binaries: general; stars: early-type; stars: emission-line, Be; stars: massive; X-rays: stars; Be Stars; Binaries:general; Binarity; Hard X ray; High quality; Stars: emission-line be; Stars: massive; Stars:early type; X-ray emission; X-ray:stars; Multidisciplinary
Abstract :
[en] Some Be stars exhibit a bright and extremely hard X-ray emission, whose origin is debated. In this context, it has been advocated that stripped helium-star sdO companions could play a significant role. Using high quality datasets, we examined (1) the binarity of these peculiar Be stars and (2) the X-ray emission of known Be+sdO systems. In this contribution, we present the result of these two studies and assess their impact on the proposed scenario.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Nazé, Yaël ; Université de Liège - ULiège > Département d'astrophysique, géophysique et océanographie (AGO) > Groupe d'astrophysique des hautes énergies (GAPHE) ; F.R.S.-FNRS Senior Research Associate, Belgium
Rauw, Grégor ; Université de Liège - ULiège > Département d'astrophysique, géophysique et océanographie (AGO) > Groupe d'astrophysique des hautes énergies (GAPHE)
Smith, Myron A.; NSF OIR Lab, Tucson, United States
Motch, Christian; Université de Strasbourg, CNRS, Observatoire Astronomique de Strasbourg, UMR 7550, Strasbourg, France
Language :
English
Title :
sdO and peculiar X-ray emissions
Publication date :
2023
Journal title :
Bulletin de la Société Royale des Sciences de Liège
ISSN :
0037-9565
eISSN :
1783-5720
Publisher :
Societe Royale des Sciences de Liege
Volume :
92
Issue :
2
Peer reviewed :
Editorial Reviewed verified by ORBi
Funding text :
Y.N. and G.R. acknowledge support from the Fonds National de la Recherche Scientifique (Belgium), the European Space Agency (ESA) and the Belgian Federal Science Policy Office (BELSPO) in the framework of the PRODEX Programme (contracts linked to XMM-Newton). M.A.S. acknowledges support from Chandra grant #362675.
Bjorkman, K. S., Miroshnichenko, A. S., McDavid, D. and Pogrosheva, T. M. (2002) A Study of π Aquarii during a Quasi-normal Star Phase: Refined Fundamental Parameters and Evidence for Binarity. ApJ, 573(2), 812–824. https://doi.org/10.1086/340751.
Bodensteiner, J., Shenar, T. and Sana, H. (2020) Investigating the lack of main-sequence companions to massive Be stars. A&A, 641, A42. https://doi.org/10.1051/0004-6361/202037640.
Boubert, D. and Evans, N. W. (2018) On the kinematics of a runaway Be star population. MNRAS, 477(4), 5261–5278. https://doi.org/10.1093/mnras/sty980.
Harmanec, P., Habuda, P., Štefl, S., Hadrava, P., Korčáková, D., Koubský, P., Krtička, J., Kubát, J., Škoda, P., Šlechta, M. and Wolf, M. (2000) Properties and nature of Be stars. XX. Binary nature and orbital elements of gamma Cas. A&A, 364, L85–L88.
Jernigan, J. G. (1976) Gamma Cassiopeiae. IAU Circ., 2900, 2.
Klement, R., Carciofi, A. C., Rivinius, T., Ignace, R., Matthews, L. D., Torstensson, K., Gies, D., Vieira, R. G., Richardson, N. D., Domiciano de Souza, A., Bjorkman, J. E., Hallinan, G., Faes, D. M., Mota, B., Gullingsrud, A. D., de Breuck, C., Kervella, P., Curé, M. and Gunawan, D. (2019) Prevalence of SED Turndown among Classical Be Stars: Are All Be Stars Close Binaries? ApJ, 885(2), 147. https://doi.org/10.3847/1538-4357/ab48e7.
Langer, N., Baade, D., Bodensteiner, J., Greiner, J., Rivinius, T., Martayan, C. and Borre, C. C. (2020) γ Cas stars: Normal Be stars with discs impacted by the wind of a helium-star companion? A&A, 633, A40. https://doi.org/10.1051/0004-6361/201936736.
