V. Ali-Lagoa; J. de Leon; J. Licandro; M. Delbo; H. Campins; N. Pinilla-Alonso;M. S. Kelley


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Abbreviated Journal Title

Astron. Astrophys.


minor planets, asteroids: general; surveys; infrared: planetary systems; NEAR-EARTH ASTEROIDS; INFRARED-SURVEY-EXPLORER; MAIN-BELT; SPECTROSCOPIC; SURVEY; THERMAL-MODEL; WATER-ICE; 65 CYBELE; 24 THEMIS; ORGANICS; FAMILIES; Astronomy & Astrophysics


Aims. Our aim is to obtain more information about the physical nature of B-type asteroids and extend previous work by studying their physical properties as derived from fitting an asteroid thermal model to their NASA's Wide-field Infrared Survey Explorer (WISE) data. We also examine the Pallas collisional family, a B-type family with a moderately high albedo in contrast to the large majority of B-types. Methods. We applied a combination of the near-Earth asteroid thermal model and a model of the reflected sunlight to WISE asteroid data in order to derive up to four parameters: effective diameter (D), the so-called infrared beaming parameter (eta), ratio of infrared to visible albedo (R-p = p(IR)/p(V)), and visible geometric albedo (p(V)). Results. We obtained the effective diameter, geometric visible albedo, infrared-to-visible albedo ratio, and beaming parameter for greater than or similar to 100 B-types asteroids and plotted the value distributions of p(V), R-p, and eta ((p) over bar (V) = 0.07 +/- 0.03, (R) over bar (p) = 1.0 +/- 0.2, and (eta) over bar = 1.0 +/- 0.1). By combining the IR and visible albedos with 2.5 mu m reflectances from the literature we obtained the ratio of reflectances at 3.4 and 2.5 mu m, from which we found statistically significant indications that the presence of a 3-mu m absorption band related to water may be commonplace among the B-types. Finally, the Pallas collisional family members studied (similar to 50 objects) present moderately high values of p(V), (p) over bar (V) = 0.14 +/- 0.05, which is significantly higher than the average albedo of B-types. In addition, this family presents the lowest and most homogeneously distributed R-p-values of our whole sample, which shows that this group is clearly different from the other B-types, probably because its members are fragments likely originating from the same region of (2) Pallas, a particularly high-albedo B-type asteroid.

Journal Title

Astronomy & Astrophysics



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