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Variable Star
Variable star A variable star is a star whose brightness as seen from Earth (its apparent magnitude) fluctuates. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as either: Intrinsic variables, whose luminosity actually changes; for example, because the star periodically swells and shrinks. Extrinsic variables, whose apparent changes in brightness are due to changes in the amount of their light that can reach Earth; for example, because the star has an orbiting companion that sometimes Trifid Nebula contains Cepheid variable stars eclipses it. Many, possibly most, stars have at least some variation in luminosity: the energy output of our Sun, for example, varies by about 0.1% over an 11-year solar cycle.[1] Contents Discovery Detecting variability Variable star observations Interpretation of observations Nomenclature Classification Intrinsic variable stars Pulsating variable stars Eruptive variable stars Cataclysmic or explosive variable stars Extrinsic variable stars Rotating variable stars Eclipsing binaries Planetary transits See also References External links Discovery An ancient Egyptian calendar of lucky and unlucky days composed some 3,200 years ago may be the oldest preserved historical document of the discovery of a variable star, the eclipsing binary Algol.[2][3][4] Of the modern astronomers, the first variable star was identified in 1638 when Johannes Holwarda noticed that Omicron Ceti (later named Mira) pulsated in a cycle taking 11 months; the star had previously been described as a nova by David Fabricius in 1596. This discovery, combined with supernovae observed in 1572 and 1604, proved that the starry sky was not eternally invariable as Aristotle and other ancient philosophers had taught. -
Further Observations of the Lambda 10830 He Line in Stars and Their Significance As a Measure of Stellar Activity
General Disclaimer One or more of the Following Statements may affect this Document This document has been reproduced from the best copy furnished by the organizational source. It is being released in the interest of making available as much information as possible. This document may contain data, which exceeds the sheet parameters. It was furnished in this condition by the organizational source and is the best copy available. This document may contain tone-on-tone or color graphs, charts and/or pictures, which have been reproduced in black and white. This document is paginated as submitted by the original source. Portions of this document are not fully legible due to the historical nature of some of the material. However, it is the best reproduction available from the original submission. Produced by the NASA Center for Aerospace Information (CASI) or I CALIFORNIA INSTITUTE OF TECHNOLOGY BIG BEAR SOLA R OBSERVATORY HALE OBSERVATORIES 4 I r -b cb c^ a y CNN (NASA-CR-145974) FURTHER CBSEPVATIONS CF N76-14992 THE LAMEDA 1083u He LING, IN STARS AND THEIR SIGNIFIC!NCE AS A MEAEURE OF STELLAR ACTIVITY (dale CbseEvatories, Pasadena, Unclas Calif.) 28 p HC $4.('. CSCL J3A G3;89 1,7726 t I FURTHER OBSERVATIONS OF THE XZ0830 HE LINE IN STARS AND THEIR SIGNIFICANCE AS A MEASURE OF STELLAR ACTIVITY H. Zirin HALE OBSERVATORIES CARNEGIE INSTITUTION OF WASHINGTON CALIFORNIA INSTITUTE OF TECHNOLOGY BBSO #0150 November, 1975 ABSTRACT Measurements of the x10830 He line in 198 stars are given, f along with data on other features in that spectral range. Nearly 80% of all G and K stars show some 110830; of these, half are variable and 1/4 show emission. -
Macrocosmo Nº33
HA MAIS DE DOIS ANOS DIFUNDINDO A ASTRONOMIA EM LÍNGUA PORTUGUESA K Y . v HE iniacroCOsmo.com SN 1808-0731 Ano III - Edição n° 33 - Agosto de 2006 * t i •■•'• bSÈlÈWW-'^Sif J fé . ’ ' w s » ws» ■ ' v> í- < • , -N V Í ’\ * ' "fc i 1 7 í l ! - 4 'T\ i V ■ }'- ■t i' ' % r ! ■ 7 ji; ■ 'Í t, ■ ,T $ -f . 