The Nature of Comets
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Measuring and Modelling Forward Light Scattering in the Human Eye
MEASURING AND MODELLING FORWARD LIGHT SCATTERING IN THE HUMAN EYE A thesis submitted to The University of Manchester, for the degree of Doctor of Philosophy, in the Faculty of Life Sciences. 2015 Pablo Benito López Optometry THESIS CONTENT THESIS CONTENT ...................................................................................................................... 2 LIST OF FIGURES ....................................................................................................................... 5 LIST OF TABLES ........................................................................................................................ 10 LIST OF EQUATIONS ............................................................................................................... 11 ABBREVIATIONS LIST ........................................................................................................... 12 ABSTRACT ................................................................................................................................... 13 DECLARATION .......................................................................................................................... 14 THESIS FORMAT ....................................................................................................................... 14 COPYRIGHT STATEMENT .................................................................................................... 15 ACKNOWLEDGEMENTS ...................................................................................................... -
Herschel Images of Fomalhaut. an Extrasolar Kuiper Belt at the Height
Astronomy & Astrophysics manuscript no. acke c ESO 2018 November 7, 2018 Herschel images of Fomalhaut⋆ An extrasolar Kuiper Belt at the height of its dynamical activity B. Acke1,⋆⋆, M. Min2,3, C. Dominik3,4, B. Vandenbussche1 , B. Sibthorpe5, C. Waelkens1, G. Olofsson6, P. Degroote1, K. Smolders1,⋆⋆⋆, E. Pantin7, M. J. Barlow8, J. A. D. L. Blommaert1, A. Brandeker6, W. De Meester1, W. R. F. Dent9, K. Exter1, J. Di Francesco10, M. Fridlund11, W. K. Gear12, A. M. Glauser5,13, J. S. Greaves14, P. M. Harvey15, Th. Henning16, M. R. Hogerheijde17, W. S. Holland5, R. Huygen1, R. J. Ivison5,18, C. Jean1, R. Liseau19, D. A. Naylor20, G. L. Pilbratt11, E. T. Polehampton20,21, S. Regibo1, P. Royer1, A. Sicilia-Aguilar16,22, and B.M. Swinyard21 (Affiliations can be found after the references) Received ; accepted ABSTRACT 8 Context. Fomalhaut is a young (2 ± 1 × 10 years), nearby (7.7 pc), 2 M⊙ star that is suspected to harbor an infant planetary system, interspersed with one or more belts of dusty debris. Aims. We present far-infrared images obtained with the Herschel Space Observatory with an angular resolution between 5.7′′ and 36.7′′ at wave- lengths between 70 µm and 500 µm. The images show the main debris belt in great detail. Even at high spatial resolution, the belt appears smooth. The region in between the belt and the central star is not devoid of material; thermal emission is observed here as well. Also at the location of the star, excess emission is detected. We aim to construct a consistent image of the Fomalhaut system. -
The Comet's Tale
THE COMET’S TALE Newsletter of the Comet Section of the British Astronomical Association Volume 5, No 1 (Issue 9), 1998 May A May Day in February! Comet Section Meeting, Institute of Astronomy, Cambridge, 1998 February 14 The day started early for me, or attention and there were displays to correct Guide Star magnitudes perhaps I should say the previous of the latest comet light curves in the same field. If you haven’t day finished late as I was up till and photographs of comet Hale- got access to this catalogue then nearly 3am. This wasn’t because Bopp taken by Michael Hendrie you can always give a field sketch the sky was clear or a Valentine’s and Glynn Marsh. showing the stars you have used Ball, but because I’d been