Investigating Particle Acceleration in the Wolf–Rayet Bubble G2.4+1.4

Prajapati, Prachi; Tej, Anandmayee; Palacio, Santiago; Benaglia, P.; Ch, Ishwara-Chandra; Vig, S.; Mandal, Samir; Ghosh, S. K.

doi:10.3847/2041-8213/ab4992

Cited by 23 publications

(16 citation statements)

References 41 publications

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“…Wolf-Rayet nebulae entered the X-rays domain with Asca (Wrigge et al 2005) Rosat and Chandra (Guerrero & Chu 2008), XMM-Newton (Toalá et al 2012) observations from their (shocked) stellar winds witnessing emission of optically-thin high temperature plasma. More recently, a radio non-thermal synchrotron counterpart of the stellar wind bubble of a Wolf-Rayet ring nebula indicated that these circumstellar nebulae are the site of particles accelelration (Prajapati et al 2019). This accumulation of observations motivates the present numerical efforts aiming at understanding the peculiar vicinity of young Wolf-Rayet stars.…”

Section: Introductionmentioning

confidence: 93%

On the bipolarity of Wolf-Rayet nebulae

Meyer

2021

Preprint

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Wolf-Rayet stars are amongst the rarest but also most intriguing massive stars. Their extreme stellar winds induce famous multi-wavelength circumstellar gas nebulae of various morphologies, spanning from circles and rings to bipolar shapes. This study is devoted to the investigation of the formation of young, asymmetric Wolf-Rayet gas nebulae and we present a 2.5dimensional magneto-hydrodynamical toy model for the simulation of Wolf-Rayet gas nebulae generated by wind-wind interaction. Our method accounts for stellar wind asymmetries, rotation, magnetisation, evolution and mixing of materials. It is found that the morphology of the Wolf-Rayet nebulae of blue supergiant ancestors is tightly related to the wind geometry and to the stellar phase transition time interval, generating either a broadened peanut-like or a collimated jet-like gas nebula. Radiative transfer calculations of our Wolf-Rayet nebulae for dust infrared emission at 24 µm show that the projected diffuse emission can appear as oblate, bipolar, ellipsoidal or ring structures. Important projection effects are at work in shaping observed Wolf-Rayet nebulae. This might call a revision of the various classifications of Wolf-Rayet shells, which are mostly based on their observed shape. Particularly, our models question the possibility of producing pre-Wolf-Rayet wind asymmetries, responsible for bipolar nebulae like NGC 6888, within the single red supergiant evolution channel scenario. We propose that bipolar Wolf-Rayet nebulae can only be formed within the red supergiant scenario by multiple/merged massive stellar systems, or by single high-mass stars undergoing additional, e.g. blue supergiant, evolutionary stages prior to the Wolf-Rayet phase.

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Section: Introductionmentioning

confidence: 93%

On the bipolarity of Wolf-Rayet nebulae

Meyer

2021

Preprint

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“…For a typical WR lifespan (through the WC or WO phase) of ∼ 5 × 10 5 yr, and a maximum wind power of 10 38 erg s −1 (e.g. Prajapati et al 2019), one obtains E winds ∼ 1 × 10 51 erg, comparable to E SN . Mass loss rates for WR stars are 10 −5 M yr −1 (Crowther 2007) and with the total fraction of 12 C + 16 O being on the order of 0.65 (e.g.…”

Section: Constraints On the Radiation Environmentmentioning

confidence: 99%

Icy Exomoons Evidenced by Spallogenic Nuclides in Polluted White Dwarfs

Doyle,

Desch,

Young

2021

Preprint

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We present evidence that excesses in Be in polluted white dwarfs (WDs) are the result of accretion of icy exomoons that formed in the radiation belts of giant exoplanets. Here we use excess Be in the white dwarf GALEX J2339-0424 as an example. We constrain the parent body abundances of rock-forming elements in GALEX J2339-0424 and show that the over abundance of beryllium in this WD cannot be accounted for by differences in diffusive fluxes through the WD outer envelope nor by chemical fractionations during typical rock-forming processes. We argue instead that the Be was produced by energetic proton irradiation of ice mixed with rock. We demonstrate that the MeV proton fluence required to form the high Be/O ratio in the accreted parent body is consistent with irradiation of ice in the rings of a giant planet within its radiation belt, followed by accretion of the ices to form a moon that is later accreted by the WD. The icy moons of Saturn serve as useful analogs. Our results provide an estimate of spallogenic nuclide excesses in icy moons formed by rings around giant planets in general, including those in the solar system. While excesses in Be have been detected in two polluted WDs to date, including the WD described here, we predict that excesses in the other spallogenic elements Li and B, although more difficult to detect, should also be observed, and that such detections would also indicate pollution by icy exomoons formed in the ring systems of giant planets.

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“…We can learn more about the relativistic particle population by fitting the observed spectrum with a nonthermal emission model. We follow a similar approach as in Prajapati et al (2019) and model the non-thermal electron distribution as a power law with a spectral index p = 2.6, with a hardening at E e < 10 MeV due to ionization losses, and a high-energy cutoff at ∼ 100 GeV produced by synchrotron losses. The particle distribution normalization is set by the condition U NT = η mag U mag , with U NT the energy density in relativistic particles and η mag is a parameter in the range 3 × 10 −3 -0.75 (in accordance to the allowed range for B).…”

Section: Non-thermal Emission In S305mentioning

confidence: 99%

Probing the physical conditions and star formation processes in the Galactic HII region S305

Dewangan,

Sharma,

Pandey

et al. 2020

Preprint

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We present multi-scale and multi-wavelength observations of the Galactic H ii region S305, which is excited by massive O8.5V and O9.5V stars. Infrared images reveal an extended sphere-like shell (extension ∼7.5 pc; at T d = 17.5-27 K) enclosing the S305 H ii region (size ∼5.5 pc; age ∼1.7 Myr). The extended structure observed in the Herschel temperature map indicates that the molecular environment of S305 is heated by the massive O-type stars. Regularly spaced molecular condensations and dust clumps are investigated toward the edges of the infrared shell, where the PAH and H 2 emission is also observed. The molecular line data show a signature of an expanding shell of molecular gas in S305. GMRT 610 and 1280 MHz continuum maps reveal overdensities of the ionized emission distributed around two O-type stars, which are surrounded by the horseshoe envelope (extension ∼2.3 pc). A molecular gas deficient region/cavity is identified toward the center of the horseshoe envelope, which is well traced with PAH, H 2 , molecular, and dust emission. The edges of the infrared shell are found to be located in the front of the horseshoe envelope. All these outcomes provide the observational evidence of the feedback of O-type stars in S305. Moreover, non-thermal radio emission is detected in S305 with an average spectral index α ∼ −0.45. The variations in α, ranging from −1.1 to 1.3, are explained due to soft synchrotron emission and either optically-thicker thermal emission at high frequencies or a suppression of the low-frequency emission by the Razin-Tsytovich effect.

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Investigating Particle Acceleration in the Wolf–Rayet Bubble G2.4+1.4

Cited by 23 publications

References 41 publications

On the bipolarity of Wolf-Rayet nebulae

On the bipolarity of Wolf-Rayet nebulae

Icy Exomoons Evidenced by Spallogenic Nuclides in Polluted White Dwarfs

Probing the physical conditions and star formation processes in the Galactic HII region S305

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