Atmospheric Extinction and Photometry
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Asteroid Impact, Not Volcanism, Caused the End-Cretaceous Dinosaur Extinction
Asteroid impact, not volcanism, caused the end-Cretaceous dinosaur extinction Alfio Alessandro Chiarenzaa,b,1,2, Alexander Farnsworthc,1, Philip D. Mannionb, Daniel J. Luntc, Paul J. Valdesc, Joanna V. Morgana, and Peter A. Allisona aDepartment of Earth Science and Engineering, Imperial College London, South Kensington, SW7 2AZ London, United Kingdom; bDepartment of Earth Sciences, University College London, WC1E 6BT London, United Kingdom; and cSchool of Geographical Sciences, University of Bristol, BS8 1TH Bristol, United Kingdom Edited by Nils Chr. Stenseth, University of Oslo, Oslo, Norway, and approved May 21, 2020 (received for review April 1, 2020) The Cretaceous/Paleogene mass extinction, 66 Ma, included the (17). However, the timing and size of each eruptive event are demise of non-avian dinosaurs. Intense debate has focused on the highly contentious in relation to the mass extinction event (8–10). relative roles of Deccan volcanism and the Chicxulub asteroid im- An asteroid, ∼10 km in diameter, impacted at Chicxulub, in pact as kill mechanisms for this event. Here, we combine fossil- the present-day Gulf of Mexico, 66 Ma (4, 18, 19), leaving a crater occurrence data with paleoclimate and habitat suitability models ∼180 to 200 km in diameter (Fig. 1A). This impactor struck car- to evaluate dinosaur habitability in the wake of various asteroid bonate and sulfate-rich sediments, leading to the ejection and impact and Deccan volcanism scenarios. Asteroid impact models global dispersal of large quantities of dust, ash, sulfur, and other generate a prolonged cold winter that suppresses potential global aerosols into the atmosphere (4, 18–20). These atmospheric dinosaur habitats. -
Introduction to Astronomy from Darkness to Blazing Glory
Introduction to Astronomy From Darkness to Blazing Glory Published by JAS Educational Publications Copyright Pending 2010 JAS Educational Publications All rights reserved. Including the right of reproduction in whole or in part in any form. Second Edition Author: Jeffrey Wright Scott Photographs and Diagrams: Credit NASA, Jet Propulsion Laboratory, USGS, NOAA, Aames Research Center JAS Educational Publications 2601 Oakdale Road, H2 P.O. Box 197 Modesto California 95355 1-888-586-6252 Website: http://.Introastro.com Printing by Minuteman Press, Berkley, California ISBN 978-0-9827200-0-4 1 Introduction to Astronomy From Darkness to Blazing Glory The moon Titan is in the forefront with the moon Tethys behind it. These are two of many of Saturn’s moons Credit: Cassini Imaging Team, ISS, JPL, ESA, NASA 2 Introduction to Astronomy Contents in Brief Chapter 1: Astronomy Basics: Pages 1 – 6 Workbook Pages 1 - 2 Chapter 2: Time: Pages 7 - 10 Workbook Pages 3 - 4 Chapter 3: Solar System Overview: Pages 11 - 14 Workbook Pages 5 - 8 Chapter 4: Our Sun: Pages 15 - 20 Workbook Pages 9 - 16 Chapter 5: The Terrestrial Planets: Page 21 - 39 Workbook Pages 17 - 36 Mercury: Pages 22 - 23 Venus: Pages 24 - 25 Earth: Pages 25 - 34 Mars: Pages 34 - 39 Chapter 6: Outer, Dwarf and Exoplanets Pages: 41-54 Workbook Pages 37 - 48 Jupiter: Pages 41 - 42 Saturn: Pages 42 - 44 Uranus: Pages 44 - 45 Neptune: Pages 45 - 46 Dwarf Planets, Plutoids and Exoplanets: Pages 47 -54 3 Chapter 7: The Moons: Pages: 55 - 66 Workbook Pages 49 - 56 Chapter 8: Rocks and Ice: -
Could a Nearby Supernova Explosion Have Caused a Mass Extinction? JOHN ELLIS* and DAVID N
Proc. Natl. Acad. Sci. USA Vol. 92, pp. 235-238, January 1995 Astronomy Could a nearby supernova explosion have caused a mass extinction? JOHN ELLIS* AND DAVID N. SCHRAMMtt *Theoretical Physics Division, European Organization for Nuclear Research, CH-1211, Geneva 23, Switzerland; tDepartment of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637; and *National Aeronautics and Space Administration/Fermilab Astrophysics Center, Fermi National Accelerator Laboratory, Batavia, IL 60510 Contributed by David N. Schramm, September 6, 1994 ABSTRACT We examine the possibility that a nearby the solar constant, supernova explosions, and meteorite or supernova explosion could have caused one or more of the comet impacts that could be due to perturbations of the Oort mass extinctions identified by paleontologists. We discuss the cloud. The first of these has little experimental support. possible rate of such events in the light of the recent suggested Nemesis (4), a conjectured binary companion of the Sun, identification of Geminga as a supernova remnant less than seems to have been excluded as a mechanism for the third,§ 100 parsec (pc) away and the discovery ofa millisecond pulsar although other possibilities such as passage of the solar system about 150 pc away and observations of SN 1987A. The fluxes through the galactic plane may still be tenable. The supernova of y-radiation and charged cosmic rays on the Earth are mechanism (6, 7) has attracted less research interest than some estimated, and their effects on the Earth's ozone layer are of the others, perhaps because there has not been a recent discussed. -
Arxiv:1905.02734V1 [Astro-Ph.GA] 7 May 2019 As Part of This Work, We Infer the Distances, Reddenings and Types of 799 Million Stars
Draft version May 9, 2019 Typeset using LATEX preprint style in AASTeX62 A 3D Dust Map Based on Gaia, Pan-STARRS 1 and 2MASS Gregory M. Green,1 Edward Schlafly,2, 3 Catherine Zucker,4 Joshua S. Speagle,4 and Douglas Finkbeiner4 1Kavli Institute for Particle Astrophysics and Cosmology, Stanford University 452 Lomita Mall, Stanford, CA 94305-4060, USA 2Lawrence Berkeley National Laboratory One Cyclotron Road Berkeley, CA 94720, USA 3Hubble Fellow 4Harvard Astronomy, Harvard-Smithsonian Center for Astrophysics 60 Garden St., Cambridge, MA 02138, USA (Received ?; Revised ?; Accepted ?) Submitted to ? ABSTRACT We present a new three-dimensional map of dust reddening, based on Gaia paral- laxes and stellar photometry from Pan-STARRS 1 and 2MASS. This map covers the sky north of a declination of 30◦, out to a distance of several kiloparsecs. This new − map contains three major improvements over our previous work. First, the inclusion of Gaia parallaxes dramatically improves distance estimates to nearby stars. Second, we incorporate a spatial prior that correlates the dust density across nearby sightlines. This produces a smoother map, with more isotropic clouds and smaller distance uncer- tainties, particularly to clouds within the nearest kiloparsec. Third, we infer the dust density with a distance resolution that is four times finer than in our previous work, to accommodate the improvements in signal-to-noise enabled by the other improvements. arXiv:1905.02734v1 [astro-ph.GA] 7 May 2019 As part of this work, we infer the distances, reddenings and types of 799 million stars. We obtain typical reddening uncertainties that are 30% smaller than those reported in ∼ the Gaia DR2 catalog, reflecting the greater number of photometric passbands that en- ter into our analysis. -