C/2014 UN271 (Bernardinelli-Bernstein): The Nearly Spherical Cow of Comets

  title={C/2014 UN271 (Bernardinelli-Bernstein): The Nearly Spherical Cow of Comets},
  author={Pedro H. Bernardinelli and Gary M. Bernstein and Benjamin T. Montet and Robert J. Weryk and Richard J. Wainscoat and Michel Aguena and Sahar Allam and Felipe Andrade-Oliveira and James T. Annis and Santiago {\'A}vila and E. Bertin and David Brooks and David L. Burke and A. Carnero Rosell and Matias Carrasco Kind and Jorge Carretero and R. Cawthon and C. J. Conselice and Matteo Costanzi and L. N. da Costa and M. E. S. Pereira and Juan Carlos de Vicente and H. Thomas Diehl and S. Everett and I. Ferrero and Brenna L. Flaugher and Joshua A. Frieman and Juan Garc'ia-Bellido and Enrique Gazta{\~n}aga and David W. Gerdes and Daniel Gruen and Robert A. Gruendl and Julia Gschwend and Gaston R. Guti{\'e}rrez and Samuel R. Hinton and Devon L. Hollowood and Klaus Honscheid and David J. James and Kyler W. Kuehn and Nikolay Kuropatkin and Ofer Lahav and Marcio A. G. Maia and Jennifer L. Marshall and Felipe Menanteau and Ramon Miquel and Robert Morgan and R. L. C. Ogando and Francisco Paz-Chinch{\'o}n and A. Pieres and Andr'es A. Plazas Malag'on and Mario Rodr{\'i}guez-Monroy and A. K. Romer and Aaron Roodman and E. Sanchez and Michael S. Schubnell and S. Serrano and Ignacio Sevilla-Noarbe and M. Smith and Marcelle Soares-Santos and Eric Suchyta and Mollye E. C. Swanson and Gregory G. Tarl{\'e} and C. To and Michael Troxel and T. N. Varga and Alistair R. Walker and Y. Zhang},
  journal={The Astrophysical Journal Letters},
Comet C/2014 UN271 (Bernardinelli-Bernstein), incoming from the Oort cloud, is remarkable in having the brightest (and presumably largest) nucleus of any well-measured comet and having been discovered at the heliocentric distance r h ≈ 29 au, farther than any Oort cloud comet. In this work, we describe the discovery process and observations and the properties that can be inferred from images recorded until the first reports of activity in 2021 June. The orbit has i = 95°, with a perihelion of… 
A Look at Outbursts of Comet C/2014 UN271 (Bernardinelli–Bernstein) near 20 au
Cometary activity may be driven by ices with very low sublimation temperatures, such as carbon monoxide ice, which can sublimate at distances well beyond 20 au. This point is emphasized by the
Hubble Space Telescope Detection of the Nucleus of Comet C/2014 UN271 (Bernardinelli–Bernstein)
We present a high-resolution observation of the distant comet C/2014 UN271 (Bernardinelli–Bernstein) using the Hubble Space Telescope on 2022 January 8. The signal of the nucleus was successfully
Are there any pristine comets? Constraints from pebble structure
We show that if comets (or any small icy planetesimals such as Kuiper belt objects) are composed of pebble piles, their internal radiogenic as well as geochemical heating results in considerably
A Search of the Full Six Years of the Dark Energy Survey for Outer Solar System Objects
We present a search for outer solar system objects in the 6 yr of data from the Dark Energy Survey (DES). The DES covered a contiguous 5000 deg2 of the southern sky with ≈80,000 3 deg2 exposures in
The unpopular Package: A Data-driven Approach to Detrending TESS Full-frame Image Light Curves
The majority of observed pixels on the Transiting Exoplanet Survey Satellite (TESS) are delivered in the form of full-frame images (FFIs). However, the FFIs contain systematic effects such as
The LCO Outbursting Objects Key Project: Overview and Year 1 Status
The LCO Outbursting Objects Key (LOOK) Project uses the telescopes of the Las Cumbres Observatory (LCO) Network to (1) systematically monitor a sample of previously discovered over the whole sky, to


C/2010 U3 (Boattini): A Bizarre Comet Active at Record Heliocentric Distance
We present a photometric and dynamical study of comet C/2010 U3 (Boattini), which was seen active in prediscovery data as early as 2005 November at a new inbound record heliocentric distance of rH =
No Rotational Variability in C/2014 UN271 (Bernardinelli-Bernstein) at 23.8 au and 21.1 au as Seen by TESS
The recent discovery of a hundred-kilometer-scale comet, C/2014 UN271 (Bernardinelli-Bernstein), has provoked interest in the activity displayed by such a large body inbound from the Oort cloud. We
Distant Comet C/2017 K2 and the Cohesion Bottleneck
The distant long-period comet C/2017 K2 (PANSTARRS) has been outside the planetary region of the solar system for ∼3 Myr, negating the possibility that heat retained from the previous perihelion
Origin and Evolution of Long-period Comets
We develop an evolutionary model of the long-period comet (LPC) population, starting from their birthplace in a massive trans-Neptunian disk that was dispersed by migrating giant planets. Most comets
CO-driven Activity in Comet C/2017 K2 (PANSTARRS)
Comet C/2017 K2 (PANSTARRS) was discovered by the Pan-STARRS1 (PS1) Survey on 2017 May 21 at a distance of 16.09 au from the Sun, the second most distant discovery of an active comet. Pre-discovery
A Comet Active Beyond the Crystallization Zone
We present observations showing inbound long-period comet C/2017 K2 (PANSTARRS) to be active at a record heliocentric distance. Nucleus temperatures are too low (60–70 K) either for water ice to
Stellar Occultation by 2060 Chiron
Abstract A 14th magnitude double star was occulted by 2060 Chiron on 1993 November 7. Observations of this event were obtained from five locations in California. An occultation by Chiron's nucleus
CO in distantly active comets
Activity of most comets near the Sun is dominated by sublimation of frozen water, the most abundant ice in comets. Some comets, however, are active well beyond the water-ice sublimation limit of ~3
Activity of comets at large heliocentric distances pre-perihelion
Remote investigations of ancient matter in the solar system have traditionally been carried out through observations of long-period (LP) comets, which are less affected by solar irradiation than