J/A+A/649/A84 IR band features around HD100546 (Habart+, 2021)
Spatial distribution of the aromatic and aliphatic carbonaceous nanograin
features in the protoplanetary disk around HD 100546.
Habart E., Bouteraon T., Brauer R., Ysard N., Pantin E., Marchal A.,
Jones A.P.
<Astron. Astrophys. 649, A84 (2021)>
=2021A&A...649A..84H 2021A&A...649A..84H (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Infrared sources ; Spectroscopy
Keywords: protoplanetary disk - infrared: planetary systems
Abstract:
Carbonaceous nanograins are present at the surface of protoplanetary
disks around Herbig Ae/Be stars, where most of the ultraviolet energy
from the central star is dissipated. Efficiently coupled to the gas,
they are unavoidable to understand the physics and chemistry of these
disks. Furthermore, nanograins are able to trace the outer flaring
parts of the disk and possibly the gaps from which the larger grains
are missing. However, their evolution through the disks, from internal
to external regions, is only poorly understood so far.
Our aim is to examine the spatial distribution and evolution of the
nanodust emission in the emblematic (pre-)transitional protoplanetary
disk HD 100546. This disk shows many structures (annular gaps, rings,
and spirals) and reveals very rich carbon nanodust spectroscopic
signatures (aromatic, aliphatic) in a wide spatial range of the disk
(∼20-200au).
We analysed adaptive optics spectroscopic observations in the 3-4um
range (angular resolution of ∼0.1") and imaging and spectroscopic
observations in the 8-12um range (angular resolution of ∼0.3"). The
hyperspectral cube was decomposed into a sum of spatially coherent
dust components using a Gaussian decomposition algorithm. We compared
the data to model predictions using the heterogeneous dust evolution
model for interstellar solids (THEMIS), which is integrated in the
radiative transfer code POLARIS by calculating the thermal and
stochastic heating of micro- and nanometre-sized dust grains for a
given disk structure.
We find that the aromatic features at 3.3, 8.6, and 11.3um, and
the aliphatic features between 3.4 and 3.5um are spatially
extended; each band shows a specific morphology dependent on the local
physical conditions. The aliphatic-to-aromatic band ratio, 3.4/3.3,
increases with the distance from the star from ∼0.2 (at 0.2" or 20au)
to ∼0.45 (at 1" or 100au), suggesting UV processing.
In the 8-12um observed spectra, several features characteristic
of aromatic particles and crystalline silicates are detected. Their
relative contribution changes with the distance to the star.
The model predicts that the features and adjacent continuum are due to
different combinations of grain sub-populations, in most cases with a
high dependence on the intensity of the UV field.
The model reproduces the spatial emission profiles of the bands well,
except for the inner 20-40au, where the observed emission of the 3.3
and 3.4um bands is, unlike the predictions, flat and no longer
increases with the UV field.
With our approach that combines observational data in the near- to
mid-IR and disk modelling, we deliver constraints on the spatial
distribution of nano-dust particles as a function of the disk
structure and radiation field.
Description:
NACOdatacube_HD100546.fits:
Reduced NACO data of spatially resolved infrared emission in the
L-band (3-4 microns) of proto-planetary disc around Ae/Be Herbig star
HD100546. Spectra are in arbitrary units. Acquisition has been made
with NAOS CONICA at the VLT. The raw data-set reference is
075.C-0624(A).
spectra.dat:
Reduced VISIR data of spatially resolved infrared emission in the
N-band (8-13 microns) of proto-planetary disc around Ae/Be Herbig star
HD100546. The first column gives the wavelength in micron. The other
columns gives the VISIR extracted spectra in Jy/arcsec^2 at different
distances d from the star (d= 0.00", d=0.50", d=1.00", d=1.25",
d=1.50", d=1.75", d=2.00"). Acquisition has been made with VISIR at
the VLT. The data was obtained as part of the VISIR GTO program on
circumstellar disks.
Objects:
-------------------------------------------------------
RA (2000) DE Designation(s)
-------------------------------------------------------
11 33 25.44 -70 11 41.2 HD100546 = HIP 56379
-------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
spectra.dat 71 512 Reduced VISIR data of spatially resolved infrared
emission in the N-band (8-13 microns) of
proto-planetary disc around Ae/Be Herbig star
HD 100546
list.dat 225 1 Information on fits datacube
fits/* . 1 Data cube
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See also:
J/A+A/592/A83 : HD 100546 and TW Hya model abundances (Kama+, 2016)
Byte-by-byte Description of file: spectra.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
2- 8 F7.4 um lambda Wavelength in micron
10- 17 E8.3 Jy/arcsec2 sp0.00 Spectra at star distance d=0.00"
19- 26 E8.3 Jy/arcsec2 sp0.50 Spectra at star distance d=0.50"
28- 35 E8.3 Jy/arcsec2 sp1.00 Spectra at star distance d=1.00"
37- 44 E8.3 Jy/arcsec2 sp1.25 Spectra at star distance d=1.25"
46- 53 E8.3 Jy/arcsec2 sp1.50 Spectra at star distance d=1.50"
55- 62 E8.3 Jy/arcsec2 sp1.75 Spectra at star distance d=1.75"
64- 71 E8.3 Jy/arcsec2 sp2.00 ?=- Spectra at star distance d=2"
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Byte-by-byte Description of file: list.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 h RAh Right Ascension (J2000)
4- 5 I2 min RAm Right Ascension (J2000)
7- 19 F13.10 s RAs Right Ascension (J2000)
20 A1 --- DE- Declination sign (J2000)
21- 22 I2 deg DEd Declination (J2000)
24- 25 I2 arcmin DEm Declination (J2000)
27- 38 F12.9 arcsec DEs Declination (J2000)
40- 41 I2 --- Nx Number of pixels along X-axis
43 I1 --- Ny Number of pixels along Y-axis
45- 47 I3 --- Nz Number of slices
49- 52 I4 Kibyte size Size of FITS file
54- 81 A28 --- FileName Name of FITS file, in subdirectory fits
83-225 A143 --- Title Title of the FITS file
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Acknowledgements:
Emilie Habart, emilie.habart(at)ias.u-psud.fr
(End) Patricia Vannier [CDS] 29-Mar-2021