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Astronomy 142, Spring 2013 2 April 2013
Astronomy 142, Spring 2013 2 April 2013 Today in Astronomy 142: distances to the galaxies Standard candles and standard rulers. Cepheids, and Henrietta Leavitt’s invention of standard candles. The extragal acti c nature of the spiral nebulae and the Shapley-Curtis debate. Type Ia supernovae as standard candles. The extragalactic distance The Small Magellanic Cloud, site of the scale. discovery of Leavitt’s Law. (Photograph by Weihao Wang (NRAO).) 2 April 2013 Astronomy 142, Spring 2013 1 Standard candles and standard rulers There’s only one direct distance measurement method for individual objects more than a few light-hours away – trig parallax – and it only works on objects within a few hundred parsecs, these days. (> 10 kpc, after Gaia is deployed.) Distance being key, astronomers have often sought standard candles or rulers to aid in its determination. Standard candle: an object with a well-determined luminosity L known a priori, whose distance is therefore rLf4(or equivalently 5log r10 pc mM ) . Standard ruler: an object with length d perpendicular to the line of sight is known a priori, whose distance is rdsin d . 2 April 2013 Astronomy 142, Spring 2013 2 Henrietta Leavitt and standard candles Today tens of thousands of Cepheid variable stars are known, a large fraction of which – about 2400 – were discovered by Henrietta Leavitt, perhaps the most illustrious of the women Henrietta Swan Leavitt (AIP photo) who worked as “computers” in Edward Pickering’s group at Harvard College Observatory. 969 of them are in the Small Magellanic Cloud (Leavitt 1908), and therefore all about the same distance (~60 kpc). -
AAS NEWSLETTER Issue 127 a Publication for the Members of the American Astronomical Society
October 2005 AAS NEWSLETTER Issue 127 A Publication for the members of the American Astronomical Society PRESIDENT’S COLUMN know that Henrietta Swan Leavitt measured the Cepheid variable stars in the Magellanic Clouds Robert Kirshner, [email protected] to establish the period-luminosity relation, and that Inside this rung on the distance ladder let Hubble reach As I write this, summer is definitely winding down, M31 and other nearby galaxies. And I recognized George Johnson’s name from his thoughtful pieces 3 and the signs of Fall on a college campus are all in the New York Times science pages. Who Served Us Well: around: urgent overtime work on the last licks of John N. Bahcall summer renovations is underway, vast piles of trash and treasure from cleaning out dorm rooms are But I confess, though I walk on the streets where accumulating, with vigorous competitive double- she lived, work in a building connected by a 5 parking of heavily-laden minivans just ahead. With labyrinth to the one she worked in, and stand on Katrina Affected the Galaxy overhead most of the night, and the the distance ladder every day, my cerebral cortex Physics and summer monsoon in progress in Arizona, the pace is a little short on retrievable biographical details Astronomy (KAPA) of supernova studies slackens just a bit (for me, for Henrietta Swan Leavitt. Johnson has plumbed Community Bulletin anyway) and I had time to do a little summer reading. the Harvard archives, local census records, and the correspondence of Harvard College Board There were too many mosquitoes in Maine to read in a hammock, but there was enough light on the Observatory Directors to give us a portrait of screened porch. -
Student Exploration: Big Bang Theory – Hubble's
McCarthy Physical Science 2017 Name: Date: Student Exploration: Big Bang Theory – Hubble’s Law Vocabulary: absolute brightness, absorption spectrum, apparent brightness, Big Bang theory, blueshift, Cepheid variable, Doppler shift, Hubble constant, Hubble’s law, luminosity, megaparsec, period, redshift, spectrograph Prior Knowledge Questions (Do these BEFORE using the Gizmo.) Standing by the side of a lonely highway at night, you see two motorcycle headlights, one in each direction. The headlight on your left appears brighter than the one on your right. 1. If the headlights are equally bright, which motorcycle is closer? Explain: 2. Suppose the dim-looking headlight on the right is actually a small light on the front of a bicycle. What can you conclude about the distance of the motorcycle and bicycle? Gizmo Warm-up In 1912, an astronomer named Henrietta Swan Leavitt studied a class of stars called Cepheid variables. These stars change from bright to dim to bright again. Her discoveries led to a method of measuring distances to other galaxies and eventually helped to support the Big Bang theory of the origin of the universe. In the Big Bang Theory – Hubble’s Law Gizmo™, select Region A. Look at the image of the Andromeda Galaxy, a galaxy relatively close to our own Milky Way galaxy. 1. Locate the two Cepheid variables, the stars that change in brightness over time. Star A-091 is the yellow star, and A-171 is the white star. A. Which star reaches a greater apparent brightness? B. Which star takes longer to pulse? 2. Because both stars are in the same galaxy, they are about the same distance from Earth. -
00:00 [Narrator] 1. the NASA/ESA Hubble Space Telescope Is Named After the Famous Astronomer Edwin Hubble. He Discovered That T
