Discovery of the 'missing' mode in HR 1217 by the Whole Earth Telescope

Autor(en)

Donald W. Kurtz, Steven D. Kawaler, Reed L. Riddle, Mike D. Reed, Margarida S. Cunha, Matt A. Wood, Nicole M. Silvestri, Todd K. Watson, Noel Dolez, Pawel A. Moskalik, S Zola, E Pallier, Joyce Ann Guzik, Travis S. Metcalfe, Anjum S. Mukadam, R. Edward Nather, Beverley J. Winget, Denis J. Sullivan, Kazuhiro Sekiguchi, Xianjun J. Jiang, R R Shobbrook, B N Ashoka, S Seetha, Santosh Joshi, Darragh O'Donoghue, Gerald Handler, M Müller, J M Gonzalez Perez, Jan Erik Solheim, Ana Ulla, S O Kepler, Antonio Kanaan, A. F M da Costa, L Fraga, O Giovannini, Jaymie M. Matthews

Abstrakt

HR 1217 is a prototypical rapidly oscillating Ap star that has presented a test to the theory of non-radial stellar pulsation. Prior observations showed a clear pattern of five modes with alternating frequency spacings of 33.3 and 34.6 μHz, with a sixth mode at a problematic spacing of 50.0 μHz (which equals 1.5 × 33.3 μHz) to the high-frequency side. Asymptotic pulsation theory allowed for a frequency spacing of 34 μHz, but Hipparcos observations rule out such a spacing. Theoretical calculations of magnetoacoustic modes in Ap stars by Cunha predicted that there should be a previously undetected mode 34 μHz higher than the main group, with a smaller spacing between it and the highest one. In this Letter, we present preliminary results from a multisite photometric campaign on the rapidly oscillating Ap star HR 1217 using the 'Whole Earth Telescope'. While a complete analysis of the data will appear in a later paper, one outstanding result from this run is the discovery of a newly detected frequency in the pulsation spectrum of this star, at the frequency predicted by Cunha.

Organisation(en)

Institut für Astrophysik

Externe Organisation(en)

University of Central Lancashire, Iowa State University, Case Western Reserve University, Universidade do Porto, Florida Institute of Technology, University of Washington, Southwestern University, Laboratoire d’Astrophysique de Toulouse-Tarbes, Polish Academy of Sciences (PAS), Pedagogical University of Cracow, Los Alamos National Laboratory, University of Texas, Austin, Victoria University of Wellington, Subaru Telescope, Chinese Academy of Sciences (CAS), Australian National University, Indian Space Research Organization, Uttar Pradesh State Observatory, University of Cape Town, University of Tromsø - The Arctic University of Norway, University of Oslo, Universidad de Vigo, Universidade Federal do Rio Grande do Sul, Universidade Federal de Santa Catarina, University of British Columbia (UBC)

Journal

Monthly Notices of the Royal Astronomical Society

Band

330

ISSN

0035-8711

Publikationsdatum

2002

Peer-reviewed

Ja

ÖFOS 2012

103003 Astronomie

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/discovery-of-the-missing-mode-in-hr-1217-by-the-whole-earth-telescope(98357e8d-af5d-46f9-abe1-5aaaf04492b9).html