| 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. |
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| 3. |
- Vergani, S. D., et al.
(författare)
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GRB 091127/SN 2009nz and the VLT/X-shooter spectroscopy of its host galaxy : probing the faint end of the mass-metallicity relation
- 2011
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 535, s. A127-
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Tidskriftsartikel (refereegranskat)abstract
- We perform a detailed study of the gamma-ray burst GRB 091127/SN 2009nz host galaxy at z = 0.490 using the VLT/X-shooter spectrograph in slit and integral-field unit (IFU) mode. From the analysis of the optical and X-ray afterglow data obtained from ground-based telescopes and Swift-XRT, we confirm the presence of a bump associated with SN 2009nz and find evidence of a possible jet break in the afterglow lightcurve. The X-shooter afterglow spectra reveal several emission lines from the underlying host, from which we derive its integrated properties. These properties agree with those of previously studied GRB-SN hosts and, more generally, with those of the long GRB host population. We use the Hubble Space Telescope and ground-based images of the host to determine its stellar mass (M⋆). Our results extend to lower M⋆ values the M-Z plot derived for the sample of long GRB hosts at 0.3 < z < 1.0 adding new information to probe the faint end of the M-Z relation and the shift of the LGRB host M-Z relation from that found from emission-line galaxy surveys. Thanks to the IFU spectroscopy, we can build the two-dimensional (2D) velocity, velocity dispersion, and star formation rate (SFR) maps. They show that the host galaxy has perturbed rotation kinematics with evidence of a SFR enhancement consistent with the afterglow position. Based on observations made with ESO Telescopes at Paranal Observatory under programmes ID 084.A-0260 and 086.A-0874.
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| 4. |
- Semenov, V. E., et al.
(författare)
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Reduction of the Multipactor Threshold Due to Electron Cyclotron Resonance
- 2012
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Ingår i: IEEE Transactions on Plasma Science. - : Institute of Electrical and Electronics Engineers (IEEE). - 0093-3813 .- 1939-9375. ; 40:11, s. 3062-3069
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Tidskriftsartikel (refereegranskat)abstract
- Single-surface multipactor on metal surfaces is studied in the case when the microwave electric field is superimposed on a dc electric and a permanent magnetic field. Based on a simple analysis of the electron motion, it is predicted that considerable reduction in the multipactor threshold is possible when the electron cyclotron frequency is equal to the microwave field frequency and the permanent magnetic field has the proper orientation with respect to the metal surface. The prediction is confirmed by numerical simulations, and some experimental indications of the reduced multipactor threshold are also presented.
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| 5. |
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| 6. |
- Kossyi, I.A., et al.
(författare)
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Electrical breakdown in space-borne microwave equipment
- 2010
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Ingår i: Europhysics News. - 1432-1092 .- 0531-7479. ; 41:6
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Tidskriftsartikel (refereegranskat)abstract
- An experimental and numerical investigation is made of multipactor discharges in a coaxial waveguide. Particular attention is given to the determination of the multipactor threshold and the distribution of the impact energy of the electrons. Simulations are carried out for different parameters of the secondary emission coefficient of the electrode surfaces. This makes it possible to determine these parameters through a comparison between the numerical and experimental results. The comparison also shows that the observed multipactor is mainly of polyphase (non-resonant) nature and represents a mixture of single- and double-surface multipactor discharges.
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| 7. |
- Kossyi, I.A., et al.
(författare)
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Experimental and numerical investigation of multipactor discharges in a coaxial waveguide
- 2010
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Ingår i: Journal of Physics D: Applied Physics. - : IOP Publishing. - 1361-6463 .- 0022-3727. ; 43:34
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Tidskriftsartikel (refereegranskat)abstract
- An experimental and numerical investigation is made of multipactor discharges in a coaxial waveguide. Particular attention is given to the determination of the multipactor threshold and the distribution of the impact energy of the electrons. Simulations are carried out for different parameters of the secondary emission coefficient of the electrode surfaces. This makes it possible to determine these parameters through a comparison between the numerical and experimental results. The comparison also shows that the observed multipactor is mainly of polyphase (non-resonant) nature and represents a mixture of single- and double-surface multipactor discharges.
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