In chapter 5, the secular evolution of Mars' orbit drives the evolution of the equilibrium relationship between the Martian atmospheric pressure and the large CO2 ice deposit on the Martian south polar cap. I construct the first self-consistent conceptual framework capable of predicting the existence and shape of the Martian residual south polar cap and the buried CO2.
INTRODUCTION
- Hot Love
- An Overturning Heart
- A New Heart
- A Match Made on Mars
The RSPC is a 1β10 m thick CO2 ice deposit that has a mass ~1% of the present-day atmosphere (Thomas et al., 2016) and a general structure that is intra- and interannually stable. The RSPC is therefore not the equilibrium reservoir of Leighton and Murray (1966) because its small mass (~1% of the Martian atmosphere, Thomas et al., 2016) is insufficient to counteract secular changes in the polar energy budget like Mars bumper. ' orbit developed.
DYNAMICAL CONSTRAINTS ON THE CORE MASS OF HOT JUPITER HAT-P- 13b
Abstract
Introduction
However, Becker & Batygin (2013) have shown that the existence of this third companion does not disrupt the secular dynamic that allows HAT-P-13b eb's eccentricity to be associated with its love number k2b. Using existing constraints on the orbital eccentricity of HAT-P-13b from radial velocity measurements, Batygin et al.
Methods
The 1Ο uncertainties in the RMS (RMS/ β2π ) of the binned PLD model are plotted in light green. To do this, we first calculate the stellar flux by integrating a PHOENIX stellar flux model (Husser et al. 2013) for each bandpass, weighted by the mean spectral response curve of the subarray.2 We use a PHOENIX model with an effective temperature of Teff = 5700 K, a surface gravity of log g = 4.0, and a modestly enhanced metallicity of [Fe/H] = 0.5.
Results
Effective daily temperature was calculated by taking the error-weighted average of the best-fitting temperatures in each band. Both models assume a solar composition, a plane-parallel atmosphere with molecular abundances set to local thermal equilibrium values. 2008) models assume a uniform distribution of heat across the dayside and vary the amount of incident energy at the top of the dayside atmosphere to approximate the effects of redistribution to the nightside.
Discussion
If the planets are coplanar, their apsides will be aligned in much less than the age of the HAT-P-13 system (Mardling 2007; Batygin et al. 2009). That study investigated the effects of the inclination angle between the orbits of HAT-P-13b and HAT-P-13c (Ξibβc) on eb and found that if the orbits are nearly isosceles (Ξππβπ β€ 10Β°), then the limit cycle in ebb will have a width of less than 3% ebb and the width of the limit cycle of the angle between the apses is β€4Β° (calculated from Equations and (17) of Mardling 2010).
Conclusions
The unique opportunity to independently constrain the core mass and atmospheric properties of this hot Jupiter with a modestly sized core makes the HAT-P-13 system an important case study for dynamical constraints on the core masses of gas giant planets.
Acknowledgments
Secondary Spitzer Eclipses of the Dense, Modestly Irradiated Giant Exoplanet HAT-P-20b Using Pixel-Level Correlation. A unified theory for the atmospheres of hot and very hot Jupiters: Two classes of irradiated atmospheres. 1969 Evolution of the Protoplanetary Cloud and Formation of the Earth and Planets (Moscow: Nauka) English translation: NASA TTF-677.
SUBLIMATION PIT DISTRIBUTION INDICATES CONVECTION CELL SURFACE VELOCITIES OF ~10 CENTIMETERS PER YEAR IN SPUTNIK PLANITIA, PLUTO
Abstract
Finally, we investigate the surface rheology of the convection cells and estimate that the minimum ice viscosity required to support the geometry of the observed wells is of order Pa s, based on the argument that wells will relax before expanding to their observed radii of several hundred meters if the viscosity was lower than this value.
Introduction
Finally, we discuss our results in the context of other surface measurements and other hypotheses for the spatial distribution of pits on the cells in SP, such as control of the pit distribution due to a thermal gradient across the cells (e.g. White et al., 2017 ).
Methods
Here, Ξ΅ is the emissivity, ππ΅ is the Stefan-Boltzmann constant, and TPit is the temperature of the well walls. We therefore take PS as the power per unit area available to sublimate the well walls and cause radial growth of the wells. The probability density function of the pit growth rate, with most likely rate (solid), 1Ο (dashed) and 2Ο (dash-dot) uncertainties indicated.
Results
3.1-3.4 and 3.7-3.9, the number of pits per map area, the best-fit intercept and slope with 68% confidence, the best-fit velocity with 68% and 95% confidence intervals, the length from the propagation center to the edge cell, and the duration of convection. We only report the number of pits, slopes, and intercepts for III-L because other values ββwould be unphysical (see Section 3.5.5).
Discussion
First, the laboratory-annealed N2 ice may not be representative of the ice in the SP (Moore et al., 2016b). Fits the upper and lower half of the left side of cell III, in the same style as fig. Fits the upper and lower half of the right side of cell I, in the same style as fig.
Conclusion
We argue that sublimation is the process that primarily determines the radius of the pits because viscous relaxation acts preferentially on long wavelengths (i.e. determining pit depth) compared to short wavelength (i.e. pit edges) and the pits do not are relaxed. We favor the hypothesis that the surface motion of the cell determines the pit distribution because (i) the sublimation rates we calculate indicate that pit production on the ~100 m scale occurs on the same time scale as convection and (ii) the presence of dense pits surrounded by an area of ββthinner pits in the centers of some cells is inconsistent with viscous relaxation governed by a monotonic temperature gradient. Finally, the correlation between the well distributions of three adjacent cells (I, II, and III), together with the disturbance of the boundary trough between cells I and II, indicates that the underlying convective cells interact and are unstable on timescales comparable to the age. of the cells.
