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27-544: The variable nature of RR Lyrae was discovered by the Scottish astronomer Williamina Fleming at Harvard Observatory in 1901. The distance of RR Lyrae remained uncertain until 2002 when the Hubble Space Telescope 's fine guidance sensor was used to determine the distance of RR Lyrae within a 5% margin of error , yielding a value of 262 parsecs (855 light-years ). When combined with measurements from

54-667: A US citizen in 1907. She died of pneumonia in Boston on 21 May 1911, aged 54. The women of the Harvard Computers were famous during their lifetimes but were largely forgotten in the following century. In 2015, Lindsay Smith Zrull, curator of Harvard's Plate Stacks collection, was working to catalog and digitize the astronomical plates for Digital Access to a Sky Century @ Harvard (DASCH)and discovered about 118 boxes, each containing 20 to 30 notebooks, from women computers and early Harvard astronomers. Smith Zrull realized that

81-502: A long-term project to obtain the optical spectra of as many stars as possible and to index and classify stars by spectra. Fleming was placed in charge of the Draper Catalogue project. A disagreement soon developed regarding classifying the stars. The analysis had been started by Nettie Farrar, but she left a few months later to be married. Antonia Maury advocated for a complex classification scheme. Fleming, however, wanted

108-575: A maid in the home of Professor Edward Charles Pickering , the director of the Harvard College Observatory (HCO). Pickering's wife Elizabeth recommended Williamina as having talents beyond custodial and maternal arts, and in 1879, Pickering hired Fleming to conduct part-time administrative work at the observatory. In 1881, Pickering formally invited Fleming to join the HCO and taught her how to analyze stellar spectra. She became one of

135-421: A much more simple, straightforward approach. The latest Harvard College Observatory images contained photographed spectra of stars that extended into the ultraviolet range, which allowed much more accurate classifications than recording spectra by hand through an instrument at night. Fleming devised a system for classifying stars according to the relative amount of hydrogen observed in their spectra , known as

162-591: A senior pupil of at least thirteen years old, served as an apprentice, typically for five years, to learn the teaching profession. Pupil-teachers acted as a teacher of younger children, learning from observation and practical application, while simultaneously completing their own educations. It was widely criticized for its inability to provide adequate professional preparation, in the 1870s and 1880s, pupil teachers began being offered instruction at centres nationwide throughout Britain, which were designed to improve their training. The centres provided professional training by

189-562: A short cycle lasting 0.567 days (13 hours, 36 minutes). Each radial pulsation causes the radius of the star to vary between 5.1 and 5.6 times the Sun's radius . This star belongs to a subset of RR Lyrae-type variables that show a characteristic behavior called the Blazhko effect , named after Russian astronomer Sergey Blazhko . This effect is observed as a periodic modulation of a variable star's pulsation strength or phase; sometimes both. It causes

216-539: Is also credited with the discovery of the first white dwarf : The first person who knew of the existence of white dwarfs was Mrs. Fleming; the next two, an hour or two later, Professor E. C. Pickering and I. With characteristic generosity, Pickering had volunteered to have the spectra of the stars which I had observed for parallax looked up on the Harvard plates. All those of faint absolute magnitude turned out to be of class G or later. Moved with curiosity I asked him about

243-797: Is noted for her discovery of the Horsehead Nebula in 1888. Williamina Paton Stevens was born in Dundee , Scotland, at 86 Nethergate, on 15 May 1857 to Mary Walker and Robert Stevens, a carver and gilder. She was one of six children. Her younger sister, Johanna Stevens, would also later work at Harvard College Observatory. Starting at the age of fourteen, she went to work as a pupil-teacher . In 1877, she married James Orr Fleming, an accountant and widower, also of Dundee. The couple had one son, Edward P. Fleming. In 1878, aged 21, she and her husband emigrated to Boston, Massachusetts, US. After her husband abandoned her and her young son, she worked as

270-517: Is to enable full-text search of the research: "If you search for Williamina Fleming, you're not going to just find a mention of her in a publication where she wasn't the author of her work. You're going to find her work." In July 2017, the Wolbach Library at the Center for Astrophysics | Harvard & Smithsonian unveiled a display showcasing Fleming's work, including the log book containing

297-707: The Galactic Center at periapsis , and taking it as far as 59.9 kly (18.4 kpc) at apapsis . Williamina Fleming Williamina Paton Stevens Fleming (15 May 1857 – 21 May 1911) was a Scottish astronomer. She was a single mother hired by the director of the Harvard College Observatory to help in the photographic classification of stellar spectra. She helped develop a common designation system for stars and cataloged more than ten thousand stars, 59 gaseous nebulae , over 310 variable stars , and 10 novae and other astronomical phenomena. Among several career achievements that advanced astronomy, Fleming

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324-455: The Hipparcos satellite and other sources, the result is a distance estimate of 258  pc (841  ly ). This type of low-mass star has consumed the hydrogen at its core, evolved away from the main sequence , and passed through the red giant stage. Energy is now being produced by the thermonuclear fusion of helium at its core, and the star has entered an evolutionary stage called

351-421: The horizontal branch (HB). The effective temperature of an HB star's outer envelope will gradually increase over time. When its resulting stellar classification enters a range known as the instability strip —typically at stellar class A —the outer envelope can begin to pulsate. RR Lyrae shows just such a regular pattern of pulsation, which is causing its apparent magnitude to vary between 7.06 and 8.12 over

