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61-526: Edwin Hubble classified spiral galaxies of this type as "SB" (spiral, barred) in his Hubble sequence and arranged them into sub-categories based on how open the arms of the spiral are. SBa types feature tightly bound arms, while SBc types are at the other extreme and have loosely bound arms. SBb-type galaxies lie in between the two. SB0 is a barred lenticular galaxy . A new type, SBm, was subsequently created to describe somewhat irregular barred spirals , such as

122-626: A Bachelor of Science degree by 1910. For a year he was also a student laboratory assistant for the physicist Robert Millikan , a future Nobel Prize winner. Hubble also became a member of the Kappa Sigma fraternity. A Rhodes Scholar , he spent three years at The Queen's College, Oxford studying jurisprudence instead of science (as a promise to his dying father), and later added studies in literature and Spanish, eventually earning his master's degree. In 1909, Hubble's father moved his family from Chicago to Shelbyville, Kentucky , so that

183-425: A peer-reviewed scientific journal until 1929. Hubble's findings fundamentally changed the scientific view of the universe. Supporters state that Hubble's discovery of nebulae outside of our galaxy helped pave the way for future astronomers. Although some of his more renowned colleagues simply scoffed at his results, Hubble ended up publishing his findings on nebulae. This published work earned him an award titled

244-436: A supermassive black hole in the galactic center but occur nonetheless. Since so many spiral galaxies have bar structures, it is likely that they are recurring phenomena in spiral galaxy development. The oscillating evolutionary cycle from spiral galaxy to barred spiral galaxy is thought to take on average about two billion years. Recent studies have confirmed the idea that bars are a sign of galaxies reaching full maturity as

305-413: A disturbance in the orbital resonances of stars in the bar structure leads to an inward collapse in which the bar becomes thicker and shorter though the exact mechanism behind this buckling instability remains hotly debated. Barred spiral galaxies with high mass accumulated in their center thus tend to have short, stubby bars. Such buckling phenomena are significantly suppressed and delayed by the presence of

366-508: A fixed quantity depending on that distance. This reasoning allowed Leavitt to establish that the logarithm of the period is linearly related to the logarithm of the star's average intrinsic optical luminosity (which is the amount of power radiated by the star in the visible spectrum ). At the time, there was an unknown scale factor in this brightness since the distances to the Magellanic Clouds were unknown. Leavitt expressed

427-608: A graduate of Radcliffe College , worked at the Harvard College Observatory as a " computer ", tasked with examining photographic plates in order to measure and catalog the brightness of stars. Observatory Director Edward Charles Pickering assigned Leavitt to the study of variable stars of the Small and Large Magellanic Clouds , as recorded on photographic plates taken with the Bruce Astrograph of

488-544: A sample of 25 of the Cepheids variables in the Small Magellanic Cloud, published in 1912. This paper was communicated and signed by Edward Pickering, but the first sentence indicates that it was "prepared by Miss Leavitt". In the 1912 paper, Leavitt graphed the stellar magnitude versus the logarithm of the period and determined that, in her own words, A straight line can be readily drawn among each of

549-469: A third place in a single high school track and field meet in 1906, and he played a variety of positions on the basketball court, from center to shooting guard . Hubble led the University of Chicago's basketball team to their first Big Ten Conference title in 1907 . Hubble's studies at the University of Chicago were concentrated on mathematics , astronomy and philosophy , which resulted in

610-441: A variety of methods. In 1929 Hubble examined the relationship between these distances and their radial velocities as determined from their redshifts . All of his estimated distances are now known to be too small, by up to a factor of about 7. This was due to factors such as the fact that there are two kinds of Cepheid variables or confusing bright gas clouds with bright stars. However, his distances were more or less proportional to

