The Hertzsprung-Russell Diagram Help Sheet
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Gerbert of Aurillac: Astronomy and Geometry in Tenth Century Europe
October 25, 2018 15:56 WSPC/INSTRUCTION FILE Sigismondi-Gerbert International Journal of Modern Physics: Conference Series c World Scientific Publishing Company GERBERT OF AURILLAC: ASTRONOMY AND GEOMETRY IN TENTH CENTURY EUROPE COSTANTINO SIGISMONDI Sapienza University of Rome, Physics Dept., and Galileo Ferraris Institute P.le Aldo Moro 5 Roma, 00185, Italy. e-mail: [email protected] University of Nice-Sophia Antipolis - Dept. Fizeau (France); IRSOL, Istituto Ricerche Solari di Locarno (Switzerland) Received 6 Feb 2012 Revised Day Month Year Gerbert of Aurillac was the most prominent personality of the tenth century: as- tronomer, organ builder and music theoretician, mathematician, philosopher, and finally pope with the name of Silvester II (999-1003). Gerbert introduced firstly the arabic num- bers in Europe, invented an abacus for speeding the calculations and found a rational approximation for the equilateral triangle area, in the letter to Adelbold here discussed. Gerbert described a semi-sphere to Constantine of Fleury with built-in sighting tubes, used for astronomical observations. The procedure to identify the star nearest to the North celestial pole is very accurate and still in use in the XII century, when Computa- trix was the name of Polaris. For didactical purposes the Polaris would have been precise enough and much less time consuming, but here Gerbert was clearly aligning a precise equatorial mount for a fixed instrument for accurate daytime observations. Through the sighting tubes it was possible to detect equinoxes and solstices by observing the Sun in the corresponding days. The horalogium of Magdeburg was probably a big and fixed- mount nocturlabe, always pointing the star near the celestial pole. -
The Dunhuang Chinese Sky: a Comprehensive Study of the Oldest Known Star Atlas
25/02/09JAHH/v4 1 THE DUNHUANG CHINESE SKY: A COMPREHENSIVE STUDY OF THE OLDEST KNOWN STAR ATLAS JEAN-MARC BONNET-BIDAUD Commissariat à l’Energie Atomique ,Centre de Saclay, F-91191 Gif-sur-Yvette, France E-mail: [email protected] FRANÇOISE PRADERIE Observatoire de Paris, 61 Avenue de l’Observatoire, F- 75014 Paris, France E-mail: [email protected] and SUSAN WHITFIELD The British Library, 96 Euston Road, London NW1 2DB, UK E-mail: [email protected] Abstract: This paper presents an analysis of the star atlas included in the medieval Chinese manuscript (Or.8210/S.3326), discovered in 1907 by the archaeologist Aurel Stein at the Silk Road town of Dunhuang and now held in the British Library. Although partially studied by a few Chinese scholars, it has never been fully displayed and discussed in the Western world. This set of sky maps (12 hour angle maps in quasi-cylindrical projection and a circumpolar map in azimuthal projection), displaying the full sky visible from the Northern hemisphere, is up to now the oldest complete preserved star atlas from any civilisation. It is also the first known pictorial representation of the quasi-totality of the Chinese constellations. This paper describes the history of the physical object – a roll of thin paper drawn with ink. We analyse the stellar content of each map (1339 stars, 257 asterisms) and the texts associated with the maps. We establish the precision with which the maps are drawn (1.5 to 4° for the brightest stars) and examine the type of projections used. -
Chapter 3: Familiarizing Yourself with the Night Sky
Chapter 3: Familiarizing Yourself With the Night Sky Introduction People of ancient cultures viewed the sky as the inaccessible home of the gods. They observed the daily motion of the stars, and grouped them into patterns and images. They assigned stories to the stars, relating to themselves and their gods. They believed that human events and cycles were part of larger cosmic events and cycles. The night sky was part of the cycle. The steady progression of star patterns across the sky was related to the ebb and flow of the seasons, the cyclical migration of herds and hibernation of bears, the correct times to plant or harvest crops. Everywhere on Earth people watched and recorded this orderly and majestic celestial procession with writings and paintings, rock art, and rock and stone monuments or alignments. When the Great Pyramid in Egypt was constructed around 2650 BC, two shafts were built into it at an angle, running from the outside into the interior of the pyramid. The shafts coincide with the North-South passage of two stars important to the Egyptians: Thuban, the star closest to the North Pole at that time, and one of the stars of Orion’s belt. Orion was The Ishango Bone, thought to be a 20,000 year old associated with Osiris, one of the Egyptian gods of the lunar calendar underworld. The Bighorn Medicine Wheel in Wyoming, built by Plains Indians, consists of rocks in the shape of a large circle, with lines radiating from a central hub like the spokes of a bicycle wheel. -
Explore the Universe Observing Certificate Second Edition