reffing in the magnitude estimate and I an ice hockey match at The formal session started after will make the reduction. From Peterborough! Despite this I was lunch, and I opened the talks with these magnitude estimates I can at the IOA to welcome the first some comments on visual build up a light curve which arrivals and to get things set up observation. Detailed instructions shows the variation in activity for the day, which was more are given in the Section guide, so between different comets. Hale- reminiscent of May than here I concentrated on what is Bopp has demonstrated that February. The University now done with the observations and comets can stray up to a offers an undergraduate why it is important to be accurate magnitude from the mean curve, astronomy course and lectures are and objective when making them. -
Instrumental Methods for Professional and Amateur
Instrumental Methods for Professional and Amateur Collaborations in Planetary Astronomy Olivier Mousis, Ricardo Hueso, Jean-Philippe Beaulieu, Sylvain Bouley, Benoît Carry, Francois Colas, Alain Klotz, Christophe Pellier, Jean-Marc Petit, Philippe Rousselot, et al. To cite this version: Olivier Mousis, Ricardo Hueso, Jean-Philippe Beaulieu, Sylvain Bouley, Benoît Carry, et al.. Instru- mental Methods for Professional and Amateur Collaborations in Planetary Astronomy. Experimental Astronomy, Springer Link, 2014, 38 (1-2), pp.91-191. 10.1007/s10686-014-9379-0. hal-00833466 HAL Id: hal-00833466 https://hal.archives-ouvertes.fr/hal-00833466 Submitted on 3 Jun 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Instrumental Methods for Professional and Amateur Collaborations in Planetary Astronomy O. Mousis, R. Hueso, J.-P. Beaulieu, S. Bouley, B. Carry, F. Colas, A. Klotz, C. Pellier, J.-M. Petit, P. Rousselot, M. Ali-Dib, W. Beisker, M. Birlan, C. Buil, A. Delsanti, E. Frappa, H. B. Hammel, A.-C. Levasseur-Regourd, G. S. Orton, A. Sanchez-Lavega,´ A. Santerne, P. Tanga, J. Vaubaillon, B. Zanda, D. Baratoux, T. Bohm,¨ V. Boudon, A. Bouquet, L. Buzzi, J.-L. Dauvergne, A. -
The Comet's Tale
THE COMET’S TALE Journal of the Comet Section of the British Astronomical Association Number 33, 2014 January Not the Comet of the Century 2013 R1 (Lovejoy) imaged by Damian Peach on 2013 December 24 using 106mm F5. STL-11k. LRGB. L: 7x2mins. RGB: 1x2mins. Today’s images of bright binocular comets rival drawings of Great Comets of the nineteenth century. Rather predictably the expected comet of the century Contents failed to materialise, however several of the other comets mentioned in the last issue, together with the Comet Section contacts 2 additional surprise shown above, put on good From the Director 2 appearances. 2011 L4 (PanSTARRS), 2012 F6 From the Secretary 3 (Lemmon), 2012 S1 (ISON) and 2013 R1 (Lovejoy) all Tales from the past 5 th became brighter than 6 magnitude and 2P/Encke, 2012 RAS meeting report 6 K5 (LINEAR), 2012 L2 (LINEAR), 2012 T5 (Bressi), Comet Section meeting report 9 2012 V2 (LINEAR), 2012 X1 (LINEAR), and 2013 V3 SPA meeting - Rob McNaught 13 (Nevski) were all binocular objects. Whether 2014 will Professional tales 14 bring such riches remains to be seen, but three comets The Legacy of Comet Hunters 16 are predicted to come within binocular range and we Project Alcock update 21 can hope for some new discoveries. We should get Review of observations 23 some spectacular close-up images of 67P/Churyumov- Prospects for 2014 44 Gerasimenko from the Rosetta spacecraft. BAA COMET SECTION NEWSLETTER 2 THE COMET’S TALE Comet Section contacts Director: Jonathan Shanklin, 11 City Road, CAMBRIDGE. CB1 1DP England. Phone: (+44) (0)1223 571250 (H) or (+44) (0)1223 221482 (W) Fax: (+44) (0)1223 221279 (W) E-Mail: [email protected] or [email protected] WWW page : http://www.ast.cam.ac.uk/~jds/ Assistant Director (Observations): Guy Hurst, 16 Westminster Close, Kempshott Rise, BASINGSTOKE, Hampshire. -
Investigating the Neutral Sodium Emissions Observed at Comets
