2011 HM₁₀₂: DISCOVERY OF A HIGH-INCLINATION L5 NEPTUNE TROJAN IN THE SEARCH FOR A POST-PLUTO NEW HORIZONS TARGET

Abstract

We present the discovery of a long-term stable L5 (trailing) Neptune Trojan\nin data acquired to search for candidate Trans-Neptunian objects for the New\nHorizons spacecraft to fly by during an extended post-Pluto mission. This\nNeptune Trojan, 2011 HM102, has the highest inclination (29.4 degrees) of any\nknown member of this population. It is intrinsically brighter than any single\nL5 Jupiter Trojan at H~8.18. We have determined its gri colors (a first for any\nL5 Neptune Trojan), which we find to be similar to the moderately red colors of\nthe L4 Neptune Trojans, suggesting similar surface properties for members of\nboth Trojan clouds. We also present colors derived from archival data for two\nL4 Neptune Trojans (2006 RJ103 and 2007 VL305), better refining the overall\ncolor distribution of the population. In this document we describe the\ndiscovery circumstances, our physical characterization of 2011 HM102, and this\nobject's implications for the Neptune Trojan population overall. Finally, we\ndiscuss the prospects for detecting 2011 HM102 from the New Horizons spacecraft\nduring their close approach in mid- to late-2013.\n