671-522: Is a barred lenticular galaxy . of barred Magellanic spiral Edwin Hubble Edwin Powell Hubble (November 20, 1889 – September 28, 1953) was an American astronomer. He played a crucial role in establishing the fields of extragalactic astronomy and observational cosmology . Hubble proved that many objects previously thought to be clouds of dust and gas and classified as " nebulae " were actually galaxies beyond

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732-575: Is embedded. However, that latter finding has been actively debated in the literature. The following relationship between a Population I Cepheid's period P and its mean absolute magnitude M v was established from Hubble Space Telescope trigonometric parallaxes for 10 nearby Cepheids: with P measured in days. The following relations can also be used to calculate the distance to classical Cepheids . Classical Cepheids (also known as Population I Cepheids, type I Cepheids, or Delta Cepheid variables) undergo pulsations with very regular periods on

793-535: Is the direct proportionality law holding for Classical Cepheid variables , sometimes called the Leavitt Law . Discovered in 1908 by Henrietta Swan Leavitt , the relation established Cepheids as foundational indicators of cosmic benchmarks for scaling galactic and extragalactic distances . The physical model explaining the Leavitt's law for classical cepheids is called kappa mechanism . Leavitt,

854-581: The American Association for the Advancement of Science that results from a six-year survey with the Mt. Wilson telescope did not support the expanding universe theory. According to a Los Angeles Times article reporting on Hubble's remarks, "The nebulae could not be uniformly distributed, as the telescope shows they are, and still fit the explosion idea. Explanations which try to get around what

915-606: The Andromeda Nebula and Triangulum Nebula . His observations, made in 1924, proved conclusively that these nebulae were much too distant to be part of the Milky Way and were, in fact, entire galaxies outside our own; thus today they are no longer considered nebulae . This was first hypothesized as early as 1755 when Immanuel Kant 's General History of Nature and Theory of the Heavens appeared. Hubble's hypothesis

976-732: The Boyden Station of the Harvard Observatory in Arequipa , Peru . She identified 1777 variable stars, of which she classified 47 as Cepheids. In 1908 she published her results in the Annals of the Astronomical Observatory of Harvard College , noting that the brighter variables had the longer period. Building on this work, Leavitt looked carefully at the relation between the periods and the brightness of

1037-483: The Magellanic Clouds , which were once classified as irregular galaxies, but have since been found to contain barred spiral structures. Among other types in Hubble's classifications for the galaxies are the spiral galaxy, elliptical galaxy and irregular galaxy. Although theoretical models of galaxy formation and evolution had not previously expected galaxies becoming stable enough to host bars very early in

1098-556: The Milky Way . He used the strong direct relationship between a classical Cepheid variable 's luminosity and pulsation period (discovered in 1908 by Henrietta Swan Leavitt ) for scaling galactic and extragalactic distances . Hubble confirmed in 1929 that the recessional velocity of a galaxy increases with its distance from Earth, a behavior that became known as Hubble's law , although it had been proposed two years earlier by Georges Lemaître . The Hubble law implies that

1159-484: The Southern Pinwheel Galaxy . Bars are thought to be temporary phenomena in the lives of spiral galaxies; the bar structures decay over time, transforming galaxies from barred spirals to more "regular" spiral patterns. Past a certain size the accumulated mass of the bar compromises the stability of the overall bar structure. Simulations show that many bars likely experience a "buckling" event in which

1220-533: The United States declared war on Germany in 1917 during World War I , Hubble rushed to complete his Ph.D. dissertation so he could join the military. Hubble volunteered for the United States Army and was assigned to the newly created 86th Division , where he served in the 2nd Battalion, 343rd Infantry Regiment. He rose to the rank of major, and was found fit for overseas duty on July 9, 1918;

