Letters of Intent received in 2016

LoI 2018-1884
Focus Meeting: A Century of Asteroid Families

Topics

A Look Back: The History of Asteroid Families (before Yarkovsky)
Families in the Era of the Yarkovsky Effect
Families as a Probe of Catastrophic Collisions
New Results in Asteroid Family Science
A Look Forward: Predictions for the Future

Rationale

In 1918, Kiyotsugu Hirayama published a manuscript in the
Astronomical Journal titled "Groups of asteroids probably of common
origin", opening the field study of asteroid families. The IAU 2018
General Assembly represents the 100th anniversary of this seminal
work. In the intervening 100 years, Hirayama's initial insight that
these groups of objects were not random has been supported by
countless studies spanning orbital elements, colors, spectral
taxonomy, albedo, rotation, impact physics, and dynamical evolution.
This wealth of information has become a key aspect in family
identification and interpretation, expanding our understanding of
family-forming processes.

Asteroid families have provided unique insights into the forces
shaping both our Solar System and other planetary systems. Families
provide us observable evidence of large-scale catastrophic impacts in
the Solar System, giving us the tools to test impact physics on
planetary scales. Families also have been critical in revealing the
fingerprints left on the Solar System by gravitational mean motion and
secular resonances as well as the Yarkovsky effect, the most important
non-gravitational force for sculpting the Main Belt of asteroids and
supplying new objects into near-Earth space. The quantification and
simulation of the Yarkovsky force has enabled age dating of asteroid
families, providing us a chronology of the impacts in the inner Solar
System. Families allow us to probe the heterogeneity of the
protoplanetary disk in the terrestrial planet region, and homogeneity
of the parent bodies prior to the family-forming collision. And
recently, collisional families have been identified beyond the Main
Belt in populations as diverse as the Jovian irregular satellites and
the Trans-Neptunian Objects.

In this Focus Meeting we propose to review the history of asteroid
family science; highlight some of the major results as well as
watershed moments in the field; discuss new work being done; and
provide predictions for the future of the field in light of the new
techniques and data sets that are currently being developed. An
asteroid family Focus Meeting would provide the international
community a chance to celebrate the centennial of the birth of this
field, reflect on the broader insights provided by asteroid families,
and chart a new, unified path forward in the era of large surveys that
are ongoing or will be beginning in the near future. Asteroid
families will continue to be a touchstone for Solar System science in
the next century, providing insights and test populations for
planetary formation models not available in any other way.