William P. Bidelman

William Pendry Bidelman ( ; September 25, 1918 – May 3, 2011) was an American astronomer.

Bidelman's undergraduate degree was from Harvard College, He was a physicist in the Army during World War II. Bidelman taught for ~41 years at The University of Chicago,

He co-discovered the class of barium stars with Philip Keenan, the phosphorus and the mercury stars, and was the first to describe the hydrogen-deficient carbon stars.

Born in Los Angeles, California, Bidelman was raised in North Dakota, where he met his future wife of 69 years. He was a father of four and a grandfather. He graduated in 1940. who discovered the first definite evidence that the Milky Way Galaxy is a spiral galaxy, and, with Philip Keenan, the Morgan-Keenan (MK) system of stellar classification. As a graduate student, Bidelman assisted Morgan and Keenan by taking some of the spectrograms for their book, An Atlas of Stellar Spectra.

For his 1943 dissertation, Bidelman reported the Double Cluster in the I Persei association is physically associated with neighborhood supergiant stars, and is part of an association of O- and B-type stars, and designated 47 stars as its members. Bidelman received his Ph.D. in 1943. The Yerkes astronomy graduate program directed by Otto Struve began issuing degrees in 1940, and he was among their first ten graduates.

Career Though the colors of a star's spectrum appear similar to a rainbow, a rainbow emits no light. Information about elements present at a star's surface, and many other features are found within the spectrum of a star. Bidelman served in the U.S. Army's Ballistic Research Laboratory at Aberdeen Proving Ground for over 2 years during World War II. He attended the 1942 American Astronomical Society's annual meeting despite a small assembly due to gasoline rationing during World War II.

University of Chicago, Yerkes Observatory Yerkes, located in the village of Williams Bay, Wisconsin is where faculty and students lived, and they rarely visited the Chicago campus. In 1945, when Bidelman left Aberdeen he was hired at Yerkes as an Instructor. In addition to Bidelman, by 1946 the Yerkes astronomy staff included Paul Ledoux, Arne Slettebak, Armin Deutsch, Marshall Wrubel, Arthur D. Code, Carlos Cesco, Víctor M. Blanco, W. W. Morgan, Otto Struve, Jesse L. Greenstein, Gerard P. Kuiper, George Van Biesbroeck, Louis G. Henyey Anne B. Underhill, Guido Münch, Nancy G. Roman, and the two future Nobel Prize winners, Subrahmanyan Chandrasekhar and Gerhard Herzberg. Other astronomers at Yerkes when Bidelman was there were Kaj Strand, W. Albert Hiltner, Aden B. Meinel, and visiting professors Bengt Strömgren from Denmark, and Jan Oort, Hendrik C. van de Hulst and Adriaan Blaauw from the Netherlands.

A spectrum from the star Capella. Vertical absorption lines are related to the elements and ions present in a star's atmosphere. A spectrum from an R CrB star in black and white displays some of its complexity. As a spectroscopist, Bidelman needed to identify the origins of lines like these. Bidelman spent long hours observing in remote west Texas at McDonald Observatory

Otto Struve, who directed both Yerkes and McDonald, has been described as dedicated yet demanding. His managerial style included daily inspections of the faculty to see if they were working. Despite reports of tensions there was also "close knit camaraderie" and "boisterous parties" evidenced by Yerkes "spontaneous party songs" including "The Billy Bidelman Song". Sung to the tune of "The Battle Hymn of the Republic", it consisted of repeating three times the line: "Struve, Kuiper, Hiltner, Morgan, Chandrasekhar too," followed by: "And Billy Bidelman".

To accurately understand the stars, astronomers must compensate for the impact of dust between the stars that will make them appear dimmer and redder than they are. Dust causes the sky to redden at sunset and sunrise, when being seen at the horizon through more of our atmosphere.

In 1946, W. W. Morgan and William P. Bidelman published a paper on interstellar reddening using the MK system of spectral classifications and photoelectric photometry. Morgan later said this paper with Bidelman on interstellar reddening was "the principal paper along the way" to the UBV system, which he devised with Harold Johnson.

Star clusters are contain stars born at the same time out of the same material and are the same distance from Earth, and can be valuable in understanding how stars change over time. became first to note the concentration of type M supergiant stars around χ Per, suggesting they were young Population I objects.