Investigating the neutral sodium emissions observed at comets K. S. Birkett M.Sci. Physics, Imperial College London, UK (2012) Department of Space and Climate Physics University College London Mullard Space Science Laboratory, Holmbury St. Mary, Dorking, Surrey. RH5 6NT. United Kingdom THESIS Submitted for the degree of Doctor of Philosophy, University College London 2017 2 I, Kimberley Si^anBirkett, confirm that the work presented in this thesis is my own. Where information has been derived from other sources, I confirm that this has been indicated in the thesis. 3 Abstract Neutral sodium emission is typically very easy to detect in comets, and has been seen to form a distinct neutral sodium tail at some comets. If the source of neutral cometary sodium could be determined, it would shed light on the composition of the comet, therefore allowing deeper understanding of the conditions present in the early solar system. Detection of neutral sodium emission at other solar system objects has also been used to infer chemical and physical processes that are difficult to measure directly. Neutral cometary sodium tails were first studied in depth at comet Hale-Bopp, but to date the source of neutral sodium in comets has not been determined. Many authors considered that orbital motion may be a significant factor in conclusively identifying the source of neutral sodium, so in this work details of the development of the first fully heliocentric distance and velocity dependent orbital model, known as COMPASS, are presented. COMPASS is then applied to a range of neutral sodium observations, includ- ing spectroscopic measurements at comet Hale-Bopp, wide field images of comet Hale- Bopp, and SOHO/LASCO observations of neutral sodium tails at near-Sun comets. -
Lecture 7: Propagation, Dispersion and Scattering
Satellite Remote Sensing SIO 135/SIO 236 Lecture 7: Propagation, Dispersion and Scattering Helen Amanda Fricker Energy-matter interactions • atmosphere • study region • detector Interactions under consideration • Interaction of EMR with the atmosphere scattering absorption • Interaction of EMR with matter Interaction of EMR with the atmosphere • EMR is attenuated by its passage through the atmosphere via scattering and absorption • Scattering -- differs from reflection in that the direction associated with scattering is unpredictable, whereas the direction of reflection is predictable. • Wavelength dependent • Decreases with increase in radiation wavelength • Three types: Rayleigh, Mie & non selective scattering Atmospheric Layers and Constituents JeJnesnesne n2 020505 Major subdivisions of the atmosphere and the types of molecules and aerosols found in each layer. Atmospheric Scattering Type of scattering is function of: 1) the wavelength of the incident radiant energy, and 2) the size of the gas molecule, dust particle, and/or water vapor droplet encountered. JJeennsseenn 22000055 Rayleigh scattering • Rayleigh scattering is molecular scattering and occurs when the diameter of the molecules and particles are many times smaller than the wavelength of the incident EMR • Primarily caused by air particles i.e. O2 and N2 molecules • All scattering is accomplished through absorption and re-emission of radiation by atoms or molecules in the manner described in the discussion on radiation from atomic structures. It is impossible to predict the direction in which a specific atom or molecule will emit a photon, hence scattering. • The energy required to excite an atom is associated with short- wavelength, high frequency radiation. The amount of scattering is inversely related to the fourth power of the radiation's wavelength (!-4). -
J,Zv__. Department of Electrical Engineering San Jose State University San Jose, CA 95192-0084 Tel