Keywords: Distances, Cepheids, Henrietta Leavitt Hubblecast Episode 116: Henrietta Leavitt — the woman Visual notes who measured the Universe 00:00 [Narrator] 1. The NASA/ESA Hubble Space Telescope is named after the famous astronomer Edwin Hubble. He discovered that there are galaxies outside of our own and that the Universe is expanding. However, these remarkable discoveries wouldn’t have been possible without one exceptional astronomer before him — Henrietta Swan Leavitt. 00:30 2. Henrietta Leavitt — the woman who measured the Universe 00:40 [Narrator] 3. Henrietta Leavitt was born in Lancaster, Massachusetts in 1868. She studied at Oberlin College, Ohio, and then Harvard University's Society for the Collegiate Instruction of Women. It wasn’t until her final year at university that she began to study astronomy — but this sparked a keen interest that she would pursue for the rest of her life. 01:10 4.She began to work at Harvard Observatory as a “computer” — one of several skilled women hired to process astronomical data. She helped with cataloguing the brightness of every measurable star and was quickly promoted to be head of the photographic stellar photometry department. 01:34 5. Supplied with photographic plates of the stars in the southern sky, Leavitt was tasked with classifying variable stars — ones that fluctuate in brightness. 01:47 6. While studying these changing stars she noticed a pattern: the brighter the star, the longer the period of the fluctuations. The easily measured length of the star’s fluctuations directly leads to its brightness — and to its distance. The observation of these Cepheid variables turned out to be the key to a fundamental change in our understanding of the Universe. -
At the Harvard Observatory
Book Reviews 117 gravitational wave physicists, all of whom are members of an international group of over a thousand scientists engaged with the detection apparatus at two widely separated sites, one in Livingston, Louisiana and the other in Hanford, Washington. The emails research- ers in the collaboration exchanged and the queries Collins sent to the physicists who acted for him as “key informants” provide the bulk of the material for Collins’ “real- time” observations of this discovery in the making. At times, Collins finds the community of researchers exasperating and wrong-headed in their, in his view, overly secretive attitudes to their results. But Collins is not a detached witness of the events he describes and analyses. Instead, he is overall a highly enthusias- tic fan of the gravitational wave community. Collins has not sought out for Gravity’s Kiss the kinds of evidence one might have expected a historian to have pursued. Gravity’s Kiss, however, should be read on its terms. It is a work of reportage from an “embedded” sociologist of science with long experience of, and valuable connections in, the gravitational wave community. Along the way, he offers sharp insights into the work- ing of these scientists. Collins proves to be an excellent guide to the operations of a “Big Science” collaboration and the intense scrutiny of, and complicated negotiations around, the “[v]ery interesting event on ER8.” Robert W. Smith University of Alberta [email protected] “Girl-Hours” at the Harvard Observatory The Glass Universe: How the Ladies of the Harvard Observatory Took the Measure of the Stars. -
Hardy 1 Williamina Fleming
Hardy 1 Williamina Fleming: Breaking Barriers with A Universe of Glass Isabella L. Hardy Junior Division Individual Performance paper 500 words In the past, women in the sciences were often overlooked, so for National History Day, I chose to focus on an under-recognized female scientist. Early in my research, I found Williamina Paton Fleming. I was surprised I had never encountered her although I had heard of her colleagues, Annie Jump Cannon and Henrietta Leavitt. I have always loved studying the stars and am fascinated by the role of women in astronomy whose important contributions are sometimes forgotten. Williamina Fleming’s unique ability to interpret astronomical photographs changed astronomy in nineteenth- century America and beyond, breaking barriers for scientists and for women. In preliminary research, I located Harvard’s digital scans of Fleming's diary and excellent period photographs, as well as many academic articles about her and other women at the Harvard Observatory. I was also privileged to interview Dr. Lindsay Smith, current Curator of Astronomical Photographs at Harvard. She was extremely helpful in suggesting sources and later reviewed the performance script. Not much is known about Fleming’s early years in Scotland. After her husband abandoned her, she worked for Harvard Observatory Director Edward Pickering, who hired her for the new project to map the night sky. The process involved taking images though telescopes, then mapping all the stars in that small section of sky. Using this process, Fleming discovered stars, novae, and nebulae and encouraged the work of other astronomers, while facilitating many important discoveries. I chose performance to give a voice to a person who has been largely unnoticed. -
Henrietta Leavitt
