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(4015) Wilson-Harrington: An Extinct Comet?. Alessondra Springmann SpaceGrant Final Presentation 8/20/2009. Characterizing Asteroids by their Colors and Orbits. Talk Overview. What is an asteroid? Photometry (4015) Wilson-Harrington: an extinct comet?
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(4015) Wilson-Harrington: An Extinct Comet? Alessondra Springmann SpaceGrant Final Presentation 8/20/2009 Characterizing Asteroids by their Colors and Orbits
Talk Overview • What is an asteroid? • Photometry • (4015) Wilson-Harrington: an extinct comet? • (21) Lutetia: color change as it rotates? • Astrometry • Near-Earth Objects (NEOs): Orbit Recovery
Green Asteroids in the Wild Main Belt Asteroids Near Earth Asteroids Trojan Asteroids
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]
Photometry Measuring changes in brightness of astronomical objects As an asteroid rotates, it reflects changing amounts of light to the observer Produces sinusoidal lightcurve
(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
(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
(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?
(21) Lutetia PLOT GOES HERE; it’s on lab; I’ll get it tomorrow
(21) Lutetia PLOT GOES HERE; will insert tomorrow
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
NEO Recovery Initial observations (of a few hours on one night) are not enough to constrain an orbit Important to be certain about orbits
Acknowledgements Paul Weissman Stephen Lowry James Bauer SpaceGrant Caltech SFP Office
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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