J/ApJ/933/L44 Photometry of comet Bernardinelli-Bernstein (Kelley+, 2022)
A look at outbursts of comet C/2014 UN271 (Bernardinelli-Bernstein) near 20au.
Kelley M.S.P., Kokotanekova R., Holt C.E., Protopapa S., Bodewits D.,
Knight M.M., Lister T., Usher H., Chatelain J., Gomez E., Greenstreet S.,
Angel T., Wooding B.
<Astrophys. J., 933, L44 (2022)>
=2022ApJ...933L..44K 2022ApJ...933L..44K
ADC_Keywords: Comets ; Photometry ; Optical ; Magnitudes, absolute
Keywords: Optical astronomy ; Broad band photometry ; Long period comets ;
Coma dust ; Comet surfaces
Abstract:
Cometary activity may be driven by ices with very low sublimation
temperatures, such as carbon monoxide ice, which can sublimate at
distances well beyond 20au. This point is emphasized by the discovery
of the Oort cloud comet C/2014 UN271 (Bernardinelli-Bernstein) and
its observed activity out to ∼26au. Through observations of this
comet's optical brightness and behavior, we can potentially discern
the drivers of activity in the outer solar system. We present a study
of the activity of comet Bernardinelli-Bernstein with broad-band
optical photometry taken at 19-20au from the Sun (2021 June to
2022 February) as part of the LCO Outbursting Objects Key (LOOK)
Project. Our analysis shows that the comet's optical brightness during
this period was initially dominated by cometary outbursts, stochastic
events that ejected ∼107 to ∼108kg of material on short (<1day)
timescales. We present evidence for three such outbursts occurring in
2021 June and September. The nominal nuclear volumes excavated by
these events are similar to the 10-100m pit-shaped voids on the
surfaces of short-period comet nuclei, as imaged by spacecraft. Two
out of three Oort cloud comets observed at large pre-perihelion
distances exhibit outburst behavior near 20au, suggesting such events
may be common in this population. In addition, quiescent CO-driven
activity may account for the brightness of the comet in 2022 January
to February, but that variations in the cometary active area (i.e.,
the amount of sublimating ice) with heliocentric distance are also
possible.
Description:
We present a study of the activity of comet Bernardinelli-Bernstein
with broad-band optical photometry taken at 19-20au from the Sun
(2021 June to 2022 February) as part of the LCO Outbursting Objects
Key (LOOK) Project.
Images of comet Bernardinelli-Bernstein were taken by our team and by
schoolchildren in Wales as part of the Comet Chasers educational
outreach program through the Faulkes Telescope Project. Observations
were taken with LCO's 1m robotic telescopes, specifically those
located at Siding Spring Observatory, Australia; South African
Astronomical Observatory, South Africa; and the Cerro Tololo
Inter-American Observatory, Chile.
For most observations, we used the SDSS g' and r' filters, although
the w (effectively g+r+i), V, and R filters were used in a few
circumstances. The telescopes tracked the proper motion of the comet,
and exposure times were typically 300s with two exposures per filter.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 84 179 Observational circumstances and photometry
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See also:
B/comets : Database of the orbital elements of comets (Rocher, 2007)
II/371 : The Dark Energy Survey (DES): Data Release 2 (Abbott+, 2021)
J/A+A/374/712 : Photometric observations of comets (Szabo+, 2001)
J/AJ/134/973 : SDSS Stripe 82 star catalogs (Ivezic+, 2007)
J/A+A/527/A113 : 67P/Churyumov-Gerasimenko R-band light curve (Tubiana+, 2011)
J/A+A/548/A12 : 67P/Churyumov-Gerasimenko R-band light curve (Lowry+, 2012)
J/ApJ/750/99 : The Pan-STARRS1 photometric system (Tonry+, 2012)
J/ApJ/776/L20 : C/2012 S1 (comet ISON) R photometry (Meech+, 2013)
J/ApJ/793/50 : Observed light curve of (3200) Phaethon (Ansdell+, 2014)
J/AJ/154/196 : Properties of comet 49P/Arend-Rigaux, 1984-2012 (Eisner+, 2017)
J/ApJ/867/105 : ATLAS all-sky stellar ref. cat. ATLAS-REFCAT2 (Tonry+, 2018)
J/AJ/157/186 : r'-band photometry of comet 96P/Machholz 1 (Eisner+, 2019)
J/ApJS/258/41 : TNOs from the full six years of DES (Bernardinelli+, 2022)
J/MNRAS/521/1518 : Comet 162P/Siding Spring photometry (Donaldson+, 2023)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 16 A16 "datime" Date Mid-observation time; UTC
18- 25 F8.3 yr Year [2021.472/2022.145] Date as decimal year; UTC
27- 28 A2 --- Filt Observation filter (gp, rp, R, V or w) (1)
30 A1 --- Cal Photometric calibration filter, PS1 system
32- 37 F6.3 AU rh [19.27/20.2] Target heliocentric distance
39- 44 F6.3 AU Delta [19.34/20.2] Target-observer distance
46- 50 F5.3 deg theta [2.6/2.9] Sun-comet-observer (phase) angle
52- 55 F4.2 --- Airmass [1.08/1.65] Mean airmass of the images
57- 59 F3.1 arcsec Seeing [1.4/3] FWHM of point sources
61 I1 --- Nimg [1/3] Number of images
63- 65 I3 s Exp [95/900] Total exposure time
67- 72 F6.3 mag mag [18.27/19.9] Apparent magnitude in 6 arcsec
radius aperture
74- 78 F5.3 mag e_mag [0.05/0.14] Uncertainty in mag
80- 84 F5.3 mag rMAG [5/6.4] Effective r-band absolute magnitude,
Hr (2)
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Note (1): Filter systems are PS1 (r, g, w), SDSS (rp, gp), or
Johnson-Cousins (V, R).
Note (2): rh=1au, Delta=1au, theta=0deg.
g-band photometry has been scaled by the average color.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Katia van der Woerd [CDS] 03-Feb-2025