DOCSLIB.ORG

Komethale-Bopp Buch

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Komethale-Bopp Buch 2 Hale- Bopp ESO Press Releases Richard M. West, ESO __________________________________________________________________ ESO Press Releases Comet Hale-Bopp Update (August 2, 1996) This is a summary of recent developments around this comet; the previouswas published on the ESO Web on January 9, 1996. It is based on information received directly by email and also from IAU Circulars and on other Hale-Bopp WWW pages. C/1995 O1 (Hale-Bopp) has been observed at AU). This distance then increases and reaches a many professional and amaterur observatories maximum of 455 million km (3.053 AU) in late during the past months. Various reports have October 1996 after which it will begin to appeared which all indicate that this decrease until it reaches its smallest value on extraordinary comet continues to develop in a March 22-23, 1997, at 197 million km (1.315 way that permits us to hope that it will indeed AU). become a beautiful and unusual sight early next Comet Hale-Bopp will thus remain quite far year. The following information does not pretend away from the Earth, over 13 times more distant to be complete, but rather to concentrate on some than bright Comet Hyakutake that came within of the critical issues in this connection. 15 million km only, when it passed the Earth in late March 1996. Orbit and ephemeris Comet Hale-Bopp is now located in the Improved orbital elements and the southern constellation of Serpens Cauda (The corresponding ephemerides have recently been Serpent's Tail), well inside the bright band of the computed by Syuichi Nakano (Japan) and Don Milky Way. It moves steadily northwards and Yeomans (USA), based onmore than 1000 will pass the celestial equator on December 6. It accurate positions available up to July 1996. The will reach its northernmost position (+45 deg derived orbital elements agree very well and declination) a few days before the perihelion already now allow to predict the comet's passage. positions early next year to an accuracy of the During the period when it is brightest, it will order of 10 arcsec. There is little doubt that be best observable from the northern hemisphere. further observations will reduce this uncertainty In February and most of March 1997 the best to about just a few arcsec in due time. The orbital time will be in the morning twilight and later in calculations now definitively confirm that the the evening twilight. image found on a photographic plate obtained in April 1993, does indeed belong to this comet. Current appearance and activity The deduced orbital period (at perihelion) is Recent reports, many of which are published around 2500 years. However, this period changes on the List of Recent Comet Brightness with time because of the gravitational attraction Estimates by the International Comet Quarterly, of the large planets and it was apparently longer indicate that Comet Hale-Bopp reached naked- in the past. At this moment, it is not yet possible eye brightness (visual magnitude 6) in late June to calculate with reasonable accuracy the time of 1996. This, however, is only true for perfectly the previous apparation, but further positional dark sites; in most places, a small binocular observations will gradually improve this. It is not telescope will still be needed to see the comet. likely, though, that it will be possible to identify The size of the coma is now visually historical observations of this comet from the estimated at about 20 arcminutes and some earlier return. observers have reported a short dust tail of up to The perihelion passage takes place at about 0.5 - 1 deg, possibly even 1.5 deg. This tail will 3:22 UT in the morning of Tuesday, April 1, undoubtedly develop further during the coming 1997. The perihel distance will be about 136.8 months. From the geometry, it is almost certain million km (0.914 AU) and the comet will be that there will be interesting tail displays in early placed on the opposite side of the Sun, as seen 1997. A set of predictions by Klaus Beisser from the Earth, cf. the view of the orbit. (Nuremberg) will be placed at this Website In 1996, the comet will make the closest shortly. approach to the Earth on August 3, at which time Interesting CCD pictures have been published the distance will be about 409 million km (2.733 recently on the Web, showing the gradual Jurasternwarte 1998, H. Jost Hale- Bopp 2 - 2 __________________________________________________________________ ESO Press Releases development of the comet, e.g. at the Crni Vrh It would be important to know the size of the Observatory in Slovenia. Exposures with higher nucleus of Comet Hale-Bopp to support these spatial resolution have also been obtained in the estimates. Unfortunately, no further second half of July, for instance at the Calar Alto measurements, direct or indirect, have been