3 j i A 'A ! : 1 l 4/ í o dia que o ceu explodiu! t \ Constelação de Andrômeda - Parte II Desnudando a princesa acorrentada £ Dicas Digitais: Softwares e afins, ATM, cursos online e publicações eletrônicas revista macroCOSMO .com Ano III - Edição n° 33 - Agosto de I2006 Editorial Além da órbita de Marte está o cinturão de asteróides, uma região povoada com Redação o material que restou da formação do Sistema Solar. Longe de serem chamados como simples pedras espaciais, os asteróides são objetos rochosos e/ou metálicos, [email protected] sem atmosfera, que estão em órbita do Sol, mas são pequenos demais para serem considerados como planetas. Até agora já foram descobertos mais de 70 Diretor Editor Chefe mil asteróides, a maior parte situados no cinturão de asteróides entre as órbitas Hemerson Brandão de Marte e Júpiter. [email protected] Além desse cinturão podemos encontrar pequenos grupos de asteróides isolados chamados de Troianos que compartilham a mesma órbita de Júpiter. Existem Editora Científica também aqueles que possuem órbitas livres, como é o caso de Hidalgo, Apolo e Walkiria Schulz Ícaro. [email protected] Quando um desses asteróides cruza a nossa órbita temos as crateras de impacto. A maior cratera visível de nosso planeta é a Meteor Crater, com cerca de 1 km de Diagramadores diâmetro e 600 metros de profundidade. -
Index to JRASC Volumes 61-90 (PDF)
THE ROYAL ASTRONOMICAL SOCIETY OF CANADA GENERAL INDEX to the JOURNAL 1967–1996 Volumes 61 to 90 inclusive (including the NATIONAL NEWSLETTER, NATIONAL NEWSLETTER/BULLETIN, and BULLETIN) Compiled by Beverly Miskolczi and David Turner* * Editor of the Journal 1994–2000 Layout and Production by David Lane Published by and Copyright 2002 by The Royal Astronomical Society of Canada 136 Dupont Street Toronto, Ontario, M5R 1V2 Canada www.rasc.ca — [email protected] Table of Contents Preface ....................................................................................2 Volume Number Reference ...................................................3 Subject Index Reference ........................................................4 Subject Index ..........................................................................7 Author Index ..................................................................... 121 Abstracts of Papers Presented at Annual Meetings of the National Committee for Canada of the I.A.U. (1967–1970) and Canadian Astronomical Society (1971–1996) .......................................................................168 Abstracts of Papers Presented at the Annual General Assembly of the Royal Astronomical Society of Canada (1969–1996) ...........................................................207 JRASC Index (1967-1996) Page 1 PREFACE The last cumulative Index to the Journal, published in 1971, was compiled by Ruth J. Northcott and assembled for publication by Helen Sawyer Hogg. It included all articles published in the Journal during the interval 1932–1966, Volumes 26–60. In the intervening years the Journal has undergone a variety of changes. In 1970 the National Newsletter was published along with the Journal, being bound with the regular pages of the Journal. In 1978 the National Newsletter was physically separated but still included with the Journal, and in 1989 it became simply the Newsletter/Bulletin and in 1991 the Bulletin. That continued until the eventual merger of the two publications into the new Journal in 1997. -
Revisiting the Un-Named Fleming Variables
Revisiting the Un-named Fleming Variables Krisne Larsen, Department of Physics and Earth Sciences, Central Conneccut State University In a presentation at the 1997 AAVSO Annual Meeting, Dorrit Hoffleit brought attention to fourteen of the nearly 300 variables directly discovered by Williamina Fleming or discovered under her direction at the HCO. These fourteen stars had not been given permanent designations in the General Catalog of Variable Stars (GCVS) at the time of her talk (and its subsequent article in JAAVSO Volume 26). In the intervening thirteen years since her original presentation, a number of these stars have been further observed, both by AAVSO members and automated optical and infrared telescopes (such as IRAS, 2MASS and Hipparcos) and their variability confirmed at visible and/or infrared wavelengths. This poster revisits these fourteen stars and summarizes our current knowledge about them and their status as observed variable stars. As of September 29, 2010, there were only 38 reads of Hoffleit’s JAAVSO article through the ADS database. Several of these hits (in various years) belong to this poster’s author. Note that there was initially very little interest in this paper (and by extension, in these stars) by those who do not directly subscribe to JAAVSO. [Graph taken directly from ADS website http://adsabs.harvard.edu/] AAVSO member Raymond Berg presented a paper at the 1999 AAVSO Annual Meeting in which he detailed his “limited study” of three of these stars. He found no variability in NSV 840, NSV 1214, or NSV 3379 in 21 observations over the course of a month (Berg 2000). -