1281-904: The cluster variables found in them. It was hardly noted at the time that there was a discrepancy in the relations found for several types of pulsating variable all known generally as Cepheids. This discrepancy was confirmed by Edwin Hubble 's 1931 study of the globular clusters around the Andromeda Galaxy . The solution was not found until the 1950s, when it was shown that population II Cepheids were systematically fainter than population I Cepheids. The cluster variables ( RR Lyrae variables ) were fainter still. Period-luminosity relations are known for several types of pulsating variable stars : type I Cepheids; type II Cepheids; RR Lyrae variables; Mira variables ; and other long-period variable stars . The Classical Cepheid period-luminosity relation has been calibrated by many astronomers throughout

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1342-452: The redshift -distance relation, and published observational support for it, two years before the discovery of Hubble's law. Although he used the term "velocities" in his paper (and "apparent radial velocities" in the introduction), he later expressed doubt about interpreting these as real velocities. In 1931 he wrote a letter to the Dutch cosmologist Willem de Sitter expressing his opinion on

1403-470: The "apparent velocities" in question are usually thought of as an increase in proper distance that occurs due to the expansion of the universe . Light traveling through an expanding metric will experience a Hubble-type redshift, a mechanism somewhat different from the Doppler effect , although the two mechanisms become equivalent descriptions related by a coordinate transformation for nearby galaxies. In

1464-509: The "formative years" end. A 2008 investigation found that only 20 percent of the spiral galaxies in the distant past possessed bars, compared with about 65 percent of their local counterparts. The general classification is "SB" (spiral barred). The sub-categories are based on how open or tight the arms of the spiral are. SBa types feature tightly bound arms. SBc types are at the other extreme and have loosely bound arms. SBb galaxies lie in between. SBm describes somewhat irregular barred spirals. SB0

1525-424: The 1930s, Hubble was involved in determining the distribution of galaxies and spatial curvature . These data seemed to indicate that the universe was flat and homogeneous, but there was a deviation from flatness at large redshifts. According to Allan Sandage , Hubble believed that his count data gave a more reasonable result concerning spatial curvature if the redshift correction was made assuming no recession. To

1586-479: The 1980 documentary Cosmos: A Personal Voyage by astronomer Carl Sagan , Hubble's life and work are portrayed on screen in episode 10, "The Edge of Forever". The play Creation's Birthday , written by Cornell physicist Hasan Padamsee, tells Hubble's life story. Period-luminosity relation In astronomy, a period-luminosity relation is a relationship linking the luminosity of pulsating variable stars with their pulsation period. The best-known relation

1647-495: The 86th Division moved overseas, but never saw combat as it was broken up and its personnel used as replacements in other units. After the end of World War I, Hubble spent a year at University of Cambridge , where he renewed his studies of astronomy. In 1919, Hubble was offered a staff position at the Carnegie Institution for Science 's Mount Wilson Observatory, near Pasadena, California , by George Ellery Hale ,

1708-565: The American Association Prize and five hundred dollars from Burton E. Livingston of the Committee on Awards. Hubble also devised the most commonly used system for classifying galaxies , grouping them according to their appearance in photographic images. He arranged the different groups of galaxies in what became known as the Hubble sequence. Hubble went on to estimate the distances to 24 extra-galactic nebulae, using

1769-615: The Chief of the External Ballistics Branch of the Ballistic Research Laboratory during which he directed a large volume of research in exterior ballistics which increased the effective firepower of bombs and projectiles. His work was facilitated by his personal development of several items of equipment for the instrumentation used in exterior ballistics, the most outstanding development being

1830-451: The Sun and up to 100,000 times more luminous. These Cepheids are yellow bright giants and supergiants of spectral class F6 – K2 and their radii change by of the order of 10% during a pulsation cycle. Leavitt's work on Cepheids in the Magellanic Clouds led her to discover the relation between the luminosity and the period of Cepheid variables . Her discovery provided astronomers with

1891-524: The Sun from the center of the galaxy in the " Great Debate " and Hubble to move the Milky Way galaxy from the center of the universe. With the period-luminosity relation providing a way to accurately measure distances on an inter-galactic scale, a new era in modern astronomy unfolded with an understanding of the structure and scale of the universe. The discovery of the expanding universe by Georges Lemaitre and Hubble were made possible by Leavitt's groundbreaking research. Hubble often said that Leavitt deserved

