Pulsation–decline relationships in R Coronae Borealis stars |
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| Authors: | Lisa A Crause Warrick A Lawson Arne A Henden |
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| Institution: | South African Astronomical Observatory, PO Box 9, Observatory 7935, South Africa;Department of Astronomy, University of Cape Town, Private Bag, Rondebosch 7700, South Africa;School of Physical, Environmental and Mathematical Sciences, University of New South Wales, Australian Defence Force Academy, Canberra, ACT 2600, Australia;American Association of Variable Star Observers, 25 Birch Street, Cambridge, MA 02138, USA |
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| Abstract: | Decline onset times were measured in long-term visual light curves for five R Coronae Borealis (RCB) variable stars. These included RY Sgr and V854 Cen, the two RCB stars previously reported to have a relationship between dust formation events and pulsational variations. Analysis of the decline epochs showed that all decline onsets for a given star obey a linear ephemeris tied to the object's dominant radial pulsation period. Thus, in addition to confirming the pulsation–decline correlation for RY Sgr and V854 Cen, this same behaviour was demonstrated in UW Cen, R CrB and S Aps for the first time. This general result firmly establishes the connection between radial pulsation and mass loss in the RCB stars. The dominant pulsation period of ≈40 d for all of these objects therefore represents the characteristic time-scale on which these stars produce dust. |
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| Keywords: | stars: AGB and post-AGB stars: carbon stars: mass-loss stars: oscillations stars: variables: other |
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