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

Abstract

We present visible and near-infrared photometric and spectroscopic observations of interstellar object 2I/Borisov taken from 2019 September 10 to 2019 November 29 using the GROWTH, the APO ARC 3.5 m and the NASA/IRTF 3.0 m combined with post and pre-discovery observations of 2I obtained by ZTF from 2019 March 17 to 2019 May 5. Comparison with imaging of distant Solar System comets shows an object very similar to mildly active Solar System comets with an out-gassing rate of $\sim$10${}^{27}$ mol/sec. The photometry, taken in filters spanning the visible and NIR range shows a gradual brightening trend of $\sim 0.03$ mags/day since 2019 September 10 UTC for a reddish object becoming neutral in the NIR. The lightcurve from recent and pre-discovery data reveals a brightness trend suggesting the recent onset of significant H${}_2$O sublimation with the comet being active with super volatiles such as CO at heliocentric distances $>$6 au consistent with its extended morphology. Using the advanced capability to significantly reduce the scattered light from the coma enabled by high-resolution NIR images from Keck adaptive optics taken on 2019 October 04, we estimate a diameter of 2I's nucleus of $\lesssim$1.4 km. We use the size estimates of 1I/'Oumuamua and 2I/Borisov to roughly estimate the slope of the ISO size-distribution resulting in a slope of $\sim$3.4$\pm$1.2, similar to Solar System comets and bodies produced from collisional equilibrium.

arXiv comment22 pages, 7 figures, 1 table. Accepted for publication in AJ on 12 May 2020

References in corpus (66)

• The Zwicky Transient Facility: System Overview, Performance, and First Results
• The Zwicky Transient Facility: Data Processing, Products, and Archive
• The Pan-STARRS1 Photometric System
• The Zwicky Transient Facility: Science Objectives
• Empirical Color Transformations Between SDSS Photometry and Other Photometric Systems
• Solar System Objects Observed in the SDSS Commissioning Data
• The taxonomic distribution of asteroids from multi-filter all-sky photometric surveys
• The Zwicky Transient Facility: Surveys and Scheduler
• Spitzer IRS Spectroscopy of IRAS-Discovered Debris Disks
• The SED Machine: a robotic spectrograph for fast transient classification
• Interstellar Interloper 1I/2017 U1: Observations from the NOT and WIYN Telescopes
• The GROWTH Marshal: A Dynamic Science Portal for Time-Domain Astronomy
• Impact Craters on Pluto and Charon Indicate a Deficit of Small Kuiper Belt Objects
• A Fully Automated Integral Field Spectrograph Pipeline for the SEDMachine: pysedm
• Thermal Properties, Sizes, and Size Distribution of Jupiter-Family Cometary Nuclei
• Seasonal Mass Transfer on the Nucleus of Comet 67P/Chuyumov-Gerasimenko
• An Observational Upper Limit on the Interstellar Number Density of Asteroids and Comets
• Initial Characterization of Interstellar Comet 2I/2019 Q4 (Borisov)
• Color Confirmation of Asteroid Families
• Spectroscopy and thermal modelling of the first interstellar object 1I/2017 U1 'Oumuamua
• Water Ice and Dust in the Innermost Coma of Comet 103P/Hartley 2
• Comparison of Asteroids Observed in the SDSS with a Catalog of Known Asteroids
• The carbon monoxide-rich interstellar comet 2I/Borisov
• Unusually High CO Abundance of the First Active Interstellar Comet
• Spitzer Observations of Interstellar Object 1I/`Oumuamua
• Large Impacts around a Solar Analog Star in the Era of Terrestrial Planet Formation
• Likely Transiting Exocomets Detected by Kepler
• Terrestrial deuterium-to-hydrogen ratio in water in hyperactive comets
• Kuiper belt: formation and evolution
• CO in distantly active comets
• Spitzer Evidence for a Late Heavy Bombardment and the Formation of Urelites in η Corvi at ~1 Gyr
• 2I/Borisov: A C${}_2$ depleted interstellar comet
• Low Albedos Among Extinct Comet Candidates
• Influence of sub- and super-solar metallicities on the compositions of solid planetary building blocks
• Col-OSSOS: Colors of the Interstellar Planetesimal 1I/`Oumuamua
• Ensemble Properties of Comets in the Sloan Digital Sky Survey
• Detection of CN gas in Interstellar Object 2I/Borisov
• APO Time Resolved Color Photometry of Highly-Elongated Interstellar Object 1I/'Oumuamua
• The Main Belt Comets and Ice in the Solar System
• Implications of the interstellar object 1I/'Oumuamua for planetary dynamics and planetesimal formation
• Spitzer Space Telescope Observations of the Nucleus of Comet 103P/Hartley 2
• Comet 17P/Holmes in Outburst: The Near Infrared Spectrum
• Comet 67P outbursts and quiescent coma at 1.3 AU from the Sun: dust properties from Rosetta/VIRTIS-H observations
• The extraordinary composition of the "blue comet" C/2016 R2 (PanSTARRS)
• The Nucleus of Interstellar Comet 2I/Borisov
• Implications for planetary system formation from interstellar object 1I/2017 U1 (`Oumuamua)
• Tidal fragmentation as the origin of 1I/2017 U1 ('Oumuamua)
• The Orbit and Size-Frequency Distribution of Long Period Comets Observed by Pan-STARRS1
• A Comet Active Beyond the Crystallization Zone
• Col-OSSOS: The Colours of the Outer Solar System Origins Survey
• Pre-discovery Activity of New Interstellar Comet 2I/Borisov Beyond 5 AU
• Detection of a Water Tracer in Interstellar Comet 2I/Borisov
• Interstellar object 'Oumuamua as an extinct fragment of an ejected cometary planetesimal
• Strong CO${}^{+}$ and N${}_2^{+}$ Emission in Comet C/2016 R2 (Pan-STARRS)
• Extreme Debris Disk Variability -- Exploring the Diverse Outcomes of Large Asteroid Impacts During the Era of Terrestrial Planet Formation
• Multiple Rings of Millimeter Dust Emission in the HD 15115 Debris Disk
• The Persistent Activity of Jupiter-Family Comets at 3 to 7 AU
• Carbon Chain Depletion of 2I/Borisov
• Spin states of asteroids in the Eos collisional family
• Coma Anisotropy and the Rotation Pole of Interstellar Comet 2I/Borisov
• Fragmentation Kinematics in Comet 332P/Ikeya-Murakami
• The splitting of double-component active asteroid P/2016 J1 (PANSTARRS)
• SDSS Observations of Kuiper Belt Objects: Colors and Variability
• Infrared Spectroscopy of HR 4796A's Bright Outer Cometary Ring + Tenuous Inner Hot Dust Cloud
• Retrograde orbits excess among observable interstellar objects
• Seasonal Evolution on the Nucleus of Comet C/2013 A1 (Siding Spring)

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