Observatory (Spain) and with the Mons telescope reported, since an upper limit of about 40 km of the IAC on the Canary Islands, which show up was found from exposures with the Hubble to six jets in the inner coma. Space Telescope. Most astronomers believe that Thus there is little doubt that the dramatic it will turn out to be somewhat larger than that of outflow of dust from Comet Hale-Bopp's nucleus Comet Halley (largest dimension 15 km), but we continues. Moreover, an analysis of images cannot be sure yet. In the same connection, it has obtained with the ESO Schmidt telescope in not yet been possible to measure the rotation August 1995 ESO Press Photos 24a-c/95 show period of the nucleus. During the second half of that some of the dust must have emanated from 1995, outburst were seen to occur at a mean time the nucleus more than three years earlier. interval of about 19.5 days, but it is not certain Together with the April 1993 image which was that this really represents the rotation period. obtained when Comet Hale-Bopp was still nearly The further development of Comet Hale-Bopp 2,000 million km (13 AU) from the Sun, this will be followed with great interest. We shall proves beyond doubt that the comet was active probably have to wait until early 1997, before we already at a very large heliocentric distance. will know how bright this comet will become at The emission of gaseous species has also perihelion. been vigorous. CO molecules were detected already at a heliocentric distance of 7 AU and the Molecules in Comet Hale-Bopp current production rate at 4 AU is about 10e29 Due to its unsual brightness at large mol/s. From measurements of the OH emission, heliocentric distance, it has already been possible the water production has been found to be of the to observe Comet Hale-Bopp with some of the same order. This is very high when compared to best sub-millimetre telescopes in the world and other comets at the same distance. several molecules have been found during the past months. As was the case for Comet How bright will Comet Hale-Bopp become Hyakutake, some of these molecules are 'parents', in 1997? i.e. molecules which are emitted from the This is the most urgent question, now asked nucleus and which later break down into by all astronomers who prepareobservations for 'daughter' molecules in the coma. next year. As is usual in such cases, no one can Until the advent of infrared and sub- give an answer that is completely trustworthy. millimetre techniques, it was not possible to Nevertheless, the currently observed activity and observe the 'parent' molecules directly. Now, its continued and steady increase, combined with however, their numbers and distribution, as well the fact that this comet must have been near the as the motions, can be measured and already Sun several times before, makes it rather unlikely yield interesting clues about the composition of that it will deceive its many fans. the cometary nucleus. A current, conservative brightness prediction Information about these observations have is that Comet Hale-Bopp will reach a total visual recently been published on several IAU magnitude of at least -1 at perihelion. In fact, by Circulars. Another place to look for the latest combining about 300 amateur observations up to news on this front is the Comet Hale-Bopp (1995 the end of July 1996, Alan Fitzsimmons finds a O1) Observers' Bulletin Board and Archives at perihelion magnitude of -2.6. This calculation the University of Maryland (USA). In addition to also indicates that the absolute magnitude, i.e. the above mentioned molecules, CO and H2O, the brightness the comet would have, it it were which were detected earlier at larger heliocentric seen at exactly 1 AU geocentric and 1 AU distances, the following have now been found: heliocentric distance, is extremely bright, H2S (IAUC 6408; May 27) and CS, H2CO, HCN actually the second brightest cometary absolute and CH3OH (IAUC 6421; June 19). A dramatic magnitude since the year 1450, after Comet increase was observed in the H2S production Sarabat of 1729. Nevertheless, Charles Morris between May and June. (So now we know that finds a less steep brightening, although itstill Comet Hale-Bopp does not smell good!) predicts a negative magnitude at perihelion. Jurasternwarte 1998, H. Jost Hale- Bopp 2 - 3 __________________________________________________________________ ESO Press Releases By means of optical spectra, the CN molecule, presumable a 'daughter' of HCN, was detected already in March 1996 (IAU 6361; March 28) and C2 and C3 emission was seen in April 1996 (IAUC 6400; May 17). Jurasternwarte 1998, H. Jost Hale- Bopp 2 - 4 __________________________________________________________________ ESO Press Releases Comet Hale-Bopp Update (April 01, 1997) This is a summary of recent developments around this comet; the previous was published on the ESO Web on comet-hale-bopp-summary-mar25-97.
