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21.
We describe interferometric observations of the Asteroid (41) Daphne in the thermal infrared obtained with the Mid-Infrared Interferometric Instrument (MIDI) and the Auxiliary Telescopes (ATs) of the European Southern Observatory (ESO) Very Large Telescope Interferometer (VLTI). We derived the size and the surface thermal properties of (41) Daphne by means of a thermophysical model (TPM), which is used for the interpretation of interferometric data for the first time. From our TPM analysis, we derived a volume equivalent diameter for (41) Daphne of 189 km, using a non-convex 3-D shape model derived from optical lightcurves and adaptive optics images (B. Carry, private communication). On the other hand, when using the convex shape of Kaasalainen et al. (Kaasalainen, M., Mottola, S., Fulchignoni, M. [2002]. Icarus 159, 369-395) in our TPM analysis, the resulting volume equivalent diameter of (41) Daphne is between 194 and 209 km, depending on the surface roughness. The shape of the asteroid is used as an a priori information in our TPM analysis. No attempt is made to adjust the shape to the data. Only the size of the asteroid and its thermal parameters such as, albedo, thermal inertia and roughness are adjusted to the data. We estimated our model systematic uncertainty to be of 4% and of 7% on the determination of the asteroid volume equivalent diameter depending on whether the non-convex or the convex shape is used, respectively. In terms of thermal properties, we derived a value of the surface thermal inertia smaller than 50 J m−2 s−0.5 K−1 and preferably in the range between 0 and ∼30 J m−2 s−0.5 K−1. Our TPM analysis also shows that Daphne has a moderate macroscopic surface roughness. 相似文献
22.
Depositional and structural evolution of a foreland basin margin in a magnetostratigraphic framework: the eastern Swiss Molasse Basin 总被引：4，自引：1，他引：3
O. Kempf A. Matter D. W. Burbank M. Mange 《International Journal of Earth Sciences》1999,88(2):253-275
This integrated study of the sedimentology, magnetostratigraphic chronology and petrography of the mostly continental clastics
of the Oligocene to Miocene Swiss Molasse Basin underpins a reconstruction of facies architecture and delineates relationships
between the depositional evolution of a foreland-basin margin and exhumation phases and orogenic events in the adjacent orogen.
A biostratigraphically based high-resolution magnetostratigraphy provides a detailed temporal framework and covers nearly
the whole stratigraphic record of the Molasse Basin (31.5–13 Ma). Three transverse alluvial fan systems evolved at the southern
basin margin. They are characterized by distinct petrographic compositions and document the exhumation and denudation history
of the growing eastern Swiss Alps. Enhanced northward propagation of the orogenic wedge is interpreted to have occurred between
31.5 and 26 Ma. During the period 24–19 Ma, intense in-sequence and out-of-sequence thrusting took place as Molasse strata
were accreted to the orogenic wedge. A third active tectonic phase, possibly caused by backthrusting of the Plateau Molasse,
probably occurred between ca. 15 and 13 Ma. Fan head migration between 31.5 and 13 Ma is probably controlled by the structural
evolution of the thrust front due to Molasse accretion and backthrusting.
Received: 11 March 1998 / Accepted: 12 March 1999 相似文献
23.
D. Defrère O. Absil J.-P. Berger T. Boulet W. C. Danchi S. Ertel A. Gallenne F. Hénault P. Hinz E. Huby M. Ireland S. Kraus L. Labadie J.-B. Le Bouquin G. Martin A. Matter A. Mérand B. Mennesson S. Minardi J. D. Monnier B. Norris G. Orban de Xivry E. Pedretti J.-U. Pott M. Reggiani E. Serabyn J. Surdej K. R. W. Tristram J. Woillez 《Experimental Astronomy》2018,46(3):475-495
The development of high-contrast capabilities has long been recognized as one of the top priorities for the VLTI. As of today, the VLTI routinely achieves contrasts of a few 10??3 in the near-infrared with PIONIER (H band) and GRAVITY (K band). Nulling interferometers in the northern hemisphere and non-redundant aperture masking experiments have, however, demonstrated that contrasts of at least a few 10??4 are within reach using specific beam combination and data acquisition techniques. In this paper, we explore the possibility to reach similar or higher contrasts on the VLTI. After reviewing the state-of-the-art in high-contrast infrared interferometry, we discuss key features that made the success of other high-contrast interferometric instruments (e.g., integrated optics, nulling, closure phase, and statistical data reduction) and address possible avenues to improve the contrast of the VLTI by at least one order of magnitude. In particular, we discuss the possibility to use integrated optics, proven in the near-infrared, in the thermal near-infrared (L and M bands, 3-5 \(\upmu \)m), a sweet spot to image and characterize young extra-solar planetary systems. Finally, we address the science cases of a high-contrast VLTI imaging instrument and focus particularly on exoplanet science (young exoplanets, planet formation, and exozodiacal disks), stellar physics (fundamental parameters and multiplicity), and extragalactic astrophysics (active galactic nuclei and fundamental constants). Synergies and scientific preparation for other potential future instruments such as the Planet Formation Imager are also briefly discussed. This project is called Hi-5 for High-contrast Interferometry up to 5 μm. 相似文献