X-ray Observations of Bow Shocks around Runaway O Stars. The case of \(\zeta\) Oph and BD+43\(^{\circ}\)3654

• Published in: arXiv.org
• Main Authors: Toalá, J A, Oskinova, L M, González-Galán, A, Guerrero, M A, Ignace, R, Pohl, M
• Format: Paper
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 26.02.2016
• Subjects: Comets; Emission analysis; Plasma temperature; Predictions; Stars; Thermal emission; Thermal radiation; X-ray astronomy; XMM (spacecraft)
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1602.07805

Non-thermal radiation has been predicted within bow shocks around runaway stars by recent theoretical works. We present X-ray observations towards the runaway stars \(\zeta\) Oph (Chandra and Suzaku) and BD+43\(^{\circ}\)3654 (XMM-Newton) to search for the presence of non-thermal X-ray emission. We found no evidence of non-thermal emission spatially coincident with the bow shocks, nonetheless, diffuse emission is detected in the vicinity of \(\zeta\) Oph. After a careful analysis of its spectral characteristics we conclude that this emission has a thermal nature with a plasma temperature of \(T \approx 2 \times10^{6}\) K. The cometary shape of this emission seems to be in line with recent predictions of radiation-hydrodynamic models of runaway stars. The case of BD+43\(^{\circ}\)3654 is puzzling as non-thermal emission has been reported in a previous work for this source.