TNOs are Cool: A Survey of the Transneptunian Region     

Thomas G. Müller  Emmanuel Lellouch  Hermann Böhnhardt  John Stansberry  Antonella Barucci  Jacques Crovisier  Audrey Delsanti  Alain Doressoundiram  Elisabetta Dotto  René Duffard  Sonia Fornasier  Olivier Groussin  Pedro J. Gutiérrez  Olivier Hainaut  Alan W. Harris  Paul Hartogh  Daniel Hestroffer  Jonathan Horner  Dave Jewitt  Mark Kidger  Csaba Kiss  Pedro Lacerda  Luisa Lara  Tanya Lim  Michael Mueller  Raphael Moreno  Jose-Luis Ortiz  Miriam Rengel  Pablo Santos-Sanz  Bruce Swinyard  Nicolas Thomas  Audrey Thirouin  David Trilling 《Earth, Moon, and Planets》2009,105(2-4):209-219

Over one thousand objects have so far been discovered orbiting beyond Neptune. These trans-Neptunian objects (TNOs) represent the primitive remnants of the planetesimal disk from which the planets formed and are perhaps analogous to the unseen dust parent-bodies in debris disks observed around other main-sequence stars. The dynamical and physical properties of these bodies provide unique and important constraints on formation and evolution models of the Solar System. While the dynamical architecture in this region (also known as the Kuiper Belt) is becoming relatively clear, the physical properties of the objects are still largely unexplored. In particular, fundamental parameters such as size, albedo, density and thermal properties are difficult to measure. Measurements of thermal emission, which peaks at far-IR wavelengths, offer the best means available to determine the physical properties. While Spitzer has provided some results, notably revealing a large albedo diversity in this population, the increased sensitivity of Herschel and its superior wavelength coverage should permit profound advances in the field. Within our accepted project we propose to perform radiometric measurements of 139 objects, including 25 known multiple systems. When combined with measurements of the dust population beyond Neptune (e.g. from the New Horizons mission to Pluto), our results will provide a benchmark for understanding the Solar debris disk, and extra-solar ones as well.  相似文献   

A Multi-Wavelength Simultaneous Study of the Composition of the Halley Family Comet 8P/Tuttle     

E. Jehin  D. Bockelée-Morvan  N. Dello Russo  J. Manfroid  D. Hutsemékers  H. Kawakita  H. Kobayashi  R. Schulz  A. Smette  J. Stüwe  M. Weiler  C. Arpigny  N. Biver  A. Cochran  J. Crovisier  P. Magain  H. Rauer  H. Sana  R. J. Vervack  H. Weaver  J.-M. Zucconi 《Earth, Moon, and Planets》2009,105(2-4):343-349

We report on simultaneous optical and infrared observations of the Halley Family comet 8P/Tuttle performed with the ESO Very Large Telescope. Such multi-wavelength and coordinated observations are a good example of what can be done to support space missions. From high resolution optical spectroscopy of the CN (0,0) 388 nm and NH₂ (0,9,0) 610 nm bands using UVES at UT2 we determined ¹²C/¹³C = 90 ± 10 and ¹⁴N/¹⁵N = 150 ± 20 in CN and we derived a nuclear spin temperature of NH₃ of 29 ± 1 K. These values are similar to those found in Oort-Cloud and Jupiter Family comets. From low resolution long slit spectroscopy with FORS1 at UT2 we determined the CN, C₃ and C₂ production rates and the parent and daughter scale lengths up to 5.2 10⁵ km tailward. From high resolution IR spectroscopy with CRIRES at UT1 we measured simultaneously the production rates and mixing ratios of H₂O, HCN, C₂H₂, CH₄, C₂H₆, and CH₃OH.  相似文献   

Ground-Based Observations of the Martian Atmosphere in Support of Space Missions     

Thérèse Encrenaz 《Earth, Moon, and Planets》2009,105(2-4):127-134

Although Mars is a favored target for planetary exploration, there is still a need for complementary ground-based observing programs of the Martian atmosphere, and this need will remain in the future. Indeed, as the atmosphere is very tenuous (less than 0.01 bar at the surface), the lines are very narrow and a high spectral resolving power (above 10⁴) is required over large spectral intervals. In addition, ground-based observations of Mars allow the instantaneous mapping of the whole planet, and thus the study of diurnal effects, which cannot be achieved from an orbiter. Recent ground-based achievements about the Martian atmospheric science include the first detection of H₂O₂ in the submillimeter range, the measurement of winds from CO millimetric transitions, the first detection of CH₄ and the O₃, H₂O₂, H₂O, and CH₄ mapping in the infrared. With an ELT, it will be possible to study at high spatial resolution transient atmospheric phenomena and to search for traces of minor constituents with unprecedented sensitivity. With ALMA, it will be also possible to search for minor species and to map the mesospheric winds for better constraining the climate models.  相似文献   

