STARS: INDIVIDUAL (WR 134); STARS: MASS LOSS; STARS: WOLF-RAYET
Abstract :
[en] The apparently single WN 6 type star WR 134 (HD 191765) is distinguished among the Wolf-Rayet star population by its strong, presumably cyclical (P~2.3 day) spectral variations. A true periodicity-which is still very much debated-would render WR 134 a prime candidate for harboring either a collapsed companion or a rotating, large-scale, inhomogeneous outflow. We have carried out an intensive campaign of spectroscopic and photometric monitoring of WR 134 from 1989 to 1997 in an attempt to reveal the true nature of this object. This unprecedentedly large data set allows us to confirm unambiguously the existence of a coherent 2.25+/-0.05 day periodicity in the line-profile changes of He II lambda4686, although the global pattern of variability is different from one epoch to another. This period is only marginally detected in the photometric data set. Assuming the 2.25 day periodic variability to be induced by orbital motion of a collapsed companion, we develop a simple model that aims to investigate (1) the effect of this strongly ionizing, accreting companion on the Wolf-Rayet wind structure, and (2) the expected emergent X-ray luminosity. We argue that the predicted and observed X-ray fluxes can only be matched if the accretion on the collapsed star is significantly inhibited. Additionally, we performed simulations of line-profile variations caused by the orbital revolution of a localized, strongly ionized wind cavity surrounding the X-ray source. A reasonable fit is achieved between the observed and modeled phase-dependent line profiles of He II lambda4686. However, the derived size of the photoionized zone substantially exceeds our expectations, given the observed low-level X-ray flux. Alternatively, we explore rotational modulation of a persistent, largely anisotropic outflow as the origin of the observed cyclical variability. Although qualitative, this hypothesis leads to greater consistency with the observations.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Morel, Thierry ; Département de Physique, Université de Montréal, C.P. 6128, Succ. Centre-Ville, Montréal, Québec, H3C 3J7, Canada
Marchenko, Sergey V
Eenens, Philippe R J
Moffat, Anthony F J
Koenigsberger, Gloria
Antokhin, Igor I
Eversberg, Thomas
Tovmassian, Gaghik H
Hill, Grant M
Cardona, Octavio
St-Louis, Nicole
Language :
English
Title :
A 2.3 Day Periodic Variability in the Apparently Single Wolf-Rayet Star WR 134: Collapsed Companion or Rotational Modulation?
Publication date :
01 June 1999
Journal title :
Astrophysical Journal
ISSN :
0004-637X
eISSN :
1538-4357
Publisher :
University of Chicago Press, Chicago, United States - Illinois
Antokhin, I. I., Aslanov, A. A., & Cherepashchuk, A. M. 1982, Soviet Astron. Lett., 8, 156
Antokhin, I. I., Bertrand, J.-F., Lamontagne, R., Moffat, A. F. J., & Matthews, J. M. 1995, AJ, 109, 817
Antokhin, I.I., & Cherepashchuk, A. M. 1984, Soviet Astron. Lett., 10, 155
Antokhin, I. I., Cherepashchuk, A. M., & Yagola, A. G. 1998, Ap&SS, 354, 111
Antokhin, I. I., Irsmambetova, T. R., Moffat, A. F. J., Cherepashchuk, A. M., & Marchenko, S. V. 1992, ApJS, 82, 395
Antokhin, I. I., & Volkov, I. M. 1987, Inf. Bull. Variable Stars, 2973, 1
Bappu, M. K. V. 1951, AJ, 56, 120
Benensohn, J. S., Lamb, D. Q., & Taam, R. E. 1997, ApJ, 478, 723
Blondin, J. M. 1994, ApJ, 435, 756
Blondin, J. M., Kallman, T. R., Fryxell, B. A., & Taam, R. E. 1990, ApJ, 356, 591
Brandt, N., & Podsiadlowski, P. 1995, MNRAS, 274, 461
Campana, S. 1997, A&A, 320, 840
Chalabaev, A., & Maillard, J. P. 1983, A&A, 127, 279
Cherepashchuk, A. M. 1975, Astrophysics, 10, 218
