Béla Harkányi (Baron) (Hungarian: [ˈbe:lɒ 'hɒrka:ɲi]; 11 April 1869 – 2 January 1932) was a Hungarian astrophysicist. Harkányi was first to determine the temperatures (in 1902) and the diameters (in 1910) of individual stars other than the Sun.
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Scientific achievements Harkányi's most outstanding result was the first determination of the surface temperature for individual stars other than the Sun. Prior to 1902, when his relevant study was published, data only existed for the Sun's effective temperature. The range of temperatures of other stars had very roughly been bracketed by Scheiner in 1894. Harkányi realized that the recent success in determining the form of blackbody spectrum offered a way to determine stellar temperatures by fitting the blackbody curve to spectrophotometric observations of stars to determine the location of the maximum of the blackbody curve, from which the temperature follows applying Wien's displacement law. It is notable that this method works even if the maximum is outside the spectral range of observations. Using Vogel's (1880) spectrophotometric data, available at 7 or 8 wavelength values, Harkányi performed the fit and obtained Wien temperatures for 5 stars (Sirius, Vega, Arcturus, Aldebaran, and Betelgeuze). The values obtained tend to be on the low side by 500/2500 K for late/early type stars, respectively. Sources of the error include errors in the observational data; application of the Wien approximation instead of the full Planck blackbody spectrum; and a very rough extinction correction. Nevertheless, it took…
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Harkányi B.: A sarkmagasság ingadozása. Die Bestimmung und die Theorie Polhöhenschwankungen. Budapest (1896) Harkányi B.: A Nova Persei (3.1901) photometrikus megfigyelése. Ógyallai Kis. Kiadv. 1. (1901) Harkányi B., A Nova (3.1901) Persei photometriai megfigyelése az Ó-Gyallai observatoriumon. Mat. Term. Ért. 19, 374-393 (1901) Harkányi B.: Beobachtungen der Nova (3. 1901) Persei. Astr. Nachr. 155, 155 (1901) Harkányi B.: Photometrische Beobachtungen der Nova (3.1901) Persei. Astr. Nachr. 156, 79 (1901) Harkányi B.: Über die Temperaturbestimmung der Fixsterne auf spectralphotometrischem Wege. Astr. Nachr. 158, 17 (1902) Harkányi B., Über die Flächenhelligkeit, photometrische Größe und Temperatur der Sterne Astr. Nachr. 185, 33 (1910) Harkányi B., Darstellung der photometrischen und photographischen Größe als Funktion der Temperatur der Sterne Astr. Nachr. 186, 161 (1910) Harkányi B.: Adalékok a csillagok fejlõdésének elméletéhez (székfoglaló). Mat. Term. Ért. 39, 30-47 (1922) Harkányi B.: Über den Einfluß der absoluten Größe auf die effektive Temperatur der Sterne. Astr. Nachr. 217, 365 (1923) Harkányi B.: Über die Kapteynschen Parallaxenformeln. Astr. Nachr. 223, 135 (1925) PhD thesis:
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Biography Harkányi was born in Budapest in a prosperous noble family. His parents were Károly Harkányi and monostori Emilia Vörös. From 1895 the family held the title of Baron. After finishing secondary school and three years of undergraduate studies in Budapest, Béla Harkányi went on to study one year in Leipzig, then in Strasbourg (teachers: F. Kohlrausch, E. Cohn, H. Kobold), occasionally visiting major astronomical institutes in Germany and the United States, including Lick Observatory. He obtained his PhD in 1896 at the Royal Hungarian University of Sciences in Budapest. Next he spent two years at the Observatory of Paris with postgraduate studies, attending, among others, Poincaré's university lectures. In the first half of 1899 he worked in the Observatory of Potsdam under J. F. Hartmann, following which he started work in the astronomical observatory of Miklós Konkoly-Thege in Ógyalla. Here he conducted observational photometry while he also developed an interest in theoretical astrophysics, under the influence of his friend and associate, Radó Kövesligethy. He also collaborated with Loránd Eötvös in the gravivariometric experiments in 1901. In 1903 he left Ógyalla and moved back to Budapest, where from 1907 he became Privatdozent in the Institute for Cosmography and Geophysics of…
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Béla Harkányi (Baron) (Hungarian: [ˈbe:lɒ 'hɒrka:ɲi]; 11 April 1869 – 2 January 1932) was a Hungarian astrophysicist. Harkányi was first to determine the temperatures (in 1902) and the diameters (in 1910) of individual stars other than the Sun.
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Harkányi B.: A sarkmagasság-változások meghatározása és elméleti magyarázata. Dokt. ért., Budapest (1896) Descriptive and popular astronomy articles:
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Harkányi B.: Megemlékezés Gothard Jenőről. TTud. Közl. 1, 839-845 (1909) Harkányi B.: Eugene V. Gothard. Astrophys. J. 31, 1 (1910)
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Harkányi B.: Az észak-amerikai observatóriumokról. Math. Phys. Lapok 3, 139 (1894) Harkányi B.: Az égitestek hőmérsékletének meghatározása. Math. Phys. Lapok 12, 256-274 (1903) Harkányi B.: Az anomal dispersio szerepe az asztrofizikában. Math. Phys. Lapok 13, 143-155 (1904) Harkányi B.: A forgási ellipsoid meridián-hosszának minimumáról állandó térfogat mellett. Math. Phys. Lapok 20, 163-168 (1911) Harkányi B.: A fénysebesség változásának szerepe asztronómiai jelenségeknél. Math. Phys. Lapok 23, 33-38 (1914) Harkányi B.: A napfoltok mágneses polaritásának törvényeirõl. Stella 1, 21-25 (1926) Harkányi B.: (Rövid hírek.). Stella 2, 14-27 (1927) Harkányi B.: (Könyvismertetés.). Stella 2, 70-71 (1927) Other papers:
