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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 and Keck Observations

Bolin, Bryce T. and Lisse, Carey M. and Kasliwal, Mansi M. and Quimby, Robert M. and Tan, Hanjie and Copperwheat, Chris and Lin, Zhong-Yi and Morbidelli, Alessandro and Bauer, James and Burdge, Kevin B. and Coughlin, Michael and Fremling, Christoffer and Itoh, Ryosuke and Koss, Michael and Masci, Frank J. and Maeno, Syota and Mamajek, Eric E. and Marocco, Federico and Murata, Katsuhiro and Sitko, Michael L. and Stern, Daniel and Walters, Richard and Yan, Lin and Andreoni, Igor and Bhalerao, Varun and Bodewits, Dennis and De, Kishalay and Deshmukh, Kunal P. and Bellm, Eric C. and Blagorodnova, Nadejda and Buzasi, Derek and Cenko, S. Bradley and Chang, Chan-Kao and Chojnowski, Drew and Dekany, Richard and Duev, Dmitry A. and Graham, Matthew and Juric, Mario and Kramer, Emily A. and Kulkarni, Shrinivas R. and Kupfer, Thomas and Mahabal, Ashish and Neill, James D. and Ngeow, Chow-Choong and Penprase, Bryan and Riddle, Reed and Rodriguez, Hector and Rosnet, Philippe and Sollerman, Jesper and Soumagnac, Maayane T. (2019) 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. . (Unpublished)

