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Abstract
Most of the major planets in the Solar System support populations of co-orbiting bodies, known as Trojans, at their L4 and L5 Lagrange points. In contrast, Earth has only one known co-orbiting companion. This paper presents the results from a search for Earth Trojans using the DECam instrument on the Blanco Telescope at CTIO. This search found no additional Trojans in spite of greater coverage compared to previous surveys of the L5 point. Therefore, the main result of this work is to place the most stringent constraints to date on the population of Earth Trojans. These constraints depend on assumptions regarding the underlying population properties, especially the slope of the magnitude distribution (which in turn depends on the size and albedo distributions of the objects). For standard assumptions, we calculate upper limits to a 90% confidence limit on the L5 population of N ET < 1 for magnitude H < 15.5, N ET =60-85 for H < 19.7, and N ET = 97 for H=20.4. This latter magnitude limit corresponds to Trojans ∼300 m in size for albedo 0.15. At H=19.7, these upper limits are consistent with previous L4 Earth Trojan constraints and significantly improve L5 constraints.
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Affiliation(s)
- Larissa Markwardt
- Department of Astronomy, University of Michigan, 1085 South University Avenue, Ann Arbor, MI 48109, USA
| | - D. W. Gerdes
- Department of Astronomy, University of Michigan, 1085 South University Avenue, Ann Arbor, MI 48109, USA
- Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, MI 48109, USA
| | - R. Malhotra
- Lunar and Planetary Laboratory, The University of Arizona, 1629 E University Boulevard, Tucson, AZ 85721, USA
| | - J. C. Becker
- Department of Astronomy, University of Michigan, 1085 South University Avenue, Ann Arbor, MI 48109, USA
- Division of Geological and Planetary Sciences, California Institute of Technology, 1200 E California Blvd, Pasadena CA 91125, USA
| | - S. J. Hamilton
- Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, MI 48109, USA
| | - F. C. Adams
- Department of Astronomy, University of Michigan, 1085 South University Avenue, Ann Arbor, MI 48109, USA
- Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, MI 48109, USA
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