LIGHTCURVES OF THE KARIN FAMILY ASTEROIDS - Advances in Geosciences - page 317

LIGHTCURVES OF THE KARIN FAMILY ASTEROIDS
TAKASHI ITO and FUMI YOSHIDA ∗
National Astronomical Observatory of Japan
Osawa 2-21-1, Mitaka, Tokyo 181-8588, Japan
∗ [e-mail]
We present the first results of a long-term campaign of photometric observa-
tions of the Karin family asteroids. This family is very compact, and is supposed
to be extremely young, with an estimated age of about 5.8 Myrs. The purpose
of our observations is to determine the rotational properties, the colors and
hopefully the overall shapes of the largest possible number of family members,
since this might provide important information about the physics of the orig-
inal break-up event that quite recently produced this family. The lightcurves
that we have already obtained for 12 objects are of a generally good quality.
We have also obtained some indication that the largest member of the family,
(832) Karin, might exhibit some color variation across its surface. This might
be an interesting result, but it has to be confirmed by future observations.
1. Introduction
The Karin family was recognized quite recently, with the estimated age
of only about 5.8 Myrs. 1 This family consists of about 70 asteroids with
sizes ranging from about 1.5 to 20 km in diameter. 2 Most asteroid families
are very old, and they have undergone significant collisional and dynamical
evolution since their formation, which likely masks the properties of the
original collisions. But the remarkably young Karin family asteroids pos-
sibly preserve some signatures of the original collisional event that formed
the family. This extraordinary feature of the Karin family provides us with
several significant opportunities for the research of young asteroids such as
potentially detecting tumbling motion, obtaining distribution of rotation
period, and estimating the shapes of newly created asteroid fragments.
Driven by these motivations, we have begun a program since November
2002 to observe the lightcurves of all the Karin family members. The poten-
tial result derived from our observation could be a strong constraint on
laboratory and numerical experiments of collisional fragmentation. 3 In the
∗ Corresponding author.
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