NEOWISE Observations of Distant Active Long-period Comets C/2014 B1 (Schwartz), C/2017 K2 (Pan-STARRS), and C/2010 U3 (Boattini)
The Astronomical Journal(2024)
摘要
Hyperactive comet activity typically becomes evident beyond the frost line (3
to 4 au) where it becomes too cold for water-ice to sublimate. If carbon
monoxide (CO) and carbon dioxide (CO2) are the species that drive activity at
sufficiently large distances, then detailed studies on the production rates of
these species are extremely valuable to examine the formation of the solar
system because these two species (beyond water) are next culpable for driving
cometary activity. The NEOWISE reactivated mission operates at two imaging
bandpasses, W1 and W2 at 3.4 and 4.6 microns, respectively, with the W2 channel
being fully capable of detecting CO and CO2 at 4.67 and 4.23 microns in the
same bandpass. It is extremely difficult to study CO2 from the ground due to
contamination in Earth's atmosphere. We present our W1 and W2 photometry, dust
measurements, and findings for comets C/2014 B1 (Schwartz), C/2017 K2
(Pan-STARRS), and C/2010 U3 (Boattini), hereafter, B1, K2, and U3,
respectively. Our results assess CO and CO2 gas production rates observed by
NEOWISE. We have determined: (1) comets B1 and K2 have CO2 and CO gas
production rates of 1e27 and 1e29 molecules per second, respectively, if one
assumes the excess emission is attributed to either all CO or all CO2; (2) B1
and K2 are considered hyperactive in that their measured AfRho dust production
values are on the order of greater than or equal to 1e3 cm; and (3) the CO and
CO2 production rates do not always follow the expected convention of increasing
with decreased heliocentric distance, while B1 and K2 exhibit noticeable dust
activity on their inbound leg orbits.
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关键词
Long period comets,Infrared astronomy,Photometry,Astronomy data analysis,Comet volatiles
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