Polarization Observations and Models Constrain the Properties of the Bow Shock around HD 230561

Lin, Austin A.; Shrestha, Manisha; Wolfe, Tristan; Hoffman, Jennifer L.; Stencel, R. E.

doi:10.3847/2515-5172/ab3d45

Cited by 2 publications

(2 citation statements)

References 7 publications

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“…In summary, the multiwavelength polarization simulation results we present here can reasonably reproduce the polarization of some bow shock systems like HD 230561 (Lin et al 2019). Because we have considered spherical grains only, our simulations are less applicable to cases where magnetic fields likely play a role in aligning dust grains, such as the Galactic Center sources studied by Buchholz et al (2011Buchholz et al ( , 2013, but they may still provide useful insights.…”

Section: Unresolved Bow Shockmentioning

confidence: 85%

“…Several authors have obtained unresolved polarization observations of bow shocks that we can compare with our simulations. Lin et al (2019) found the intrinsic (ISP-corrected) broadband optical polarization of the candidate bow shock system HD 230561 (spectral type A5) to be 1.05%. Comparing this observation with our model for KMH dust in the 𝑉-band (assuming no dust inside the shock) allowed these authors to constrain the viewing angle to 𝑖 ≈ 60 • or 80 • 𝑖 130 • and the optical depth of the shock region to 𝜏 0 2.…”

Section: Unresolved Bow Shockmentioning

confidence: 99%

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Polarization simulations of stellar wind bow shock nebulae – II. The case of dust scattering

Shrestha

Neilson

Hoffman

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We study the polarization produced by scattering from dust in a bow shock-shaped region of enhanced density surrounding a stellar source, using the Monte Carlo radiative transfer code SLIP. Bow shocks are structures formed by the interaction of the winds of fast-moving stars with the interstellar medium. Our previous study focused on the polarization produced in these structures by electron scattering; we showed that polarization is highly dependent on inclination angle and that multiple scattering changes the shape and degree of polarization. In contrast to electron scattering, dust scattering is wavelength-dependent, which changes the polarization behaviour. Here we explore different dust particle sizes and compositions and generate polarized spectral energy distributions for each case. We find that the polarization SED behaviour depends on the dust composition and grain size. Including dust emission leads to polarization changes with temperature at higher optical depth in ways that are sensitive to the orientation of the bow shock. In various scenarios and under certain assumptions, our simulations can constrain the optical depth and dust properties of resolved and unresolved bow shock-shaped scattering regions.Constraints on optical depth can provide estimates of local ISM density for observed bow shocks. We also study the impact of dust grains filling the region between the star and bow shock. We see that as the density of dust between the star and bow shock increases, the resulting polarization is suppressed for all the optical depth regimes.

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Section: Unresolved Bow Shockmentioning

confidence: 85%

Section: Unresolved Bow Shockmentioning

confidence: 99%

Polarization simulations of stellar wind bow shock nebulae – II. The case of dust scattering

Shrestha

Neilson

Hoffman

et al. 2020

Monthly Notices of the Royal Astronomical Society

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Carbon Chain Depletion of 2I/Borisov

Kareta¹,

Andrews²,

Noonan³

et al. 2020

ApJL

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The composition of comets in the Solar System come in multiple groups thought to encode information about their formation in different regions of the outer protosolar disk. The recent discovery of the second interstellar object, 2I/Borisov, allows for spectroscopic investigations into its gas content and a preliminary classification of it within the Solar System comet taxonomies to test the applicability of planetesimal formation models to other stellar systems. We present spectroscopic and imaging observations from 2019 September 20th through October 26th from the Bok, MMT, and LBT telescopes. We identify CN in the comet's spectrum and set precise upper limits on the abundance of C2 on all dates. We use a Haser model to convert our integrated fluxes to production rates and find Q(CN) = 5.0 +/-2.0 * 10^24 mol/s on September 20 th and Q(CN) = (1.1 -1.9) * 10^24 mols/s on later dates, both consistent with contemporaneous observations. We set our lowest upper limit on a C2 production rate, Q(C2) < 1.6 10^23 mols/s on October 10th. The measured ratio upper limit for that date Q(C2)/Q(CN) < 0.095 indicates that 2I/Borisov is strongly in the (carbon chain) 'depleted' taxonomic group. The only comparable Solar System comets have detected ratios near this limit, making 2I/Borisov statistically likely to be more depleted than any known comet. Most 'depleted' comets are Jupiter Family Comets, perhaps indicating a similarity in formation conditions between the most depleted of the JFCs and 2I/Borisov. More work is needed to understand the applicability of our knowledge of Solar System comet taxonomies onto interstellar objects and we discuss future work that could help to clarify the usefulness of the approach.

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Polarization Observations and Models Constrain the Properties of the Bow Shock around HD 230561

Cited by 2 publications

References 7 publications

Polarization simulations of stellar wind bow shock nebulae – II. The case of dust scattering

Polarization simulations of stellar wind bow shock nebulae – II. The case of dust scattering

Carbon Chain Depletion of 2I/Borisov

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