Lightcurves of the Dynamically Cold Classical Trans-Neptunian Objects
Abstract
The dynamically Cold Classical trans-Neptunian objects (TNOs) have low inclination, low eccentricity, and are not in Neptune resonances. Because they have likely remained far from the Sun, and formed near where they exist today, these TNOs are thought to be primordial and thus important to understand our Solar System's formation and evolution. Even though more than 600 Cold Classicals (CCs) are known, only 19 have been studied for rotational lightcurves. In addition to this low number, most of the studied CCs are the larger objects and known wide binary systems and thus our understanding of this population is highly biased. Therefore, in order to improve our knowledge of the CCs and give context to the next flyby of the NASA's New Horizons mission, we started a survey of the CCs with the Discovery Channel and the Magellan telescopes for lightcurves and colors. Our survey is the first entirely dedicated to the study of the rotational and physical properties of this population. Over the past three years, we observed some 40 non-binary CCs with absolute magnitudes from 5 to 7.2 mag. Sparse and complete lightcurves obtained through our survey are used to constrain the contact binary fraction, the shape and rotational frequency distributions of the CCs. By comparing the properties of the Cold Classicals to the other dynamical groups, we aim to extract the primordial characteristics of the trans-Neptunian population. We also report the discovery of the first two likely contact binaries detected through lightcurves in this dynamical group. Using our results and the literature, we estimate that only about 10% of the CCs could be contact binaries, which is significantly lower than our estimate of contact binaries in the Plutino population of some 40-50%. This low population of CC contact binaries is also surprising given that the CC have a larger fraction of equal-sized wide-binary systems while the Plutinos have very few known wide binaries. This suggests the different scattering histories of the TNO populations affected the formation of contact binaries. Finally, a new equal-sized wide binary, 2014 LQ28, was identified from our observations. This work is supported by the National Science Foundation, grant #1734484.
- Publication:
-
AAS/Division for Planetary Sciences Meeting Abstracts #50
- Pub Date:
- October 2018
- Bibcode:
- 2018DPS....5030205T