Cherepashchuk, A. M, & Aslanov, A. A. 1984, Ap&SS, 102, 97
Crampton, D. 1971, MNRAS, 153, 303
Cranmer, S. R., & Owocki, S. P. 1996, ApJ, 462, 469
Cui, W. 1997, ApJ, 482, L163
De Donder, E., Vanbeveren, D., & van Bever, J. 1997, A&A, 318, 812
Esteban, C., & Rosado, M. 1995, A&A, 304, 491
Firmani, C., Koenigsberger, G., Bisiacchi, G. F., Moffat, A. F. J. & Isserstedt,J. 1980, ApJ, 239, 607
Fullerton, A. W., Gies, D. R., & Bolton, C. T. 1996, ApJS, 103, 475
Fullerton. A. W., Massa, D. L., Prinja, R. K., Owocki, S. P., & Cranmer, S. R. 1997, A&A, 327, 699
Gies, D. R., & Bolton, C. T. 1986, ApJS, 61, 419
Gosset, E., & Vreux, J.-M. 1996, in Wolf-Rayet Stars in the Framework of Stellar Evolution: Proceedings of the 33d Liège International Astrophysical Colloquium, ed. J.-M. Vreux et al. (Liège: Inst. d'Astrophys.), 231
Gosset, E., Vreux, J.-M., & Andrillat, Y. 1994, Ap&SS, 221, 181
Hansen, B. M. S., & Phinney, E. S. 1997, MNRAS, 291, 569
Harries, T. J., Hillier, D. J., & Howarth, I. D. 1998, MNRAS, 296, 1072
Harries, T. J., Howarth, I. D., Schulte-Ladbeck, R. E., & Hillier, D. J. 1999, MNRAS, 302, 499
Hartman, J. W. 1997, A&A, 322, 127
Hatchett, S., & McCray, R. 1977, ApJ, 211, 552
Heemskerk, M. H. M., &van Paradijs, J. 1989, A&A, 223, 154
Hellings, P., &de Loore, C. 1986, A&A, 161,75
Hillier, D. J. 1991, A&A, 247, 455
Hogg, D. E. 1989, AJ, 98, 282
Ignace, R., Cassinelli, J. P., Morris, P., & Brown, J. C. 1998, in Proc. ESO Astrophys. Symp., Cyclical Variability in Stellar Winds, ed. L. Kaper & A W. Fullerton (Garching: Springer), 29
Johns, C. M., & Basri, G. 1995, AJ, 109, 2800
Kallman, T. R., & McCray, R. 1982, ApJS, 50, 263
Kaper, L., et al. 1997, A&A, 327, 281
Kretschmar, P., et al. 1997, A&A, 325, 623
Kumar, C. K., Kallman, T. R., & Thomas, R. J. 1983, ApJ, 272, 219
Lago, M. T. V. T., & Gameiro, J. F. 1998, MNRAS, 294, 272
Lamers, H. J. G. L. M., Cerruti-Sola, M., & Perinotto, M. 1987, ApJ, 314, 726 (LCP)
Lamontagne, R. 1983, Ph.D. thesis, Univ. Montréal
Lépine, S, & Moffat, A. F. J. 1999, ApJ, 514,909
Lépine, S., Moffat, A. F. J., &Henriksen, R. N. 1996, ApJ, 466,392
Lipunov, V. M. 1982, Soviet Astron. Lett., 8,194
Lorimer, D. R, Bailes, M., & Harrison, P. A. 1997, MNRAS, 289, 592
Lyne, A. G., Andersen, B., & Salter, M. J. 1982, MNRAS, 201, 503
Lyne, A. G, & Lorimer, D. R. 1994, Nature, 369, 127
Marchenko, S. V. 1988, Kinemat. Phys. Celest. Bodies, 4(5), 25
Marchenko, S. V., Antokhin, I. I., Bertrand, J.-F., Lamontagne, R., Moffat, A. F. J., Piceno, A., & Matthews, J. M. 1994, AJ, 108, 678
Marchenko, S. V., & Moffat, A. F. J. 1998a, ApJ, 499, L195
_. 1998b, A&A, 341, 211
Marchenko, S. V., Moffat, A. F. J., Antokhin, I. I., Eversberg, T., & Tovmassian, G. H. 1996b, in Wolf-Rayet Stars in the Framework of Stellar Evolution: Proceedings of the 33d Liège International Astrophysical Colloquium, ed. J.-M. Vreux et al. (Liège: Inst. d'Astrophys.), 261
Marchenko, S. V., Moffat, A. F. J., Eversberg, T., Hill, G. M., Tovmassian, G. H., Morel, T., & Seggewiss, W. 1998a, MNRAS, 294, 642
Marchenko, S. V., Moffat, A. F. J., Lamontagne, R., Tovmassian, G. H. 1996a, ApJ, 461, 386
Marchenko, S. V., et al. 1998b, A&A, 331, 1022
McCandliss, S. R. 1988, Ph.D. thesis, Univ. Colorado
McCandliss, S. R., Bohannan, B., Robert, C., & Moffat, A. F. J. 1994, Ap&SS, 221, 155
McCray, R. 1977, Highlights Astron., 4, 155
Mitra, A. 1998, ApJ, 499, 385
Moffat, A. F. J. 1982, in IAU Symp. 99, Wolf-Rayet Stars: Observations, Physics, Evolution, ed. C. W. H. de Loore & A. J. Willis (Dordrecht: Kluwer), 263
Moffat, A. F. J., & Marchenko, S. V. 1993a, in ASP Conf. Ser. 35, Massive Stars : Their Lives in the Interstellar Medium, ed. J. P. Cassinelli & E. B. Churchwell (San Francisco: ASP), 250