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1952-759: The astronomer Mario Livio reported in Nature that a letter he found in the Lemaître archive demonstrated that the redaction had been made by Lemaître himself, who apparently saw no point in publishing scientific content which had already been reported in 1929 by Hubble. However, the fact remains that Lemaître published the law in French, two years prior to Hubble. During Hubble's life the Nobel Prize in Physics did not cover work done in astronomy. Hubble spent much of

2013-528: The boys' basketball team. After a year of high-school teaching, he entered graduate school with the help of his former professor from the University of Chicago to study astronomy at the university's Yerkes Observatory , where he received his Ph.D. in 1921. His dissertation was titled "Photographic Investigations of Faint Nebulae". At Yerkes, he had access to its 40-inch refractor built in 1897, as well as an innovative 26-inch (61 cm) reflector. After

2074-563: The bulk of his correspondence, photographs, notebooks, observing logbooks, and other materials, are held by the Huntington Library in San Marino, California. They were donated by his wife Grace Burke Hubble upon her death in 1980. In 2011, the journal Nature reported claims that Hubble might have played a role in the redaction of key parts of the 1931 English translation of Lemaître's 1927 paper, which formulated what

2135-577: The completion of the 100-inch (2.5 m) Hooker Telescope , then the world's largest. At that time, the prevailing view of the cosmos was that the universe consisted entirely of the Milky Way galaxy. Using the Hooker Telescope at Mount Wilson , Hubble identified Cepheid variables , a standard candle discovered by Henrietta Swan Leavitt . Comparing their apparent luminosity to their intrinsic luminosity gives their distance from Earth. Hubble found Cepheids in several nebulae , including

2196-539: The family could live in a small town, ultimately settling in nearby Louisville . His father died in the winter of 1913, while Edwin was still in England. In the following summer, Edwin returned home to care for his mother, two sisters, and younger brother, along with his brother William. The family moved once more to Everett Avenue, in Louisville's Highlands neighborhood, to accommodate Edwin and William. Hubble

2257-449: The first " standard candle " with which to measure the distance to faraway galaxies . Cepheids were soon detected in other galaxies, such as Andromeda (notably by Edwin Hubble in 1923–24), and they became an important part of the evidence that "spiral nebulae" are independent galaxies located far outside of the Milky Way . Leavitt's discovery provided the basis for a fundamental shift in cosmology, as it prompted Harlow Shapley to move

2318-562: The founder and director of the observatory. Hubble remained on staff at Mount Wilson until his death in 1953. Shortly before his death, Hubble became the first astronomer to use the newly completed giant 200-inch (5.1 m) reflector Hale Telescope at the Palomar Observatory near San Diego, California. Hubble also worked as a civilian for United States Army at Aberdeen Proving Ground in Maryland during World War II as

2379-501: The great telescope sees, he said, fail to stand up. The explosion, for example, would have had to start long after the earth was created, and possibly even after the first life appeared here." (Hubble's estimate of what we now call the Hubble constant would put the Big Bang only 2 billion years ago.) Hubble married Grace Lillian (Burke) Leib (1889–1980), daughter of John Patrick and Luella (Kepford) Burke, on February 26, 1924. Hubble

2440-576: The greater their relative speed of separation. If interpreted that way, Hubble's measurements on 46 galaxies lead to a value for the Hubble constant of 500 km/s/Mpc, which is much higher than the currently accepted values of 74 km/s/Mpc (cosmic distance ladder method) or 68 km/s/Mpc ( CMB method ) due to errors in their distance calibrations. Yet the reason for the redshift remained unclear. Georges Lemaître predicted on theoretical grounds based on Einstein's equations for general relativity