Coordinated Study on Solar Wind Turbulence During the Venus-Express, ACE and Ulysses Alignment of August 2007     

R. Bruno  V. Carbone  Z. Vörös  R. D’Amicis  B. Bavassano  M. B. Cattaneo  A. Mura  A. Milillo  S. Orsini  P. Veltri  L. Sorriso-Valvo  T. Zhang  H. Biernat  H. Rucker  W. Baumjohann  D. Jankovičová  P. Kovács 《Earth, Moon, and Planets》2009,104(1-4):101-104

At the end of August 2007, Venus, Earth and Ulysses were aligned within a few degrees. This unusual event gives the opportunity to attempt a coordinated study on the radial evolution of solar wind turbulence and coronal transients like CMEs between 0.7 and 1.4 AU. Interplanetary magnetic field data and moments of proton velocity distribution function such as density, speed and temperature are required for this programme and will be provided by ACE at Earth, Venus Express at Venus and Ulysses at 1.4 AU. This project has been recently proposed as a Coordinated Investigation Programme (CIP35) for the International Heliophysical Year.  相似文献   

Duality properties of Gorringe–Leach equations     

Yves Grandati  Alain Bérard  Hervé Mohrbach 《Celestial Mechanics and Dynamical Astronomy》2009,103(2):133-141

In the category of motions preserving the angular momentum direction, Gorringe and Leach exhibited two classes of differential equations having elliptical orbits. After enlarging slightly these classes, we show that they are related by a duality correspondence of the Arnold–Vassiliev type. The specific associated conserved quantities (Laplace–Runge–Lenz vector and Fradkin–Jauch–Hill tensor) are then dual reflections of each other.  相似文献   

A new low-mass eclipsing binary: NSVS 02502726     

Ö. Çakırlı  C. İbanogˇlu  C. Güngör 《New Astronomy》2009,14(5):496-502

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The unusual interacting pair of galaxies IC 3481 and IC 3481A: An optical-NIR photometric and spectroscopic analysis     

J.A. Pérez Grana  S.N. Kemp  E. de la Fuente  A.C. Katsiyannis  J. Meaburn 《New Astronomy》2009,14(6):556-566

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Optical spectroscopy of V1123 Tauri and its visual companion     

Carlos M. Gutiérrez 《New Astronomy》2009,14(2):149-151

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Structural control over equilibrium silicon and oxygen isotopic fractionation: A first-principles density-functional theory study     

Merlin Méheut  Michele Lazzeri  Etienne Balan  Francesco Mauri 《Chemical Geology》2009,258(1-2):28-37

Isotopic fractionation factors for oxygen and silicon in selected silicates (quartz, enstatite, forsterite, lizardite, kaolinite) are calculated using first-principles methods based on density-functional theory. Good agreement between theory and experiment is found in the case of oxygen. In the case of silicon, agreement and differences with existing estimates of equilibrium fractionation factors are discussed. The relationship between silicon and oxygen fractionation factors, silicate polymerization degree and chemical composition is studied and compared with previous semi-empirical models.  相似文献   

Defining organominerals: Comment on ‘Defining biominerals and organominerals: Direct and indirect indicators of life’ by Perry et al. (2007, Sedimentary Geology, 201, 157–179)     

Christian Défarge  Pascale Gautret  Joachim Reitner  Jean Trichet 《Sedimentary Geology》2009,213(3-4):152-155

The paper by Perry et al. (2007, Defining biominerals and organominerals: Direct and indirect indicators of life, Sedimentary Geology, 201, 157–179) proposes to introduce “the new term ‘organomineral’” to describe mineral products whose formation is induced by by-products of biological activity, dead and decaying organisms, or nonbiological organic compounds, to be distinguished from the biomineral components of living organisms. The substantive ‘organomineral’, however, is not new: it was first introduced in 1993, with basically the same definition and distinction from biominerals, at the 7th International Symposium on Biomineralization (Défarge and Trichet, 1995, From biominerals to ‘organominerals’: The example of the modern lacustrine calcareous stromatolites from Polynesian atolls, Bulletin de l'Institut Océanographique de Monaco, n° spéc. 14, vol. 2, pp. 265–271). Thereafter, more than twenty-five papers by various authors have been devoted to organominerals and organomineral formation (‘organomineralization’) processes. Only two of these papers are cited by Perry et al., and without any reference to the definitions, or even the terms ‘organomineral’ or ‘organomineralization’, which they included. Moreover, Perry et al. tend to enlarge the original concept of organomineral to encompass all minerals containing organic matter, whether these organic compounds are active or passive in the mineralization, which introduces ambiguities detrimental to a fine understanding of present and past geobiological processes. Finally, Perry et al. propose to consider organominerals as indirect biosignatures that could be used in the search for evidence of life in the geological record and extraterrestrial bodies. This latter proposition also is problematical, in that organominerals may be formed in association with prebiotic or abiotic organic matter.  相似文献