Load more

Recommended publications
  • Ionic Emissions in Comet C/2016 R2 (Pan-STARRS)
    MNRAS 000,1–12 (2019) Preprint 23 April 2020 Compiled using MNRAS LATEX style file v3.0 Ionic emissions in comet C/2016 R2 (Pan-STARRS) Kumar Venkataramani1;2? Shashikiran Ganesh1 and Kiran S.Baliyan1 1 Astronomy & Astrophysics Division, Physical Research Laboratory, Ahmedabad, India. 2 Department of Physics, Leach Science Center, Auburn University, Auburn, AL, USA. 23 April 2020 ABSTRACT We carried out observations of a peculiar comet, C/2016 R2 (Pan-STARRS), using a low resolution spectrograph mounted on the 1.2m telescope at Mount Abu Infrared Observatory, India. The comet was observed on two dates in January 2018, when it was at a heliocentric distance of 2.8 AU. Study based on our observations revealed that the optical spectrum of this comet is quite unusual as compared to general cometary spectra. Most of the major cometary emissions like C2,C3 and CN were absent in comet C/2016 R2. However, the comet spectrum + + showed very strong emission bands from ionic species like CO and N2 . A mean N2/CO ratio of 0.09 ± 0.02 was derived from the spectra and an extremely low depletion factor of 1.6 ± 0.4 has been estimated for this ratio as compared to the solar nebula. We have also detected minor + + emission features beyond 5400 Å, albeit marginally. The column densities of CO and N2 were calculated from their emission bands. The optical spectrum suggests that the cometary ice is dominated by CO. The low depletion factor of N2/CO ratio in this comet, as compared to the solar nebula and the unusual spectrum of the comet are consequences of distinctive processing at the location of its formation in the early solar nebula.
    [Show full text]
  • COMET NOTES Elizabeth Roemer U. S. Naval Observatory Flagstaff
    COMET NOTES Elizabeth Roemer U. S. Naval Observatory Flagstaff Station The fourth new comet of 1963 was discovered on September 14 by Z. Pereyra of Córdoba, Argentina, and reported to Copen- hagen and Harvard by G. M. lannini of the Córdoba Observatory. Located not far from a Hydrae at the time of discovery, Comet Pereyra was of second magnitude and had a tail many degrees in length. Alan McClure, observing the new comet on the morning of September 16 with binoculars from Mount Pinos, north of Los Angeles, reported a narrow tail about 10° long and a total bright- ness of sixth magnitude. Many early observations and approxi- mate positions came from Smithsonian Baker-Nunn Satellite Tracking Stations around the world, while accurate positions were obtained by H. L. Giclas (Lowell), Stokes (Mount Stromlo), K. Tomita (Tokyo), M, Antal (Skalnaté Pleso), and J. A. Bruwer (Johannesburg). Similar orbits for Comet Pereyra were calculated by M. P. Candy, L. E. Cunningham, and by G. M. lannini, all of whom found a very small perihelion distance (0.005 a.u.) and angular elements much like those of the family of sun-grazing comets that includes the comets 1668, 1843 1, 18801, 1882 II, 1887 1, and 1945 VII. Perihelion passage occurred on August 23, and thus Comet Peryera was three weeks past perihelion and on the far side of the sun from the earth at the time of discovery. As Cun- ningham pointed out, Comet Pereyra might have been a very spectacular object under better observing conditions. Because of the rapid increase in heliocentric distance (2 a.u.
    [Show full text]
  • Susan Wyckoff Department of Physics Arizona State University Tempe, AZ
    GROUND-BASED COMETARY SPECTROSCOPY Susan Wyckoff Department of Physics Arizona State University Tempe, AZ 85281 Abstract The return of comet Halley presents a rallying point for astronomers to discuss data on recent comets in the light of new developments in the field of cometary astronomy. The observational problems presented by bright comets near perihelion are discussed. High and low resolution spectra (3100-8000A) of the bright comets Kohoutek, Kobayashi-Berger-MiIon, West and d'Arrest are presented. Digital reduction of calibrated photographic spectra to relative intensity versus wavelength can provide useful information. The reduction of comet spectra to absolute intensities involves, however, large uncertainties and should be interpreted cautiously. New data on recent comets lead to the following results: (1) tentative identification of a new ion in the tail of comets, namely, NH+, (2) spectroscopic resolution of the fragmented nucleus of comet West, and (3) an accurate monochromatic intensity profile of the C0+ emission (4020A) in comet West which shows a striking asymmetry in the sunward and antisunward directions, 2 x 104 km < |p| < 5 x 105 km. I. Introduction Although dirty snowball models of comets have received general acceptance, specific details of such models are poorly determined. One of the primary goals of cometary spectroscopy is to determine abundances in comets and thereby infer conditions prevalent in the proto-solar nebula. We have as yet little understanding of cometary surface compositions, nor how they vary from comet to comet or with successive perihelion passages. In fact we cannot yet identify with certainty parents of the large majority of unstable molecular ions and radicals observed in the comae and tails of comets.
