magma ocean Archives - Page 5 of 6 - Astrobiology

Astrogeology, Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Exoplanets, -moons, -comets, Lava / magma ocean / Volcanic Worlds, Status Report

Ocean Circulation on Tide-locked Lava Worlds, Part I: An Idealized 2D Numerical Model

by Keith CowingAugust 26, 2024August 26, 2024

A magma ocean is expected to exist on the dayside of tide-locked planets if surface temperature exceeds the melting temperature of typical crust.

Scaling laws of the magma ocean depth (D; top), horizontal velocity (U; middle), and ocean heat transport convergence (H; bottom) in Regime I. Left panels: sensitivity of D, U, and H to vertical viscosity (Az) and vertical diffusivity (kz) when dominated by thermal forcing. Right panels: sensitivity of D, U, and H to wind stress (τ ) and substellar temperature (Tsub) when dominated by wind forcing. Note that in the right panels, results are still from the thermal forcing-dominated scaling when wind stress is zero. Colors are results from scaling laws, and filled circles are results from numerical simulations. For numerical results, their exact values are indicated. -- astro-ph.EP

Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Lava / magma ocean / Volcanic Worlds, Status Report

Ocean Circulation on Tide-locked Lava Worlds, Part II: Scalings

by Keith CowingAugust 26, 2024August 26, 2024

On tidally locked lava planets, magma ocean can form on the permanent dayside. The circulation of the magma ocean can be driven by stellar radiation and atmospheric winds.

Number densities of condensate droplets and gas molecules, and their respective molecular weights, as a function of height R/Rp for the atmosphere shown in Figure 8 with Kzz = 1×104 . Left: Numbers of dots at each height in the atmosphere represent the relative number densities of droplets, and the symbol sizes are proportional to droplet sizes. Right: Numbers of dots represent the relative number densities of molecules. In both plots, colors indicate molecular weights at each height (note different color scales in the two panels). Curves for absolute number densities of droplets (left) and gas molecules (right) are overlain for comparison. -- astro-ph.EP

Astrogeology, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Status Report, Water/Hycean Worlds & Oceanography

Phase Equilibria of Sub-Neptunes and Super-Earths

by Keith CowingAugust 22, 2024

We investigate the consequences of non-ideal chemical interaction between silicate and overlying hydrogen-rich envelopes for rocky planets using basic tenets of phase equilibria. Based on our current understanding of the […]

Mass - radius relations of puffy Venuses. a: M-R relations compared to observed exoplanets. The grey line is the M-R for terrestrial planets with an Earth-like core mass fraction of 0.325 (Plotnykov & Valencia 2020). Colored solid lines are puffy Venus radii assuming different Teq, with the fiducial, OC-like volatile C and H abundances. The orange dashed line is the M-R for Teq = 2000 K planets with a convective deep atmosphere to the MO surface, instead of a deep radiative zone. The shaded region is the range of M-R space an air-less rocky world can occupy for all possible Fe/Si ∈ [0, 1]. Planets less dense than this region require a volatile component. Measured exoplanet samples are from the NASA Exoplanet Archive (2023), and only contain those with relative errors below 30%. The nine planets highlighted with black circles are our preferred puffy Venus candidates. In rising mass order, they are GJ 1252 b, TOI-500 b, TOI-561 b, Kepler-10 b, Kepler-36 b, HD 219134 b, HD 3167 b, WASP-47 e, and 55 Cnc e. TOI-561 b’s radius is from Patel et al. (2023); its mass is from Brinkman et al. (2023) b: M-R of puffy Venuses with a range of chondritic C abundances, more opaque lines correspond to less C. They are color-coded by temperature - Teq = 1000 K (blue) and 2000 K (orange). The dashed orange line is for wet CI composition, while the solid line with the same color is for dry CI composition. The dotted portion of dry CI, 1000 K line are atmospheres that should experience graphite precipitation; see text. c: M-R of models assuming different chemical scenarios - I (solid), local chemical equilibrium throughout the atmosphere, II (dash-dot), chemical equilibrium at the MO surface, and a CO2 + H2O atmosphere (dotted). Fiducial OC C and H abundances are used. Same color-coding as b. The solid 1000 K and 2000 K lines in a, the 2 OC lines in b, and the 2 Scenario I lines in c are the same. -- astro-ph.EP

Astrochemistry, Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Lava / magma ocean / Volcanic Worlds, Status Report, Venus

Puffy Venuses: the Mass-Radius Impact of Carbon-Rich Atmospheres on Lava Worlds

by Keith CowingMay 16, 2024May 16, 2024

The recent advancements in exoplanet observations enable the potential detection of exo-Venuses, rocky planets with carbon-rich atmospheres. How extended these atmospheres can be, given high carbon abundances, has not been […]

Lifetime (in Myr) of the MO-outgassed atmosphere as a function of planetary mass (x-axis), and incoming XUV flux (LXUV, y-axis), normalized by the solar XUV flux received by the Earth 4.5 Ga (L sun XUV(t=4.5 Ga)) from Ribas et al. (2005), for the cases most prone to hydrodynamic escape (∆IW “ ´5 and Φ “ 0.1). The loci in which the crossover mass matches the molecular mass of H2O (black), CO or N2 (purple), and CO2 (white) are also represented. -- astro-ph.EP