378-461: The light curve of RR Lyrae to change from cycle to cycle. In 2014, Time-series photometric observations demonstrated the physical origin of this effect. As with other RR Lyrae-type variables, RR Lyrae itself has a low abundance of elements other than hydrogen and helium – what astronomers term its metallicity : It belongs to the Population II category of stars that formed during

405-531: The 2,500+ volumes were outside the scope of her work with DASCH but wanted to see the material preserved and made accessible. Smith Zrull contacted librarians at the Harvard–Smithsonian Center for Astrophysics . In response, the Wolbach Library launched Project PHaEDRA (Preserving Harvard's Early Data and Research in Astronomy). Daina Bouquin, Wolbach's Head Librarian, explained that the objective

432-576: The Horsehead Nebula discovery. The library has dozens of volumes of Fleming's work in its PHaEDRA collection. As of August 2017 , about 200 of over 2,500 volumes had been transcribed. The task is expected to take years to complete fully. Some of the notebooks are listed via the Smithsonian Digital Volunteers Web site, which encourages volunteers to transcribe them. Pupil-teacher Pupil teacher

459-525: The Pickering-Fleming system. Stars showing hydrogen as the most abundant element were classified A; those of hydrogen as the second-most abundant element, B; and so on. Later, her colleague Annie Jump Cannon reordered the classification system based on the surface temperature of stars, resulting in the Harvard spectral classification , which is still in use today. In 1890, the HCO published

486-547: The best teachers in the elementary school system, but were not standardized. Most students who participated in centre programs spent half of their training on theory at the centralized school and half of their training with hands-on teaching in schools. In the Anglo-Caribbean, the system was widely used until the 1950s, offering students contracts of a specific period. The most promising primary students were selected for recruitment as educators. In exchange for offsetting

513-508: The companion of 40 Eridani. Characteristically, again, he telephoned to Mrs. Fleming who reported within an hour or so, that it was of Class A. In 1910, Fleming published her discovery of white dwarf stars . Her other notable publications include A Photographic Study of Variable Stars (1907), a list of 222 variable stars she had discovered; and Spectra and Photographic Magnitudes of Stars in Standard Regions (1911). She became

540-431: The costs of their own education, they assisted teachers in instructing younger classmates. Upon completing their own education, pupil teachers were required to pass examinations to begin their own independent teaching. In some cases, the pupil teacher system was used as a stepping-stone to provide a basis of payment for secondary education before students were able to attend regular normal school training. While in theory,

567-413: The discovery. The first Dreyer Index Catalogue omitted Fleming's name from the list of contributors, having then discovered sky objects at Harvard, attributing the entire work merely to "Pickering". However, by the time the second Dreyer Index Catalogue was published in 1908, Fleming and her female colleagues at the HCO were sufficiently well-known and received proper credit for their discoveries. Fleming

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594-557: The early period of the Universe when there was a lower abundance of metals in star-forming regions. The trajectory of this star is carrying it along an orbit that is close to the plane of the Milky Way, taking it no more than 680 ly (210 pc) above or below this plane. The Blazhko period for RR Lyrae is 39.1 ± 0.3 days . The orbit has a high eccentricity , bringing RR Lyrae as close as 6.80  kly (2.08  kpc ) to

621-452: The first Henry Draper Catalogue due to years of work by their female computer team, a catalog with more than 10,000 stars classified according to their spectrum. Fleming did the majority of these classifications. Fleming also made it possible to go back and compare recorded plates by organizing thousands of photographs by telescope along with other identifying factors. In 1898, she was appointed Curator of Astronomical Photographs at Harvard,

648-555: The first woman to hold the position. At the 1893 World's Fair in Chicago, Fleming openly advocated for other women in the sciences in her talk "A Field for Woman's Work in Astronomy", where she openly promoted hiring female assistants in astronomy. Her speech suggested she agreed with the prevailing idea that women were inferior but felt that, if given more significant opportunities, they would be able to become equals; in other words,

675-543: The founding members of the Harvard Computers , an all-women cadre of human computers hired by Pickering to compute mathematical classifications and edit the observatory's publications. In 1886, Mary Anna Draper , the wealthy widow of astronomer Henry Draper , started the Henry Draper Memorial to fund the HCO's research. In response, the HCO began work on the first Henry Draper Catalogue ,

702-616: The sex differences in this regard were more culturally constructed than biologically grounded. During her career, Fleming discovered a total of 59 gaseous nebulae , over 310 variable stars , and 10 novae . Most notably, in 1888, Fleming discovered the Horsehead Nebula on a telescope- photogrammetry plate made by astronomer W. H. Pickering , brother of E.C. Pickering. She described the bright nebula (later known as IC 434 ) as having "a semicircular indentation 5 minutes in diameter 30 minutes south of Zeta Orionis ". Subsequent professional publications neglected to give credit to Fleming for

729-463: Was a training program in wide use before the twentieth century, as an apprentice system for teachers. With the emergence in the beginning of the nineteenth century of education for the masses, demand for teachers increased. By 1840, it had become evident that the academic preparation of students for teacher training in a college system was inadequate. In 1846, Britain formalized a pupil-teacher system, focusing on training middle-class teachers, in which

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