    [Show full text]
  • The Astronomer Magazine Index
    The Astronomer Magazine Index The numbers in brackets indicate approx lengths in pages (quarto to 1982 Aug, A4 afterwards) 1964 May p1-2 (1.5) Editorial (Function of CA) p2 (0.3) Retrospective meeting after 2 issues : planned date p3 (1.0) Solar Observations . James Muirden , John Larard p4 (0.9) Domes on the Mare Tranquillitatis . Colin Pither p5 (1.1) Graze Occultation of ZC620 on 1964 Feb 20 . Ken Stocker p6-8 (2.1) Artificial Satellite magnitude estimates : Jan-Apr . Russell Eberst p8-9 (1.0) Notes on Double Stars, Nebulae & Clusters . John Larard & James Muirden p9 (0.1) Venus at half phase . P B Withers p9 (0.1) Observations of Echo I, Echo II and Mercury . John Larard p10 (1.0) Note on the first issue 1964 Jun p1-2 (2.0) Editorial (Poor initial response, Magazine name comments) p3-4 (1.2) Jupiter Observations . Alan Heath p4-5 (1.0) Venus Observations . Alan Heath , Colin Pither p5 (0.7) Remarks on some observations of Venus . Colin Pither p5-6 (0.6) Atlas Coeli corrections (5 stars) . George Alcock p6 (0.6) Telescopic Meteors . George Alcock p7 (0.6) Solar Observations . John Larard p7 (0.3) R Pegasi Observations . John Larard p8 (1.0) Notes on Clusters & Double Stars . John Larard p9 (0.1) LQ Herculis bright . George Alcock p10 (0.1) Observations of 2 fireballs . John Larard 1964 Jly p2 (0.6) List of Members, Associates & Affiliations p3-4 (1.1) Editorial (Need for more members) p4 (0.2) Summary of June 19 meeting p4 (0.5) Exploding Fireball of 1963 Sep 12/13 .
    [Show full text]
  • The Comet Halley Dust and Gas Environment
    THE COMET HALLEY DUST AND GAS ENVIRONMENT NEILDIVINE 1, H. FECHTIG 2, T.I. GOMBOSI 3,4, M. S. HANNER 1, H. U. KELLER 5, S. M. LARSON 6, D. A. MENDIS 7, RAY L. NEWBURN, JR. 1, R. REINHARD s, Z. SEKANINA 1, and D.K. YEOMANS 1 (Received 19 November, 1985) Abstract. Quantitative descriptions of environments near the nucleus of comet P/Halley have been developed to support spacecraft and mission design for the flyby encounters in March, 1986. To summarize these models as they exist just before the encounters, we review the relevant data from prior Halley apparitions and from recent cometary research. Orbital elements, visual magnitudes, and parameter values and analysis for the nucleus, gas and dust are combined to predict Halley's position, production rates, gas and dust distributions, and electromagnetic radiation field for the current perihelion passage. The predicted numerical results have been useful for estimating likely spacecraft effects, such as impact damage and attitude perturbation. Sample applications are cited, including design of a dust shield for spacecraft structure, and threshold and dynamic range selection for flight experiments. We expect that the comet's activity may be more irregular than these smoothly varying models predict, and that comparison with the flyby data will be instructive. Table of Contents 1. Introduction 2. Orbital elements and nongravitational forces 2.1. Nongravitational forces and comet Halley 2.2. Recent orbital work on comet Halley 3. Overview of cometary activity 3.1. The semi-empirical photometric theory 3.2. Predictions for Halley in 1986 4. Parameters for the nucleus 4.1.
