TY - JOUR
T1 - Comet 240P/NEAT Is Stirring
AU - Kelley, Michael S.P.
AU - Bodewits, Dennis
AU - Ye, Quanzhi
AU - Farnham, Tony L.
AU - Bellm, Eric C.
AU - Dekany, Richard
AU - Duev, Dmitry A.
AU - Helou, George
AU - Kupfer, Thomas
AU - Laher, Russ R.
AU - Masci, Frank J.
AU - Prince, Thomas A.
AU - Rusholme, Ben
AU - Shupe, David L.
AU - Soumagnac, Maayane T.
AU - Zolkower, Jeffry
N1 - Publisher Copyright:
© 2019. The American Astronomical Society. All rights reserved..
PY - 2019/11/20
Y1 - 2019/11/20
N2 - Comets are primitive objects that formed in the protoplanetary disk, and have been largely preserved over the history of the solar system. However, they are not pristine, and surfaces of cometary nuclei do evolve. In order to understand the extent of their primitive nature, we must define the mechanisms that affect their surfaces and comae. We examine the lightcurve of comet 240P/NEAT over three consecutive orbits, and investigate three events of significant brightening (Δm ∼ -2 mag). Unlike typical cometary outbursts, each of the three events are long-lived, with enhanced activity for at least 3-6 months. The third event, observed by the Zwicky Transient Facility, occurred in at least two stages. The anomalous behavior appears to have started after the comet was perturbed by Jupiter in 2007, reducing its perihelion distance from 2.53 to 2.12 au. We suggest that the brightening events are temporary transitions to a higher baseline activity level, brought on by the increased insolation, which has warmed previously insulated sub-surface layers. The new activity is isolated to one or two locations on the nucleus, indicating that the surface or immediate sub-surface is heterogeneous. Further study of this phenomenon may provide insight into cometary outbursts, the structure of the near-surface nucleus, and cometary nucleus mantling.
AB - Comets are primitive objects that formed in the protoplanetary disk, and have been largely preserved over the history of the solar system. However, they are not pristine, and surfaces of cometary nuclei do evolve. In order to understand the extent of their primitive nature, we must define the mechanisms that affect their surfaces and comae. We examine the lightcurve of comet 240P/NEAT over three consecutive orbits, and investigate three events of significant brightening (Δm ∼ -2 mag). Unlike typical cometary outbursts, each of the three events are long-lived, with enhanced activity for at least 3-6 months. The third event, observed by the Zwicky Transient Facility, occurred in at least two stages. The anomalous behavior appears to have started after the comet was perturbed by Jupiter in 2007, reducing its perihelion distance from 2.53 to 2.12 au. We suggest that the brightening events are temporary transitions to a higher baseline activity level, brought on by the increased insolation, which has warmed previously insulated sub-surface layers. The new activity is isolated to one or two locations on the nucleus, indicating that the surface or immediate sub-surface is heterogeneous. Further study of this phenomenon may provide insight into cometary outbursts, the structure of the near-surface nucleus, and cometary nucleus mantling.
UR - http://www.scopus.com/inward/record.url?scp=85077872382&partnerID=8YFLogxK
U2 - 10.3847/2041-8213/ab53e0
DO - 10.3847/2041-8213/ab53e0
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AN - SCOPUS:85077872382
SN - 2041-8205
VL - 886
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 1
M1 - L16
ER -