Validating scattering-induced (sub)millimetre disc polarization through the spectral index, wavelength-dependent polarization pattern, and polarization spectrum: the case of HD 163296

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F20%3A00553648" target="_blank" >RIV/67985815:_____/20:00553648 - isvavai.cz</a>

Výsledek na webu

<a href="https://doi.org/10.1093/mnras/staa1499" target="_blank" >https://doi.org/10.1093/mnras/staa1499</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1093/mnras/staa1499" target="_blank" >10.1093/mnras/staa1499</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Validating scattering-induced (sub)millimetre disc polarization through the spectral index, wavelength-dependent polarization pattern, and polarization spectrum: the case of HD 163296

Popis výsledku v původním jazyce

A number of young circumstellar discs show strikingly ordered (sub)millimetre polarization orientations along the minor axis, which is strong evidence for polarization due to scattering by similar to 0.1 mm-sized grains. To test this mechanism further, we model the ALMA dust continuum and polarization data of HD 163296 using RADMC-3D. We find that scattering by grains with a maximum size of 90 mu m simultaneously reproduces the polarization observed at Band 7 and the unusually low spectral index (alpha similar to 1.5) between Bands 7 and 6 in the optically thick inner disc as a result of more efficient scattering at the shorter wavelength. The low spectral index of similar to 2.5 inferred for the optically thin gaps is reproduced by the same grains, as a result of telescope beam averaging of the gaps (with an intrinsic alpha similar to 4) and their adjacent optically thick rings (where alpha less than or similar to 2). The tension between the grain sizes inferred from polarization and spectral index disappears because the low a values do not require large mm-sized grains. In addition, the polarization fraction has a unique azimuthal variation: higher along the major axis than the minor axis in the gaps, but vice versa in the rings. We find a rapidly declining polarization spectrum (with p alpha lambda(-3) approximately) in the gaps, which becomes flattened or even inverted towards short wavelengths in the optically thick rings. These contrasting behaviours in the rings and gaps provide further tests for scattering-induced polarization via resolved multiwavelength observations.

Název v anglickém jazyce

Validating scattering-induced (sub)millimetre disc polarization through the spectral index, wavelength-dependent polarization pattern, and polarization spectrum: the case of HD 163296

Popis výsledku anglicky

A number of young circumstellar discs show strikingly ordered (sub)millimetre polarization orientations along the minor axis, which is strong evidence for polarization due to scattering by similar to 0.1 mm-sized grains. To test this mechanism further, we model the ALMA dust continuum and polarization data of HD 163296 using RADMC-3D. We find that scattering by grains with a maximum size of 90 mu m simultaneously reproduces the polarization observed at Band 7 and the unusually low spectral index (alpha similar to 1.5) between Bands 7 and 6 in the optically thick inner disc as a result of more efficient scattering at the shorter wavelength. The low spectral index of similar to 2.5 inferred for the optically thin gaps is reproduced by the same grains, as a result of telescope beam averaging of the gaps (with an intrinsic alpha similar to 4) and their adjacent optically thick rings (where alpha less than or similar to 2). The tension between the grain sizes inferred from polarization and spectral index disappears because the low a values do not require large mm-sized grains. In addition, the polarization fraction has a unique azimuthal variation: higher along the major axis than the minor axis in the gaps, but vice versa in the rings. We find a rapidly declining polarization spectrum (with p alpha lambda(-3) approximately) in the gaps, which becomes flattened or even inverted towards short wavelengths in the optically thick rings. These contrasting behaviours in the rings and gaps provide further tests for scattering-induced polarization via resolved multiwavelength observations.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10308 - Astronomy (including astrophysics,space science)

Projekt

—

Návaznosti

—

Rok uplatnění

2020

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Monthly Notices of the Royal Astronomical Society

ISSN

0035-8711

e-ISSN

1365-2966

Svazek periodika

496

Číslo periodika v rámci svazku

1

Stát vydavatele periodika

GB - Spojené království Velké Británie a Severního Irska

Počet stran výsledku

13

Strana od-do

169-181

Kód UT WoS článku

000560784700014

EID výsledku v databázi Scopus

2-s2.0-85088563714