J/A+A/556/A123 Near-IR imaging polarimetry of HD142527 (Canovas+, 2013)
Near-infrared imaging polarimetry of HD142527.
Canovas H., Menard F., Hales A., Jordan A., Schreiber M.R., Casassus S.,
Gledhill T.M., Pinte C.
<Astron. Astrophys. 556, A123 (2013)>
=2013A&A...556A.123C 2013A&A...556A.123C
ADC_Keywords: Stars, variable ; Stars, nearby ; Polarization
Keywords: protoplanetary disks - stars: variables: T Tauri, Herbig Ae/Be -
techniques: polarimetric
Abstract:
HD 142527 is a pre-transition disk with strong evidence for ongoing
planet formation. Recent observations show a disrupted disk with
spiral arms, a dust-depleted inner cavity and the possible presence of
gas streams driving gas from the outer disk toward the central star.
We aim to derive the morphology of the disk, and the distribution and
properties of the dust at its surface. We have obtained polarized
differential images of HD 142527 at H and Ks bands with NaCo at the
VLT. Combining these images with classical PSF-subtraction, we are
able to derive the polarization degree of this disk. Results. At
H band the polarization degree of the disk varies between 10% and 25%.
This result cannot be reproduced by dust distributions containing
highly porous material. The polarization is better matched by
distributions of compact particles, with maximum sizes at least up to
a few microns, in agreement with previous observations. We also
observe two regions of low emission (nulls) in total and in polarized
intensity. In particular, one of these nulls is at roughly the same
position as the maximum of the horse-shoe shape observed in sub-
millimeter continuum emission ALMA band-7 (345GHz) observations. We
discuss the possible link between these two features.
Description:
Imaging polarimetry data of the protoplanetary disk HD 142527 and the
comparison (diskless) star HD 161743 is provided here.
The observations were performed with NaCo/VLT in H and Ks filters,
with exposure times ranging from 0.4s to 15s. All the images shown
here were normalized to 1s exposure time.
Each FITS file is a data-cube that contains 4 images of 160x160 pixels
(4.32"x4.32"). In all files, the images inside the Cube-FITS are
organized as: Stokes I image, Stokes Q image, Stokes U image,
Polarized Intensity (PI) Image. The images were reduced with
custom-made IDL routines. The raw data can be found in the ESO public
archive service, under program ID: 089.C-0480(A), PI: SCHREIBER, M.
Objects:
------------------------------------------------------
RA (2000) DE Designation(s)
------------------------------------------------------
15 56 41.89 -42 19 23.3 HD 142527 = TYC 7846-688-1
17 48 57.93 -38 07 07.5 HD 161743 = TYC 7885-524-1
------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
list.dat 68 10 FITS file list in fits directory
fits/* . 10 I,Q,U,PI image cube-FITS
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See also:
J/A+A/546/A24 : VLT/NaCo images of HD 142527 (Rameau+, 2012)
Byte-by-byte Description of file: list.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Name HD name (HD 142527 or HD 161743)
11- 19 F9.5 deg RAdeg Right Ascension of center (J2000)
20- 28 F9.5 deg DEdeg Declination of center (J2000)
30- 35 F6.4 arcsec/pix Scale [0.0272] Scale of the image
37- 39 I3 pix Nx [160] Number of pixels along X-axis
40 A1 --- --- [x]
41- 43 I3 pix Ny [160] Number of pixels along Y-axis
44 A1 --- --- [x]
45 I1 --- Nz [4] Number of Stokes parameters
47- 50 F4.1 s Exp [0.4/15] Exposure time
52- 53 A2 --- Filt [H Ks] Filter
55- 68 A14 --- FileName Name of FITS file in subdirectory fits
--------------------------------------------------------------------------------
Acknowledgements:
Hector Canovas, <hectorcan( at )gmail.com>
References:
Canovas et al., 2011A&A...531A.102C 2011A&A...531A.102C
Data-reduction techniques for high-contrast imaging polarimetry.
(End) Hector Canovas [Univ. Valparaiso, Chile], E. Perret [CDS] 05-Jul-2013