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Characterization of the Nucleus, Morphology and Activity of Interstellar comet 2I/Borisov by Optical and Near-Infrared GROWTH, Apache Point, IRTF, ZTF

Status Report From: arXiv.org e-Print archive
Posted: Friday, November 1, 2019

Bryce T. Bolin, Carey M. Lisse, Mansi M. Kasliwal, Robert Quimby, Hanjie Tan, Quanzhi Ye, Chris Copperwheat, Yanga R. Fernandez, Zhong-Yi Lin, Alessandro Morbidelli, James Bauer, Kevin B. Burdge, Michael Coughlin, Christoffer Fremling, Ryosuke Itoh, Michael Koss, Frank J. Masci, Syota Maeno, Eric E. Mamajek, Federico Marocco, Katsuhiro Murata, Michael L. Sitko, Daniel Stern, Richard Walters, Lin Yan, Igor Andreoni, Varun Bhalerao, Dennis Bodewits, Kishalay De, Kunal P. Deshmukh, Eric C. Bellm, Nadejda Blagorodnova, Derek Buzasi, S. Bradley Cenko, Chan-Kao Chang, Drew Chojnowski, Richard Dekany, Dmitry A. Duev, Matthew Graham, George Helou, Mario Juric, Emily A. Kramer, Shrinivas R. Kulkarni, Thomas Kupfer, Ashish Mahabal, James D. Neill, Chow-Choong Ngeow, Bryan Penprase, Thomas A. Prince, Reed Riddle, Hector Rodriguez, Philippe Rosnet, Jesper Sollerman, Maayane T. Soumagnac

(Submitted on 30 Oct 2019)

We present visible and near-infrared observations of interstellar comet 2I/Borisov taken from 2019 September 10 to 2019 October 25 using the GROWTH collaboration, the APO ARC 3.5 m, and the NASA/IRTF 3.0 m combined with pre-discovery observations obtained by the Zwicky Transient Facility between 2019 March 17 and 2019 May 05. Comparison with previous photometric imaging surveys of distant comets shows an object similar to mildly active Solar System comets with an out-gassing rate of ∼1027 mol/sec. Photometry spanning the visible to NIR range shows a gradual brightening trend of ∼0.03 mags/day since 2019 September 10 for a neutral to reddish colored object dominated by its surrounding coma. Combining the recent data with pre-discovery ZTF observations of 2I reveals a brightness trend comparable to cometary out-gassing models driven by CO at rh > 6 au, consistent with its morphology and with activity starting ≳10 au from the Sun. The latest photometric trends suggest the onset of significant H2O sublimation. We use high-resolution NIR Keck images taken on 2019 October 04 to estimate a hard upper limit to the diameter of ∼3 km confirmed with high-resolution images from the Hubble Space Telescope (Jewitt et al. HST GO/DD Prop. 16009). The true size is likely a factor of 2-3 smaller due to dust affecting the measurement. In addition, we find no evidence for rotational variation during the seven-hour duration of the HST observations implying a strong dust component to total cross-section of 2I. We combine the size estimate of 1I/'Oumuamua, with our upper limit of 2I's size to estimate the slope of the interstellar object cumulative size-distribution resulting in a slope of ∼-2.7, similar to Solar System comets, though the true slope could be significantly steeper due to small number statistics and if the true size of 2I is much smaller than our limit.

Comments: 24 pages, 9 figures, 2 tables. Submitted to AAS Journals

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

Cite as: arXiv:1910.14004 [astro-ph.EP](or arXiv:1910.14004v1 [astro-ph.EP] for this version)

Submission history

From: Bryce Bolin 

[v1] Wed, 30 Oct 2019 17:41:35 UTC (1,772 KB)

https://arxiv.org/abs/1910.14004


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