This group, along with the Double Cluster, was later named the Perseus OB1 Association. Bidelman also became first to see that S Persei is part of the Per OB1 association, which was later confirmed. Among the first stars that were studied at far-infrared wavelengths, M-type supergiants may be used to find the spiral arms of the Milky Way galaxy. How red supergiant stars evolved was considered an "astronomical puzzle", so the Double Cluster was used to test ideas about the evolution of red supergiant stars during the 1960s.

Unlike most the usual relatively young star clusters including few supergiant stars, 18 were found in the Double Cluster of Perseus by 2007, which Robert F. Wing noted as the 60th anniversary of Bidelman's "important paper", saying Bidelman's 1947 two-dimensional classifications of the then-known supergiants in h and χ Per had "served as the benchmark" for later studies of the red supergiant stars.

Vertical Lines of H-alpha and Balmer lines are shown using spectra from many dwarf stars. Weak Balmer lines show a star's atmosphere to be hydrogen-deficient. Hydrogen is the most abundant element in the Universe, so stars displaying very little hydrogen in their atmospheres are chemically peculiar stars. There are many kinds of hydrogen-deficient stars. Upsilon Sagittarii is a hydrogen-deficient star. It is a very luminous, variable, and unusual eclipsing binary with a spectrum quite difficult to classify. In 1949, Bidelman was possibly the first to suggest that Upsilon (υ) Sagittarii's violet-shifted absorption lines, which apparently takes place during some conjunctions of this binary pair when star 2 advances in front of star 1, could be caused by gas streaming from the primary star. Bidelman suggested when the displaced H-alpha(Hα) absorption line was present, it happened at regular intervals when the primary star was furthest away from Earth.

Upsilon Sag was the only example of a star of its type until Bidelman discovered another star similar to it, HD 30353. This star became known as "Bidelman's star".

Stars make elements, and what a star makes depend on its mass at its beginning. When Bidelman and Keenan noticed a strong line of ionized barium at the position λ4554 in the spectra of stars theories said were too young and the wrong kind to produce any barium, it created a mystery for astronomers. When Hertzsprung and Russell independently plotted stars on a chart of luminosity vs. temperature, they found there are patterns. The HR Diagram is a tool used by astronomers to know what stars are and how they will change. Bidelman and Keenan were the first to regard the barium star red giants as different from other red giants and to describe them as a spectroscopic class. Barium is a heavy metal element made by certain advanced stars with a helium-burning shell surrounding a spent carbon core In addition to the λ4554 barium line, some other characteristics of the group were two enhanced strontium (SR II) lines, at λ4077 and another at λ4215 blended with the head of the CN band, and also an enhanced G band due to CH and possibly CN.

G, K, and M-type giants, the most complex area of the Hertzsprung–Russell diagram (HR) diagram, have spectra so complicated "many astronomers have shied away from studying them".

A star follows a pattern as it ages that depends on its mass at the beginning. Here, a chart depicting temperature and luminosity shows how a star five times the mass of the Sun changes from a main sequence star into a white dwarf and a planetary nebula.

Eventually, Robert McClure discovered that essentially all barium stars began with a companion star that made the s-process elements, and when the companion star aged into a white dwarf, a stellar wind moved what was made by one star to the other star,

Bidelman was the first to find three unusual A- and F-type high-latitude bright stars, HR 6144, 89 Herculis, and HD 161796 in the high galactic plane, an unexpected place for supergiant stars to be found.

Astronomers expect to find massive young stars that are five to twenty times the mass of the Sun, on the galactic plane, a place where stars form, but it is rare to find stars like Her 89, with a spectrum that appears to be a young supergiant so far from the Galactic plane. Regarding these stars with characteristics of Population I supergiants, yet found at high galactic latitude, another astronomer wrote, "If I were a theoretician, I would simply say, 'They can't be, therefore they aren't'".

Bidelman's 1951 study also isolated the G- and K-type giant stars with weak G-bands as a class of peculiar giants.

University of California, Lick Observatory (1953–1963) alt=On top of Mount Hamilton, Lick Observatory sits while star trails suggests the movements of the night sky. Lick Observatory was the first permanently occupied observatory built on a mountain. The night sky over Mount Hamilton displays star trails due to the Earth's rotation.

