April 2021 Volume 47 Number 2 in the Pages of the Gemini
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Mathématiques Et Espace
Atelier disciplinaire AD 5 Mathématiques et Espace Anne-Cécile DHERS, Education Nationale (mathématiques) Peggy THILLET, Education Nationale (mathématiques) Yann BARSAMIAN, Education Nationale (mathématiques) Olivier BONNETON, Sciences - U (mathématiques) Cahier d'activités Activité 1 : L'HORIZON TERRESTRE ET SPATIAL Activité 2 : DENOMBREMENT D'ETOILES DANS LE CIEL ET L'UNIVERS Activité 3 : D'HIPPARCOS A BENFORD Activité 4 : OBSERVATION STATISTIQUE DES CRATERES LUNAIRES Activité 5 : DIAMETRE DES CRATERES D'IMPACT Activité 6 : LOI DE TITIUS-BODE Activité 7 : MODELISER UNE CONSTELLATION EN 3D Crédits photo : NASA / CNES L'HORIZON TERRESTRE ET SPATIAL (3 ème / 2 nde ) __________________________________________________ OBJECTIF : Détermination de la ligne d'horizon à une altitude donnée. COMPETENCES : ● Utilisation du théorème de Pythagore ● Utilisation de Google Earth pour évaluer des distances à vol d'oiseau ● Recherche personnelle de données REALISATION : Il s'agit ici de mettre en application le théorème de Pythagore mais avec une vision terrestre dans un premier temps suite à un questionnement de l'élève puis dans un second temps de réutiliser la même démarche dans le cadre spatial de la visibilité d'un satellite. Fiche élève ____________________________________________________________________________ 1. Victor Hugo a écrit dans Les Châtiments : "Les horizons aux horizons succèdent […] : on avance toujours, on n’arrive jamais ". Face à la mer, vous voyez l'horizon à perte de vue. Mais "est-ce loin, l'horizon ?". D'après toi, jusqu'à quelle distance peux-tu voir si le temps est clair ? Réponse 1 : " Sans instrument, je peux voir jusqu'à .................. km " Réponse 2 : " Avec une paire de jumelles, je peux voir jusqu'à ............... km " 2. Nous allons maintenant calculer à l'aide du théorème de Pythagore la ligne d'horizon pour une hauteur H donnée. -
The Skyscraper 2009 04.Indd
A Better Galaxy Guide: Early Spring M67: One of the most ancient open clusters known and Craig Cortis is a great novelty in this regard. Located 1.7° due W of mag NGC 2419: 3.25° SE of mag 6.2 66 Aurigae. Hard to find 4.3 Alpha Cancri. and see; at E end of short row of two mag 7.5 stars. Highly NGC 2775: Located 3.7° ENE of mag 3.1 Zeta Hydrae. significant and worth the effort —may be approximately (Look for “Head of Hydra” first.) 300,000 light years distant and qualify as an extragalactic NGC 2903: Easily found at 1.5° due S of mag 4.3 Lambda cluster. Named the Intergalactic Wanderer. Leonis. NGC 2683: Marks NW “crook” of coathanger-type triangle M95: One of three bright galaxies forming a compact with easy double star mag 4.2 Iota Cancri (which is SSW by triangle, along with M96 and M105. All three can be seen 4.8°) and mag 3.1 Alpha Lyncis (at 6° to the ENE). together in a low power, wide field view. M105 is at the NE tip of triangle, midway between stars 52 and 53 Leonis, mag Object Type R.A. Dec. Mag. Size 5.5 and 5.3 respectively —M95 is at W tip. Lynx NGC 3521: Located 0.5° due E of mag 6.0 62 Leonis. M65: One of a pair of bright galaxies that can be seen in NGC 2419 GC 07h 38.1m +38° 53’ 10.3 4.2’ a wide field view along with M66, which lies just E. -
Eating Planets for Lunch and Dinner: Signatures of Planet Consumption by Evolving Stars
Draft version September 13, 2019 Typeset using LATEX twocolumn style in AASTeX62 Eating Planets for Lunch and Dinner: Signatures of Planet Consumption by Evolving Stars Alexander P. Stephan,1, 2 Smadar Naoz,1, 2 B. Scott Gaudi,3 and Jesus M. Salas1, 2 1Department of Physics and Astronomy, University of California, Los Angeles, Los Angeles, CA 90095, USA 2Mani L. Bhaumik Institute for Theoretical Physics, University of California, Los Angeles, Los Angeles, CA 90095, USA 3Department of Astronomy, The Ohio State University, Columbus, OH 43210, USA (Received XXX; Revised YYY; Accepted ZZZ) Submitted to ApJ ABSTRACT Exoplanets have been observed around stars at all stages of stellar evolution, in