The Location of Oort Cloud Comets C/2011 L4 Panstarrs and C/2012 S1 ISON, on a Comets' Evolutionary Diagram

Abstract: We plot the Secular Light Curves (SLCs) of comets C/2011 L4 Panstarrs and C/2012 S1 ISON. The brightness of C/2011 L4 Panstarrs and C/2012 S1 ISON increase steeply after discovery but both decrease in slope sharply at ~4-5 AU, a characteristic of Oort Cloud cometary light curves that we refer to as a Slope Discontinuity Event (SDE). After the SDE, the SLC of C/2011 L4 continues to increase and has a surge near perihelion. The SLC of comet C/2012 S1 ISON on the other hand, is very odd and exhibits a SDE plus a near-standstill after the event. We found five comets with similar behavior: C/1996 Q1 Tabur, C/1999 S4 LINEAR, C/2002 O4 H\"onig, C/2010 X1 Elenin and C/2012 T5 Bressi, all of which disintegrated. Thus we predict that comet ISON will disintegrate too. We compiled published production rates of water, dust and CO and used them to calculate the Mass Loss Budget. We use this information for ISON to calculate the diameter and to plot 29 comets in an Evolutionary Diagram that separates comets by class. We find a diameter D = 1030+-70 m in excellent agreement with the upper limit found by Delamere et al. (2013), D(mean) < 1126 m. It is evident that the Secular Light Curves, exhibit complexity beyond current scientific understanding. Note: The comet disintegrated as predicted (CBET 3731), while this paper was being refereed.

• The paper identifies slope discontinuity events (SDEs) in SLCs marking significant photometric changes at 4–5 AU.
• It refines cometary diameters and mass-loss rates to project the disintegration of comet ISON.
• The study introduces a Remaining Returns vs. Mass-Loss Age diagram to classify comet evolution accurately.

Overview of "The Location of Oort Cloud Comets C/2011 L4. Panstarrs and C/2012 S1 ISON, on a Comet Evolutionary Diagram"

The paper authored by Ignacio Ferrín investigates the photometric behavior of two noteworthy Oort Cloud comets, C/2011 L4 Panstarrs and C/2012 S1 ISON, through the use of Secular Light Curves (SLCs) to understand their evolutionary positions. By employing 16,673 photometric observations, the study extrapolates actionable insights related to the disintegration processes of these celestial bodies, examines their secular light curves for slope discontinuity events, and speculates their positions on an evolutionary diagram indicating potential evolutionary paths.

Key Findings and Numerical Results

The research highlights the detection of Slope Discontinuity Events (SDEs) in the light curves of both comets, a phenomenon characterized by a sudden drop in brightness slope at heliocentric distances of around 4-5 AU. This behavior is notable due to its recurrence in Oort Cloud comets, providing insight into the evolutionary status and the potential disintegration of these bodies as seen in other comets sharing similar SLC behaviors.

A significant outcome from the analysis is the prediction of disintegration for comet ISON, corroborated by historical data of five other comets: C/1996 Q1 Tabur, C/1999 S4 LINEAR, C/2002 O4 Hönig, C/2010 X1 Elenin, and C/2012 T5 Bressi, each exhibiting similar SDE-related standstills and eventual disintegration.

Furthermore, the paper derives a revised diameter for comet ISON, estimated at 1030±70 meters, aligning with previous measurements by Delamere et al. (2013) which pegged an upper limit of 1126 meters. This accuracy in measurements underscores the effective methodology employed in analyzing the mass-loss budget and comet characteristics.

Theoretical Contributions

The work introduces a Remaining Returns vs. Mass-Loss Age diagram as an innovative means for categorizing and predicting comet evolutionary behavior. This diagram suggests that comets have finite remaining returns governed by mass-loss rates, and the diagram effectively delineates cometary classes: Oort Cloud comets on the left, Jupiter Family comets in the middle, and disintegrated comets on the threshold of destruction.

Theoretical deductions imply that the mass-loss budget and measured SDEs can serve as critical indicators of a comet’s evolutionary status. The authorities involved derive evolutionary lines, positing that sublimating comets will follow lines of negative slope on the diagram until eventual disintegration at the RR = 1 line.

Implications and Future Directions

Practically, the research aids in refining predictions regarding comet lifespan and stability while supporting the study of cometary disintegration critical for understanding broader solar system dynamics. Theoretically, this work extends our understanding of sublimation processes and heliocentric influence on cometary structures, providing a framework that accommodates variable albedo, diameter, and compositional factors, which influence the comet’s evolution and potential scenarios of activity or disintegration.

Future advancements will likely explore the accuracy and predictive capabilities of the Remaining Returns vs. Mass-Loss Age diagram by integrating additional comets. Further observations may align these theoretical frameworks with observational data to address eventual disintegration and other evolutionary phenomena, offering insights into the long-term dynamical evolution of comets stemming from the Oort Cloud and beyond. These studies reinforce the importance of understanding the role of volatiles like CO and CO2 in controlling sublimation and activity in dynamically new comets as they approach the Sun.