| 1. |
- Hawarden, Timothy G., et al.
(author)
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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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In: Future Giant Telescopes (Proceedings of the SPIE). - : SPIE. - 081944619X ; 4840, s. 299-308
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Conference paper (peer-reviewed)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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| 2. |
- Andersen, Torben, et al.
(author)
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The Euro50 Extremely Large Telescope
- 2003
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In: Future Giant Telescopes. Proceedings of the SPIE.. - 081944619X ; 4840, s. 214-225
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Conference paper (peer-reviewed)abstract
- Euro50 is a proposed optical telescope with an equivalent primary mirrordiameter of 50 m. Partners of the collaboration are institutes inSweden, Spain, Ireland, Finland, and the UK. The telescope will have asegmented primary mirror and an aplanatic Gregorian configuration withtwo elliptical mirrors. For a 50 m telescope there would be noeconomical advantage in going to a spherical primary. The size of theprimary mirror segments (2 m) has been selected on the basis of aminimization of cost. An adaptive optics system will be integrated intothe telescope. The telescope will have three operational modes: Seeinglimited observations, single conjugate adaptive observations in theK-band, and dual conjugate observations also in the K-band. An upgradeto adaptive optics also in the visible down to 500 nm is foreseen. Therewill be an enclosure to protect the telescope against adverse weatherand wind disturbances. Integrated simulation models are underdevelopment. The project time will be 10 years and the cost some 591MEuros.
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| 3. |
- Darudi, Ahmad, et al.
(author)
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The Robotic Earthshine Telescope
- 2010
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In: Proceedings of the SPIE. - : SPIE. - 1996-756X .- 0277-786X. ; 7733, s. 8-77332
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Conference paper (peer-reviewed)abstract
- Lund Observatory is presently designing and constructing a robotic telescope dedicated to studies of the Earth's albedo by measuring the ratio between the intensity of the dark and bright sides of the Moon. The telescope will operate both in broadband and narrow-band modes over the entire visible wavelength range and will transmit observational results back to the operation team over the Internet. Design challenges, in particular related to choice of CCD and stray light suppression, are described, together with the design of the optics, control system, and enclosure. Finally we present results from laboratory tests. The telescope will go into operation in the first half of 2011.
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| 4. |
- Gontcharov, Alexander, et al.
(author)
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Adaptive optics for the Euro50: design and performance
- 2003
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In: Future Giant Telescopes. Proceedings of the SPIE. - : SPIE. - 081944619X ; 4840, s. 36-46
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Conference paper (peer-reviewed)abstract
- The optical design for the proposed Euro50 extremely large telescopewith integrated adaptive optics (AO) is presented. For atmosphericturbulence correction, we propose using single and dual-conjugate AOsystems working with natural and laser guide stars. The corrective shapeof the deformable mirrors (DMs) is derived from an analytical algorithmbased on minimization of the sum of the residual power spectra of thephase fluctuations seen by guide stars after correction. Predictions forperformance of the Euro50 ELT with Dual-conjugate AO are given for the Kband using a seven layer atmospheric model for the atmosphere at theObservatorio del Roque de los Muchachos (ORM) on La Palma. The averageStrehl ratio is used to quantify the system performance for differentvalues of actuator pitch and DM conjugation altitudes. The influence ofthe outer scale and telescope pointing on the RMS stroke of the DMs ispresented. It is concluded that construction of such a system isfeasible and that there is a need for development of a simulation toolto verify the analytical calculations. Precise knowledge of the outerscale of the atmosphere at the ORM is needed to establish the dynamicalrange of the mirrors.
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| 5. |
- Gröningsson, Per, et al.