RASC Observing Committee Explore the Universe Observing Certificate Second Edition Explore the Universe Observing Certificate Welcome to the Explore the Universe Observing Certificate Program. This program is designed to provide the observer with a well-rounded introduction to the night sky visible from North America. Using this observing program is an excellent way to gain knowledge and experience in astronomy. Experienced observers find that a planned observing session results in a more satisfying and interesting experience. This program will help introduce you to amateur astronomy and prepare you for other more challenging certificate programs such as the Messier and Finest NGC. The program covers the full range of astronomical objects. Here is a summary: Observing Objective Requirement Available Constellations and Bright Stars 12 24 The Moon 16 32 Solar System 5 10 Deep Sky Objects 12 24 Double Stars 10 20 Total 55 110 In each category a choice of objects is provided so that you can begin the certificate at any time of the year. In order to receive your certificate you need to observe a total of 55 of the 110 objects available. Here is a summary of some of the abbreviations used in this program Instrument V – Visual (unaided eye) B – Binocular T – Telescope V/B - Visual/Binocular B/T - Binocular/Telescope Season Season when the object can be best seen in the evening sky between dusk. and midnight. Objects may also be seen in other seasons. Description Brief description of the target object, its common name and other details. Cons Constellation where object can be found (if applicable) BOG Ref Refers to corresponding references in the RASC’s The Beginner’s Observing Guide highlighting this object. -
The Zodiac: Comparison of the Ancient Greek Mythology and the Popular Romanian Beliefs
THE ZODIAC: COMPARISON OF THE ANCIENT GREEK MYTHOLOGY AND THE POPULAR ROMANIAN BELIEFS DOINA IONESCU *, FLORA ROVITHIS ** , ELENI ROVITHIS-LIVANIOU *** Abstract : This paper intends to draw a comparison between the ancient Greek Mythology and the Romanian folk beliefs for the Zodiac. So, after giving general information for the Zodiac, each one of the 12 zodiac signs is described. Besides, information is given for a few astronomical subjects of special interest, together with Romanian people believe and the description of Greek myths concerning them. Thus, after a thorough examination it is realized that: a) The Greek mythology offers an explanation for the consecration of each Zodiac sign, and even if this seems hyperbolic in almost most of the cases it was a solution for things not easily understood at that time; b) All these passed to the Romanians and influenced them a lot firstly by the ancient Greeks who had built colonies in the present Romania coasts as well as via commerce, and later via the Romans, and c) The Romanian beliefs for the Zodiac is also connected to their deep Orthodox religious character, with some references also to their history. Finally, a general discussion is made and some agricultural and navigator suggestions connected to Pleiades and Hyades are referred, too. Keywords : Zodiac, Greek, mythology, tradition, religion. PROLOGUE One of their first thoughts, or questions asked, by the primitive people had possibly to do with sky and stars because, when during the night it was very dark, all these lights above had certainly arose their interest. So, many ancient civilizations observed the stars as well as their movements in the sky. -
Winter Constellations
Winter Constellations *Orion *Canis Major *Monoceros *Canis Minor *Gemini *Auriga *Taurus *Eradinus *Lepus *Monoceros *Cancer *Lynx *Ursa Major *Ursa Minor *Draco *Camelopardalis *Cassiopeia *Cepheus *Andromeda *Perseus *Lacerta *Pegasus *Triangulum *Aries *Pisces *Cetus *Leo (rising) *Hydra (rising) *Canes Venatici (rising) Orion--Myth: Orion, the great hunter. In one myth, Orion boasted he would kill all the wild animals on the earth. But, the earth goddess Gaia, who was the protector of all animals, produced a gigantic scorpion, whose body was so heavily encased that Orion was unable to pierce through the armour, and was himself stung to death. His companion Artemis was greatly saddened and arranged for Orion to be immortalised among the stars. Scorpius, the scorpion, was placed on the opposite side of the sky so that Orion would never be hurt by it again. To this day, Orion is never seen in the sky at the same time as Scorpius. DSO’s ● ***M42 “Orion Nebula” (Neb) with Trapezium A stellar nursery where new stars are being born, perhaps a thousand stars. These are immense clouds of interstellar gas and dust collapse inward to form stars, mainly of ionized hydrogen which gives off the red glow so dominant, and also ionized greenish oxygen gas. The youngest stars may be less than 300,000 years old, even as young as 10,000 years old (compared to the Sun, 4.6 billion years old). 1300 ly. 1 ● *M43--(Neb) “De Marin’s Nebula” The star-forming “comma-shaped” region connected to the Orion Nebula. ● *M78--(Neb) Hard to see. A star-forming region connected to the Orion Nebula. -