In October 1953, Bidelman was hired as an assistant astronomer at Lick Observatory. The Bidelman family lived on Mount Hamilton and the children attended a one-room school where it was an hour's drive to the nearest grocery store.

Otto Struve had left the Chicago for The University of California in 1950. He and George Herbig also gave ten lectures together on stellar spectroscopy at Berkeley during the 1954–55 academic year. Bidelman served on the program committee for the American Association for the Advancement of Science and Astronomical Society of the Pacific meeting in 1955.

In 1953, Bidelman was the first to describe the hydrogen–deficient carbon star group, although Hans Ludendorff had found the appearance of weak hydrogen in R CrB in 1906. He researched emission-line stars for his catalogue and bibliography at Yerkes Observatory (Wisconsin) and McDonald Observatory (Texas), and spent six weeks during the summer at the Mount Wilson and Palomar observatories (California), funded by the Department of Naval Research. While at Yerkes, Morgan, Strömgren, and Chandrasekhar had encouraged Bidelman to prepare such a catalogue, and his catalogue and bibliography of 1,640 middle and late-type emission-line stars was among the ten most-cited papers in astronomy in 1954. Bidelman's catalogue included many stars with Ca II H and K emission. In 1996, Helmut Abt researched which papers published in 1954 were cited most frequently from 1955 to 1995, and Bidelman's Catalog and Bibliography ranked among the top four. Stars vary from the relatively hot O and B-type stars to the relatively cooler and reddish M stars. Bidelman served on the Astronomical Society of the Pacific's Nominating Committee and Publications Committees in 1955. When Seth B. Nicholson, Chairman of the Publications Committee for thirteen years retired, he nominated Bidelman as the next chairman. Bidelman resigned from the Nominating Committee, and became the Editor of the Publications of the Astronomical Society of the Pacific. the scientific journal of the ASP, which gives the Bruce Gold Medal.

In 1957, the Directors discussed but did not act on making the editor a salaried position. In 1958, the Publications Committee published over 100 papers, over 20 book reviews, and two symposia. Re-elected to the Board of Directors, Bidelman was authorized to spend up to $1,000 for editorial assistance in 1959, and they published over 90 papers from ~38 institutions, 15 book reviews and a symposium. His report noted it was a time-consuming task, made more difficult because he had been out of the country for two months that year. in 1960, they published six issues including 100 papers from ten countries, other articles and book reviews, and fulfilled reprint orders.

He was Third Vice President of ASP in 1961, and they published six issues totaling 543 pages, including 100 articles from the United States and nine other countries, and other papers. Bidelman's annual report said being "largely responsible for the welfare" of the journal for approximately five years had been a considerable burden and having found it impossible to find a sufficiently competent technical assistant on Mount Hamilton and not being able to fulfill his obligations to both the university and to ASP, he requested to resign effective July 1, 1961, his resignation became effective in mid-August and an assistant editor was added to the staff in September. Bidelman summarized his experiences in a 1989 talk entitled "A funny thing happened on the way to the Stanford Press - reminiscences of Five Years with the PASP". He continued on the ASP Publications Committee, no longer as chair, in 1962, 1963, 1964, 1965, 1966, 1967, 1968, 1969, and 1970. When Helmut Abt explored the number of reference errors in astronomy journal articles in 1992, he said the only astronomical editor he was aware of who checked every reference in his journal and found many errors "to which he called the author's attention—was William P. Bidelman when he edited these Publications".

While he was editor, Bidelman was the general supervisor of the students at Lick Observatory. According to Hyron Spinrad, Bidelman encouraged astronomy students at the Berkeley campus to make observations at Lick Observatory. Spinrad recalled: "I don't know how he was regarded on Mt. Hamilton, but at Berkeley he was regarded as sort of a good will emissary from the mountain".

In March 1962, Bidelman used three peculiar stars, 3 Centauri, κ Cancri and 112 Herculis, to make the first certain identification of the rare element gallium II (Ga II) in stellar spectra, with lab work assistance by Charles H. Corliss at the National Bureau of Standards, which they reported in May 1962.

T Tauri, the prototype of the T-Tauri stars, is a young star found in the constellation Taurus. Bidelman noted that it was at present "impossible to explain these abundance anomalies in terms of known nucleogenesis patterns".

