., et al.
(författare)
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Critical science with the largest telescopes: science drivers for a 100m ground-based optical-IR telescope
- 2003
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Ingår i: Future Giant Telescopes (Proceedings of the SPIE). - : SPIE. - 081944619X ; 4840, s. 299-308
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Konferensbidrag (refereegranskat)abstract
- Extremely large filled-aperture ground-based optical-IR telescopes, or ELTs, ranging from 20 to 100m in diameter, are now being proposed. The all-important choice of the aperture must clearly be driven by the potential science offered. We here highlight science goals from the Leiden Workshop in May 2001 suggesting that for certain critical observations the largest possible aperture - assumed to be 100m (theproposed European OverWhelmingly Large telescope (OWL) - is strongly tobe desired. Examples from a long list include: COSMOLOGY: Identifying the first sources of ionisation in the universe, out to z >=14 Identifying and studying the first generation of dusty galaxies More speculatively, observing the formation of the laws of physics, via the evolution of the fundamental physical contants in the very early Universe, by high-resolution spectroscopy of very distant quasars. NEARER GALAXIES: Determining detailed star-formation histories of galaxies out to the Virtgo Cluster, and hence for all major galaxy types (not just those available close to the Local Group of galaxies). THE SOLAR SYSTEM: A 100-m telescope would do the work of a flotilla of fly-by space probes for investigations ranging from the evolution ofplanetary sutfaces and atmospheres to detailed surface spectroscopy of Kuiper Belt Objects. (Such studies could easily occupy it full-time.) EARTHLIKE PLANETS OF NEARBY STARS: A prospect so exciting as perhaps to justify the 100-m telescope on its own, is that of the direct detectionof earthlike planets of solar-type stars by imaging, out to at least 25 parsecs (80 light years) from the sun, followed by spectroscopic and photometric searches for the signature of life on the surfaces of nearer examples.
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