1. (4015) Wilson-Harrington: An Extinct Comet?
Characterizing Asteroids by their Colors and Orbits
Alessondra Springmann
SpaceGrant Final Presentation
8/20/2009

2. Talk Overview What is an asteroid? Photometry Astrometry
(4015) Wilson-Harrington: an extinct comet?
(21) Lutetia: color change as it rotates?
Astrometry
Near-Earth Objects (NEOs): Orbit Recovery

3. Asteroids in the Wild Main Belt Asteroids Near Earth Asteroids
Green
Main Belt Asteroids
Near Earth Asteroids
Trojan Asteroids
Asteroids in the Wild

4. Asteroid Formation: The Early Days
Orbital resonances from planets excited material in the asteroid belt, preventing material in this region from forming a planet
Larger asteroids formed early in the solar system’s history
Smaller asteroids are the products of later collisions [Bottke et al. 2005]

5. Photometry Measuring changes in brightness of astronomical objects
As an asteroid rotates, it reflects changing amounts of light to the observer
Produces sinusoidal lightcurve

6. (4015) Wilson-Harrington Discovered as a comet in 1949
On a cometary orbit
No cometary activity observed in the 60 years since its discovery
Near-Earth object

7. (4015) Wilson-Harrington

8. (4015) Wilson-Harrington
Object’s light is combined with background stars’ for most of the observations
Have to reject “apulse” data points
Future work: subtract signal from stars so that asteroid light is not combined with star light

9. (21) Lutetia Main belt asteroid Target of the ESA Rosetta mission
Surface composition characteristics hotly debated (rocky? metallic?)
Can we get color information as a function of rotational phase?

10. (21) Lutetia
PLOT GOES HERE; it’s on lab; I’ll get it tomorrow

11. (21) Lutetia
PLOT GOES HERE; will insert tomorrow

12. Near-Earth Objects
Unstable orbits (a few million years before they’re ejected from the solar system or collide with another object)
Some objects are comets from either the Kuiper Belt or Oort Cloud

13. NEO Recovery
Initial observations (of a few hours on one night) are not enough to constrain an orbit
Important to be certain about orbits

14. Recovery Example

15. Acknowledgements Paul Weissman Stephen Lowry James Bauer SpaceGrant
Caltech SFP Office

16. References
Bottke, Durda, Nesvorny, Jedicke, Morbidelli, Vokrouhlicky, & Levison, 2005, "The fossilized size distribution of the main asteroid belt", Icarus 175:111

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