Magisterarbeit
MAGISTERARBEIT Titel der Magisterarbeit “Imaging and photometry of U Antliae and AQ Andromedae using the Herschel space telescope” Verfasser Bernhard Baumann, Bakk.rer.nat. angestrebter akademischer Grad Magister der Naturwissenschaften (Mag.rer.nat.) Wien, 2012 Studienkennzahl lt. Studienblatt: A 066 861 Studienrichtung lt. Studienblatt: Magisterstudium Astronomie Betreuer: A. Univ. Prof. Dr. Franz Kerschbaum Danksagung Die hier vorgestellte Magisterarbeit wurde in Zusammenarbeit mit dem MESS Konsor- tium (http://www.univie.ac.at/space/MESS/) und dem Institut f¨ur Astronomie in Wien (http://astro.univie.ac.at/) erstellt. Ich bedanke mich bei Franz Kerschbaum, dass ich bei diesen internationalen Projekten, Herschel Space Telescope und MESS, mitarbeiten durfte und f¨ur die Betreuung der Ar- beit. Mein herzlicher Dank gilt der AGB-Arbeitsgruppe (http://www.univie.ac.at/agb/), besonders Roland Ottensamer f¨ur die vielen wertvollen Diskussionen, Anregungen und Korrekturen sowie Marko Mecina f¨ur die gute Zusammenarbeit als Studienkollege. Weiteren Korrekturlesern wie Verena Baumgartner und meinem Bruder Michael gilt mein Dank. Zu guter Letzt m¨ochte ich mich bei meinen Eltern sowie meinem Bruder Michael f¨ur die Unterst¨utzung und Motivation w¨ahrend meines Studiums bedanken. Wien, im M¨arz 2012. Zusammenfassung Die vorliegende Magisterarbeit beinhaltet die Beobachtungsauswertung und die Datenre- duktion zweier Asymptotic Giant Branch (AGB) Sterne, U Ant und AQ And, welche mithilfe des Herschel Weltraumteleskops aufgezeichnet wurden. Die Ergebnisse dieser Datenreduktion werden mit der Modellierung in DUSTY verglichen, welche den Strah- lungstransport in staubigen Umgebungen rund um Sterne simuliert. Mit den Ergebnis- sen ist es m¨oglich, R¨uckschl¨usse ¨uber die aktuelle und anschließende Entwicklung der Sterne zu ziehen. -
R Aquarii: Understanding the Mystery of Its Jets by Model Comparison Michelle Marie Risse Iowa State University
Iowa State University Capstones, Theses and Graduate Theses and Dissertations Dissertations 2009 R Aquarii: Understanding the mystery of its jets by model comparison Michelle Marie Risse Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/etd Part of the Physics Commons Recommended Citation Risse, Michelle Marie, "R Aquarii: Understanding the mystery of its jets by model comparison" (2009). Graduate Theses and Dissertations. 10565. https://lib.dr.iastate.edu/etd/10565 This Thesis is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. R Aquarii: Understanding the mystery of its jets by model comparison by Michelle Marie Risse A thesis submitted to the graduate faculty in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Major: Astrophysics Program of Study Committee: Lee Anne Willson, Major Professor Steven D. Kawaler Craig A. Ogilvie David B. Wilson Iowa State University Ames, Iowa 2009 Copyright c Michelle Marie Risse, 2009. All rights reserved. ii TABLE OF CONTENTS LISTOFTABLES ................................... iv LISTOFFIGURES .................................. v CHAPTER1. Intent ................................. 1 CHAPTER2. Introduction ............................. 2 2.1 -
Time-Series Ensemble Photometry and the Search for Variable Stars in the Open Cluster M11