2 HENRIETTA LEAVITT BIOGRAPHY 980L HENRIETTA LEAVITT MEASURING DISTANCE IN THE UNIVERSE Born Died July 4, 1868 December 12, 1921 Lancaster, Massachusetts Cambridge, Massachusetts By Cynthia Stokes Brown, adapted by Newsela Henrietta Swan Leavitt studied distant stars that dim and brighten. These are called Cepheid variable stars. She made it possible for others to measure huge cosmic distances, discover additional galaxies, and begin mapping the Universe. 2 3 \Leavitt was a minister’s daughter. Her family moved frequently. period ranges from about one day to nearly four months. She attended the Society for Collegiate Instruction of Women, which is Leavitt studied thousands of photographs of these stars. She discovered now part of Harvard University. It was a school she had dreamed of a way to determine how bright they are and how far away they are. attending. In her senior year she discovered her calling — astronomy. She found that the longer a star’s period, the brighter it was. By comparing how bright a star appeared, and how bright it actually was, Leavitt could estimate how much of the star’s light had been lost while reaching Earth, At the Harvard College Observatory and how far away the star actually was. Leavitt liked astronomy so much that after graduation she became a volun- Leavitt published her first paper on the period-luminosity relationship in teer at the Harvard College Observatory as a “computer.” This was the 1908. Four years after that she published a table of the periods of 25 name used for women who examined tiny dots on photographs of the night Cepheid variables. -
Observational Cosmology - 30H Course 218.163.109.230 Et Al
Observational cosmology - 30h course 218.163.109.230 et al. (2004–2014) PDF generated using the open source mwlib toolkit. See http://code.pediapress.com/ for more information. PDF generated at: Thu, 31 Oct 2013 03:42:03 UTC Contents Articles Observational cosmology 1 Observations: expansion, nucleosynthesis, CMB 5 Redshift 5 Hubble's law 19 Metric expansion of space 29 Big Bang nucleosynthesis 41 Cosmic microwave background 47 Hot big bang model 58 Friedmann equations 58 Friedmann–Lemaître–Robertson–Walker metric 62 Distance measures (cosmology) 68 Observations: up to 10 Gpc/h 71 Observable universe 71 Structure formation 82 Galaxy formation and evolution 88 Quasar 93 Active galactic nucleus 99 Galaxy filament 106 Phenomenological model: LambdaCDM + MOND 111 Lambda-CDM model 111 Inflation (cosmology) 116 Modified Newtonian dynamics 129 Towards a physical model 137 Shape of the universe 137 Inhomogeneous cosmology 143 Back-reaction 144 References Article Sources and Contributors 145 Image Sources, Licenses and Contributors 148 Article Licenses License 150 Observational cosmology 1 Observational cosmology Observational cosmology is the study of the structure, the evolution and the origin of the universe through observation, using instruments such as telescopes and cosmic ray detectors. Early observations The science of physical cosmology as it is practiced today had its subject material defined in the years following the Shapley-Curtis debate when it was determined that the universe had a larger scale than the Milky Way galaxy. This was precipitated by observations that established the size and the dynamics of the cosmos that could be explained by Einstein's General Theory of Relativity. -
Women in Astronomy: an Introductory Resource Guide
Women in Astronomy: An Introductory Resource Guide by Andrew Fraknoi (Fromm Institute, University of San Francisco) [April 2019] © copyright 2019 by Andrew Fraknoi. All rights reserved. For permission to use, or to suggest additional materials, please contact the author at e-mail: fraknoi {at} fhda {dot} edu This guide to non-technical English-language materials is not meant to be a comprehensive or scholarly introduction to the complex topic of the role of women in astronomy. It is simply a resource for educators and students who wish to begin exploring the challenges and triumphs of women of the past and present. It’s also an opportunity to get to know the lives and work of some of the key women who have overcome prejudice and exclusion to make significant contributions to our field. We only include a representative selection of living women astronomers about whom non-technical material at the level of beginning astronomy students is easily available. Lack of inclusion in this introductory list is not meant to suggest any less importance. We also don’t include Wikipedia articles, although those are sometimes a good place for students to begin. Suggestions for additional non-technical listings are most welcome. Vera Rubin Annie Cannon & Henrietta Leavitt Maria Mitchell Cecilia Payne ______________________________________________________________________________ Table of Contents: 1. Written Resources on the History of Women in Astronomy 2. Written Resources on Issues Women Face 3. Web Resources on the History of Women in Astronomy 4. Web Resources on Issues Women Face 5. Material on Some Specific Women Astronomers of the Past: Annie Cannon Margaret Huggins Nancy Roman Agnes Clerke Henrietta Leavitt Vera Rubin Williamina Fleming Antonia Maury Charlotte Moore Sitterly Caroline Herschel Maria Mitchell Mary Somerville Dorrit Hoffleit Cecilia Payne-Gaposchkin Beatrice Tinsley Helen Sawyer Hogg Dorothea Klumpke Roberts 6. -