At the University of Michigan, Freeman D. Miller and Bidelman began to direct the complete reactivation of the Curtis Schmidt telescope, to search for stars with spectra that showed unusual chemical compositions. the telescope was moved to the Cerro Tololo Inter-American Observatory (CTIO) in Chile, for astronomical viewing in the Southern Hemisphere which was completed in 1967. and the two later conducted research using objective-prism plates taken with by the Curtis Schmidt.

In the early 1960s Bidelman gave a colloquium at Case Western Reserve University in Cleveland, Ohio, where Bidelman suggested it would be feasible to reclassify all stars listed in the Henry Draper Catalogue on the MK system. Graduate student, Nancy Houk heard Bidelman's colloquium and became interested in classifying. Only about 23,000 of the HD stars had Morgan-Keenan classifications, and those had been classified by different people using different standards and sometimes chosen out of interest, creating a biased sample.

Reclassifying all HD stars the same way would create a vast data set that could be used as a teaching data set for a computer to encourage automated classifications which would be as better telescopes looked at for fainter stars. Houk eventually led the Michigan Survey and because it was anticipated that the work which she began in 1970 would not be completed until 2004, Bidelman used the same Curtis Schmidt objective-prism lens plates to begin an "early results" program. Bidelman recalled:

By 1964, Bidelman reported finding ~150 peculiar stars, about 80% were believed to be new discoveries. In 1966, Bidelman reported finding Praseodymium III in χ Lupi and with the Curtis Schmidt telescope, Bidelman and Robert Victor made provisional identifications of 23 peculiar stars including 3 new metallic line stars. By 1969, Bidelman and his assistants discovered ~90 new, mainly F- and G-type supergiant stars, 33 new B-type emission (Be) stars, ~75 new metallic-line stars, over 150 new peculiar A-type stars, and other astronomical objects of interest.

With the help of MacConnell and research assistants Bond, Frye and Humphreys, Bidelman discovered 53 new Barium (Ba II) stars, 26 new late-type giants which had strong Ca II emission lines, new supergiants of various spectral classes and G- and K-type stars with very weak CH absorption in their spectra.

The first worldwide milestone in creating one or more astronomical data centers was the first discussion in 1966 at a National Science Foundation event in Maryland. The second was when Bidelman was president of the International Astronomical Union's Commission 45 and they discussed the issue at the 1967 IAU meeting in Prague Czechoslovakia. At this meeting in Prague: "W.P. Bidelman spoke of the need for a general reference catalogue giving full bibliographic data for individual stars". Bidelman said it would include about a million stars and require the resources of an organization like NASA, and some members of the Commission supported the proposal. In a letter in 1969, Luboš Perek wrote that an astronomer who wanted a star's MK classification might search through 5 to 100 papers "according to his temperament" then give up, or take a plate to determine the type, or choose another star. Astronomers might observe the same star under different names. In 1969, Bidelman became one of the six astronomers funded by the Astronomical Society of the Pacific to study the feasibility of a computerized data center. The Observatory housing the Otto Struve Telescope at McDonald Observatory, Texas. In 1970, the first official IAU debate on astronomical data centers took place. The Strasbourg Astronomical Data Center, NASA Astrophysics Data System, and data centers in Japan and by the Astronomical Council of the USSR Academy of Science were among the first centers developed, and said many goals in creating data centers were eventually met and, as A. Heck noted, "sometimes largely facilitated by not-so-quickly-expected technologies such as the electronic networking of the planet".

By the end of the school year, Bidelman resigned to accept the position of Director of the Warner and Swasey Observatory and Chairman of Astronomy at Case Western Reserve University (CWRU) in Ohio. given to the university by the Warner & Swasey Company in 1920. Due to light pollution from the city of Cleveland, by the 1950s viewing was difficult and the Burrell Schmidt telescope was relocated ~30 miles away to Geauga County. Using CTIO objective –prism plates they found nearly 800 previously unknown A-type peculiar stars. They also found 34 weak G-band giants stars in the southern hemisphere. Their study was called a "major contribution" in providing data to help identify the relatively rare Population II stars. It created an unbiased sample, and doubled the number of known peculiar A-type (Ap) stars. After nineteen years of study by various investigators, in 2014, Beers et al. studied 302 of the Bidelman-MacConnell possible weak-metal stars and concluded that a metal-weak thick disk (MWTD) is present in the Milky Way galaxy, and noted its importance in understanding the development of our galaxy.

