Geoscience Reference
In-Depth Information
had a red surface at the rotation phase around 0.2-0.3 when seen in
September 2003.
Here we also have to add details as to what we observed in our 2003
observation. Although the existence of old and mature surface on (832)
Karin is surely interesting, we need to be aware that the detection of the
mature surface could be caused by an artificial effect. In our 2003 obser-
vation, the major color change occurred only through the
I
band color
(Fig. 3(b)) at the rotation phase corresponding to the minimum brightness
of this asteroid (Fig. 3(a)). Hence, another explanation might be possible:
“The apparent magnitude of this asteroid was close to the instrumental
limit in the
I
band color sensitivity, and the derived
I
magnitudes are
not correct”. This hypothesis will be denied or confirmed by our future
observations.
4.2.
Future observation
Our observation of the Karin family asteroids has just begun, and will
continue getting better and more accurate lightcurves of more asteroids
untilwecoverallthemembers(
70) of this family. We also need to return
to the same asteroids more than once in order to determine their spin axis
orientation and shape.
From the photometric information of (832) Karin, if its surface color
variation is real, this could be a firm explanation of the relationship
between the spectrum of the asteroid surface and its dynamical history.
We will keep observing this asteroid, which sometimes shows us a red
surface and sometime does not, to determine its rotational and shape
properties. We anticipate that the observation of this asteroid at the oppo-
sition in March 2006, when this asteroid will be observed at a different
aspect angle from the Earth, will add to our knowledge of this intriguing
asteroid.
Recent study has revealed that there are many more asteroid families
that are as young as the Karin family: For example, an S-type cluster
called the Iannini family is about 5 Myr-old, and a C-type cluster called
the Veritas family is about 8.3 Myr-old.
17
We have also started photometric
observation research on some of these young asteroid families to compare
their characters with that of the Karin family as well as of well-known
old families. In the near future, an impending deluge of large-scale sky
surveys will yield a far larger amount of information with much higher
accuracy about younger (and probably smaller) asteroid families, which will
∼