tom.,-ta -s co_;t., PROPOSAL SUMMARY PRINCIPAL INVESTIGATOR: Prof. Essam A. Marouf tJ,%- 9- j,zv__. Department of Electrical Engineering San Jose State University San Jose, CA 95192-0084 Tel. (408)924-3969 emarouf@ email.sj su.edu PROPOSAL TITLE: Radio Occultation Investigation of the Rings of Saturn and Uranus ABSTRACT: a) Objectives and Justification for Work: The proposed work addresses two main objectives. i) To pursue the development of the random diffraction screen model for analytical/computational characterization of the extinction and near-forward scattering by ring models that include panicle crowding, uniform clustering, and clustering along preferred orientations (anisotropy). The characterization is crucial for proper interpretation of past (Voyager) and future (Cassini) ring occultation observations in terms of physical ring properties, and is needed to address outstanding puzzles in the interpretation of the Voyager radio occultation data sets. it) To continue the development of spectral analysis techniques to identify and characterize the power scattered by all features of Saturn's rings that can be resolved in the Voyager radio occultation observations, and to use the results to constrain the maximum particle size and its abundance. Characterization of the variability of surface mass density among the main ring features and within individual features is important for constraining the ring mass and is relevant to investigations of ring dynamics and origin. b) Accomplishments of Prior Year's Work: 1) Completed the developed of the stochastic geometo, (random screen) model for the interaction of electromagnetic waves with of planetary ring models; used the model to relate the oblique optical depth and the angular spectrum of the near forward scattered signal to statistical averages of the stochastic geometry of the randomly blocked area. -
Comet Kohoutek (NASA 990 Convair )
Madrid, UCM, Oct 27, 2017 Comets in UV Shustov B., Sachkov M., Savanov I. Comets – major part of minor body population of the Solar System There are a lot of comets in the Solar System. (Oort cloud contains cometary 4 bodies which total mass is ~ 5 ME , ~10 higher than mass of the Main Asteroid Belt). Comets keep dynamical, mineralogical, chemical, and structural information that is critically important for understanding origin and early evolution of the Solar System. Comets are considered as important objects in the aspect of space threats and resources. Comets are intrinsically different from one another (A’Hearn+1995). 2 General comments on UV observations of comets Observations in the UV range are very informative, because this range contains the majority of аstrophysically significant resonance lines of atoms (OI, CI, HI, etc.), molecules (CO, CO2, OH etc.), and their ions. UV background is relatively low. UV imaging and spectroscopy are both widely used. In order to solve most of the problems, the UV data needs to be complemented observations in other ranges including ground-based observations. 3 First UV observations of comets from space Instruments Feeding Resolu Spectral range Comets Found optics tion Orbiting Astronomical 4x200mm ~10 Å 1100-2000 Å Bennett OH (1657 Å) Observatory (OAO-2) ~20 Å 2000-4000 Å С/1969 Y1 OI (1304 Å) 2 scanning spectrophotometers Launched in 1968 Orbiting Geophysical ~100cm2 Bennett Lyman-α Observatory (OGO-5) С/1969 Y1 halo Launched in 1968 Aerobee sounding D=50mm ~1 Å 1100-1800 Å Tago- Lyman-α halo rocket Sato- wide-angle all-reflective Kosaka spectrograph С/1969 Y1 Launched in 1970 Skylab 3 space station D=75mm Kohoutek Huge Lyman- Launched in 1973 С/1969 Y1 α halo NASA 990 Convair D=300mm Kohoutek OH (3090Å) aircraft. -
HST Observations of Spokes in Saturn's B Ring
Icarus 173 (2005) 508–521 www.elsevier.com/locate/icarus HST observations of spokes in Saturn’s B ring Colleen A. McGhee a,∗, Richard G. French a, Luke Dones b, Jeffrey N. Cuzzi c, Heikki J. Salo d, Rebecca Danos e a Astronomy Department, Wellesley College, Wellesley, MA 02481, USA b Southwest Research Institute, Boulder, CO 80302, USA c NASA Ames Research Center, Moffett Field, CA 94035, USA d University of Oulu, Astronomy Division, PO Box 3000, Oulu, Finland e Department of Physics and Astronomy, UCLA, Los Angeles, CA, 90095-1547, USA Received 11 June 2004; revised 31 August 2004 Available online 11 November 2004 Abstract As part of a long-term study of Saturn’s rings, we have used the Hubble Space Telescope’s (HST) Wide Field