In 1962 and 1966, Bidelman had reported that the wavelength of λ 3984 varied somewhat from star to star, and stated differences in the ratios of mercury isotopes could be the reason. Bidelman was the first to note this, and in 1974, Michaud, Reeves and Charland, considering the isotopic abundances to be real, and that Hg was in fact overabundant and not an artifact of blending, suggested the mercury overabundances were due to radiation pressure that caused the element to pile up until radiation and gravitational forces almost cancelled each other, then its isotopes would separate, sorting themselves. Michaud suggested that element segregation would proceed naturally due to gravitational settling and radiation pressure if the stellar atmosphere was steady.

The movement that is intrinsic to a star, or part of its "property", is called the "proper motion" of a star. In 1975, Bidelman and San-Gak Lee reported spectral classifications for 601 proper-motion stars that had been listed in both a Lowell Observatory survey under Henry L. Giclas, and the Luyten Two-Tenths Catalogue and supplement, and their report included data from Gerard Kuiper. Kuiper and Bidelman had been at Yerkes Observatory at the same time. Bidelman called it "very important spectroscopic work When Kuiper ran out of stars of large proper motion and parallax in a region of sky, he observed the planets and their moons "nicely lined up" in that region. When Kuiper found evidence of an atmosphere on Saturn's moon, Titan, his research changed focus and much of his data on proper motion stars remained unpublished.

In 1975, Peter Pesch replaced Bidelman as Director of the Observatory and Chairman of the Astronomy department. While Bidelman had been the observatory director, were part of a group from CWRU who wanted to begin their own observatory. The outlook for employment in research astronomy was bleak, so the group began a mail-order business and took part-time jobs to solve their "food on the table problem" while seeking to build an observatory in California, and Bidelman gave them their first cash donation. Other donations followed, and the Monterey Institute for Research in Astronomy opened in 1984.

In 1977, Congress agreed to fund the orbiting Hubble Space Telescope, named after Edwin Hubble. In September 1977, Bidelman served on the Ad Hoc Advisory Subcommittee for NASA's Space Telescope.

In 1976, Bidelman headed an IAU working group on the proper designation for astronomical objects. Bidelman stated he wanted to make a slightly off-topic point about nomenclature, and asked whether the star under discussion, VI Cyg #5 is the same star as BD+40° 4220. Informed it is and another one of its names is V729 Cyg, Bidelman responded, "Well, I'd like to say, as a member of an IAU Commission concerned with such things, that one should adopt a consistent labeling for a star". After being seconded by Underhill, he added: "We don't all have encyclopedic memories". and was moved first to a better viewing site in Ohio, then later to Kitt Peak, Arizona, in 1979. Bidelman also conducted research with infrared and ultraviolet data as they became available. When the telescope at Kitt Peak became operational in 1981, Bidelman continued his "early-results" research involving "systematic, but nonetheless somewhat cursory inspection" to classify stars for the northern hemisphere that had been given HD numbers, and published the spectral data in 1983. Bidelman identified 175 peculiar or otherwise interesting stars, most thought to be new discoveries.

Bidelman was the first to identify the peculiar F str λ4077 dwarfs. As part of the "early results" program, in 1981, 1983 and 1985 Bidelman found 21 stars he identified as "F str λ 4077". Almost nothing was known about these stars other than Bidelman's spectral classification. Later researchers found evidence that about half are main-sequence counterparts of Barium stars.

Bidelman retired from teaching at Case Western in 1986. As a Professor Emeritus, Bidelman continued with the Henry Draper Reclassification project with Houk and the Michigan Spectral Survey and compiled identification of stars in the IRAS Low-Resolution Spectral Catalogue.