Astrochemistry, Astrogeology, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Lava / magma ocean / Volcanic Worlds, Status Report

Volatile Atmospheres Of Lava Worlds

by Keith CowingMay 16, 2024

A magma ocean (MO) is thought to be a ubiquitous stage in the early evolution of rocky planets and exoplanets. During the lifetime of the MO, exchanges between the interior […]

Self-consistent atmosphere models of 55 Cnc e. The NIRCam relative eclipse depths are offset to a mean depth of 60 ppm. Previous Spitzer measurements 24 are shown in gray. The black dashed lines are blackbody models at the temperatures indicated in the plot. The vaporized-rock model was simulated using the rocky composition that corresponds to the bulk silicate Earth; using other plausible rock compositions results in qualitatively similar results (Extended Data Fig. 7). The atmosphere models are simulated either in a parameter exploration of CHONSP elemental abundances or with the assumption of volatile equilibrium with an underlying magma ocean. The models shown are selected from those that provide adequate fits to the data. The volatile atmosphere models with enhanced outgassing of rock-forming elements can cause substantial changes in the eclipse depth and the emission spectra. The models are smoothed to R=100 for the clarity of illustration. Model results binned to the same wavelength channels as the MIRI data are shown as colored points. The oxygen fugacity (fO2 ) describes the redox condition of the magma and fO2=IW-4 means a condition more reduced than the iron-wustite (IW) buffer by 4 orders of magnitude. The full sets of atmospheric models are described in Methods and Extended Data Figs. 8 and 9. -- astro-ph.EP

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Lava / magma ocean / Volcanic Worlds, Status Report

A Secondary Atmosphere On The Rocky Exoplanet 55 Cancri e

by Keith CowingMay 11, 2024

Characterizing rocky exoplanets is a central endeavor of astronomy, and yet the search for atmospheres on rocky exoplanets has hitherto resulted in either tight upper limits on the atmospheric mass […]

Venus, Earth, and Mars -- NASA

Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Habitable Zones, Lava / magma ocean / Volcanic Worlds, Mars, Status Report, Venus

The Evolutionary Divergence Of Mars, Venus and Earth

by Keith CowingApril 23, 2024May 11, 2024

Mars, Venus and Earth are expected to have started in a hot molten state. Here, we discuss how these three terrestrial planets diverged in their evolution and what mechanisms could […]

Total atmospheric surface pressure (bar) and volume mixing ratio of NH3, and CO2 output from the atmospheremagma ocean system over the parameter space which we have sampled, outlined in table 1. This corresponds to the output of step 2 in the schematic presented in figure 1. Points are colour-coded by the log of the planetary hydrogen budget, in units part-per-million of the planetary mass. Histograms of the distribution of NH3 mixing ratios (top left), CO2 mixing ratios (top right) and total surface pressures (lower right) from across the model runs are shown alongside. -- astro-ph.EP

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Lava / magma ocean / Volcanic Worlds, Status Report, Water/Hycean Worlds & Oceanography

Distinguishing Oceans Of Water From Magma On Mini-Neptune K2-18b

by Keith CowingJanuary 12, 2024May 11, 2024

Mildly rradiated mini-Neptunes have densities potentially consistent with them hosting substantial liquid water oceans (`Hycean’ planets).

Outgoing thermal emission as a function of surface temperature. The dashed-dotted line is the classic runaway curve obtained with fully convective profiles, independently from the stellar radiation spectrum and internal flux. With self-consistent profiles, this function depends on the type of the host star and the internal flux ϕint. Dashed curves are obtained with Earth geothermal flux. For T-1 and ϕint < 0.01 Wm−2 , the runaway greenhouse can end without full vaporization of the ocean. Low-pressure liquidus, solidus and melting (melt fraction = 40%) temperatures are indicated for an Earth mantle composition. Surface pressure is 270 bars except in the blue area where Tsurf is below the critical temperature of H2O and psurf is given by the saturation vapor pressure of H2O. These curves are based on the profiles shown in Extended Data Figure 2 -- astro-ph.EP

Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Lava / magma ocean / Volcanic Worlds, Status Report, Water/Hycean Worlds & Oceanography

A Cool Runaway Greenhouse Without Surface Magma Ocean

by Keith CowingNovember 17, 2023May 11, 2024

Water vapour atmospheres with content equivalent to the Earth’s oceans, resulting from impacts or a high insolation, were found to yield a surface magma ocean. This was, however, a consequence […]

Mantle temperature field and velocity field of superEarth 55 Cancri e for the reference model. High velocities (larger than three times the mean mantle velocity) are plotted with a red arrow. The magma ocean is indicated in red (fully molten) and orange (partially molten). -- astro-ph.EP

Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Lava / magma ocean / Volcanic Worlds, Status Report

Interior Dynamics Of Super-Earth 55 Cancri e

by Keith CowingAugust 3, 2023May 11, 2024

The ultra-short-period super-Earth 55 Cancri e has a measured radius of 1.8 Earth radii. Previous thermal phase curve observations suggest a strong temperature contrast between the dayside and nightside of […]