Binocular Universe: You're My Hero! December 2010
Binocular Universe: You're My Hero! December 2010 Phil Harrington on't you just love a happy ending? I know I do. Picture this. Princess Andromeda, a helpless damsel in distress, chained to a rock as a ferocious D sea monster loomed nearby. Just when all appeared lost, our hero -- Perseus! -- plunges out of the sky, kills the monster, and sweeps up our maiden in his arms. Together, they fly off into the sunset on his winged horse to live happily ever after. Such is the stuff of myths and legends. That story, the legend of Perseus and Andromeda, was recounted in last month's column when we visited some binocular targets within the constellation Cassiopeia. In mythology, Queen Cassiopeia was Andromeda's mother, and the cause for her peril in the first place. Left: Autumn star map from Star Watch by Phil Harrington Above: Finder chart for this month's Binocular Universe. Chart adapted from Touring the Universe through Binoculars Atlas (TUBA), www.philharrington.net/tuba.htm This month, we return to the scene of the rescue, to our hero, Perseus. He stands in our sky to the east of Cassiopeia and Andromeda, should the Queen's bragging get her daughter into hot water again. The constellation's brightest star, Mirfak (Alpha [α] Persei), lies about two-thirds of the way along a line that stretches from Pegasus to the bright star Capella in Auriga. Shining at magnitude +1.8, Mirfak is classified as a class F5 white supergiant. It radiates some 5,000 times the energy of our Sun and has a diameter 62 times larger. -
Wynyard Planetarium & Observatory a Autumn Observing Notes
Wynyard Planetarium & Observatory A Autumn Observing Notes Wynyard Planetarium & Observatory PUBLIC OBSERVING – Autumn Tour of the Sky with the Naked Eye CASSIOPEIA Look for the ‘W’ 4 shape 3 Polaris URSA MINOR Notice how the constellations swing around Polaris during the night Pherkad Kochab Is Kochab orange compared 2 to Polaris? Pointers Is Dubhe Dubhe yellowish compared to Merak? 1 Merak THE PLOUGH Figure 1: Sketch of the northern sky in autumn. © Rob Peeling, CaDAS, 2007 version 1.2 Wynyard Planetarium & Observatory PUBLIC OBSERVING – Autumn North 1. On leaving the planetarium, turn around and look northwards over the roof of the building. Close to the horizon is a group of stars like the outline of a saucepan with the handle stretching to your left. This is the Plough (also called the Big Dipper) and is part of the constellation Ursa Major, the Great Bear. The two right-hand stars are called the Pointers. Can you tell that the higher of the two, Dubhe is slightly yellowish compared to the lower, Merak? Check with binoculars. Not all stars are white. The colour shows that Dubhe is cooler than Merak in the same way that red-hot is cooler than white- hot. 2. Use the Pointers to guide you upwards to the next bright star. This is Polaris, the Pole (or North) Star. Note that it is not the brightest star in the sky, a common misconception. Below and to the left are two prominent but fainter stars. These are Kochab and Pherkad, the Guardians of the Pole. Look carefully and you will notice that Kochab is slightly orange when compared to Polaris. -
Taurus Stars Membership in the Pleiades Open Cluster
Taurus stars membership in the Pleiades open cluster Tadross, A. L., Hanna, M. A., Awadalla, N. S. National Research Institute of Astronomy & Geophysics, NRIAG, 11421 Helwan, Cairo, Egypt ABSTRACT In this paper, we study the characteristics and physical properties of the young open cluster Pleiades using Near Infra-Red, JHK pass bands. Our results have been compared with those found in new optical UBV observations. The membership validity of some variable binary stars, which are Located in Taurus constellation, and their relation with Pleiades cluster have been achieved. 1. INTRODUCTION Pleiades and Hyades are the most famous star clusters in Northern Hemisphere which can be seen by the naked eye in the constellation Taurus the bull. The star cluster surrounding Aldebaran (the eye of the bull) is the Hyades. Pleiades (NGC 1432; M45; Melotte 22; Seven Sisters) is more famous than Hyades because it is more compact cluster and easy seen, higher in the sky (~ 10 degrees from Aldebaran), see Fig 1. Pleiades is located at J (2000) α = 03h: 47m: 24s; δ = +24o: 07’: 12’’; G. long. = 166.642o and G. lat. = -23.457o. The distance to the Pleiades is an important first step in the so- called cosmic distance ladder, a sequence of distance scales for the whole universe. The optical photometry catalogs of Webda and Dais refer to Pleiades as a rich young cluster located at 135-150 pcs away from Earth. In optically observations, Pleiades covers a diameter of about 110 arcmin on the sky; its core and tidal radii are about 33 and 330 arcmins respectively. -
A Basic Requirement for Studying the Heavens Is Determining Where In
