C/2014 UN<inf>271</inf>(Bernardinelli-Bernstein): The Nearly Spherical Cow of Comets
Authors
Allam, S
Andrade-Oliveira, F
Avila, S
Burke, DL
Carnero Rosell, A
Kind, MC
Da Costa, LN
Pereira, MES
De Vicente, J
Everett, S
Ferrero, I
Flaugher, B
Frieman, J
Gruen, D
Gutierrez, G
Honscheid, K
James, DJ
Kuropatkin, N
Lahav, O
Maia, MAG
Ogando, RLC
Malagón, AAP
Rodriguez-Monroy, M
Romer, AK
Sanchez, E
Schubnell, M
Serrano, S
Smith, M
Soares-Santos, M
Suchyta, E
Troxel, MA
Varga, TN
Walker, AR
Zhang, Y
Publication Date
2021Journal Title
Astrophysical Journal Letters
ISSN
2041-8205
Publisher
American Astronomical Society
Volume
921
Issue
2
Language
en
Type
Article
This Version
VoR
Metadata
Show full item recordCitation
Bernardinelli, P., Bernstein, G., Montet, B., Weryk, R., Wainscoat, R., Aguena, M., Allam, S., et al. (2021). C/2014 UN<inf>271</inf>(Bernardinelli-Bernstein): The Nearly Spherical Cow of Comets. Astrophysical Journal Letters, 921 (2) https://doi.org/10.3847/2041-8213/ac32d3
Abstract
C/2014 UN271 (Bernardinelli-Bernstein) is a comet incoming from the Oort
cloud which is remarkable in having the brightest (and presumably largest)
nucleus of any well-measured comet, and having been discovered at heliocentric
distance $r_h\approx29$ au farther than any Oort-cloud member. We describe the
properties that can be inferred from images recorded until the first reports of
activity in June 2021. The orbit has $i=95^\circ,$ with perihelion of 10.97 au
to be reached in 2031, and previous aphelion at $40,400\pm260$ au. Backwards
integration of the orbit under a standard Galactic tidal model and known
stellar encounters suggests this is a pristine new comet, with a perihelion of
$q\approx18$ au on its previous perihelion passage 3.5 Myr ago. The photometric
data show an unresolved nucleus with absolute magnitude $H_r=8.0,$ colors that
are typical of comet nuclei or Damocloids, and no secular trend as it traversed
the range 34--23 au. For $r$-band geometric albedo $p_r,$ this implies a
diameter of $150 (p_r/0.04)^{-0.5}$ km. There is strong evidence of brightness
fluctuations at $\pm0.2$ mag level, but no rotation period can be discerned. A
coma consistent with a ``stationary' $1/\rho$ surface-brightness distribution
grew in scattering cross-section at an exponential rate from $A f \rho\approx1$
m to $\approx150$ m as the comet approached from 28 to 20 au. The activity is
consistent with a simple model of sublimation of a surface species in radiative
equilibrium with the Sun. The inferred enthalpy of sublimation matches those of
$CO_2$ and $NH_3$. More-volatile species -- $N_2,$ $CH_4,$ and $CO$ -- must be
far less abundant on the sublimating surfaces.
Keywords
astro-ph.EP, astro-ph.EP
Sponsorship
STFC (ST/T003081/1)
Identifiers
apjlac32d3, ac32d3, aas34873
External DOI: https://doi.org/10.3847/2041-8213/ac32d3
This record's URL: https://www.repository.cam.ac.uk/handle/1810/330492
Rights
Licence:
http://creativecommons.org/licenses/by/4.0/
Statistics
Total file downloads (since January 2020). For more information on metrics see the
IRUS guide.
Recommended or similar items
The current recommendation prototype on the Apollo Repository will be turned off on 03 February 2023. Although the pilot has been fruitful for both parties, the service provider IKVA is focusing on horizon scanning products and so the recommender service can no longer be supported. We recognise the importance of recommender services in supporting research discovery and are evaluating offerings from other service providers. If you would like to offer feedback on this decision please contact us on: support@repository.cam.ac.uk