High-sensitivity radio study of the non-thermal stellar bow shock EB27

Benaglia, P.; Palacio, Santiago; Hales, Christopher A.; Colazo, Marcelo

doi:10.1093/mnras/stab662

Cited by 17 publications

(36 citation statements)

References 52 publications

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“…At the time of writing, low-frequency bow shock studies have only been slightly more successful, as only two runaway stellar bow shocks have been confidently detected at radio frequencies. The prototype radio bow shock was discovered by Benaglia et al (2010) around BD+43 o 3654 and further observed by Brookes (2016) and Benaglia et al (2021). More recently, MeerKAT observations of the X-ray binary Vela X-1 discovered radio emission from its known bow shock (Van den Eĳnden et al 2022).…”

Section: Introductionmentioning

confidence: 94%

“…In this scenario, developed over the past decade by many authors (e.g. Benaglia et al 2010Benaglia et al , 2021 Table 2. Summary of the radio measurements for the bow shocks considered in the calculations in Section 4.…”

Section: Non-thermal/synchrotron Emissionmentioning

confidence: 99%

“…Firstly, by definition, the efficiency cannot exceed one. Secondly, the magnetic field cannot exceed a maximum value 𝐵 max , imposed by the condition that the stellar wind should be compressible in order for the bow shock to have formed (Del Palacio et al 2018;Benaglia et al 2021):…”

Section: Sourcementioning

confidence: 99%

“…The latter scenario has been considered extensively in the literature, due to its possible ability to yield non-thermal sources of very-high energy emission via inverse Compton scattering of IR or stellar photons (Del Valle & Romero 2012;Schulz et al 2014;Toalá et al 2016Toalá et al , 2017De Becker et al 2017). This possibility has motivated searches for radio emission as signatures of such non-thermal electron populations (e.g., Peri et al 2015;Benaglia et al 2021), but the results in this work introduce the question whether the radio band is the best place to search: does the free-free/thermal emission complicate this approach?…”

Section: Future Expectations: Thermal Versus Non-thermal Detectabilitymentioning

confidence: 99%

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Radio detections of IR-selected runaway stellar bow shocks

Eijnden

Saikia²,

Mohamed

2022

Monthly Notices of the Royal Astronomical Society

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Massive stars moving at supersonic peculiar velocities through the interstellar medium (ISM) can create bow shocks, arc-like structures at the interface between the stellar wind and the ISM. Many such bow shocks have been detected and catalogued at IR wavelengths, but detections in other wavebands remain rare. Strikingly, while electrons are expected to be accelerated in the bow shock and their non-thermal emission may include synchrotron emission at low frequencies, only two massive runaway stellar bow shocks have to date been detected in the radio band. Here, we examine a sample of fifty IR-detected bow shocks from the E-BOSS catalogues in recently released radio images from the Rapid ASKAP Continuum Survey (RACS). We identify three confident and three likely counterparts, as well as three inconclusive candidates requiring confirmation via follow-up observations. These detections significantly increase the number of known radio massive stellar bow shocks and highlight the advantage of dedicated searches with current and next-generation radio telescopes. We investigate the underlying radio emission mechanism for these radio sources, finding a mix of free-free-dominated and synchrotron-dominated systems. We also discuss the non-detected targets by putting constraints on their emission properties and investigating their detectability with future observations. Finally, we propose several future avenues of research to advance the study and understanding of bow shocks at radio frequencies.

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Section: Introductionmentioning

confidence: 94%

Section: Non-thermal/synchrotron Emissionmentioning

confidence: 99%

Section: Sourcementioning

confidence: 99%

Section: Future Expectations: Thermal Versus Non-thermal Detectabilitymentioning

confidence: 99%

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Radio detections of IR-selected runaway stellar bow shocks

