Easy can be Deceiving: A New Look at WR 6's Periodic Variations

André-Nicolas Chené; Guillaume Lenoir-Craig; Nicole St-Louis; Anthony F. J. Moffat

doi:10.25518/0037-9565.12349

Bulletin de la Société Royale des Sciences de Liège

0037-9565 1783-5720

Plus de Statistiques

depuis le 05 février 2011 :
Visualisation(s): 18 (2 ULiège)
Téléchargement(s): 0 (0 ULiège)

André-Nicolas Chené, Guillaume Lenoir-Craig, Nicole St-Louis & Anthony F. J. Moffat

Easy can be Deceiving: A New Look at WR 6's Periodic Variations

(Volume 93 - Année 2024 — No 3 - 41st Liège International Astrophysical Colloquium)

DOI: 10.25518/0037-9565.12349

Article

Document(s) associé(s)

Version PDF originale

Résumé

WR 6 est une étoile variable avec une période autour de 3,7 jours. La période et la forme des variations changent cependant d’une époque d’observation à l’autre. Nous suggérons que l’étude des courbes de lumière historiques révèle que des profils d’absorption sont à l’origine des variations. L’étude de la courbe de lumière intensive obtenue par le satellite BRITE montre que chaque absorption est répétée avec une période légèrement différente des autres. Nous suggérons que la variabilité soit causée par des Régions d’Interaction en Corotation dans le vent de WR 6 et que l’étoile soit en rotation différentielle.

Mots-clés : étoiles massives, vents stellaires, rotation

Abstract

WR 6 is variable with a period around 3.7 days, but the period and the shape of the variations seem to be different in every dataset. Looking at historic light curves, we suggest that variations are mostly absorption features. Examining the BRITE satellite light curve, every feature seems to have a slightly different period from one another. We propose that the variations come from Corotating Interaction Regions in WR 6’s wind and that the star shows differential rotation.

Keywords : massive stars, stellar winds, rotation

This work is distributed under the Creative Commons CC BY 4.0 Licence.

Paper presented at the 41^st Liège International Astrophysical Colloquium on “The eventful life of massive star multiples,” University of Liège (Belgium), 15–19 July 2024.

Bibliographie

[1] Firmani, C., Koenigsberger, G., Bisiacchi, G. F., Moffat, A. F. J., and Isserstedt, J. (1980) The binary nature of the single-line Wolf–Rayet star EZ CMa = HD 50896. ApJ, 239, 607–621. https://doi.org/10.1086/158148.

[2] Schmutz, W. and Koenigsberger, G. (2019) Long uninterrupted photometric observations of the Wolf–Rayet star EZ CMa by the Toronto BRITE satellite reveal a very fast apsidal motion. A&A, 624. https://doi.org/10.1051/0004-6361/201935094.

[3] Koenigsberger, G. and Schmutz, W. (2020) The nature of the companion in the Wolf–Rayet system EZ Canis Majoris. A&A, 639, A18. https://doi.org/10.1051/0004-6361/201937305.

[4] Barclay, K. D. G., Rosu, S., Richardson, N. D., Chené, A.-N., St-Louis, N., Ignace, R., and Moffat, A. F. J. (2024) Using CHIRON spectroscopy to test the hypothesis of a precessing orbit for the WN4 star EZ CMa. MNRAS, 527(2), 2198–2208. https://doi.org/10.1093/mnras/stad3289.

[5] Morel, T., St-Louis, N., and Marchenko, S. V. (1997) Optical spectroscopy of EZ Canis Majoris: Indication for large-scale structures in a Wolf–Rayet wind. ApJ, 482(1), 470–489. https://doi.org/10.1086/304122.

[6] Howarth, I. D. and Prinja, R. K. (1989) The stellar winds of 203 Galactic O stars: A quantitative ultraviolet survey. ApJS, 69, 527–592. https://doi.org/10.1086/191321.

[7] Cranmer, S. R. and Owocki, S. P. (1996) Hydrodynamical simulations of corotating interaction regions and discrete absorption components in rotating O-star winds. ApJ, 462, 469–488. https://doi.org/10.1086/177166.

[8] Aldoretta, E. J., St-Louis, N., Richardson, N. D., Moffat, A. F. J., Eversberg, T., Hill, G. M., Shenar, T., Artigau, É., Gauza, B., Knapen, J. H., Kubát, J., Kubátová, B., Maltais-Tariant, R., Muñoz, M., Pablo, H., Ramiaramanantsoa, T., Richard-Laferrière, A., Sablowski, D. P., Simón-Díaz, S., St-Jean, L., Bolduan, F., Dias, F. M., Dubreuil, P., Fuchs, D., Garrel, T., Grutzeck, G., Hunger, T., Küsters, D., Langenbrink, M., Leadbeater, R., Li, D., Lopez, A., Mauclaire, B., Moldenhawer, T., Potter, M., dos Santos, E. M., Schanne, L., Schmidt, J., Sieske, H., Strachan, J., Stinner, E., Stinner, P., Stober, B., Strandbaek, K., Syder, T., Verilhac, D., Waldschläger, U., Weiss, D., and Wendt, A. (2016) An extensive spectroscopic time series of three Wolf–Rayet stars – I. The lifetime of large-scale structures in the wind of WR 134. MNRAS, 460(3), 3407–3417. https://doi.org/10.1093/mnras/stw1188.

[9] St-Louis, N. (2013) Revealing the asymmetry of the wind of the variable Wolf–Rayet star WR1 (HD 4004) through spectropolarization. ApJ, 777(1), 9. https://doi.org/10.1088/0004-637X/777/1/9.

[10] Chené, A.-N., Moffat, A. F. J., Cameron, C., Fahed, R., Gamen, R. C., Lefèvre, L., Rowe, J. F., St-louis, N., Muntean, V., Chevrotière, A. D. L., Guenther, D. B., Kuschnig, R., Matthews, J. M., Rucinski, S. M., Sasselov, D., and Weiss, W. W. (2011) WR 110: A single Wolf–Rayet star with corotating interaction regions in its wind? ApJ, 735(1), 34. https://doi.org/10.1088/0004-637X/735/1/34.

[11] Robert, C., Moffat, A. F. J., Drissen, L., Lamontagne, R., Seggewiss, W., Niemela, V. S., Cerruti, M. A., Barrett, P., Bailey, J., Garcia, J., and Tapia, S. (1992) Photometry, polarimetry, spectroscopy, and spectropolarimetry of the enigmatic Wolf–Rayet star EZ Canis Majoris. ApJ, 397, 277–303. https://doi.org/10.1086/171786.

[12] Moffat, A. F. J., St-Louis, N., Carlos-Leblanc, D., Richardson, N. D., Pablo, H., and Ramiaramanantsoa, T. (2018) Wolf–Rayet stars with BRITE. In 3rd BRITE-Constellation Science Conference, edited by Wade, G. A., Baade, D., Guzik, J. A., and Smolec, R., Proceedings of the Polish Astronomical Society, volume 8, pages 37–42. https://www.pta.edu.pl/proc/v8p37.

Pour citer cet article

André-Nicolas Chené, Guillaume Lenoir-Craig, Nicole St-Louis & Anthony F. J. Moffat, «Easy can be Deceiving: A New Look at WR 6's Periodic Variations», Bulletin de la Société Royale des Sciences de Liège [En ligne], Volume 93 - Année 2024, No 3 - 41st Liège International Astrophysical Colloquium, 268-274 URL : https://popups.uliege.be/0037-9565/index.php?id=12349.