A1 Refereed original research article in a scientific journal
Polarimetry of M-type asteroids in the context of their surface composition
Authors: Belskaya I, Berdyugin Andrei, Krugly Y, Donchev Z, Sergeyev A, Gil-Hutton R, Mykhailova S, Bonev T, Piirola Vilppu, Berdyugina S, Kagitani M, Sakanoi T
Publisher: EDP SCIENCES S A
Publication year: 2022
Journal: Astronomy and Astrophysics
Journal name in source: ASTRONOMY & ASTROPHYSICS
Journal acronym: ASTRON ASTROPHYS
Article number: A146
Volume: 663
Number of pages: 11
ISSN: 0004-6361
eISSN: 1432-0746
DOI: https://doi.org/10.1051/0004-6361/202142784(external)
Web address : https://doi.org/10.1051/0004-6361/202142784 (external)
Aims. We aim to investigate how polarimetric observations can improve our understanding of the nature and diversity of M/X-type asteroids.
Methods. Polarimetric observations of the selected M/X-type asteroids were carried out at the Tohoku 0.6-m telescope at Haleakala Observatory, Hawaii (simultaneously in BVR filters), the 2-m telescope of the Bulgarian National Astronomical Observatory in Rozhen (in R filter), and the 2.15-m telescope of the Complejo Astronomico El Leoncito (CASLEO), Argentina (in V filter). We analysed the polarimetric characteristics of M/X-type asteroids along with the available data obtained by other techniques.
Results. New polarimetric observations of 22 M/X-type asteroids combined with published observations provide a data set of 41 asteroids for which the depth of a negative polarisation branch and/or inversion angle were determined. We found that the depth of the negative polarisation branch tends to increase with decreasing steepness of the near-infrared spectra. Asteroids with a deeper negative polarisation branch tend to have a higher radar circular polarisation ratio. We show that, based on the relationship of the depth of the negative polarisation branch and inversion angle, two main sub-types can be distinguished among M-type asteroids. We suggest that these groups may be related to different surface compositions similar to (1) irons and stony-irons and (2) enstatite and iron-rich carbonaceous chondrites.