Faculty publications - Department of Astronomy and Astrophysics

Permanent URI for this collectionhttps://hdl.handle.net/1807/16832

Celestial bodies and objects far beyond has been a captivation subject of interest dating back to early Islamic and Chinese scholars. Today, the Department of Astronomy and Astrophysics offers both graduate and undergraduate studies in astronomy, astrophysics, stars, galaxies, and cosmology. The department is an active member in observational and theoretical research on solar system dynamics, stars, stellar systems, interstellar medium, galaxies, quasars, and many more.

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    My Sixty Years in Astronomy Education: Highlights, and Lessons Learned
    (2023) Percy, John
    This article, presented as a poster paper at AstroEdu 2023, describes the author's half-century in astronomy education, highlights, and lessons learned. References are provided.
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    Long Secondary Periods in Pulsating Red Giants: A Century of Investigation
    (2022-09) John R. Percy
    Red giants (RGs) are unstable to radial pulsation. About a third of them also show a long secondary period (LSP), 5-10 times the pulsation period. The LSPs were recently ascribed to eclipses of the RG by a low-mass dust-enshrouded companion. LSPs have been known for over a century. In this paper, I use primarily AAVSO visual and photoelectric observations to look for evidence of LSPs in 103 red giant stars listed by Nancy Houk in 1963 as having LSPs, based mostly on photographic photometry. I have determined LSPs in 37 stars, and upper limits (some of them not very stringent) in 25. In the former, the ratio of LSP to pulsation period peaks strongly at 10, which suggests that most of the stars are pulsating in the first overtone. The LSPs are consistent with Houk’s in 33 of the 37 stars. I have identified 16 stars as bimodal pulsators;their period ratios are consistent with previous observational and theoretical results. For 14 stars,the periods in the General Catalogue of Variable Stars are incorrect or absent
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    Period Analysis of All-Sky Automated Survey for Supernovae (ASAS-SN) Data on a Sample of "Irregular" Pulsating Red Giants
    (2020) Percy, John R.
    All-Sky Automated Survey for Supernovae (ASAS-SN) data and, for some stars, AAVSO visual and V data have been used to study the possible periodicity of 74 "irregular" pulsating red giants (PRGs) in the AAVSO observing program. Results have been obtained and tabulated for 41 of them. For most of the tabulated stars, the new data provide more and/or better results than AAVSO data alone. All have small amplitudes. Several of the stars appear to have a long secondary period, as well as a pulsation period. A very few may be bimodal. Only about half of the periods that we derive are consistent with the periods in the VSX catalogue. We recommend that the AAVSO consider which of these small-amplitude "irregular" stars should continue to be observed, and how. Note: this version of this article includes notes on each star analyzed.
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    Magnetically controlled circumstellar plasma in the helium-weak stars
    (EDP Sciences, 2004) Shore, S. N.; Bohlender, D. A.; Bolton, C. T.; North, P.; Hill, G. M.
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    HD 37017 = V 1046 Ori. A double-lined spectroscopic binary with a B2e He-strong magnetic primary
    (EDP Sciences, 1998) Bolton, C. T. ; Harmanec, P. ; Lyons, R. W. ; Odell, A. P. ; Pyper, D. M.
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    The Supernova Legacy Survey: measurement of ΩM, ΩΛ and w from the first year data set
    (EDP Sciences, 2006) Astier, P.; Guy, J.; Regnault, N.; Pain, R.; Aubourg, E.; Balam, D.; Basa, S.; Carlberg, R. G.; Fabbro, S.; Fouchez, D.; Hook, I. M.; Howell, D. A.; Lafoux, H.; Neill, J. D.; Palanque-Delabrouille, N.; Perrett, K.; Pritchet, C. J.; Rich, J.; Sullivan, M.; Taillet, R.; Aldering, G.; Antilogus, P.; Arsenijevic, V.; Balland, C.; Baumont, S.; Bronder, J.; Courtois, H.; Ellis, R. S.; Filiol, M.; alves, A. C. Gonc¸; Goobar, A.; Guide, D.; Hardin, D.; Lusset, V.; Lidman, C.; McMahon, R.; Mouchet, M.; Mourao, A.; Perlmutter, S.; Ripoche, P.; Tao, C.; Walton, N.
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    The CNOC2 field galaxy redshift survey
    (Royal Society, 1999) Carlberg, R. G.; Yee, H. K. C.; Morris, S. L.; Lin, H.; Sawicki, M.; Wirth, G.; Patton, D.; Shepherd, C. W; Ellingson, E.; Schade, D.; Pritchet, C. J.; Hartwick, F. D. A.