Astron. Astrophys. Suppl. Ser. 131, 55-62

Physical studies of asteroids

XXXIII. The spin rate of M-type asteroids

C.-I. Lagerkvist¹ - I. Belskaya² - A. Erikson³ - V. Schevchenko² - S. Mottola³ - V. Chiorny² - P. Magnusson¹ - A. Nathues³ - J. Piironen⁴

Send offprint request: C.-I. Lagerkvist

1 - Astronomiska Observatoriet, Box 515, S-752 20 Uppsala, Sverige
2 - Astronomical Observatory, 35 Sumskaya Str., 310022 Kharkiv, Ukraine
3 - Institute of Planetary Exploration, DLR, Rudower Chaussee 5, 12489 Berlin, Germany
4 - Observatory, P.O. Box 14, FIN-00014, University of Helsinki, Finland

Received December 12, 1997; accepted January 30, 1998

Abstract:

The results from photometric lightcurve observations of nine M-type asteroids are presented. New rotation periods were determined for 6 asteroids: 217 Eudora (12.54 h), 322 Phaeo (17.56 h), 572 Rebekka (5.65 h), 757 Portland (6.58 h), 857 Glasenappia (8.23 h) and 872 Holda (7.20 h). B-V colour measurements of seventeen previously unclassified asteroids add seven asteroids to the known M-type population.

An excess of fast rotators among M-type asteroids compared to asteroids of other taxonomic types is evident. The six asteroids with slow spin rates, but hitherto classified as M, are shown to have classification parameters untypical for the M-type population.

Key words: asteroids