Abasic requirement for studying the heavens is determining where in the sky things are. To specify sky positions, astronomers have developed several coordinate systems. Each uses a coordinate grid projected on to the celestial sphere, in analogy to the geographic coordinate system used on the surface of the Earth. The coordinate systems differ only in their choice of the fundamental plane, which divides the sky into two equal hemispheres along a great circle (the fundamental plane of the geographic system is the Earth's equator) . Each coordinate system is named for its choice of fundamental plane. The equatorial coordinate system is probably the most widely used celestial coordinate system. It is also the one most closely related to the geographic coordinate system, because they use the same fun damental plane and the same poles. The projection of the Earth's equator onto the celestial sphere is called the celestial equator. Similarly, projecting the geographic poles on to the celest ial sphere defines the north and south celestial poles. However, there is an important difference between the equatorial and geographic coordinate systems: the geographic system is fixed to the Earth; it rotates as the Earth does . The equatorial system is fixed to the stars, so it appears to rotate across the sky with the stars, but of course it's really the Earth rotating under the fixed sky. The latitudinal (latitude-like) angle of the equatorial system is called declination (Dec for short) . It measures the angle of an object above or below the celestial equator. The longitud inal angle is called the right ascension (RA for short). -
Evolution of Star Clusters in Time-Variable Tidal Fields
Evolution of Star Clusters in Time-Variable Tidal Fields A Thesis Submitted to the Faculty of Drexel University by Ernest N. Mamikonyan in partial fulfillment of the requirement for the degree of Doctor of Philosophy December 12, 2013 Contents 1 Introduction 1 1.1 TypesofStarClusters............................ 2 1.1.1 GlobularClusters .......................... 3 1.1.2 OpenClusters............................ 4 1.2 Mass Function: From Young to Globular . 5 2 Arbitrary Tidal Acceleration 8 2.1 ApproximatingTidalEffects. 9 2.1.1 Tidal Acceleration Tensor . 10 2.2 Stellar Dynamics with KIRA ........................ 11 2.2.1 CircularOrbitinPoint-MassPotential . 14 2.3 GalaxyMergerSimulations . 16 2.3.1 TidalHistories............................ 19 2.4 N-BodySimulations ............................ 24 2.4.1 N-BodyUnits ............................ 26 2.4.2 Scaling ................................ 26 3 Mass Loss Model 30 i 3.1 Accelerated Two-Body Relaxation . 30 3.2 FluctuationsintheJacobiRadius. 34 3.3 Results .................................... 36 3.4 Discussion.................................. 37 3.4.1 Limitations ............................. 40 4 Globular Cluster Mass Functions 44 4.1 MassFunctionEvolution . 47 4.2 Results .................................... 48 4.2.1 SinkParticles ............................ 48 4.2.2 DiskParticles ............................ 50 4.2.3 HaloParticles ............................ 55 5 Conclusions and Future Work 57 Appendix A Implementation of Tidal Fields in KIRA 63 Appendix B Computing Tidal Acceleration from GADGET Output 66 ii List of Figures 1.1 Infrared image of the globular cluster Omega Centauri. It is the most massive cluster in the Galaxy and thought to be a remnant of a dwarf galaxy absorbed by the Milky Way. (NASA/JPL-Caltech/ NOAO/AURA/NSF)............................. 3 1.2 The Pleiades open cluster in the infrared. It is one of the most well- known and spectacular objects in the Galaxy. -
The Outermost Hii Regions of Nearby Galaxies
THE OUTERMOST HII REGIONS OF NEARBY GALAXIES by Jessica K. Werk A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy (Astronomy and Astrophysics) in The University of Michigan 2010 Doctoral Committee: Professor Mario L. Mateo, Co-Chair Associate Professor Mary E. Putman, Co-Chair, Columbia University Professor Fred C. Adams Professor Lee W. Hartmann Associate Professor Marion S. Oey Professor Gerhardt R. Meurer, University of Western Australia Jessica K. Werk Copyright c 2010 All Rights Reserved To Mom and Dad, for all your love and encouragement while I was taking up space. ii ACKNOWLEDGMENTS I owe a deep debt of gratitude to a long list of individuals, institutions, and substances that have seen me through the last six years of graduate school. My first undergraduate advisor in Astronomy, Kathryn Johnston, was also my first Astronomy Professor. She piqued my interest in the subject from day one with her enthusiasm and knowledge. I don’t doubt that I would be studying something far less interesting if it weren’t for her. John Salzer, my next and last undergraduate advisor, not only taught me so much about observing and organization, but also is responsible for convincing me to go on in Astronomy. Were it not for John, I’d probably be making a lot more money right now doing something totally mind-numbing and soul-crushing. And Laura Chomiuk, a fellow Wesleyan Astronomy Alumnus, has been there for me through everything − problem sets and personal heartbreak alike. To know her as a friend, goat-lover, and scientist has meant so much to me over the last 10 years, that confining my gratitude to these couple sentences just seems wrong.