many cases orbiting in configurations that will eventually lead to the planets being engulfed or consumed by their host stars, such as Hot Jupiters or ultra-short period planets. Furthermore, objects such as polluted white dwarfs provide strong evidence that the consumption of planets by stars is a common phenomenon. This consumption causes several significant changes in the stellar properties, such as changes to the stellar spin, luminosity, chemical composition, or mass loss processes. Here, we explore this wide variety of effects for a comprehensive range of stellar and planetary masses and stages of stellar evolution, from the main sequence over red giants to the white dwarfs. We determine that planet consumption can cause transient luminosity features that last on the order of centuries to millennia, and that the post-consumption stellar spins can often reach break-up speeds. Furthermore, stellar moss loss can be caused by this spin-up, as well as through surface grazing interactions, leading to to the formation of unusual planetary nebula shapes or collimated stellar gas ejections. -
The Brightest Stars Seite 1 Von 9
The Brightest Stars Seite 1 von 9 The Brightest Stars This is a list of the 300 brightest stars made using data from the Hipparcos catalogue. The stellar distances are only fairly accurate for stars well within 1000 light years. 1 2 3 4 5 6 7 8 9 10 11 12 13 No. Star Names Equatorial Galactic Spectral Vis Abs Prllx Err Dist Coordinates Coordinates Type Mag Mag ly RA Dec l° b° 1. Alpha Canis Majoris Sirius 06 45 -16.7 227.2 -8.9 A1V -1.44 1.45 379.21 1.58 9 2. Alpha Carinae Canopus 06 24 -52.7 261.2 -25.3 F0Ib -0.62 -5.53 10.43 0.53 310 3. Alpha Centauri Rigil Kentaurus 14 40 -60.8 315.8 -0.7 G2V+K1V -0.27 4.08 742.12 1.40 4 4. Alpha Boötis Arcturus 14 16 +19.2 15.2 +69.0 K2III -0.05 -0.31 88.85 0.74 37 5. Alpha Lyrae Vega 18 37 +38.8 67.5 +19.2 A0V 0.03 0.58 128.93 0.55 25 6. Alpha Aurigae Capella 05 17 +46.0 162.6 +4.6 G5III+G0III 0.08 -0.48 77.29 0.89 42 7. Beta Orionis Rigel 05 15 -8.2 209.3 -25.1 B8Ia 0.18 -6.69 4.22 0.81 770 8. Alpha Canis Minoris Procyon 07 39 +5.2 213.7 +13.0 F5IV-V 0.40 2.68 285.93 0.88 11 9. Alpha Eridani Achernar 01 38 -57.2 290.7 -58.8 B3V 0.45 -2.77 22.68 0.57 144 10. -
Chapter 1 a Theoretical and Observational Overview of Brown
Chapter 1 A theoretical and observational overview of brown dwarfs Stars are large spheres of gas composed of 73 % of hydrogen in mass, 25 % of helium, and about 2 % of metals, elements with atomic number larger than two like oxygen, nitrogen, carbon or iron. The core temperature and pressure are high enough to convert hydrogen into helium by the proton-proton cycle of nuclear reaction yielding sufficient energy to prevent the star from gravitational collapse. The increased number of helium atoms yields a decrease of the central pressure and temperature. The inner region is thus compressed under the gravitational pressure which dominates the nuclear pressure. This increase in density generates higher temperatures, making nuclear reactions more efficient. The consequence of this feedback cycle is that a star such as the Sun spend most of its lifetime on the main-sequence. The most important parameter of a star is its mass because it determines its luminosity, ef- fective temperature, radius, and lifetime. The distribution of stars with mass, known as the Initial Mass Function (hereafter IMF), is therefore of prime importance to understand star formation pro- cesses, including the conversion of interstellar matter into stars and back again. A major issue regarding the IMF concerns its universality, i.e. whether the IMF is constant in time, place, and metallicity. When a solar-metallicity star reaches a mass below 0.072 M ¡ (Baraffe et al. 1998), the core temperature and pressure are too low to burn hydrogen stably. Objects below this mass were originally termed “black dwarfs” because the low-luminosity would hamper their detection (Ku- mar 1963). -
Gas and Dust in the Magellanic Clouds