(author)
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High resolution spectroscopy of the inner ring of SN 1987A
- 2008
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 479:3, s. 761-777
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Journal article (peer-reviewed)abstract
- We discuss high resolution VLT/UVES observations (FWHM similar to 6 kms(-1)) from October 2002 (day similar to 5700 past explosion) of the shock interaction of SN 1987A and its circumstellar ring. A large number of narrow emission lines from the unshocked ring, with ion stages from neutral up to Ne V and Fe VII, have been identified. A nebular analysis of the narrow lines from the unshocked gas indicates gas densities of (similar to 1.5 - 5.0) x 10(3) cm(-3) and temperatures of similar to 6.5 x 10(3) - 2.4 x 104 K. This is consistent with the thermal widths of the lines. From the shocked component we observe a large range of ionization stages from neutral lines to [FeXIV]. From a nebular analysis we find that the density in the low ionization region is 4 x 10(6) - 10(7) cm-3. There is a clear difference in the high velocity extension of the low ionization lines and that of lines from [Fe X - XIV], with the latter extending up to similar to- 390 km s(-1) in the blue wing for [Fe XIV], while the low ionization lines extend to typically similar to- 260 km s(-1). For H alpha a faint extension up to similar to- 450 km s(-1) can be seen probably arising from a small fraction of shocked high density clumps. We discuss these observations in the context of radiative shock models, which are qualitatively consistent with the observations. A fraction of the high ionization lines may originate in gas which has yet not had time to cool, explaining the difference in width between the low and high ionization lines. The maximum shock velocities seen in the optical lines are similar to 510 km s(-1). We expect the maximum width of especially the low ionization lines to increase with time.
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| 6. |
- Gröningsson, Per, et al.
(author)
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High resolution spectroscopy of the line emission from the inner circumstellar ring of SN 1987A and its hot spots
- 2007
-
Reports (other academic/artistic)abstract
- We discuss high resolution VLT/UVES observations (FWHM ~ 6 km/s) from October 2002 (day ~5700 past explosion) of the shock interaction of SN 1987A and its circumstellar ring. A nebular analysis of the narrow lines from the unshocked gas indicates gas densities of (1.5-5.0)E3 cm-3 and temperatures of 6.5E3-2.4E4 K. This is consistent with the thermal widths of the lines. From the shocked component we observe a large range of ionization stages from neutral lines to [Fe XIV]. From a nebular analysis we find that the density in the low ionization region is 4E6-1E7 cm-3. There is a clear difference in the high velocity extension of the low ionization lines and that of lines from [Fe X-XIV], with the latter extending up to ~ -390 km/s in the blue wing for [Fe XIV], while the low ionization lines extend to typically ~ -260 km/s. For H-alpha a faint extension up to ~ -450 km/s can be seen probably arising from a small fraction of shocked high density clumps. We discuss these observations in the context of radiative shock models, which are qualitatively consistent with the observations. A fraction of the high ionization lines may originate in gas which has yet not had time to cool down, explaining the difference in width between the low and high ionization lines. The maximum shock velocities seen in the optical lines are ~ 510 km/s. We expect the maximum width of especially the low ionization lines to increase with time.
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| 7. |
- Owner-Petersen, Mette, et al.
(author)
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Control strategy for the adaptive optics of the Euro50
- 2003
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In: Future Giant Telescopes. Proceedings of the SPIE. - : SPIE. - 081944619X ; 4840, s. 427-435
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Conference paper (peer-reviewed)abstract
- The scheme presently envisaged for the EURO50 adaptive optics ispresented. The Euro50 adaptive optics will primarily work with laserguide stars (LGSs) and control of either one or two deformable mirrors(SCAO and DCAO respectively), but operation using a natural guide star(NGS) is also foreseen. The point spread function (PSF) for SCAOoperation using a single NGS is evaluated. An algorithm for optimalcontrol of the deformable mirrors (DMs) using LGSs and Shack-Hartmanwavefront sensors is presented and commented upon. It is an extension ofa recently developed algorithm for optimal control using NGSs andworking in the spatial Fourier domain. In addition the concept of avirtual wavefront sensor is introduced to overcome the difficulty intransmitting a large number (37) of LGSs to the final DCAO focus withboth adequate field and adequate aberrations. The expected performanceis estimated in form of maps of the Strehl ratio versus field angleusing a standard seven layer atmospheric model for the Observatorio delRoque de los Muchachos (ORM) site on la Palma for the case of the outerscale being either 20 m (nominal for ORM) or infinity (Kolmogorov - mostpessimistic case).
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