J/A+A/626/A42 Polarimetry of Main-Belt Asteroids (Lopez-Sisterna+, 2019)
Polarimetric survey of main-belt asteroids. VII. New results for 82 main-belt
objects.
Lopez-Sisterna C., Garcia-Migani E., Gil-Hutton R.
<Astron. Astrophys. 626, A42 (2019)>
=2019A&A...626A..42L 2019A&A...626A..42L (SIMBAD/NED BibCode)
ADC_Keywords: Minor planets ; Polarization
Keywords: minor planets, asteroids: general - techniques: polarimetric
Abstract:
We present the results of a polarimetric survey of main-belt asteroids
at Complejo Astronomico El Leoncito (CASLEO), San Juan, Argentina.
The aims of this survey are to increase the database of asteroid
polarimetry and to estimate the diversity in the polarimetric
properties of asteroids.
The survey began in 1995 and a second period began in 2013 using the
CASPOL polarimeter with a more sensitive detector to study small
asteroids, families, and special taxonomic groups. The data were
obtained using this instrument at the 2.15 m telescope of CASLEO.
We present 128 observations for 82 asteroids of different taxonomic
types. These results revealed phase-polarization curves and
polarimetric parameters for 20 asteroids, amounting to a total of 135
objects with sufficient good data in the Catalogue of Asteroid
Polarization Curves. Using the values obtained for the objects with a
taxonomic classification, we obtained the mean polarimetric parameters
for 19 taxonomic types and the Barbarians. The asteroids with large
mean scatter separation distances have a minimum of the
phase-polarization curve greater than -1%, slopes at the inversion
angle of less than 0.12-0.15% per degree, and perihelion distances
1.8<q<2.5 au; these measurements indicate the asteroids could have
high or moderate albedos and that they are objects with perihelia in
the inner asteroid belt. These large mean scatter separation distance
values could be the result of an electrostatic mechanism acting on the
small grains of the regolith, a manifestation of a coherent
backscattering mechanism, or the result of a surface formed by a
mixture of dark and bright particles.
Description:
New results of the polarimetric survey of main-belt objects at
Complejo Astronomico El Leoncito (CASLEO), San Juan, Argentina.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 76 128 Polarimetric data for the asteroids observed
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 18 A18 --- Asteroid Asteroid name
20- 29 A10 "date" Date UT Date
31- 34 I4 s Tint Total integration time
36- 39 F4.1 deg alpha Phase angle
41- 45 F5.1 deg thetasun Position angle of the scattering plane
47- 50 F4.2 % P Observed polarization
52- 55 F4.2 % e_P Error in observed polarization
57- 61 F5.1 deg theta Position angle in the equatorial
reference frame
63- 66 F4.1 deg e_theta Error in position angle in the
equatorial reference frame
68- 72 F5.2 % Pr Reduced polarization
74- 76 A3 --- Tax Bus taxonomic classification (1)
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Note (1): The taxonomic types in bold are from Tholen, D. J. 1989, in
Asteroids II, ed. R. P. Binzel, T. Gehrels, & M. S. Matthews, pp. 1139-1150.
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Acknowledgements:
Ricardo Gil-Hutton, ricardo.gil-hutton(at)conicet.gov.ar
GCP,FCEFN,UNSJ-CONICET, Argentina
(End) R. Gil-Hutton [UNSJ-CONICET, Argentina], P. Vannier [CDS] 19-May-2019