Col-OSSOS: Colors of the Interstellar Planetesimal 1I/`Oumuamua

Abstract

The recent discovery by Pan-STARRS1 of 1I/2017 U1 (`Oumuamua), on an unbound and hyperbolic orbit, offers a rare opportunity to explore the planetary formation processes of other stars, and the effect of the interstellar environment on a planetesimal surface. 1I/`Oumuamua's close encounter with the inner Solar System in 2017 October was a unique chance to make observations matching those used to characterize the small-body populations of our own Solar System. We present near-simultaneous g${}^{\prime }$, r${}^{\prime }$, and J photometry and colors of 1I/`Oumuamua from the 8.1-m Frederick C. Gillett Gemini North Telescope, and $gri$ photometry from the 4.2 m William Herschel Telescope. Our g${}^{\prime }$r${}^{\prime }$J observations are directly comparable to those from the high-precision Colours of the Outer Solar System Origins Survey (Col-OSSOS), which offer unique diagnostic information for distinguishing between outer Solar System surfaces. The J-band data also provide the highest signal-to-noise measurements made of 1I/`Oumuamua in the near-infrared. Substantial, correlated near-infrared and optical variability is present, with the same trend in both near-infrared and optical. Our observations are consistent with 1I/`Oumuamua rotating with a double-peaked period of $8.10\pm 0.42$ hours and being a highly elongated body with an axial ratio of at least 5.3:1, implying that it has significant internal cohesion. The color of the first interstellar planetesimal is at the neutral end of the range of Solar System $g-r$ and $r-J$ solar-reflectance colors: it is like that of some dynamically excited objects in the Kuiper belt and the less-red Jupiter Trojans.

Accepted to ApJL

References in corpus (10)

• Interstellar Interloper 1I/2017 U1: Observations from the NOT and WIYN Telescopes
• An Observational Upper Limit on the Interstellar Number Density of Asteroids and Comets
• 1I/2017 U1 (`Oumuamua) is Hot: Imaging, Spectroscopy and Search of Meteor Activity
• NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos
• Transneptunian objects and Centaurs from light curves
• Realistic Detectability of Close Interstellar Comets
• Col-OSSOS: z Band Photometry Reveals Three Distinct TNO Surface Types
• The Demographics of Rocky Free-Floating Planets and their Detectability by WFIRST
• Discovery of a Binary Centaur
• Similar origin for low- and high-albedo Jovian Trojans and Hilda asteroids ?

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• The Nucleus of Interstellar Comet 2I/Borisov
• 1I/`Oumuamua as a Tidal Disruption Fragment From a Binary Star System
• Solar System Physics for Exoplanet Research
• `Oumuamua as a messenger from the Local Association
• Could 1I/'Oumuamua be an icy fractal aggregate?
• Characterization of the Nucleus, Morphology and Activity of Interstellar Comet 2I/Borisov by Optical and Near-Infrared GROWTH, Apache Point, IRTF, ZTF and Keck Observations
• 1I/'Oumuamua as an N2 ice fragment of an exo-Pluto surface: I. size and compositional constraints
• Constraints on the Occurrence of 'Oumuamua-Like Objects
• The interstellar object 'Oumuamua as a fractal dust aggregate
• Destruction of molecular hydrogen ice and Implications for 1I/2017 U1 (`Oumuamua)
• Visible and near-infrared observations of interstellar comet 2I/Borisov with the 10.4-m GTC and the 3.6-m TNG telescopes
• Evidence Suggesting that 'Oumuamua is the ~30 Myr-old product of a Molecular Cloud
• Dependence of Lightcurves on Phase Angle and Asteroid Shape
• The Galactic Interstellar Object Population: A Framework for Prediction and Inference
• Properties of the Bare Nucleus of Comet 96P/Machholz 1
• Dust bombardment can explain the extremely elongated shape of 1I/'Oumuamua and the lack of interstellar objects
• Project Lyra: Catching 1I/'Oumuamua Using Nuclear Thermal Rockets
• New Insights into Interstellar Object 1I/2017 U1 (`Oumuamua) from SOHO/STEREO Nondetections
• Simultaneous visible spectrophotometry of interstellar object 3I/ATLAS with Seimei/TriCCS
• Collisional Elongation: Possible Origin of Extremely Elongated Shape of 1I/`Oumuamua
• Capture of interstellar objects I: the capture cross-section
• On the aspect ratio of Oumuamua: less elongated shape for irregular surface properties
• Numerical Simulations of Tidal Deformation and Resulting Light Curves of Small Bodies: Material Constraints of 99942 Apophis and 1I/`Oumuamua
• Rendez-vous with massive interstellar objects, as triggers of destabilisation
• Fitting the Light Curve of 1I/`Oumuamua with a Nonprincipal Axis Rotational Model and Outgassing Torques
• Observable tests for the light-sail scenario of interstellar objects
• A Real-Time Search for Interstellar Impacts on the Moon
• Detecting Interstellar Objects Through Stellar Occultations
• Configuration of Single Giant Planet Systems Generating `Oumuamua-Like Interstellar Asteroids
• On The Spin Dynamics of Elongated Minor Bodies with Applications to a Possible Solar System Analogue Composition for `Oumuamua
• Implications of evaporative cooling by H${}_2$ for 1I/`Oumuamua
• Machine Learning Methods for Automated Interstellar Object Classification with LSST