and Planetary Camera (WFPC2) to obtain several hundred high resolution images from 1996 to 2004, spanning the full range of ring tilt and solar phase angles accessible from the Earth. Using these multiwavelength observations and HST archival data, we have measured the photometric properties of spokes in the B ring, visible in a substantial number of images. We determined the spoke particle size distribution by fitting the wavelength- dependent extinction efficiency of a prominent, isolated spoke, using a Mie scattering model. Following Doyle and Grün (1990, Icarus 85, 168–190), we assumed that the spoke particles were sub-micron size spheres of pure water ice, with a Hansen–Hovenier size distribution (Hansen and Hovenier, 1974, J. Atmos. Sci. 31, 1137–1160). The WFPC2 wavelength coverage is broader than that of the Voyager data, resulting in tighter constraints on the nature of spoke particles. -
Maritime Forward Scatter Radar
MARITIME FORWARD SCATTER RADAR by Liam Yannick Daniel A thesis submitted to the University of Birmingham for the degree of DOCTOR OF PHILOSOPHY Electronic, Electrical and Systems Engineering University of Birmingham May 2016 University of Birmingham Research Archive e-theses repository This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder. ABSTRACT This thesis is dedicated to the study of forward scatter radar (FSR) in the marine environment. FSR is a class of bistatic radar where target detection occurs at very large bistatic angle, close to the radar baseline. It is a rarely studied radar topology and the maritime application is a completely novel area of research. The aim is to develop an easily deployed buoy mounted FSR network, which will provide perimeter protection for maritime assets—this thesis presents the initial stages of investigation. It introduces FSR and compares it to the more common monostatic/bistatic radar topologies, highlighting both benefits and limitations. Phenomenological principles are developed to allow formation of forward scatter signal models and provide deeper understanding of the parameters effecting the operation of an FSR system. Novel FSR hardware has been designed and manufactured and an extensive measurement campaign undertaken. -
Radio Occultation of Saturn's Rings with the Cassini Spacecraft: Ring Microstructure Inferred from Near-Forward Radio Wave
RADIO OCCULTATION OF SATURN’S RINGS WITH THE CASSINI SPACECRAFT: RING MICROSTRUCTURE INFERRED FROM NEAR-FORWARD RADIO WAVE SCATTERING A DISSERTATION SUBMITTED TO THE DEPARTMENT OF ELECTRICAL ENGINEERING AND THE COMMITTEE ON GRADUATE STUDIES OF STANFORD UNIVERSITY IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY Fraser Stuart Thomson July 2010 © 2010 by Fraser Stuart Thomson. All Rights Reserved. Re-distributed by Stanford University under license with the author. This work is licensed under a Creative Commons Attribution- Noncommercial 3.0 United States License. http://creativecommons.org/licenses/by-nc/3.0/us/ This dissertation is online at: http://purl.stanford.edu/pb657pg3502 ii I certify that I have read this dissertation and that, in my opinion, it is fully adequate in scope and quality as a dissertation for the degree of Doctor of Philosophy. Howard Zebker, Primary Adviser I certify that I have read this dissertation and that, in my opinion, it is fully adequate in scope and quality as a dissertation for the degree of Doctor of Philosophy. Per Enge I certify that I have read this dissertation and that, in my opinion, it is fully adequate in scope and quality as a dissertation for the degree of Doctor of Philosophy. Essam Marouf Approved for the Stanford University Committee on Graduate Studies. Patricia J. Gumport, Vice Provost Graduate Education This signature page was generated electronically upon submission of this dissertation in electronic format. An original signed hard copy of the signature page is on file in University Archives. iii iv Abstract The Cassini spacecraft is a robotic probe sent from Earth to orbit and explore the planet Saturn, its moons, and its expansive ring system.