2021/09/02 by Theodore Kareta, V. Reddy, Kareta, Theodore +7
Physics and Astronomy · #Astro and Planetary Science #Stellar, planetary, and galactic studies #Planetary Science and Exploration
paper · pdf · doi:10.48550/arxiv.2109.01020
The relationship between the Near-Earth Objects (3200) Phaethon and (155140)\n2005 UD is unclear. While both are parents to Meteor Showers, (the Geminids and\nDaytime Sextantids, respectively), have similar visible-wavelength reflectance\nspectra and orbits, dynamical investigations have failed to find any likely\nmethod to link the two objects in the recent past. Here we present the first\nnear-infrared reflectance spectrum of 2005 UD, which shows it to be\nconsistently linear and red-sloped unlike Phaethon's very blue and concave\nspectrum. Searching for a process that could alter some common starting\nmaterial to both of these end states, we hypothesized that the two objects had\nbeen heated to different extents, motivated by their near-Sun orbits, the\ncomposition of Geminid meteoroids, and previous models of Phaethon's surface.\nWe thus set about building a new laboratory apparatus to acquire reflectance\nspectra of meteoritic samples after heating to higher temperatures than\navailable in the literature to test this hypothesis and were loaned a sample of\nthe CI Chondrite Orgueil from the Vatican Meteorite Collection for testing. We\nfind that while Phaethon's spectrum shares many similarities with different CI\nChondrites, 2005 UD's does not. We thus conclude that the most likely\nrelationship between the two objects is that their similar properties are only\nby coincidence as opposed to a parent-fragment scenario, though the ultimate\ntest will be when JAXA's DESTINY+ mission visits one or both objects later this\ndecade. We also discuss possible paths forward to understanding Phaethon's\nproperties from dynamical and compositional grounds.\n