Initial Characterization of Active Transitioning Centaur, P/2019 LD₂ (ATLAS), Using Hubble, Spitzer, ZTF, Keck, Apache Point Observatory, and GROWTH Visible and Infrared Imaging and Spectroscopy

March 2021 • 2021AJ....161..116B

Authors • Bolin, Bryce T. • Fernandez, Yanga R. • Lisse, Carey M. • Holt, Timothy R. • Lin, Zhong-Yi • Purdum, Josiah N. • Deshmukh, Kunal P. • Bauer, James M. • Bellm, Eric C. • Bodewits, Dennis • Burdge, Kevin B. • Carey, Sean J. • Copperwheat, Chris M. • Helou, George • Ho, Anna Y. Q. • Horner, Jonathan • van Roestel, Jan • Bhalerao, Varun • Chang, Chan-Kao • Chen, Christine • Hsu, Chen-Yen • Ip, Wing-Huen • Kasliwal, Mansi M. • Masci, Frank J. • Ngeow, Chow-Choong • Quimby, Robert • Burruss, Rick • Coughlin, Michael • Dekany, Richard • Delacroix, Alexandre • Drake, Andrew • Duev, Dmitry A. • Graham, Matthew • Hale, David • Kupfer, Thomas • Laher, Russ R. • Mahabal, Ashish • Mróz, Przemyslaw J. • Neill, James D. • Riddle, Reed • Rodriguez, Hector • Smith, Roger M. • Soumagnac, Maayane T. • Walters, Richard • Yan, Lin • Zolkower, Jeffry

Abstract • We present visible and mid-infrared imagery and photometry of temporary Jovian co-orbital comet P/2019 LD₂ taken with Hubble Space Telescope/Wide Field Camera 3 (HST/WFC3), Spitzer Space Telescope/Infrared Array Camera (Spitzer/IRAC), and the GROWTH telescope network, visible spectroscopy from Keck/Low-Resolution Imaging Spectrometer (LRIS), and archival Zwicky Transient Facility observations taken between 2019 April and 2020 August. Our observations indicate that the nucleus of LD₂ has a radius between 0.2 and 1.8 km assuming a 0.08 albedo and a coma dominated by ∼100 μm-scale dust ejected at ∼1 m s^-1 speeds with a ∼1' jet pointing in the southwest direction. LD₂ experienced a total dust mass loss of ∼10⁸ kg at a loss rate of ∼6 kg s^-1 with Afρ/cross section varying between ∼85 cm/125 km² and ∼200 cm/310 km² from 2019 April 9 to 2019 November 8. If the increase in Afρ/cross section remained constant, it implies LD₂'s activity began ∼2018 November when within 4.8 au of the Sun, implying the onset of H₂O sublimation. We measure CO/CO₂ gas production of ≲10²⁷ mol s^-1/≲10²⁶ mol s^-1 from our 4.5 μm Spitzer observations; g-r = 0.59 ± 0.03, r-i = 0.18 ± 0.05, and i-z = 0.01 ± 0.07 from GROWTH observations; and H₂O gas production of ≲80 kg s^-1 scaling from our estimated C₂ production of ${Q}_{{C}_{2}}\lesssim 7.5\times {10}^{24}$ mol s^-1 from Keck/LRIS spectroscopy. We determine that the long-term orbit of LD₂ is similar to Jupiter-family comets having close encounters with Jupiter within ∼0.5 Hill radius in the last ∼3 y and within 0.8 Hill radius in ∼9 y. Additionally, 78.8% of our orbital clones are ejected from the solar system within 1 × 10⁶ yr, having a dynamical half-life of 3.4 × 10⁵ yr.

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• PDF https://iopscience.iop.org/article/10.3847/1538-3881/abd94b/pdf
• PDF https://stacks.iop.org/1538-3881/161/116/pdf
• PREPRINT http://arxiv.org/abs/2011.03782
• DATA https://archive.stsci.edu/mastbibref.php?bibcode=2021AJ....161..116B
• DATA https://hst.esac.esa.int/ehst/#/pages/search;bibcode=2021AJ....161..116B
• DATA https://irsa.ipac.caltech.edu/bibdata/2021/B/2021AJ....161..116B.html
• ELECTR https://doi.org/10.3847%2F1538-3881%2Fabd94b