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We present visible and near-infrared photometric and spectroscopic observations of interstellar comet 2I/Borisov taken from 2019 September 10 to 2019 November 03 using the GROWTH collaboration, the Apache Point Observatory ARC 3.5 m and the NASA/IRTF 3.0 m combined with post and pre-discovery observations of 2I obtained by the Zwicky Transient Facility from 2019 March 17 to 2019 May 5. Comparison with imaging of distant Solar System comets (Kelly et al. 2013) shows an object very similar to mildly active Solar System comets with an out-gassing rate of ∼10²⁷ mol/sec. The photometry, taken in filters spanning the visible and NIR range shows a gradual brightening trend of ∼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 (Ye et al. 2019) reveals a brightness trend suggesting the recent onset of significant H₂O 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 ≲3 km, though the true size is likely ∼2-3 times smaller due to the incomplete removal of dust from the measurement. We use the size estimates of 1I/'Oumuamua and 2I/Borisov to roughly estimate the slope of the interstellar object cumulative size-distribution resulting in a slope of ≳-2.9, similar to Solar System comets (Fernandez et al. 2013), though the true slope is likely significantly steeper due to small number statistics and our probable overestimation of the size of 2I.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
Kasliwal, Mansi M.0000-0002-5619-4938
Quimby, Robert M.0000-0001-9171-5236
Burdge, Kevin B.0000-0002-7226-836X
Coughlin, Michael0000-0002-8262-2924
Fremling, Christoffer0000-0002-4223-103X
Masci, Frank J.0000-0002-8532-9395
Mamajek, Eric E.0000-0003-2008-1488
Marocco, Federico0000-0001-7519-1700
Stern, Daniel0000-0003-2686-9241
Walters, Richard0000-0002-1835-6078
Yan, Lin0000-0003-1710-9339
Andreoni, Igor0000-0002-8977-1498
Bhalerao, Varun0000-0002-6112-7609
De, Kishalay0000-0002-8989-0542
Bellm, Eric C.0000-0001-8018-5348
Cenko, S. Bradley0000-0003-1673-970X
Duev, Dmitry A.0000-0001-5060-8733
Graham, Matthew0000-0002-3168-0139
Kulkarni, Shrinivas R.0000-0001-5390-8563
Mahabal, Ashish0000-0003-2242-0244
Neill, James D.0000-0002-0466-1119
Riddle, Reed0000-0002-0387-370X
Sollerman, Jesper0000-0003-1546-6615
Soumagnac, Maayane T.0000-0001-6753-1488
Additional Information:Received 2019 November 5. This work was supported by the GROWTH project funded by the National Science Foundation under PIRE Grant No 1545949. Our work includes observations obtained with the Apache Point Observatory 3.5-meter telescope, which is owned and operated by the Astrophysical Research Consortium. We thank the Director (Nancy Chanover) and Deputy Director (Ben Williams) of the Astrophysical Research Consortium (ARC) 3.5m telescope at Apache Point Observatory for their enthusiastic and timely support of our Director's Discretionary Time (DDT) proposals. We also thank Russet McMillan, Ted Rudyk, Candace Gray, Jack Dembicky and the rest of the APO technical staff for their assistance in performing the observations on the same day our DDT proposals were submitted. Based on observations obtained with the Samuel Oschin Telescope 48-inch and the 60-inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under Grant No. AST-1440341 and a collaboration including Caltech, IPAC, the Weizmann Institute for Science, the Oskar Klein Center at Stockholm University, the University of Maryland, the University of Washington, Deutsches Elektronen-Synchrotron and Humboldt University, Los Alamos National Laboratories, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, and Lawrence Berkeley National Laboratories. Operations are conducted by COO, IPAC, and UW. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. We thank Jim Lyke and Carlos Alvarez for guiding the planning and executing the adaptive optics observation with the OSIRIS instrument on Keck I. C-C Ngeow thanks the funding from MoST grant 104-2923-M-008-004-MY5. The work of DS was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. SED Machine is based upon work supported by the National Science Foundation under Grant No. 1106171 This publication has made use of data collected at Lulin Observatory, partly supported by MoST grant 108-2112- M-008-001. The results presented in this paper are based in part on observations collected with the Liverpool Telescope, which is operated on the island of La Palma by Liverpool John Moores University in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias with financial support from the UK Science and Technology Facilities Council. Visiting Astronomer at the Infrared Telescope Facility, which is operated by the University of Hawaii under contract NNH14CK55B with the National Aeronautics and Space Administration. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. FM is supported by an appointment to the NASA Postdoctoral Program at the Jet Propulsion Laboratory, administered by Universities Space Research Association under contract with NASA. The authors would like to thank E. Turner, B Draine, S. Tremaine, and M Mac-Low for many useful discussions concerning the nature and provenance of 1I and 2I. In addition, the authors would like to thank R. Jedicke and G. Helou for helpful discussion on the size distribution of comets. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555. Facility: Astrophysical Research Consortium 3.5 m , Lulin Optical Telescope, Bisei Observatory 101 cm, Keck:I (LRIS, OSIRIS), Liverpool Telescope, Mount Laguna Observatory 40-inch, NASA/Infrared Telescope Facility, Zwicky Transient Facility, Hubble Space Telescope, SED Machine.
Group:Infrared Processing and Analysis Center (IPAC), Zwicky Transient Facility, Astronomy Department
Funding AgencyGrant Number
David and Ellen Lee Postdoctoral ScholarshipUNSPECIFIED
Infrared Processing and Analysis Center (IPAC)UNSPECIFIED
Weizmann Institute of ScienceUNSPECIFIED
Stockholm UniversityUNSPECIFIED
University of MarylandUNSPECIFIED
University of WashingtonUNSPECIFIED
Deutsches Elektronen-SynchrotronUNSPECIFIED
Humboldt UniversityUNSPECIFIED
Los Alamos National LaboratoryUNSPECIFIED
University of Wisconsin-MilwaukeeUNSPECIFIED
Lawrence Berkeley National LaboratoryUNSPECIFIED
W. M. Keck FoundationUNSPECIFIED
Ministry of Science and Technology (Taipei)104-2923-M-008-004-MY5
Ministry of Science and Technology (Taipei)108-2112-M-008-001
Science and Technology Facilities Council (STFC)UNSPECIFIED
NASA Postdoctoral ProgramUNSPECIFIED
Universities Space Research Association (USRA)UNSPECIFIED
Association of Universities for Research in Astronomy (AURA)UNSPECIFIED
NASANAS 5-26555
Subject Keywords:minor planets, comets: individual (2I/Borisov), galaxy: local interstellar matter
Record Number:CaltechAUTHORS:20191120-113417232
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:99959
Deposited By: Tony Diaz
Deposited On:20 Nov 2019 21:44
Last Modified:20 Nov 2019 21:44

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