A close conjunction of Venus and Jupiter in Leo in July 2015 gave a suggestion of the conjunctions in 3 and 2 BC which Bidelman argued were a plausible explanation for the biblical Star of Bethlehem. Bidelman became interested in the Star of Bethlehem and argued it was involved planetary conjunctions. In 1991, Bidelman used astronomical tables by Bryant Tuckerman and Jean Meeus to investigate Roger Sinnott's suggestion that two close conjunctions of Venus and Jupiter on the morning of August 12, 3 BC, and the evening of June 17, 2 BC, could explain the Star of Bethlehem. He found that for these two planets, an easily observable morning conjunction is "invariably followed" by an evening conjunction approximately ten months later whenever the morning conjunction has an elongation of at least 19°. has shown the August 3 BC morning conjunction was ~4.3 arcminutes, and the June 2 BC evening conjunction was an "extremely close" 0.5 arcminutes, and Bidelman

In 1992, almost 50 years after his thesis paper,

In 1993, Bidelman provided data on 177 known and possible asymptotic giant branch stars, saying he was confident many would "prove to be interesting and important. Unfortunately, I don't know which ones!" Bidelman's list of high Strömgren c1 index high galactic latitude stars included promising post-AGB candidates to lead to finds of similar objects to better understand the post-AGB sub-groups of stars.

Invited to speak at the 1996 IAU Symposium on carbon stars Bidelman declined on advice from his doctor, but sent introductory comments in which he said:

Pointing out that observers sometimes "note things that don't seem to make much sense, but which later are realized to have been very significant indeed", he traced a brief history of "this stellar oddball" and concluded:

I hope you get my point: that if something seems a bit strange it is worth doing some serious thinking to try to make sense of it. At the very least, do tell others about it; though perhaps hard to believe, they may be smarter than you! This policy may not make you popular with the establishment but the risk is well worth taking.

Bidelman (1969) once said that the problem of the Ap stars (1969) is that "stars of unusual spectrum are doing unusual things". In 2002, Bidelman suggested the peculiar magnetic A stars may have once been close binaries that "merged and are now in the process of learning to live as single objects", and suggested in 2005 that Przybylski's Star may be one such object.

In Case Western University's 2008 astronomy department newsletter, Chair Heather Morrison wrote they were sorry to say goodbye to Professor Bidelman, who had turned 90 "and has decided to finish his distinguished career in Astronomy by retiring for a second time".

Honors Bidelman was elected to the American Astronomical Society in 1944. and was a member for over 65 years. He was president of the Cleveland Astronomical Society from 1973 to 1976. Bidelman was elected to the international science honor society Sigma Xi by Case Western Reserve University. The minor planet 9398 Bidelman (1994 SH3), discovered by the Arizona group Spacewatch at Kitt Peak on September 28, 1994, was named in his honor. The peculiar supergiant star HD 30353 is named "Bidelman's star".

Personal life alt=Four horizontal panels displaying stellar spectra with vertical lines. Bidelman wrote the section on Spectral Classification for the U.S. Navy's 1992 edition of The Explanatory Supplement to the Astronomical Almanac. In it he wrote, "The road from Secchi to Morgan and Keenan and beyond has been long and winding, and its end is still now only faintly glimpsed". William Pendry Bidelman was born on September 25, in 1918 in Los Angeles, California. but Bidelman did not use the designation "Jr.," after college. His father died suddenly when he was four, and subsequently Bidelman moved with his mother to Grand Forks, North Dakota where his grandparents (Architect Joseph Bell DeRemer and his wife Elizabeth) raised him.

At a 1977 IAU Symposium honoring the memory of Henry Norris Russell, Bidelman recalled reading during his high school years the "fascinating and inspiring" monthly articles Russell wrote for Scientific American. Saying it was "an important part of my early scientific education", Bidelman suggested they might be worth reprinting.

Asked to make some remarks at that symposium, Bidelman said he had little personal knowledge of Russell, but could believe the comments he had heard that Russell was both a great scientist and a great human being, because he had found it to be true of most other influential astronomers. In addition to Alfred Joy, Bidelman recalled "with great pleasure" Bart Bok, Cecilia Payne-Gaposchkin and Martin Schwarzschild from Harvard, and "the whole motley Yerkes crew: Struve, Greenstein, Henyey, Chandrasekhar, Kuiper and all the rest", and stated he marveled at his youthful contacts with them and their passionate devotion to science and to life. He ended his speech by saying:

Among Bidelman's many interests were baseball, philately, music, and square dancing. Bidelman died at 92 on May 3, 2011, in Tennessee.

Select bibliography These journal articles are William P. Bidelman's five most-cited works on the NASA Astrophysics Data System as of July 2017.

Gallery