Gas and dust in the Magellanic clouds A Thesis Submitted for the Award of the Degree of Doctor of Philosophy in Physics To Mangalore University by Ananta Charan Pradhan Under the Supervision of Prof. Jayant Murthy Indian Institute of Astrophysics Bangalore - 560 034 India April 2011 Declaration of Authorship I hereby declare that the matter contained in this thesis is the result of the inves- tigations carried out by me at Indian Institute of Astrophysics, Bangalore, under the supervision of Professor Jayant Murthy. This work has not been submitted for the award of any degree, diploma, associateship, fellowship, etc. of any university or institute. Signed: Date: ii Certificate This is to certify that the thesis entitled ‘Gas and Dust in the Magellanic clouds’ submitted to the Mangalore University by Mr. Ananta Charan Pradhan for the award of the degree of Doctor of Philosophy in the faculty of Science, is based on the results of the investigations carried out by him under my supervi- sion and guidance, at Indian Institute of Astrophysics. This thesis has not been submitted for the award of any degree, diploma, associateship, fellowship, etc. of any university or institute. Signed: Date: iii Dedicated to my parents ========================================= Sri. Pandab Pradhan and Smt. Kanak Pradhan ========================================= Acknowledgements It has been a pleasure to work under Prof. Jayant Murthy. I am grateful to him for giving me full freedom in research and for his guidance and attention throughout my doctoral work inspite of his hectic schedules. I am indebted to him for his patience in countless reviews and for his contribution of time and energy as my guide in this project. -
Mid-Infrared Interferometric Observations of the High-Mass Protostellar Candidate NGC 3603 IRS 9A
Dissertation submitted to the Combined Faculties for the Natural Sciences and for Mathematics of the Ruperto-Carola University of Heidelberg, Germany for the degree of Doctor of Natural Sciences Put forward by Dipl.-Phys. Stefan Vehoff born in Arnsberg (Germany) Oral examination: 29th April, 2009 Mid-infrared interferometric observations of the high-mass protostellar candidate NGC 3603 IRS 9A Referees: Prof. Dr. Rainer Wehrse Prof. Dr. Wolfgang J. Duschl Zusammenfassung Interferometrische Beobachtungen des massereichen potentiellen Protosterns NGC 3603 IRS 9A im mittleren Infrarot Wir benutzen Infrarotbeobachtungen der größten Teleskope, Interferometer und Welt- raumteleskope, um der Frage der Entstehung von massereichen Sternen nachzugehen. Das Ziel dieser Beobachtungen ist IRS 9A, ein vielversprechendes Objekt, das wahr- scheinlich der seltenen Gruppe der sehr jungen und massereichen Protosterne angehört. Im ersten Teil dieser Arbeit beschreiben wir die unmittelbaren Ergebnisse der einzelnen Beobachtungen, während wir im zweiten Teil versuchen, ein Modell für IRS 9A und seine direkte Umgebung zu konstruieren, das diese Beobachtungen nachahmen kann. Wir be- nutzen außerdem ein öffentlich zugängliches Netz von spektralen Energieverteilungen, das für eine große Anzahl von protostellaren Objekten berechnet wurde. Dabei stellen wir fest, dass das Erscheinungsbild von IRS 9A im mittleren Infrarot weder mit einfachen geometrischen Helligkeitsverteilungen, noch mit eindimensionalen Modellen der Dichtestruktur erklärt werden kann. Mittels Strahlungstransportmodellen, die aus zirkumstellaren Scheiben und Hüllen bestehen, sind wir jedoch in der Lage, alle unsere Beobachtungsdaten mit einem einzigen Modell zu erklären. Darüber hinaus zeigt der Vergleich mit dem Netz von protostellaren Objekten, dass es sich bei IRS 9A tatsäch- lich um einen massereichen Protostern handelt. Damit unterstützt unsere Untersuchung die Theorie, dass massereiche Sterne in einer ähnlichen Art und Weise entstehen wie Sterne mit geringer und mittlerer Masse. -
Clusters Nebulae & Galaxies