    [Show full text]
  • Physics of Comets (2Nd Ed.) K
    7537tp.indd 1 8/3/10 3:25 PM WORLD SCIENTIFIC SERIES IN ASTRONOMY AND ASTROPHYSICS Editor: Jayant V. Narlikar Inter-University Centre for Astronomy and Astrophysics, Pune, India Published: Volume 1: Lectures on Cosmology and Action at a Distance Electrodynamics F. Hoyle and J. V. Narlikar Volume 2: Physics of Comets (2nd Ed.) K. S. Krishna Swamy Volume 3: Catastrophes and Comets* V. Clube and B. Napier Volume 4: From Black Clouds to Black Holes (2nd Ed.) J. V. Narlikar Volume 5: Solar and Interplanetary Disturbances S. K. Alurkar Volume 6: Fundamentals of Solar Astronomy A. Bhatnagar and W. Livingston Volume 7: Dust in the Universe: Similarities and Differences K. S. Krishna Swamy Volume 8: An Invitation to Astrophysics T. Padmanabhan Volume 9: Stardust from Meteorites: An Introduction to Presolar Grains M. Lugaro Volume 10: Rotation and Accretion Powered Pulsars P. Ghosh Volume 11: Find a Hotter Place!: A History of Nuclear Astrophysics L. M. Celnikier Volume 12: Physics of Comets (3rd Edition) K. S. Krishna Swamy *Publication cancelled. Lakshmi - Physics of Comets (3rd Ed).pmd 2 7/12/2010, 2:46 PM World Scientific Series in Astronomy and Astrophysics – ol. 12 K S Krishna Swamy retired from the Tata Institute of Fundamental Research, Mumbai, India World Scientific N E W J E R S E Y • LONDON • SINGAPORE • BEIJING • SHANGHAI • H O N G K O N G • TAIPEI • CHENNAI 7537tp.indd 2 8/3/10 3:25 PM Published by World Scientific Publishing Co. Pte. Ltd. 5 Toh Tuck Link, Singapore 596224 USA office: 27 Warren Street, Suite 401-402, Hackensack, NJ 07601 UK office: 57 Shelton Street, Covent Garden, London WC2H 9HE British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library.
    [Show full text]
  • Astronomy Magazine MAY 2017 Understanding the Strangest Stars YEARS of 50 PULSARS P
    SOLAR ECLIPSE! How it really happens p. 34 The world’s best-selling astronomy magazine MAY 2017 Understanding the strangest stars YEARS OF 50 PULSARS p. 22 DISCOVER 10 WEIRD EMISSION NEBULAE p. 44 Mount Wilson’s famous telescope A short history celebrates a century p. 28 of eclipses p. 49 www.Astronomy.com Image the sky BONUS Vol. 45 with camera ONLINE • Issue 5 and tripod p. 52 CONTENT CODE p. 4 You and Your Shadow... Tele Vue-60 Tele Vue-60 Specifications: Objective: APO Air-spaced Doublet Ap/F.L./f-ratio: 60mm/ 360mm/ f/6 Length OTA: 10” Wherever and Weight OTA: 3lbs. Focuser: 1¼”, push-pull/helical fine focus Whenever You Stroll, Max. Visual Field: 4.3° (with 32mm Plössl/24 Panoptic) Tele Vue-60 OTA shown with optional equipment. Case Dim. 14”x9”x4” Total package weight as shown 5¾lbs. Never Be Without *Solar viewing with any telescope requires proper solar filtering. Your Wanderlust Companion. he August 2017 solar eclipse will be a special few moments in time. The T heirloom quality Tele Vue-60 is designed, built, and tested at Tele Vue for those moments plus all of your future observing adventures. With performance truly beyond expectation, this 4.3° max. true field, diffraction-limited 60mm is no mere toy. The Tele Vue-60 is an observing companion like no other, given its combination of ultra portability and stunning optical fidelity. This petite jewel is Fonemate:smartphone made of black anodized aluminum for lasting beauty and features a buttery- to eyepiece adapter smooth dual stage focuser for that “snap-to-focus” image.
    [Show full text]
  • THE COMET's TALE Comet Section – British Astronomical Association
    1 Halley’s Comet as depicted by the 14th Century Florentine artist Giotto di Bondone 1267? – 133.7 “The adoration of the Magi”, Scrovegni Chapel in Padua, Italy, around 1301-5. THE COMET’S TALE Comet Section – British Astronomical Association Journal – Number 37 2018 June britastro.org/comet Comet C/2016 R2 2017 Dec 14 Damian Peach 2 Table of Contents Contents Author Page 1 Director’s Welcome Nick James 3 Section Director 2 Comet C/2017 Denis Buczynski 4 Heinze Secretary 3 “Oumuamua: Neil Norman 7 Interstellar Interloper 4 The 2017 Outburst Nick James 10 of Comet 174/P Section Director 5 Naked Eye Comet or Denis Buczynski 11 Aurora Secretary 6 Spot the Similarity Denis Buczynski 12 Secretary 7 New Imager in the David Swan 16 Comet Section 8 My night at the Peter Carson 17 Telescope CCD Imaging Advisor 9 Comet Magnitudes Roger Dymock 20 10 DSLR Imaging and Justin Tilbrook 23 processing 11 Historical Amar A Sharma 28 Observations in Nikaya Observatory India 12 Alan McClure, an Denis Buczynski 32 appreciation Secretary 13 Michael Hendrie Nick James 35 Director 14 Editor’s Whimsy Janice McClean 37 Maria Mitchell and Editor- Comet’s Tale and Comet 1847/T1 BAA Newsletter 15 Contacts 42 16 Picture Gallery Please note that 43 copyright of all images belongs with the Observer 3 1 From the Director – Nick James I hope you enjoy reading this issue of moves through Cassiopeia and at the end of Comet’s Tale. Many thanks to Janice the month it may attain naked eye visibility McClean for editing this issue and to Denis as it enters Auriga.