2501-475: The high-speed clock camera, which made possible the study of the characteristics of bombs and low-velocity projectiles in flight. The results of his studies were credited with greatly improving design, performance, and military effectiveness of bombs and rockets. For his work there, he received the Legion of Merit award. Edwin Hubble's arrival at Mount Wilson Observatory, California, in 1919 coincided roughly with

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2562-410: The hope that parallaxes to some Cepheids would be measured; one year after she reported her results, Ejnar Hertzsprung determined the distances of several Cepheids in the Milky Way and that, with this calibration, the distance to any Cepheid could then be determined. The relation was used by Harlow Shapley in 1918 to investigate the distances of globular clusters and the absolute magnitudes of

2623-447: The inner stars. This effect builds over time to stars orbiting farther out, which creates a self-perpetuating bar structure. The bar structure is believed to act as a type of stellar nursery , channeling gas inwards from the spiral arms through orbital resonance , fueling star birth in the vicinity of its center. This process is also thought to explain why many barred spiral galaxies have active galactic nuclei , such as that seen in

2684-575: The later part of his career attempting to have astronomy considered part of physics, instead of being a separate science. He did this largely so that astronomers—including himself—could be recognized by the Nobel Committee for their valuable contributions to astrophysics . This campaign was unsuccessful in Hubble's lifetime, but shortly after his death, the Nobel Prize Committee decided that astronomical work would be eligible for

2745-449: The order of days to months. Cepheid variables were discovered in 1784 by Edward Pigott , first with the variability of Eta Aquilae , and a few months later by John Goodricke with the variability of Delta Cephei , the eponymous star for classical Cepheids. Most of the Cepheids were identified by the distinctive light curve shape with a rapid increase in brightness and a sharp turnover. Classical Cepheids are 4–20 times more massive than

2806-554: The physics prize. However, the Nobel prize is not awarded posthumously. On March 6, 2008, the United States Postal Service released a 41-cent stamp honoring Hubble on a sheet titled "American Scientists" designed by artist Victor Stabin . His citation reads: Often called a "pioneer of the distant stars", astronomer Edwin Hubble (1889–1953) played a pivotal role in deciphering the vast and complex nature of

2867-428: The theoretical interpretation of the redshift-distance relation: Mr. Humason and I are both deeply sensible of your gracious appreciation of the papers on velocities and distances of nebulae. We use the term 'apparent' velocities to emphasize the empirical features of the correlation. The interpretation, we feel, should be left to you and the very few others who are competent to discuss the matter with authority. Today,

2928-418: The true distances, and combining his distances with measurements of the redshifts of the galaxies by Vesto Slipher , and by his assistant Milton L. Humason , he found a roughly linear relationship between the distances of the galaxies and their radial velocities (corrected for solar motion), a discovery that later became known as Hubble's law. This meant that the greater the distance between any two galaxies,

2989-485: The twentieth century, beginning with Hertzsprung . Calibrating the period-luminosity relation has been problematic; however, a firm Galactic calibration was established by Benedict et al. 2007 using precise HST parallaxes for 10 nearby classical Cepheids. Also, in 2008, ESO astronomers estimated with a precision within 1% the distance to the Cepheid RS Puppis , using light echos from a nebula in which it

3050-511: The two series of points corresponding to maxima and minima, thus showing that there is a simple relation between the brightness of the Cepheid variables and their periods. Using the simplifying assumption that all of the Cepheids within the Small Magellanic Cloud were at approximately the same distance, the apparent magnitude of each star is equivalent to its absolute magnitude offset by

3111-556: The universe is expanding. A decade before, the American astronomer Vesto Slipher had provided the first evidence that the light from many of these nebulae was strongly red-shifted, indicative of high recession velocities. Hubble's name is most widely recognized for the Hubble Space Telescope , which was named in his honor, with a model prominently displayed in his hometown of Marshfield, Missouri . Edwin Hubble