CLUSTERS, NEBULAE & GALAXIES A NOVICE OBSERVER’S HANDBOOK By: Prof. P. N. Shankar PREFACE In the normal course of events, an amateur who builds or acquires a telescope will use it initially to observe the Moon and the planets. After the thrill of seeing the craters of the Moon, the Galilean moons of Jupiter and its bands, and the rings of Saturn he(*) is usually at a loss as to what to do next; Mars and Venus are usually disappointing as are the stars (they don’t look any bigger!). If the telescope had good resolution one could observe binaries, but alas, this is often not the case. Moreover, at this stage, the amateur is unlikely to be willing to do serious work on variable stars or on planetary observations. What can he do with his telescope that will rekindle his interest and prepare him for serious work? I believe that there is little better for him to do than hunt for the Messier objects; this book is meant as a guide in this exciting adventure. While this book is primarily a guide to the Messier objects, a few other easy clusters and nebulae have also been included. I have tried, while writing this handbook, to keep in mind the difficulties faced by a beginner. Even if one has good star maps, such as those in Norton’s Star Atlas, a beginner often has difficulty in locating some of the Messier objects because he does not know what he is expected to see! A cluster like M29 is a little difficult because it is a sparse cluster in a rich field; M97 is nominally brighter than M76, another planetary, but is more difficult to see; M33 is an approximately 6th magnitude galaxy but is far more difficult than many 9th magnitude galaxies. -
Observation Guide
May's Featured Variable: V Star Finder Chart for V Hydrae Hydrae in Hydra the Sea Serpent I bet you have seen a star twinkling —the air It is easy to estimate the brightness surrounding Earth makes it look like the star ("magnitude") of a star, but first note: is sparkling! Even if we went to outer space, • in finder charts like below, brighter stars we could see many stars change brightness. are indicated by larger dots “Variable stars" continuously dim, brighten, • the brighter the star, the lower the magnitude number and dim. Some complete the pattern in under a second, while others take years. • magnitudes are written to the nearest tenth—but without a decimal point, to enable anyone, anywhere, to One variable star that YOU can see this which could be confused as a star. So, participate in scientific discovery month is V Hydrae in the constellation Hydra 45= magnitude 4.5 through variable star astronomy the Sea Serpent. Its deep cherry red color is • in this chart, magnitudes for comparison often bright enough to be seen about 5 stars—nearby stars to compare a given degrees south of the bright star Nu Hydrae, star's brightness to—are noted American Association of Variable Star Observers from a dark sky site, but it is more easily 49 Bay State Road, Cambridge, MA 02138, USA spotted in binoculars. Find two comparison stars close to your Telephone: +1 (617) 354-0484 given variable star's brightness—one www.aavso.org | [email protected] Why is this star amazingly red? The relatively brighter and one dimmer. -
Florida State University Libraries
Florida State University Libraries Electronic Theses, Treatises and Dissertations The Graduate School Constraining the Evolution of Massive StarsMojgan Aghakhanloo Follow this and additional works at the DigiNole: FSU's Digital Repository. For more information, please contact [email protected] FLORIDA STATE UNIVERSITY COLLEGE OF ARTS AND SCIENCES CONSTRAINING THE EVOLUTION OF MASSIVE STARS By MOJGAN AGHAKHANLOO A Dissertation submitted to the Department of Physics in partial fulfillment of the requirements for the degree of Doctor of Philosophy 2020 Copyright © 2020 Mojgan Aghakhanloo. All Rights Reserved. Mojgan Aghakhanloo defended this dissertation on April 6, 2020. The members of the supervisory committee were: Jeremiah Murphy Professor Directing Dissertation Munir Humayun University Representative Kevin Huffenberger Committee Member Eric Hsiao Committee Member Harrison Prosper Committee Member The Graduate School has verified and approved the above-named committee members, and certifies that the dissertation has been approved in accordance with university requirements. ii I dedicate this thesis to my parents for their love and