J/A+A/682/A56 IRAS 16293-2422 B ALMA images (Zamponi+, 2024)
Exploring the dust grain size and polarization mechanism in the hot and massive
Class 0 disk IRAS 16293-2422 B.
Zamponi J., Maureira M.J., Liu H.B., Zhao B., Segura-Cox D., Ko C.-L.,
Caselli P.
<Astron. Astrophys. 682, A56 (2024)>
=2024A&A...682A..56Z 2024A&A...682A..56Z (SIMBAD/NED BibCode)
ADC_Keywords: YSOs ; Infrared sources
Keywords: polarization - radiative transfer - scattering -
protoplanetary disks - stars: protostars
Abstract:
Multiwavelength dust continuum and polarization observations arising
from self-scattering have been used to investigate grain sizes in
young disks. However, the likelihood of self-scattering being the
polarization mechanism in embedded disks decreases for very highly
optically thick disks and puts some of the size constraints from
polarization on hold, particularly for the younger and more massive
disks. The 1.3mm polarized emission detected toward the hot (≥400K)
Class 0 disk IRAS 16293-2422 B has been attributed to self-scattering,
predicting bare grain sizes between 200-2000um.
We aim to investigate the effects of changing the maximum grain sizes
in the resultant continuum and continuum polarization fractions from
self-scattering for a hot and massive Class 0 disk extracted from
numerical simulations of prestellar core collapse and compare with
IRAS 16293 B observations.
We compared new and archival dust continuum and polarization
observations at high-resolution between 1.3 and 18mm to a set of
synthetic models. We have developed a new public tool to automate this
process called Synthesizer. This is an easy-to-use program to generate
synthetic observations from numerical simulations.
Optical depths are in the range of 130 to 2 from 1.3 to 18mm,
respectively Predictions from significant grain growth populations,
including amax=1000um are comparable to the observations from IRAS
16293 B at all observed wavelengths. The polarization fraction
produced by self-scattering reaches a maximum of ∼0.1% at 1.3mm for a
maximum grain size of 100um, which is an order of magnitude
lower than that observed toward IRAS 16293 B.
From the comparison of the Stokes I fluxes, we conclude that
significant grain growth could be present in the young Class 0 disk
IRAS 16293 B, particularly in the inner hot region (<10au, T>300K)
where refractory organics evaporate. The polarization produced by
self-scattering in our model is not high enough to explain the
observations at 1.3 and 7mm, and effects like dichroic extinction or
polarization reversal of elongated aligned grains remain other
possible but untested scenarios.
Description:
We compiled archival multiwavelength polarization observations of IRAS
16293-2422 B at 1.3mm (ALMA Band 6), 3mm (ALMA Band 3), and 7mm (JVLA
Band Q).
We present JVLA standard continuum mode observations at the Ka (9mm)
and Ku bands (18mm) toward IRAS 16293-2422 B.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 191 8 List of fits images
fits/* . 8 Individual fits images
table1.dat 29 6 Dust opacities used in this work for different
maximum grain sizes, for different compositions,
and at four wavelengths
fig3/* . 9 *Dust opacity tables used in Fig. 3
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Note on fig3/*: Files are:
dustkappa_s-a*um.inp Dust opacity table for silicate dust
dustkappa_sg-a*um.inp Dust opacity table for silicate+graphite dust
*_sgo-a*um-80org.inp Dust opacity table for sil.+gra.+ (0.8)organics
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 22 I3 --- Nx Number of pixels along X-axis
24- 26 I3 --- Ny Number of pixels along Y-axis
28- 53 A26 "datime" Obs.date Observation date
55- 65 E11.6 Hz Freq ? Observed frequency
67- 70 I4 Kibyte size Size of FITS file
72- 92 A21 --- FileName Name of FITS file, in subdirectory fits
94-191 A98 --- Title Title of the FITS file
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 um amax Maxmium grain sizes
6- 8 A3 --- Mix Composition (1)
10- 14 F5.2 g/cm2 DO1.3mm Band 6 1.3mm dust opacity
16- 19 F4.2 g/cm2 DO3mm Band 3 3mm dust opacity
21- 24 F4.2 g/cm2 DO9mm Band Ka 9mm dust opacity
26- 29 F4.2 g/cm2 DO18mm Band Ku 18mm dust opacity
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Note (1): Compositions as follows:
sg = silicate with graphite (s-g), with mass fractions of 0.625 and 0.375,
respectively
sgo = silicate with graphite and refractory organics (s-g-o), with mass
fractions 0.625, 0.1875, and 0.1875 (80% of carbon), respectively
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Acknowledgements:
Joaquin Zamponi, jzamponi(at)mpe.mpg.de
(End) Joaquin Zamponi [MPE, Germany], Patricia Vannier [CDS] 18-Dec-2023