University of Hertfordshire Research Archive

        JavaScript is disabled for your browser. Some features of this site may not work without it.

        Browse

        All of UHRABy Issue DateAuthorsTitlesThis CollectionBy Issue DateAuthorsTitles

        Arkivum Files

        My Downloads
        View Item 
        • UHRA Home
        • University of Hertfordshire
        • Research publications
        • View Item
        • UHRA Home
        • University of Hertfordshire
        • Research publications
        • View Item

        2006 WHOLE EARTH TELESCOPE OBSERVATIONS OF GD358: A NEW LOOK AT THE PROTOTYPE DBV

        Author
        Provencal, J. L.
        Montgomery, M. H.
        Kanaan, A.
        Shipman, H. L.
        Childers, D.
        Baran, A.
        Kepler, S. O.
        Reed, M.
        Zhou, A.
        Eggen, J.
        Watson, T. K.
        Winget, D. E.
        Thompson, S. E.
        Riaz, B.
        Nitta, A.
        Kleinman, S. J.
        Crowe, R.
        Slivkoff, J.
        Sherard, P.
        Purves, N.
        Binder, P.
        Knight, R.
        Kim, S. -L.
        Chen, Wen-Ping
        Yang, M.
        Lin, H. C.
        Lin, C. C.
        Chen, C. W.
        Jiang, X. J.
        Sergeev, A. V.
        Mkrtichian, D.
        Andreev, M.
        Janulis, R.
        Siwak, M.
        Zola, S.
        Koziel, D.
        Stachowski, G.
        Paparo, M.
        Bognar, Zs.
        Handler, G.
        Lorenz, D.
        Steininger, B.
        Beck, P.
        Nagel, T.
        Kusterer, D.
        Hoffman, A.
        Reiff, E.
        Kowalski, R.
        Vauclair, G.
        Charpinet, S.
        Chevreton, M.
        Solheim, J. E.
        Pakstiene, E.
        Fraga, L.
        Dalessio, J.
        Attention
        2299/7287
        Abstract
        We report on the analysis of 436.1 hr of nearly continuous high-speed photometry on the pulsating DB white dwarf GD358 acquired with the Whole Earth Telescope (WET) during the 2006 international observing run, designated XCOV25. The Fourier transform (FT) of the light curve contains power between 1000 and 4000 mu Hz, with the dominant peak at 1234 mu Hz. We find 27 independent frequencies distributed in 10 modes, as well as numerous combination frequencies. Our discussion focuses on a new asteroseismological analysis of GD358, incorporating the 2006 data set and drawing on 24 years of archival observations. Our results reveal that, while the general frequency locations of the identified modes are consistent throughout the years, the multiplet structure is complex and cannot be interpreted simply as l = 1 modes in the limit of slow rotation. The high-k multiplets exhibit significant variability in structure, amplitude and frequency. Any identification of the m components for the high-k multiplets is highly suspect. The k = 9 and 8 modes typically do show triplet structure more consistent with theoretical expectations. The frequencies and amplitudes exhibit some variability, but much less than the high-k modes. Analysis of the k = 9 and 8 multiplet splittings from 1990 to 2008 reveal a long-term change in multiplet splittings coinciding with the 1996 sforzando event, where GD358 dramatically altered its pulsation characteristics on a timescale of hours. We explore potential implications, including the possible connections between convection and/or magnetic fields and pulsations. We suggest future investigations, including theoretical investigations of the relationship between magnetic fields, pulsation, growth rates, and convection.
        Publication date
        2009-03-01
        Published in
        The Astrophysical Journal
        Published version
        https://doi.org/10.1088/0004-637X/693/1/564
        Other links
        http://hdl.handle.net/2299/7287
        Metadata
        Show full item record
        Keep in touch

        © 2019 University of Hertfordshire

        I want to...

        • Apply for a course
        • Download a Prospectus
        • Find a job at the University
        • Make a complaint
        • Contact the Press Office

        Go to...

        • Accommodation booking
        • Your student record
        • Bayfordbury
        • KASPAR
        • UH Arts

        The small print

        • Terms of use
        • Privacy and cookies
        • Criminal Finances Act 2017
        • Modern Slavery Act 2015
        • Sitemap

        Find/Contact us

        • T: +44 (0)1707 284000
        • E: ask@herts.ac.uk
        • Where to find us
        • Parking
        • hr
        • qaa
        • stonewall
        • AMBA
        • ECU Race Charter
        • disability confident
        • AthenaSwan