Motch, C., Lopes de Oliveira, R. and Smith, M. A. (2015) The Origin of the Puzzling Hard-X-Ray Emission of γ Cassiopeiae. ApJ, 806(2), 177. https://doi.org/10.1088/0004-637X/806/2/177.
Nazé, Y. and Motch, C. (2018) Hot stars observed by XMM-Newton. II. A survey of Oe and Be stars. A&A, 619, A148. https://doi.org/10.1051/0004-6361/201833842.
Nazé, Y., Motch, C., Rauw, G., Kumar, S., Robrade, J., Lopes de Oliveira, R., Smith, M. A. and Torrejón, J. M. (2020) Three discoveries of γ Cas analogues from dedicated XMM-Newton observations of Be stars. MNRAS, 493(2), 2511–2517. https://doi.org/10.1093/mnras/staa457.
Nazé, Y., Rauw, G., Bohlsen, T., Heathcote, B., Mc Gee, P., Cacella, P. and Motch, C. (2022a) X-ray response to disc evolution in two γ Cas stars. MNRAS, 512(2), 1648–1657. https://doi.org/10.1093/mnras/stac314.
Nazé, Y., Rauw, G., Czesla, S., Smith, M. A. and Robrade, J. (2022b) Velocity monitoring of γ Cas stars reveals their binarity status. MNRAS, 510(2), 2286–2304. https://doi.org/10.1093/mnras/stab3378.
Nazé, Y., Rauw, G. and Smith, M. (2019) Surprises in the simultaneous X-ray and optical monitoring of π Aquarii. A&A, 632, A23. https://doi.org/10.1051/0004-6361/201936307.
Nazé, Y., Rauw, G., Smith, M. A. and Motch, C. (2022c) The X-ray emission of Be+stripped star binaries. MNRAS, 516(3), 3366–3380. https://doi.org/10.1093/mnras/stac2245.
Neiner, C., de Batz, B., Cochard, F., Floquet, M., Mekkas, A. and Desnoux, V. (2011) The Be Star Spectra (BeSS) Database. AJ, 142(5), 149. https://doi.org/10.1088/0004-6256/142/5/149.
Postnov, K., Oskinova, L. and Torrejón, J. M. (2017) A propelling neutron star in the enigmatic Be-star γ Cassiopeia. MNRAS, 465(1), L119–L123. https://doi.org/10.1093/mnrasl/slw223.
Rauw, G. (2022) X-ray emission of massive stars and their winds. Handbook of X-ray and Gamma-ray Astrophysics, in press. https://doi.org/10.1007/978-981-16-4544-0_79-1.
Rauw, G., Nazé, Y., Motch, C., Smith, M. A., Fló, J. G. and Lopes de Oliveira, R. (2022) The X-ray Emission of γ Cassiopeiae During the 2020-2021 Disc Eruption. A&A, 664, A184. https://doi.org/10.1051/0004-6361/202243679.
Secchi, A. (1866) Schreiben des Herrn Prof. Secchi, Directors der Sternwarte des Collegio Romano, an den Herausgeber. Astronomische Nachrichten, 68, 63. https://doi.org/10.1002/asna.18670680405.
Shao, Y. and Li, X.-D. (2014) On the Formation of Be Stars through Binary Interaction. ApJ, 796(1), 37. https://doi.org/10.1088/0004-637X/796/1/37.
Smith, M. A., Lopes de Oliveira, R. and Motch, C. (2016) The X-ray emission of the γ Cassiopeiae stars. Advances in Space Research, 58(5), 782–808. https://doi.org/10.1016/j.asr.2015.12.032.
Wang, L., Gies, D. R., Peters, G. J., Götberg, Y., Chojnowski, S. D., Lester, K. V. and Howell, S. B. (2021) The Detection and Characterization of Be+sdO Binaries from HST/STIS FUV Spectroscopy. AJ, 161(5), 248. https://doi.org/10.3847/1538-3881/abf144.
