J/A+A/470/957 H-band images of IRAS 19312+1950 (Murakawa+, 2007)
Near-infrared polarimetric study of the bipolar nebula IRAS 19312+1950.
Murakawa K., Nakashima J., Ohnaka K., Deguchi S.
<Astron. Astrophys. 470, 957 (2007)>
=2007A&A...470..957M 2007A&A...470..957M
ADC_Keywords: Stars, giant ; Infrared sources ; Polarization
Keywords: polarization - radiative transfer - stars: AGB and post-AGB
Abstract:
We obtained H-band polarimetric data of IRAS 19312+1950 using the
near-infrared camera (CIAO) on the 8m Subaru telescope. In order to
investigate the physical properties of the central star and the
nebula, we performed dust radiative transfer modeling and compared the
model results with the observed spectral energy distributions (SEDs),
the radial profiles of the total intensity image, and the fraction of
linear polarization map. The total intensity image shows a nearly
spherical core with ∼3" radius, an S-shaped arm extending ∼10" in the
northwest to southeast direction, and an extended lobe towards the
southwest. The polarization map shows a centro-symmetric vector
alignment in almost the entire nebula and low polarizations along the
S-shaped arm. These results suggest that the nebula is accompanied by
a central star, and the S-shaped arm has a physically ring-like
structure. From our radiative transfer modeling, we estimated the
stellar temperature, the bolometric luminosity, and the current
mass-loss rate to be 2800K, 7000L☉, and 5.3x10-6M☉/yr,
respectively. Taking into account previous observational results,
such as the detection of SiO maser emissions and silicate absorption
feature in the 10µm spectrum, our dust radiative transfer
analysis based on our NIR imaging polarimetry suggests that (1)
the central star of IRAS 19312+1950 is likely to be an oxygen-rich,
dust-enshrouded AGB star and (2) most of the circumstellar material
originates from other sources (e.g. ambient dark clouds) rather than
as a result of mass loss from the central star.
Objects:
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RA (2000) DE Designation(s)
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19 33 24.3 +19 56 55 IRAS 19312+1950 = MSX6C G055.3704+00.1858
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
images.dat 39 3 List of the FITS files
fits/* . 3 FITS files
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Byte-by-byte Description of file: images.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- FileName Name of the image files in subdirectory fits
12- 39 A28 --- Title Title of the file
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Acknowledgements:
Koji Murakawa, murakawa(at)mpifr-bonn.mpg.de
(End) Patricia Vannier [CDS] 07-May-2007