Lightcurves and Rotational Properties of the Pristine Cold Classical Kuiper Belt Objects

Abstract

We present a survey on the rotational and physical properties of the dynamically low inclination Cold Classical trans-Neptunian objects. The Cold Classicals (CCs) are primordial planetesimals and contain relevant information about the early phase of our Solar System and planet formation over the first 100 million years after the formation of the Sun. Our project makes use of the Magellan and the Lowell's Discovery Channel Telescopes for photometric purposes. We obtained partial/complete lightcurves for 42 CCs. We use statistical tests to derive general properties about the shape and rotational frequency distributions of the CC population, and infer that the CCs have slower rotations and are more elongated/deformed than the other trans-Neptunian objects. Based on the available full lightcurves, the mean rotational period of the CC population is 9.48$\pm$1.53h whereas the mean period of the rest of the trans-Neptunian objects is 8.45$\pm$0.58h. About 65% of the trans-Neptunian objects (excluding the CCs) have a lightcurve amplitude below 0.2mag compared to the 36% of CCs with small amplitude. We present the full lightcurve of one new likely contact binary: 2004 VC131 with a potential density of 1gcc for a mass ratio of 0.4. We also have hints that 2004 MU8 and 2004 VU75 are maybe potential contact binaries based on their sparse lightcurves but more data are needed to confirm such a find. Assuming equal-sized binaries, we find that only ~10-25% of the Cold Classicals could be contact binaries, suggesting that there is a deficit of contact binaries in this population compared to previous estimates and compared to the abundant (~40-50%) possible contact binaries in the 3:2 resonant population. This estimate is a lower limit and will increase if non equal-sized contact binaries are also considered. Finally, we put in context the early results of the New Horizons flyby of (486958) 2014 MU69.

AJ, In press

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• Evolution of MU69 from a binary planetesimal into contact by Kozai-Lidov oscillations and nebular drag
• Beyond Point Masses. II. Non-Keplerian Shape Effects are Detectable in Several TNO Binaries
• Colors of Trans-Neptunian Contact Binaries
• Light curves of ten Centaurs from K2 measurements
• Investigating the formation of small Solar System objects using stellar occultations by satellites: present, future and its use to update satellite orbits
• Light curves of transneptunian objects from the K2 mission of the Kepler Space Telescope
• A Statistical Primer on Classical Period-Finding Techniques in Astronomy
• The Luminosity Function of Ultra-Faint Trans-Neptunian Objects Detected by JWST
• Combined JWST and HST Deep Imaging to Characterize the Smallest Known Trans-Neptunian Objects
• Considering contact forces during the formation of planetesimals by gravitational collapse: mutual orbits, spin states, and shapes
• Direct contact binary planetesimal formation from gravitational collapse
• The shape and spin state of (275677) 2000 RS11 from ground-based radar and optical observations