Haverford College Haverford Scholarship Faculty Publications Astronomy 2005 Time-Series Ensemble Photometry and the Search for Variable Stars in the Open Cluster M11 Jonathan Hargis Haverford College, [email protected] E. L. Sandquist D. H. Bradstreet Follow this and additional works at: https://scholarship.haverford.edu/astronomy_facpubs Repository Citation J. R. Hargis, E. L. Sandquist, D. H. Bradstreet, Time-Series Ensemble Photometry and the Search for Variable Stars in the Open Cluster M11, 2005, The Astronomical Journal, 130, 2824. This Journal Article is brought to you for free and open access by the Astronomy at Haverford Scholarship. It has been accepted for inclusion in Faculty Publications by an authorized administrator of Haverford Scholarship. For more information, please contact [email protected]. The Astronomical Journal, 130:2824–2837, 2005 December # 2005. The American Astronomical Society. All rights reserved. Printed in U.S.A. TIME-SERIES ENSEMBLE PHOTOMETRY AND THE SEARCH FOR VARIABLE STARS IN THE OPEN CLUSTER M11 Jonathan R. Hargis1 and Eric L. Sandquist Department of Astronomy, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182; [email protected], [email protected] and David H. Bradstreet Department of Physical Sciences, Eastern University, 1300 Eagle Road, St. Davids, PA 19087-3696; [email protected] Received 2005 May 23; accepted 2005 August 9 ABSTRACT This work presents the first large-scale photometric variability survey of the intermediate-age (200 Myr) open cluster M11. Thirteen nights of data over two observing seasons were analyzed (using crowded field and ensemble photometry techniques) to obtain high relative precision photometry. In this study we focus on the detection of can- didate member variable stars for follow-up studies. -
The Photometric Catalogues of the Harvard College Observatory
ASTRONOMISCHE NACHRICHTEN. 3229. Band 135. No .13. ~ ~ ~ ~ ~~~ The Photometric Catalogues of the Harvard College Observatory. By Adward C. Piekering. Mr. S. C. Chandler, formerly employed in the Harvard comparison will reveal. Such imperfections are inevitable I College Observatory, states, in a recent number of the in such work. Astronornische Nachrichten (Vol. I 34, p. 35 j), that there are Fifteen instances of error are pointed out in the total certain errors in the photometric catalogues of that Obser- of eighty- six variable stars whose observations are printed vatory, and draws certain conclusions as to the general I in Volume XXIV, and we are given to understand that value of the whole work. As shown below in detd the i similar errors probably exist throughout the entire catalogue particular errors specified are in general confirmed, but the of over twenty thousand stars contained in that volume. inferences he has drawn regarding the whole work are not I Every astronomer is of coiirse aware that the difficulties justified. Whatever animus underlies the attack can only of identification in the case of variable stars, especially be important in so far as, if it exists, it tends to weaken ~ when they are faint, are much greater than with stars the force of sweeping assertions and deductions sought to I photometrically constant. It is somewhat as though it be drawn from scanty premises. Animus unfortunately is i shoiild be argued from a physician’s losing twenty per cent not unknown in scientific discussion, and may exist, as we I of his cholrra patients thdt he had been equally unfortunate believe it exists, if at ail, in this case, without the person in his general practice. -
A Search for Distant Galactic Cepheids Toward L= 60
A Search for Distant Galactic Cepheids Toward ℓ = 60◦1 Mark R. Metzger2,3 and Paul L. Schechter Physics Department, Room 6-216, Massachusetts Institute of Technology, Cambridge, MA 02139 [email protected], [email protected] ABSTRACT We present results of a survey of a 6-square-degree region near ℓ = 60◦, b = 0◦ to search for distant Milky Way Cepheids. Few MW Cepheids are known at distances > R0, limiting large-scale MW disk models derived from Cepheid kinematics; this work∼ was designed to find a sample of distant Cepheids for use in such models. The survey was conducted in the V and I bands over 8 epochs, to a limiting I 18, with a ≃ total of almost 5 million photometric observations of over 1 million stars. We present a catalog of 578 high-amplitude variables discovered in this field. Cepheid candidates were selected from this catalog on the basis of variability and color change, and observed again the following season. We confirm 10 of these candidates as Cepheids with periods from 4 to 8 days, most at distances > 3 kpc. Many of the Cepheids are heavily reddened by intervening dust, some with implied extinction AV > 10 mag. With a future addition of infrared photometry and radial velocities, these stars alone can provide a constraint on R0 to 8%, and in conjunction with other known Cepheids should provide good estimates of the global disk potential ellipticity. Subject headings: Cepheids — Galaxy: fundamental parameters — Galaxy: stellar content — Galaxy: structure — distance scale — techniques: photometric — surveys arXiv:astro-ph/9711293v1 25 Nov 1997 1. -