_. 1993b, AJ, 105, 339
Moffat, A. F. J., & Robert, C. 1994, ApJ, 421, 310
Moffat, A. F. J., & Shara, M. M. 1986, AJ, 92, 952
Moffat, A. F. J., et al. 1990, ApJ, 350, 767
Morel, T., St-Louis, N., & Marchenko, S. V. 1997, ApJ, 482, 470
Morel, T., St-Louis, N., Moffat, A. F. J., Cardona, O., Koenigsberger, G., & Hill, G. M. 1998, ApJ, 498, 413
Morrison, R., & McCammon, D. 1983, ApJ, 270, 119
Nugis, T., Crowther, P. A., & Willis, A. J. 1998, A&A, 333, 956
Pauldrach, A., Puls, J., & Kudritzki, R. P. 1986, A&A, 164, 86
Philp, C. J, Evans, C. R., Leonard, P. J. T., & Frail, D. A. 1996, AJ, 111, 1220
Pollock, A. M. T. 1987, ApJ, 320, 283
Pollock, A. M. T., Haberl, F., & Corcoran, M. F. 1995, in IAU Symp. 163, Wolf-Rayet Stars: Binaries, Colliding Winds, Evolution, ed. K. A. van der Hucht & P. M. Williams (Dordrecht: Kluwer), 512
Robert, C. 1992, Ph.D. thesis, Univ. Montréal
Robert, C., Moffat, A. F. J., Bastien, P., Drissen, L., & St-Louis, N. 1989, ApJ, 347, 1034
Robert, C., et al. 1992, ApJ, 397, 277
Roberts, D. H., Lehár, J, & Dreher, J. W. 1987, AJ, 93, 968
Rochowicz, K., & Niedzielski, A. 1995, Acta Astron., 45, 307
Ross, L. W. 1961, PASP, 73, 354
Ruffert, M. 1997, A&A, 317, 793
Sanders, W. T., Cassinelli, J. P., Myers, R. V., & van der Hucht, K. A. 1985, ApJ, 288, 756
Sayer, R. W., Nice, D. J., & Kaspi, V. M. 1996, ApJ, 461, 357
Scargle, J. D. 1982, ApJ, 263, 835
Schmutz, W., 1997, A&A, 321, 268
Schmutz, W., Geballe, T. R., & Schild, H. 1996, A&A, 311, L25
Schulte-Ladbeck, R. E., Nordsieck, K. H., Taylor, M., Bjorkman, K. S., Magalhães, A. M., & Wolff, M. J. 1992, ApJ, 387, 347
Shapiro, S. L., & Lightman, A. P. 1976, ApJ, 204, 555
Stevens, I. R., & Willis, A. J. 1988, MNRAS, 234, 783
St-Louis, N., Dalton, M. J., Marchenko, S. V., Moffat, A. F. J., & Willis, A. J. 1995, ApJ, 452, L57
St-Louis, N., Moffat, A. F. J., Drissen, L., Bastien, P., Robert, C. 1988, ApJ, 330,286
Tassoul, J.-L. 1990, ApJ, 358, 196
Taylor, A. R., Young, G., Peracaula, M., Kenny, H. T., Gregory, P. C. 1996, A&A, 305, 817
Underhill, A. B., Gilroy, K. K., Hill, G. M., & Dinshaw, N. 1990, ApJ, 351, 666
Vanbeveren, D. 1991, Space Sci. Rev. E, 56, 249
van den Heuvel, E. P. J. 1976, in IAU Symp. 73, Structure and Evolution of Close Binary Systems, ed. P. Eggleton, S. Mitton, & J. Whelan (Dordrecht: Reidel), 35
van den Heuvel, E. P. J., & De Loore, C. 1973, A&A, 25, 387
van der Hucht, K. A., Hidayat, B., Admiranto, A. G., Supelli, K. R., & Doom, C. 1988, A&A, 199, 217
van Kerkwijk, M. H., Geballe, T. R., King, D. L., van der Klis, M., & van Paradijs, J. 1996, A&A, 314, 521
van Leeuwen, F., Evans, D. W., Grenon, M., Grossmann, V., Mignard, F., & Perryman, M. A. C. 1997, A&A, 256, 148
Vreux, J.-M., Gosset, E., Bohannan, B., & Conti, P. S. 1992, A&A, 256, 148
Wang, Q. D. 1995, ApJ, 453, 783
Wessolowski, U. 1996, in Wolf-Rayet Stars in the Framework of Stellar Evolution: Proceedings of the 33d Liège International Astrophysical Colloquium, ed. J.-M. Vreux et al. (Liège: Inst. d'Astrophys.), 345
White, R. L., &Becker, R. H. 1996, ApJ, 451,352
White, N. E., Swank, J. H., & Holt, S. S. 1983, ApJ, 270, 711
Wijnands, R. A. D, Kuulkers, E., & Smale, A. P. 1996, ApJ, 473, L45
Williams, P. M., Dougherty, J. M., Davis, R. J., van der Hucht, K. A., Bode, M. F., & Gunawan, D. Y. A. 1997, MNRAS, 289,10
Woo, J. W., Clark, G. W., Blondin, J. M., Kallman, T. R., & Nagase, F. 1995, ApJ, 445, 896
Young, A. T., et al. 1991, PASP, 103, 221
Zhang, S. N., Yu, W., & Zhang, W. 1998, ApJ, 494, L71
Zhilyaev, B. E., & Khalack, V. R. 1996, Kinemat. Phys. Celest. Bodies, 12(2), 14