Reflector March 2021 Final Pages.Pdf
Published by the Astronomical League Vol. 73, No. 2 MARCH 2021 CELEBRITY VARIABLE STARS IMAGING TECHNIQUES EXPLAINED 75th WILLIAMINA FLEMING SIMPLE CITIZEN SOLAR SCIENCE AN EMPLOYEE-OWNED COMPANY NEW FREE SHIPPING on order of $75 or more & INSTALLMENT BILLING on orders over $350 PRODUCTS Standard Shipping. Some exclusions apply. Exclusions apply. Orion® StarShoot™ Mini 6.3mp Imaging Cameras (sold separately) Orion® StarShoot™ G26 APS-C Orion® GiantView™ BT-100 ED Orion® EON 115mm ED Triplet Awesome Autoguider Pro Refractor Color #51883 $400 Color Imaging Camera 90-degree Binocular Telescope Apochromatic Refractor Telescope Telescope Package Mono #51884 $430 #51458 $1,800 #51878 $2,600 #10285 $1,500 #20716 $600 Trust 2019 Proven reputation for Orion® U-Mount innovation, dependability and and Paragon Plus service… for over 45 years! XHD Package #22115 $600 Superior Value Orion® StarShoot™ Deep Space High quality products at Orion® StarShoot™ G21 Deep Space Imaging Cameras (sold separately) Orion® 120mm Guide Scope Rings affordable prices Color Imaging Camera G10 Color #51452 $1,200 with Dual-Width Clamps #54290 $950 G16 Mono #51457 $1,300 #5442 $130 Wide Selection Extensive assortment of award winning Orion brand 2019 products and solutions Customer Support Orion products are also available through select Orion® MagneticDobsonian authorized dealers able to Counterweights offer professional advice and Orion® Premium Linear Orion® EON 130mm ED Triplet Orion® 2x54 Ultra Wide Angle 1-Pound #7006 $25 Binoculars post-purchase support BinoViewer -
Women in Astronomy at Harvard College Observatory
Discussion Question Answers Strategies and Compromises: Women in Astronomy at Harvard College Observatory 1. What were the differences between the roles of the four women mentioned in the article? - Williamina Fleming started out simply copying and computing, but worked her way up to supervising the other women and classifying solar spectra. - Antonia Maury also classified stellar spectra, but she did so with an advanced system of her own design. The director of the observatory, Pickering, did not like her system and so she left the observatory. - Annie Jump Cannon continued the spectra work of Maury, but used the standard system. She worked for 45 years doing classification work extremely quickly and consistently. - Henrietta Leavitt studied variable stars at first, identifying thousands of new ones. She also did the research assigned to her, which related to determining how stars appeared using different photographic techniques. 2. What are the differences between their attitudes towards the roles they were assigned? - Fleming accepted any work that was asked of her, but expanded the role of women’s work by her competence in accomplishing the tasks. She was privately bitter about the low pay and status of her work. - Maury thought that her intellectual contributions were worthy of credit and regard. She insisted on being recognized in the Observatory’s publications, and she fought for her system, which was based on star’s “natural relations” to be used. However, she did not succeed in getting the system used and so left the observatory. - Cannon did not mind the role she was assigned. She did it so quickly and well she eventually gained recognition and an honorary doctorate for he accomplishments. -
Globular Clusters
Observing Globular Clusters TAAS Astronomy 101 Jon Schuchardt August 2016 Outline • What are globular clusters? • Historical significance • Shapley-Sawyer classification M5 (Serpens Caput) • How to find, observe, and report on globular clusters What are Globular Star Clusters? • Densely packed, spherical agglomerations of 104 to 107 very old stars (12-14 billion years old) that surround a galactic nucleus • Most in the Milky Way are 10,000 to 50,000 light years away from us • Diameters: 10s to 100s of light years • Densities: average about 1 star per cubic light year, but more dense in the core • About 150 globular clusters known in the Milky Way What are Globular Star Clusters? • Some globular clusters, e.g., M15, have undergone gravitational collapse in their cores • Glob cores can be millions or even billions of times more densely populated than our solar neighborhood • Imagine a night sky with thousands of stars brighter than Sirius! • Black holes of low stellar mass (10-20 solar masses) may be common at the center of globular clusters. They have been detected (2012-2013) in M22 (a pair) and M62 by detecting radio emissions using the Very Large Array M62 (Ophiuchus) Easier to “see” the black holes using radio emissions and the VLA versus a Hubble view of M22 (Sagittarius) J. Strader et al., Nature Oct 4, 2012 Hertzsprung-Russell diagrams: Typical globular cluster (left) and M55 (right) Note the “knee”” H-R Diagram for M3 (Canes Venatici) The “knee” shows where stars begin to depart the Main Sequence on their path to becoming giants Can be used to estimate the age of the cluster “The thing’s hollow -- it goes on forever -- and -- oh my God! -- it’s full of stars!” Commander David Bowman 2001: A Space Odyssey Arthur C.