encouragement. I would not have made it this far without you. iii ACKNOWLEDGMENTS I would like to thank my advisor, Professor Jeremiah Murphy. I could not go through this journey without your endless support and guidance. I am very grateful for your scientific advice and knowledge and many insightful discussions that we had during these past six years. Thank you for making such a positive impact on my life. I would like to thank my PhD committee members, Professors Eric Hsiao, Kevin Huf- fenberger, Munir Humayun and Harrison Prosper. I will always cherish your guidance, encouragement and support. I would also like to thank all of my collaborators. -
Uranometría Argentina Bicentenario
URANOMETRÍA ARGENTINA BICENTENARIO Reedición electrónica ampliada, ilustrada y actualizada de la URANOMETRÍA ARGENTINA Brillantez y posición de las estrellas fijas, hasta la séptima magnitud, comprendidas dentro de cien grados del polo austral. Resultados del Observatorio Nacional Argentino, Volumen I. Publicados por el observatorio 1879. Con Atlas (1877) 1 Observatorio Nacional Argentino Dirección: Benjamin Apthorp Gould Observadores: John M. Thome - William M. Davis - Miles Rock - Clarence L. Hathaway Walter G. Davis - Frank Hagar Bigelow Mapas del Atlas dibujados por: Albert K. Mansfield Tomado de Paolantonio S. y Minniti E. (2001) Uranometría Argentina 2001, Historia del Observatorio Nacional Argentino. SECyT-OA Universidad Nacional de Córdoba, Córdoba. Santiago Paolantonio 2010 La importancia de la Uranometría1 Argentina descansa en las sólidas bases científicas sobre la cual fue realizada. Esta obra, cuidada en los más pequeños detalles, se debe sin dudas a la genialidad del entonces director del Observatorio Nacional Argentino, Dr. Benjamin A. Gould. Pero nada de esto se habría hecho realidad sin la gran habilidad, el esfuerzo y la dedicación brindada por los cuatro primeros ayudantes del Observatorio, John M. Thome, William M. Davis, Miles Rock y Clarence L. Hathaway, así como de Walter G. Davis y Frank Hagar Bigelow que se integraron más tarde a la institución. Entre éstos, J. M. Thome, merece un lugar destacado por la esmerada revisión, control de las posiciones y determinaciones de brillos, tal como el mismo Director lo reconoce en el prólogo de la publicación. Por otro lado, Albert K. Mansfield tuvo un papel clave en la difícil confección de los mapas del Atlas. La Uranometría Argentina sobresale entre los trabajos realizados hasta ese momento, por múltiples razones: Por la profundidad en magnitud, ya que llega por vez primera en este tipo de empresa a la séptima. -
June 2006 (In the Coils of the Water Snake)
Eridanus Optics CC June 2006 Constellation: Hydra (The Female Water Snake) Introduction Although Hydra is the largest constellation in the sky, it is not very prominent. The head forms the most prominent feature and is found on the western side of the constellation. The snake follows its ‘head’ through the sky, starting east of Monoceros, ending over 100º to the east at Centaurus 2 and Lupus. The constellation thus spans close to /3 of the visible sky from West to East. (See Map 1) In Greek mythology, Hydra was the multi-headed monster slain by Hercules as one of his twelve tasks. It is also linked in legends to Corvus (the Crow) and Crater (the Cup), two constellations found on the back of Hydra. Naked eye objects A few naked eye objects are visible. Only Alfard (The Solitary One) is brighter than Magnitude 3. The name is a reference to this star being the only bright object in the area. Alfard is about 20º South of Regulus (Leo). (At an arm’s length from your eye, if you spread your hand wide, the distance between the tip of your little finger and the end of your thumb can be taken as 20º.) From dark sky sites, the head can be seen as well as several other stars along the body of the snake. To locate the head, start at Alfard and find the trinity of stars to the North (right). Further down (West), you’ll find Theta Hydrae and Omega Hydrae, followed by the head. (See Map 2). I could see only two stars of the head from Pretoria without optical aid.