BRITE-Constellation high-precision time-dependent photometry of the early O-type supergiant ζ Puppis unveils the photospheric drivers of its small- and large-scale wind structures

Tahina Ramiaramanantsoa*, Anthony F.J. Moffat, Robert Harmon, Richard Ignace, Nicole St-Louis, Dany Vanbeveren, Tomer Shenar, Herbert Pablo, Noel D. Richardson, Ian D. Howarth, Ian R. Stevens, Caroline Piaulet, Lucas St-Jean, Thomas Eversberg, Andrzej Pigulski, Adam Popowicz, Rainer Kuschnig, Elzbieta Zocłońska, Bram Buysschaert, Gerald HandlerWerner W. Weiss, Gregg A. Wade, Slavek M. Rucinski, Konstanze Zwintz, Paul Luckas, Bernard Heathcote, Paulo Cacella, Jonathan Powles, Malcolm Locke, Terry Bohlsen, André Nicolas Chené, Brent Miszalski, Wayne L. Waldron, Marissa M. Kotze, Enrico J. Kotze, Torsten Böhm

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

From 5.5 months of dual-band optical photometric monitoring at the 1 mmag level, BRITEConstellation has revealed two simultaneous types of variability in the O4I(n)fp star ζ Puppis: one single periodic non-sinusoidal component superimposed on a stochastic component. The monoperiodic component is the 1.78-d signal previously detected by Coriolis/Solar Mass Ejection Imager, but this time along with a prominent first harmonic. The shape of this signal changes over time, a behaviour that is incompatible with stellar oscillations but consistent with rotational modulation arising from evolving bright surface inhomogeneities. By means of a constrained non-linear light-curve inversion algorithm, we mapped the locations of the bright surface spots and traced their evolution. Our simultaneous ground-based multisite spectroscopic monitoring of the star unveiled cyclical modulation of its He II λ4686 wind emission line with the 1.78-d rotation period, showing signatures of corotating interaction regions that turn out to be driven by the bright photospheric spots observed by BRITE. Traces of wind clumps are also observed in the He II λ4686 line and are correlated with the amplitudes of the stochastic component of the light variations probed by BRITE at the photosphere, suggesting that the BRITE observations additionally unveiled the photospheric drivers of wind clumps in ζ Pup and that the clumping phenomenon starts at the very base of the wind. The origins of both the bright surface inhomogeneities and the stochastic light variations remain unknown, but a subsurface convective zone might play an important role in the generation of these two types of photospheric variability.

Original languageEnglish
Pages (from-to)5532-5569
Number of pages38
JournalMonthly Notices of the Royal Astronomical Society
Volume473
Issue number4
DOIs
StatePublished - 1 Feb 2018
Externally publishedYes

Funding

FundersFunder number
Austrian Fonds zur Förderung derwissenschaftlichen ForschungV431-NBL
SAAO
Technical University of Graz
Horizon 2020 Framework Programme
University of Toledo
Canadian Space Agency
Natural Sciences and Engineering Research Council of CanadaNSERC
European Research Council
Universität Wien
Fonds de recherche du Québec – Nature et technologies
Narodowe Centrum Nauki2016/21/B/ST9/01126, 2016/21/D/ST9/00656, 2015/18/A/ST9/00578, 2011/01/M/ST9/05914
Österreichische Forschungsförderungsgesellschaft
Horizon 2020670519
Foundation for Science and Technology

    Keywords

    • Outflows
    • Stars: massive
    • Stars: rotation
    • Stars: winds
    • Starspots
    • Supergiants
    • Techniques: photometric
    • Techniques: spectroscopic

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