E. Bowell¹, D. A. Oszkiewicz^2,3,*, L. H. Wasserman¹, K. Muinonen^2,4, A. Penttilä², D. E. Trilling⁵

¹Lowell Observatory, Flagstaff, Arizona, USA
²Department of Physics, University of Helsinki, Helsinki, Finland
³Institute Astronomical Observatory, Faculty of Physics, Adam Mickiewicz University, Poznań, Poland
⁴Finnish Geodetic Institute, Masala, Finland

By analyzing brightness variation with ecliptic longitude and using the Lowell Observatory photometric database, we estimate spin-axis longitudes for more than 350,000 asteroids. Hitherto, spin-axis longitude estimates have been made for fewer than 200 asteroids. We investigate longitude distributions in different dynamical groups and asteroid families. We show that asteroid spin-axis longitudes are not isotropically distributed as previously considered. We find that the spin-axis longitude distribution for Main Belt asteroids is clearly nonrandom, with an excess of longitudes from the interval 30°–110° and a paucity between 120° and 180°. The explanation of the nonisotropic distribution is unknown at this point. Further studies have to be conducted to determine if the shape of the distribution can be explained by observational bias, selection effects, a real physical process, or other mechanism.

Reference
Bowell E, Oszkiewicz DA, Wasserman LH, Muinonen K, Penttilä A and Trilling DE (in press) Asteroid spin-axis longitudes from the Lowell Observatory database. Meteoritics & Planetary Science
[doi:10.1111/maps.12230]
Published by arrangement with John Wiley & Sons

Link to Article