Variable Star Section Circular 72
The British Astronomical Association VARIABLE STAR SECTION MAY CIRCULAR 72 1991 ISSN 0267-9272 Office: Burlington House, Piccadilly, London, W1V 9AG VARIABLE STAR SECTION CIRCULAR 72 CONTENTS Director’s Change of Address 1 Appointment of Computer Secretary 1 Electronic mail addresses 1 VSS Centenary Meeting 1 Observing New variables _____ 2 Richard Fleet BAAVSS Computerization 3 Dave Me Adam Unusual Carbon Stars 4 John Isles Symbiotic Stars - New Work for the VSS 4 John Isles Binocular and Telescopic Programmes 1991 5 John Isles Analysis of Observations using Spearman’s Rank Correlation Test 13 Tony Markham VSS Reports 16 AH Draconis: 1980-89 - Light Curves 17 R CrB in 1990 21 Melvyn Taylor Minima of Eclipsing Binaries, 1988 22 John Isles Index of Unpublished BAA Observations of Variable Stars, 1906-89 27 UV Aurigae 36 Pro-Am Liason Committee Newsletter No.3 Centre Pages Castle Printers of Wittering Director’s Change of Address Please note that John Isles has moved. His postal address remains the same, but his telephone/telefax number has altered. He can now also be contacted by telex. The new numbers are given inside the front rover. Appointment of Computer Secretary Following the announcement about computerization in VSSC 69, Dave Me Adam has been appointed Computer Secretary of the VSS. Dave is already well known as the discoverer 0fN0vaPQ And 1988, in which detection he was helped by his computerized index of his photographs of the sky. We are very pleased to welcome Dave to the team and look forward to re-introducing as soon as possible the publication of an annual b∞klet of computer-plotted light curves. -
Observing Variable Stars with Binoculars
OBSERVING VARIABLE STARS - -WITH BINOCULARS by K.E.,Chilton,F.R.A.S. A Centennial Observatory Publication. public price 50¢ Price to RASC Members 35¢ Introduction This booklet is not intended to be a technical treatise on variable stars. Nor is it for the serious amateur astronomer whose instruments and capabilities carry him far beyond what is to follow. Rather, I intend this to be read and used by the beginner, equipped only with hie eyes and a pair of binoculars. The information contained herein has been gathered from many sources, including my own experience. I da not pretend, however, to be an expert on variable star observing. I write this only as a guide to those who follow, so that they may avoid some of the pitfalls involved in variable star observing.Hopefully, this booklet will enable the beginner to make a start, make a few observations, and progress into more serious work. My own equipment, aside from the telescopes housed in the observatory, consists of a pair of 7x50 binoculars, which I use to observe many of the stars mentioned herein. The only other equip- ment needed is a wrist watch, a flashlight, a comfortable lawn chair, some warm clothing, a pencil, this booklet, and the desire to learn and see something different! I wish the reader good fortune and clear skies for his debut in the field of variable star observing with binoculars. K.E.Chilton Chapter 1 Why Observe Variable Stars? Have you ever stood in the quiet solitude by a northern lake on a moonless summer night while an orchestra of crickets played their favourite symphony and myriads of stare reflected off the calm water ? Have you ever lain on your back, gazing up at the seemingly countless points of light and wondered if shepherds,long ago, had done the same ? If you watch those stars for hours and hours, you may never see a change, and if you watch them for years and years, you may be almost certain that the stars looked the same to those ancient shepherds as they do to you now.