J/A+A/664/A137 HD 163296 disk rings distribution of solids (Guidi+, 2022)
Distribution of solids in the rings of the HD 163296 disk:
a multiwavelength study.
Guidi G., Isella A., Testi L., Chandler C.J., Liu H.B., Schmid H.M.,
Rosotti G., Meng C., Jennings J., Williams J.P., Carpenter J.M.,
de Gregorio-Monsalvo I., Li H., Liu S.F., Ortolani S., Quanz S.P.,
Ricci L., Tazzari M.
<Astron. Astrophys. 664, A137 (2022)>
=2022A&A...664A.137G 2022A&A...664A.137G (SIMBAD/NED BibCode)
ADC_Keywords: Protostars ; Interferometry ; Radio continuum
Keywords: protoplanetary disks - stars: pre-main sequence -
instrumentation: interferometers - (ISM:) dust, extinction -
radiative transfer - instrumentation: high angular resolution
Abstract:
Observations at millimeter wavelengths of bright protoplanetary disks
have shown the ubiquitous presence of structures such as rings and
spirals in the continuum emission. The derivation of the underlying
properties of the emitting material is nontrivial because of the
complex radiative processes involved.
In this paper we analyze new observations from the Atacama Large
Millimeter/submillimeter Array (ALMA) and the Karl G. Jansky Very
Large Array (VLA) at high angular resolution corresponding to 5-8au to
determine the dust spatial distribution and grain properties in the
ringed disk of HD 163296. We fit the spectral energy distribution as a
function of the radius at five wavelengths from 0.9 to 9mm, using a
simple power law and a physical model based on an analytic description
of radiative transfer that includes isothermal scattering. We
considered eight dust populations and compared the models'
performance using Bayesian evidence.
Our analysis shows that the moderately high optical depth (τ>1) at
lσ≤1.3mm in the dust rings artificially lower the millimeter
spectral index, which should therefore not be considered as a reliable
direct proxy of the dust properties and especially the grain size. We
find that the outer disk is composed of small grains on the order of
200m with no significant difference between rings at 66 and 100au and
the adjacent gaps, while in the innermost ∼30au, larger grains (≥mm)
could be present. We show that the assumptions on the dust composition
have a strong impact on the derived surface densities and grain size.
In particular, increasing the porosity of the grains to 80% results in
a total dust mass about five times higher with respect to grains with
25% porosity. Finally, we find that the derived opacities as a
function of frequency deviate from a simple power law and that grains
with a lower porosity seem to better reproduce the observations of HD
163296. While we do not find evidence of differential trapping in the
rings of HD 163296, our overall results are consistent with the
postulated presence of giant planets affecting the dust temperature
structure and surface density, and possibly originating a
second-generation dust population of small grains.
Description:
We present a new set of (sub)millimeter observations of the ringed
disk around the Herbig Ae star HD 163296, obtained through multiple
ALMA and VLA programs in the past years.
The ALMA continuum maps result from the combination of programs at
Band 7, Band 4 and Band 3 with ID 2015.1.00725.S (PI Guidi),
2016.1.01086.S (PI Isella), 2017.1.01682.S (PI Guidi), and archival
Band 6 data from the DSHARP large program 2016.1.00484.L (PI Andrews).
The VLA continuum maps at Ka Band and X Band are produced from the
observing programs VLA/16B-221 (PI Isella) and VLA/17B-185 (PI Guidi).
The resulting continuum maps are shown in Figure 1 of the paper, and
named here as fig1X.fit, where X is an alphabetical character
increasing progressively with the wavelength of the image and
reflecting the order of the images in Figure 1 (from left to right,
and top to bottom). We omit the image related to archival Band 6 data
as it was already presented by Andrews et al., (2018ApJ...869L..41A 2018ApJ...869L..41A,
Cat. J/ApJ/869/L41) and available at
https://almascience.eso.org/almadata/lp/DSHARP/.
Objects:
----------------------------------------------------------
RA (2000) DE Designation(s)
----------------------------------------------------------
17 56 21.29 -21 57 21.9 HD 163296 = HIP 87819
----------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
list.dat 105 8 List of fits images
fits/* . 8 Individual fits images
--------------------------------------------------------------------------------
See also:
J/ApJ/869/L41 : DSHARP I. Sample, ALMA obs. log and overview (Andrews+, 2018)
Byte-by-byte Description of file: list.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 23 I4 --- Nx Number of pixels along X-axis
25- 28 I4 --- Ny Number of pixels along Y-axis
30- 52 A23 "datime" Obs.date Observation date
54- 62 F9.5 GHz Freq Observed frequency
64- 69 I6 Kibyte size Size of FITS file
71- 86 A16 --- FileName Name of FITS file, in subdirectory fits
88-105 A18 --- Title Title of the FITS file
--------------------------------------------------------------------------------
Acknowledgements:
Greta Guidi, greta.guidi(at)phys.ethz.ch
(End) Patricia Vannier [CDS] 05-Jul-2022