J/A+A/619/A161 ALMA images of HD 135344B (Cazzoletti+, 2018)
Evidence for a massive dust-trapping vortex connected to spirals.
Multi-wavelength analysis of the HD 135344B protoplanetary disk.
Cazzoletti P., van Dishoeck E. F., Pinilla P., Tazzari M., Facchini S.,
van der Marel N., Benisty M., Garufi A., Perez L.
<Astron. Astrophys. 619, A161 (2018)>
=2018A&A...619A.161C 2018A&A...619A.161C (SIMBAD/NED BibCode)
ADC_Keywords: YSOs ; Stars, double and multiple ; Millimetric/submm sources
Keywords: protoplanetary disks - planet-disk interaction -
stars: individual: HD 135344B - planets and satellites: formation -
instabilities
Abstract:
Spiral arms, rings and large scale asymmetries are structures observed
in high resolution observations of protoplanetary disks, and it
appears that some of the disks showing spiral arms in scattered light
also show asymmetries in millimeter-sized dust. HD 135344B is one of
these disks. Planets are invoked as the origin of these structures,
but no planet has been observed so far and up per limits are becoming
more stringent with time.
We want to investigate the nature of the asymmetric structure in the
HD 135344B disk in order to understand the origin of the spirals and
of the asymmetry seen in this disk. Ultimately, we aim at
understanding whether or not one or more planets are needed to explain
such structures.
We present new ALMA sub-0.1" resolution observations at optically thin
wavelengths (lambda=2.8mm and 1.9mm) of the HD 135344B disk. The
high spatial resolution allows us to unambiguously characterize the
mm-dust morphology of the disk. The low optical depth of continuum
emission probes the bulk of the dust content of the vortex. Moreover,
we combine the new observations with archival data at shorter
wavelengths to perform a multi-wavelength analysis and to obtain
information about the dust distribution and properties inside the
observed asymmetry.
We resolve the asymmetric disk into a symmetric ring + asymmetric
crescent, and observe that: (1) the spectral index strongly decreases
at the center of the vortex, consistent with the presence of large
grains; (2) for the first time, an azimuthal shift of the peak of the
vortex with wavelength is observed; (3) the azimuthal width of the
vortex decreases at longer wavelengths, as expected for dust traps.
These features allow to confirm the nature of the asymmetry as a
vortex. Finally, under the assumption of optically thin emission, a
lower limit to the total mass of the vortex is 0.3MJupiter.
Considering the uncertainties involved in this estimate, it is
possible that the actual mass of the vortex is higher and possibly
within the required values (∼4MJupiter) to launch spiral arms
similar to those observed in scattered light. If this is the case, no
outer planet is needed to explain the morphology.
Description:
Continuum ALMA data at 1.9mm (Band 4) and 2.8mm (Band 3) of the HD
135344B disk. These data are part of three different projects. The
Band 4 data have been observed in C40-8 configuration during ALMA
Cycle 4 in two execution blocks on September 14th, 2017 and September
28th, 2017 as part of program 2016.1.00340.S with 41 and 42 antennas.
Additional Band 4 observations were carried out during Cycle 5 in
C43-5 configuration, on January 17th, 2018 as part of the program
2017.A.00025.S using 44 antennas. The Band 3 data were observed in
Cycle 5 in the C43-8 configuration on November 11th, 2017
(2017.1.00884.S) using 44 antennas, and in the C43-5 configuration on
January 17th, 2018 (2017.A.00025.S) with 46 antennas. More details as
well as the correlator setup are described in the paper.
Objects:
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RA (2000) DE Designation(s)
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15 15 48.45 -37 09 16.0 HD 135344B = CD-36 10010B
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 153 2 List of fits images
image/* . 2 Individual fits images
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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 Obvervation date (YYYY/MM/DDThh:mm:ss.ssssss)
55- 61 F7.3 GHz Freq Observed frequency
63- 65 I3 Kibyte size Size of FITS file
67- 99 A33 --- FileName Name of FITS file, in subdirectory image
101-153 A53 --- Title Title of the FITS file
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Acknowledgements:
Paolo Cazzoletti, pcazzoletti(at)mpe.mpg.de
(End) Paolo Cazzoletti [MPE], Patricia Vannier [CDS] 14-Sep-2018