    [Show full text]
  • Millimeter-Wavelength Characterization of the CO Emission of Comets 174P/Echeclus, 29P/Schwassmann-Wachmann, and C/ 2016 R2 (Panstarrs)
    University of South Florida Scholar Commons Graduate Theses and Dissertations Graduate School November 2019 Millimeter-wavelength characterization of the CO emission of comets 174P/Echeclus, 29P/Schwassmann-Wachmann, and C/ 2016 R2 (PanSTARRS) Kacper Wierzchos University of South Florida Follow this and additional works at: https://scholarcommons.usf.edu/etd Part of the Astrophysics and Astronomy Commons, and the Physics Commons Scholar Commons Citation Wierzchos, Kacper, "Millimeter-wavelength characterization of the CO emission of comets 174P/Echeclus, 29P/Schwassmann-Wachmann, and C/2016 R2 (PanSTARRS)" (2019). Graduate Theses and Dissertations. https://scholarcommons.usf.edu/etd/8695 This Dissertation is brought to you for free and open access by the Graduate School at Scholar Commons. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Scholar Commons. For more information, please contact [email protected]. Millimeter-wavelength characterization of the CO emission of comets 174P/Echeclus, 29P/Schwassmann-Wachmann, and C/2016 R2 (PanSTARRS) by Kacper Wierzchos A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy Department of Physics College of Art and Sciences University of South Florida Co-Major Professor: Maria Womack, Ph.D. Co-Major Professor: Andreas Muller, Ph.D. Myung K. Kim, Ph.D. Matthew Pasek, Ph.D. Zhimin Shi, Ph.D. Date of Approval: November 7, 2019 Keywords: Comets, Rotational spectroscopy, Radio astronomy Copyright c 2019, Kacper Wierzchos Dedication Dedicated to my parents, who ever since an early age, encouraged my curiosity and made of me the scientist that I am today. Acknowledgements There are many factors involved in the successful completion of a Ph.D program.
    [Show full text]
  • Gerald Kuiper Descubre El Satélite De Neptuno, Nereida
    EFEMÉRIDES ASTRONÓMICAS HISTÓRICAS AGOSTO 2021 Compilador: Biólogo Juan José Durán Nájera ?? AGOSTO 2000 Se descubre un meteorito marciano clasificado como NWA 2737 en el noroeste de áfrica en el desierto del Sahara En agosto de 2000, los recolectores de meteoritos descubrieron una piedra fragmentada en nueve piezas (308 g, 128 g, 74 g, 47 g, 38 g, 6.4 g, 3.3 g, 2.0 g, y 4.3 g para una masa total de 611 g ) en la parte occidental del Sahara. Este pequeño grupo de piedras encontrado en Marruecos resultó ser el segundo "Chassignite" recuperado, un meteorito rico en olivina (~ 90% vol.) de Marte. Es clasificado como una Achondrita de Marte NWA 2737. Las texturas cumuladas están dominadas por cristales de olivino de tamaño mm, a veces encerrados poiquilíticamente en augita. Cantidades aproximadamente iguales de piroxeno y cromita más cantidades menores de vidrio (1-2%) representan la mayor parte del volumen restante. Además, hay rastros de un número sorprendentemente grande de otras pequeñas fases minerales que se encuentran especialmente dentro de pequeñas inclusiones de derretimiento del olivino. Las abundancias de REE, las proporciones de Fe / Mn y las proporciones de isótopos de oxígeno indican que NWA 2737 es claramente un meteorito marciano, y específicamente similar a Chassigny en varios aspectos. Sin embargo, en general NWA 2737 tiene una mineralogía ligeramente más rica en Mg y olivinos parduscos muy extraños creados por partículas de nano-hierro dentro del olivino. Estos cristales extrañamente teñidos aparentemente reflejan un complejo historial de oxidación de los olivinos NWA 2737 tanto en Meteorito marciano NWA 2737 Marte como en el desierto africano.
    [Show full text]