Acknowledgements
We estimate and account for the resolution effect, which causes an overestimation of the intercept and underestimation of the slope of the linear fit. We also compare our hypothesis that the pattern of pits in cells indicates cell surface velocity (due to the transport of pits growing by sublimation) with the hypothesis that the pit pattern results from a thermal gradient that induces a viscosity gradient across cells. Global composition of Pluto's surface through pixel-by-pixel spatial modeling of New Horizons Ralph/LEISA data.
HOW THE MARTIAN RESIDUAL SOUTH POLAR CAP DEVELOPS QUASI- CIRCULAR AND HEART-SHAPED PITS, TROUGHS, AND MOATS
Abstract
Introduction
Before describing landform development and attempting to understand the mechanisms leading to the development of RSPC morphology, we first refer the reader to Figure 4.1, a visual definition of the terminology used here and in the literature to describe the four main categories of landforms dissecting the RSPC: quasi-circular pits, heart-shaped pits, linear troughs and ditches (see also Thomas et al., 2016). We therefore use these data to infer the processes leading to the emergence of the multitude of morphological forms of the RSPC.
Methods
The white boxes give the true sizes of panels b-f compared to panel a, the black outline provides visual clarity of the locations. Images were imported with Martian polar stereographic projection and co-registered in ArcMap 10 to a base map constructed from Mars Reconnaissance Orbiter Context Camera images (Malin et al., 2007). Photogrammetry was used to determine the vertical displacement of features on the mesa tops using measurements of the length of shadows cast by fractures in low-angle sunlit HiRISE images.
Observations
New breaks in the thicker parts of the mesa appear without halos in the same scenes (Fig. 4.13). Fields of polygons can cover almost the entire upper surface of the interstices in unit A0 (Figure 4.16), but in thinner units they are usually limited to the edges of the interstices (e.g. Figure 4.14i). In one typically observed case, part of the collapsed area along the fault remains attached to the upper surface of the mesa, forming a crescent cave: a cave that has a smooth ramp bordering a steep escarpment (Fig. 4.18b).
Discussion
The bright, upper surface layer of mesas undergoes brittle failure, fractures, and plate fractures (Fig. 4.9-12). Bright halos that developed around new fractures in MY 32 (Fig. 4.12) may signal venting of gas from fractures on the upper surface of the mesas. Scarp slope, curvature and albedo play an important role in the development of sinkholes (Fig. 4.27).
Conclusions
We interpret that the relative efficiency of deposition and erosion at the boundary between the smooth ramp and the steep slope determines whether a crescent trench develops into a heart-shaped pit or a linear trough. The processes we infer from our observations are able to explain the morphologies present in the RSPC and provide a framework for landscape evolution models that would lead to better insight into the material properties of the RSPC. Ultimately, the processes we describe in this paper shed light on the subtle interplay between deposition and erosion on the RSPC and inform our understanding of the global Martian CO2 cycle.
Acknowledgments
Annual observations and quantification of summer H2O ice deposition on the south polar cap of Mars' CO2 ice. The seasonal variation of atmospheric pressure on Mars as influenced by the southern polar cap. Time scales of erosion and deposition recorded in the remaining south polar cap of Mars.
MARSβ SECULAR AMAZONIAN PRESSURE CYCLE, AS BUFFERED BY ITS SOUTH POLAR CO 2 DEPOSIT
Introduction
The possibility that the massive south polar CO2 deposit is in secular equilibrium with the atmosphere provides an opportunity to characterize the Martian pressure cycle throughout the Amazonian period (the past ~3 Ga). We therefore investigate the secular pressure history of Amazonian Mars as a function of its orbital history (Laskar et al., 2004) with an energy balance model, using observational constraints from modern CO2 deposition. In section 5.4 we discuss our results, their implications for the Martian climate and future research opportunities.
Numerical Methods
For all model results shown here, the model was run to convergence (that is, the subsurface temperature was identical two years in a row). The atmosphere is treated as an infinite reservoir of CO2 (i.e. the stock of condensed CO2 on the ground does not affect the pressure). In this article, pressure is reported as a fraction of the amount of CO2 available to power the Viking 1 pressure cycle.
The Secular Amazonian Pressure Curve
This means that the persistence of buried CO2 depends only on the confinement (a function of orbital parameters and latitude) and the properties of CO2. Contours and color bars are for Peq data in units of the modern atmospheric inventory. Before proceeding, we note that the base of CO2 deposition is βΌ1 km lower than the modern RSPC (Bierson et al., 2016).
Discussion
Thus, the presence of the RSPC with a net neutral mass balance (as observed by Thomas et al., 2016) separated from the. The presence of the RSPC is thus a strong indicator that the buried CO2 deposit is not sealed off from the atmosphere. Naturally, the RSPC is riddled with pits that form when the surface of the RSPC collapses (Buhler et al., 2017).
Conclusions
The higher temperature of the basal boundary condition in the sealed case means that the summertime surface temperature can rise higher for a similarly thick H2O ice sheet, increasing the emitted thermal power and leading to a lower annual net energy balance. EnTOMBR: An energy balance model to explore the binding of the massive Martian buried CO2 ice deposit. On the mystery of the perennial carbon dioxide cap at the south pole of Mars.
CONCLUDING THOUGHTS
Introduction
Gas Giant Interior Properties