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3172-415: The universe must be either expanding or contracting. Unable to believe what his own equations were telling him, Einstein introduced a cosmological constant (a " fudge factor ") to the equations to avoid this "problem". When Einstein learned of Hubble's redshifts, he immediately realized that the expansion predicted by general relativity must be real, and in later life, he said that changing his equations

3233-406: The universe's history, evidence has recently emerged of the existence of numerous spiral galaxies in the early universe. Barred galaxies are apparently predominant, with surveys showing that up to two-thirds of all spiral galaxies develop a bar. The creation of the bar is generally thought to be the result of a density wave radiating from the center of the galaxy whose effects reshape the orbits of

3294-556: The universe. His meticulous studies of spiral nebulae proved the existence of galaxies other than our own Milky Way. Had he not died suddenly in 1953, Hubble would have won that year's Nobel Prize in Physics. (The assertion that he would have won the Nobel Prize in 1953 is likely false, although he was nominated for the prize that year. ) The other scientists on the "American Scientists" sheet include Gerty Cori , biochemist; Linus Pauling , chemist, and John Bardeen , physicist. In

3355-592: The very end of his writings, he maintained this position, favouring (or at the very least keeping open) the model where no true expansion exists, and therefore that the redshift "represents a hitherto unrecognized principle of nature." There were methodological problems with Hubble's survey technique that showed a deviation from flatness at large redshifts. In particular, the technique did not account for changes in luminosity of galaxies due to galaxy evolution . Earlier, in 1917, Albert Einstein had found that his newly developed theory of general relativity indicated that

3416-511: Was "the biggest blunder of [his] life". In fact, Einstein apparently once visited Hubble and tried to convince him that the universe was expanding. Hubble also discovered the asteroid 1373 Cincinnati on August 30, 1935. In 1936 he wrote The Observational Approach to Cosmology and The Realm of the Nebulae which explained his approaches to extra-galactic astronomy and his view of the subject's history. In December 1941, Hubble reported to

3477-629: Was a dutiful son, who despite his intense interest in astronomy since boyhood, acquiesced to his father's request to study law, first at the University of Chicago and later at Oxford. In this time, he also took some math and science courses. After the death of his father in 1913, Edwin returned to the Midwest from Oxford but did not have the motivation to practice law. Instead, he proceeded to teach Spanish, physics and mathematics at New Albany High School in New Albany , Indiana, where he also coached

3538-550: Was born in 1889 to Virginia Lee Hubble (née James) (1864–1934) and John Powell Hubble, an insurance executive, in Marshfield, Missouri, and moved to Wheaton , Illinois, in 1900. In his younger days, he was noted more for his athletic prowess than his intellectual abilities, although he did earn good grades in every subject except spelling. Edwin was a gifted athlete, playing baseball , football , and running track in both high school and college. He won seven first places and

3599-405: Was later called Hubble's law and also gave observational evidence. Historians quoted in the article were skeptical that the redactions were part of a campaign to ensure Hubble retained priority. However, the observational astronomer Sidney van den Bergh published a paper suggesting that while the omissions may have been made by a translator, they may still have been deliberate. In November 2011,

3660-662: Was opposed by many in the astronomy establishment of the time, in particular by Harvard University –based Harlow Shapley . Despite the opposition, Hubble, then a thirty-five-year-old scientist, had his findings first published in The New York Times on November 23 , 1924, then presented them to other astronomers at the January 1, 1925, meeting of the American Astronomical Society . Hubble's results for Andromeda were not formally published in

3721-632: Was raised as a Protestant Christian, but some of his later statements suggest uncertainty. Hubble had a heart attack in July 1949 while on vacation in Colorado . He was cared for by his wife and continued on a modified diet and work schedule. He died of cerebral thrombosis (a blood clot in his brain) on September 28, 1953, in San Marino , California. No funeral was held for him, and his wife never revealed his burial site. Hubble's papers comprising

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