J/A+A/630/A85 SPHERE images of HD 32297 (Bhowmik+, 2019)
Spatially resolved spectroscopy of the debris disk HD 32297.
Further evidence of small dust grains.
Bhowmik T., Boccaletti A., Thebault P., Kral Q., Mazoyer J., Milli J.,
Maire A.L., van Holstein R.G., Augereau J.-C., Baudoz P., Feldt M. ,
Galicher R., Henning T., Lagrange A.-M., Olofsson J., Pantin E., Perrot C.
<Astron. Astrophys. 630, A85 (2019)>
=2019A&A...630A..85B 2019A&A...630A..85B (SIMBAD/NED BibCode)
ADC_Keywords: YSOs ; Morphology ; Polarization
Keywords: techniques: image processing - stars: individual: HD 32297 -
techniques: high angular resolution - methods: data analysis -
infrared: planetary systems
Abstract:
Spectro-photometry of debris disks in total intensity and polarimetry
can provide new insight into the properties of the dust grains therein
(size distribution and optical properties).
We aim to constrain the morphology of the highly inclined debris disk
HD32297. We also intend to obtain spectroscopic and polarimetric
measurements to retrieve information on the particle size distribution
within the disk for certain grain compositions.
We observed HD32297 with SPHERE in Y, J, and H bands in total
intensity and in J band in polarimetry. The observations are compared
to synthetic models of debris disks and we developed methods to
extract the photometry in total intensity overcoming the
data-reduction artifacts, namely the self-subtraction. The
spectro-photometric measurements averaged along the disk mid-plane are
then compared to model spectra of various grain compositions.
These new images reveal the very inner part of the system as close as
0.15". The disk image is mostly dominated by the forward
scattering making one side (half-ellipse) of the disk more visible,
but observations in total intensity are deep enough to also detect the
back side for the very first time. The images as well as the surface
brightness profiles of the disk rule out the presence of a gap as
previously proposed. We do not detect any significant asymmetry
between the northeast and southwest sides of the disk. The spectral
reflectance features a "gray to blue" color which is interpreted as
the presence of grains far below the blowout size.
The presence of sub-micron grains in the disk is suspected to be the
result of gas drag and/or "avalanche mechanisms". The blue color of
the disk could be further investigated with additional total intensity
and polarimetric observations in K and H bands respectively to confirm
the spectral slope and the fraction of polarization.
Description:
SPHERE/IRDIS and SPHERE/IFS total intensity images and SPHERE/IRDIS
polarimetric images of HD 32297, in contrast delivered by
post-processing with respect to the maximum of the star's PSF.
Objects:
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RA (2000) DE Designation(s)
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05 02 27.44 +07 27 39.7 HD 32297 = HIP 23451
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 136 3 List of fits images
fits/* . 3 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 F9.6 deg RAdeg Right Ascension of center (J2000)
10- 17 F8.5 deg DEdeg Declination of center (J2000)
19- 25 F7.5 arcsec/pix scale Scale of the image
27- 30 I4 --- Nx Number of pixels along X-axis
32- 35 I4 --- Ny Number of pixels along Y-axis
37- 60 A24 "datime" Obs.date Observation date
62- 65 I4 Kibyte size Size of FITS file
67- 88 A22 --- FileName Name of FITS file, in subdirectory fits
90-136 A47 --- Title Title of the FITS file
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Acknowledgements:
Trisha Bhowmik, Trisha.Bhowmik(at)obspm.fr
(End) Patricia Vannier [CDS] 23-Aug-2019