202 research outputs found
Padre Secchi e la spettroscopia
No full textViene analizzato il contributo di Padre Secchi alla spettroscopia stellare e solare, particolarmente in relazione allo sviluppo storico-scientifico dell'astrofisica e alla successiva classificazione spettrale di Harvard
Measuring stellar temperatures : an astrophysical laboratory for undergraduate students
No full textWhile astrophysics is a fascinating subject, it hardly lends itself to laboratory experiences accessible to undergraduate students. In this paper we describe is presented a feasible astrophysical laboratory experience, in which students are guided to take several stellar spectra, using a telescope, a spectrograph and a CCD camera, and perform a full data analysis using the equivalent widths method on some spectral lines. This allows them to derive stellar temperatures after a suitable calibration and fitting procedure. On average the estimated stars temperatures agree with known results within an error margin of 5 to 10% for cold stars, and 20 to 25% for hot stars
La ricerca di caratteristiche sensibili alla luminosità negli spettri stellari fino agli anni Venti del Novecento
No full textI contributi di studiosi italiani all'astronomia gravitazionale, astronomia osservativa e all'astronomia descrittiva alla fine del XIX secolo
No full textIl laboratorio storico in un insegnamento universitario : l'esperienza del corso di laboratorio di astronomia e astrofisica
No full textThe hydrogen abundance in stars : a first major step for quantitative astrophysics
No full textHistoriography has recognized that Saha’s work in the early 1920s was the beginning of a quantitative era in astrophysics, and the deduction of the large hydrogen abundance in stars around 1930 was a major outcome of Saha’s theory. In this paper, the development of stellar physics in these years is analysed, and the recognition of the hydrogen abundance is pointed out as the first major achievement of the quantitative era. This idea is sustained from two different points of view. First, there exists a tight scientific continuity from Saha’s investigative papers up to Russell’s 1929 paper where the hydrogen abundance was clearly worked out: the whole of the 1920s should therefore be considered as a scientific discontinuity that paved the way for modern stellar spectroscopy. Second, in 1932 the same conclusion was reached by Strömgren and Eddington, who were working on the problem of internal stellar structure. Thus, the hydrogen abundance can be viewed as the first major step of the quantitative era, as it led to the first sound theory of stellar structure, both for the inner and the surface regions of stars
Stellar temeratures by Wien's law : not so simple
No full textA star’s surface temperature is among the most important features that can be deduced from its
light. We have made measurements to see how reliably we could determine the surface
temperatures of some A to K stars using Wien’s Displacement Law. We took spectra, corrected
them for atmospheric extinction and instrumental response, found the wavelengths of their
intensity maxima, and then from Wien’s law found the surface temperatures of the observed stars.
For F to early K stars, our results agree with temperatures determined in other ways. For A and
later K stars, the agreement is poor because the spectra are appreciably different from ideal
blackbody spectra and because our equipment responds poorly to the deep red and blue
wavelengths where the spectra of these stars have their peak intensities. This paper points out
several interesting concepts in and outside the astrophysical domain that can be instructive for
undergraduate students
Physics research coming into school
No full textIn many countries, this is for example the case of Poland, the shifting of intellectual interests towards “not-strictly-science” sciences leads to shrinkage of physics programmes in secondary schools. Obviously, it does not seem reasonable to eliminate from school programmes Galileo’s laws of kinematics or Newton’s lawsof dynamics. At this point, teaching Physics risks to become a kind of “mentalexercise” – more as exemplification of mathematics than introducing into richness of problems of Physics itself.A possible recipe for this dilemma is introducing element of “live”, i.e. Modern Physics. Several such examples arrive from Italian secondary (lyceum) school system.The work in the DW “D” workshop Physics research in the classroom was greatly based on these examples.The main contributions to the Workshop came from:1) Davide Cenadelli and Antonella Testa from Università degli Studi di Milanoon Astrophysics2) Lorenzo Santi and Marisa Michelini from Università degli Studi di Udine on Physics of Elementary Particles3) Federico Corni from Università degli Studi di Modena on Solid State Physics4) Andrzej Karbowski, Grzegorz Osiński and Grzegorz Karwasz from Uniwersytet Mikołaja Kopernika, Toruń on Quantum Colllisions and on CosmologyIn the discussion participants from Belgium, Bosnia and Herzegovina, Norway, Poland, Italy took part. In addition to the scientific and didactical matters, the need for exchanging practical information (what kind of equipment, which are the waysof funding) was stressed in the discussion. Finally, we also presented the outcomes of two EU projects developed on Modern Physics and on Superconductivity and Polish Programme on Science Centres
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