Eijnden

Saikia²,

Mohamed

2022

Monthly Notices of the Royal Astronomical Society

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“…However, they are mostly visible in the infrared waveband (van Buren & McCray 1988;van Buren et al 1995;Povich et al 2008;Peri et al 2012Peri et al , 2015Kobulnicky et al 2016Kobulnicky et al , 2017 whose emission are governed by dust physics (Henney & Arthur 2019a,b,c;Henney et al 2019). Stellar wind bow shocks also exhibit polarized emission (Shrestha et al 2018(Shrestha et al , 2021 and they are suspected to be cosmic-ray accelerators (del Valle & Pohl 2018;Benaglia et al 2021). While massive stars run away, stellar evolution keeps going, and, consequently, a significant fraction of all core-collapse supernova remnants involve a runaway progenitor (Eldridge et al 2011).…”

Section: Introductionmentioning

confidence: 99%

3D MHD astrospheres: applications to IRC-10414 and Betelgeuse

Meyer,

Mignone,

Petrov

et al. 2021

Preprint

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A significative fraction of all massive stars in the Milky Way move supersonically through their local interstellar medium (ISM), producing bow shock nebulae by wind-ISM interaction. The stability of these observed astrospheres around cool massive stars challenges precedent two-dimensional (magneto-)hydrodynamical simulations of their surroundings. We present three-dimensional magneto-hydrodynamical (3D MHD) simulations of the circumstellar medium of runaway M-type red supergiant stars moving with velocity v = 50 km s −1 . We treat the stellar wind with a Parker spiral and assume a 7 µG magnetisation of the ISM. Our free parameter is the angle θ mag between ISM flow and magnetisation, taken to 0 • , 45 • and 90 • . It is found that simulation dimension, coordinate systems and grid effects can greatly affect the development of the modelled astrospheres. Nevertheless, as soon as the ISM flow and magnetisation directions differs by more than a few degrees (θ mag 5 • ), the bow shock is stabilised, most clumpiness and ragged structures vanishing. The complex shape of the bow shocks induce important projection effects, e.g. at optical Hα line, producing complex of astrospheric morphologies. We speculate that those effects are also at work around earlier-type massive stars, which would explain their diversity of their observed arc-like nebula around runaway OB stars. Our 3D MHD models are fitting well observations of the astrospheres of several runaway red supergiant stars. The results interpret the smoothed astrosphere of IRC-10414 and Betelgeuse (αOri) are stabilised by an organised, non-parallel ambient magnetic field. Our findings suggest that IRC-10414 is currently in a steady state of its evolution, and that Betelgeuse's bar is of interstellar origin.

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Astrospheres of Planet-Hosting Cool Stars and Beyond ⋅ When Modeling Meets Observations

et al. 2022

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Thanks to dedicated long-term missions like Voyager and GOES over the past 50 years, much insight has been gained on the activity of our Sun, the solar wind, its interaction with the interstellar medium, and, thus, about the formation, the evolution, and the structure of the heliosphere. Additionally, with the help of multi-wavelength observations by the Hubble Space Telescope, Kepler, and TESS, we not only were able to detect a variety of extrasolar planets and exomoons but also to study the characteristics of their host stars, and thus became aware that other stars drive bow shocks and astrospheres. Although features like, e.g., stellar winds, could not be measured directly, over the past years several techniques have been developed allowing us to indirectly derive properties like stellar mass-loss rates and stellar wind speeds, information that can be used as direct input to existing astrospheric modeling codes. In this review, the astrospheric modeling efforts of various stars will be presented. Starting with the heliosphere as a benchmark of astrospheric studies, investigating the paleo-heliospheric changes and the Balmer $\text{H}\upalpha$ H α projections to $1~\text{pc}$ 1 pc , we investigate the surroundings of cool and hot stars, but also of more exotic objects like neutron stars. While pulsar wind nebulae (PWNs) might be a source of high-energy galactic cosmic rays (GCRs), the astrospheric environments of cool and hot stars form a natural shield against GCRs. Their modulation within these astrospheres, and the possible impact of turbulence, are also addressed. This review shows that all of the presented modeling efforts are in excellent agreement with currently available observations.

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High-sensitivity radio study of the non-thermal stellar bow shock EB27

Cited by 17 publications

References 52 publications

Radio detections of IR-selected runaway stellar bow shocks

Radio detections of IR-selected runaway stellar bow shocks

3D MHD astrospheres: applications to IRC-10414 and Betelgeuse

Astrospheres of Planet-Hosting Cool Stars and Beyond ⋅ When Modeling Meets Observations

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