1,721,321 research outputs found
ON THE ENERGY EXTRACTION FROM THE INTERIOR SCHWARTZSCHILD METRIC
No full textThe binding energies of stable circular orbits within an internal Schwartzschild solution are investigated. It is shown how, under suitable circumstances, the binding energy may be equal to the total rest mass energy of a test particle
Characteristics of an hybrid atmosphere with disk-captured and degassing contributions over a rocky planet's magma ocean. A modeling approach
No full textMotivation: Early during their formation the planets capture an amount of atmosphere from the protoplanetary disk (Ikoma et al. 2018, Odert et al. 2018, Lammer et al. 2020, Kimura and Ikoma 2020). An additional proportion of their atmosphere is provided during the magma ocean stage by interior degassing. The latter mechanism is assumed to be the main provider of the final atmospheric mass. Its composition is compromised by the source silicate mineral and its chemical characterization (Gaillard and Scaillet 2014, Herbort et al. 2020). Numerous studies support the degassing of the oxidized gas species H2O and CO2 as main contributions from the magma ocean phase (Abe and Matsui 1988, Abe 1993, Elkins-Tanton 2008, Schaefer et al. 2012, Lebrun et al. 2013, Lupu et al. 2014, Gaillard and Scaillet 2014, Salvador et al. 2017, Nikolaou et al. 2019). Previous work has also shown that H2O, in particular, plays a crucial role (Hamano et al. 2013, Katyal et al. 2019, Turbet et al. 2019) in thermal blanketing. H2O possibly leads to "long-term" (Hamano et al 2013) or "conditionally continuous" (Nikolaou et al. 2019) magma oceans that effectively cease to cool. Water also ties directly to the availability of hydrogen that drives hydrodynamic escape (Airapetian et al. 2017, Lammer et al. 2018). CO2 factors into both above processes, as well (Wordsworth and Pierrehumbert 2013, Odert et al. 2018). Constraining the H2O and CO2 abundances early after formation is indispensible to the planet"s thermal evolution and extensive modeling effort has been devoted to it. Their constraint would in particular help revisit which magma ocean types among transient-conditionally continuous-permanent (Nikolaou et al. 2019) are detectable in future exoplanetary missions (ARIEL, Tinetti et al. 2018; PLATO, Rauer et al. 2014). Method: In this work we focus on the combination of degassed and disk-captured atmosphere under the assumption of chemical equilibrium. Using simulations from the 1D Convective Ocean of Magma Radiative Atmosphere and Degassing model (Nikolaou et al. 2019) we obtain the thermal evolution and degassing tracks of a rocky planet. In order to evaluate the chemical abundances under equilibrium conditions we employ the thermodynamical model GGchem (Woitke et al. 2018). We explore the atmospheric conditions during the lifetime of a magma ocean under varying mineral compositions and protoplanetary disk contributions. We discuss the results in the context of the likely magma ocean types. A.N. and P.W. wish to thank the Erwin Schrödinger International Institute for Mathematics and Physics (ESI) of the University of Vienna, Thematic Programme on "Astrophysical Origins: Pathways from Star Formation to Habitable Planets" 2019, which enabled this collaboration...
SAFIRE-A (spectroscopy of the atmosphere by far-infrared emission - Airborne): Optimized instrument configuration and new assessment of improved performance
No full textPredicting the optical performance of the Ariel Telescope using PAOS
Full text linkThe Ariel Space Mission is the M4 mission in ESA's Cosmic Vision program and will observe a large and diverse sample of exoplanetary atmospheres in the visible to the near-infrared range of the electromagnetic spectrum. Assessing the impact of diffraction, aberrations, and related systematics on the Ariel optical performance before having a system-level measurement is paramount to ensuring that the optical quality, complexity, costs, and risks are not too high.
Several codes offer Physical Optics Propagation (POP) calculations, although generally, they are not easily customizable, e.g., for Monte Carlo simulations, are not free access and publicly available, or have technical limitations such as not providing support for refractive elements.
PAOS, the Physical Ariel Optics Simulator, is an end-to-end Physical Optics Propagation (POP) model of the Ariel telescope and subsystems. PAOS implements Fresnel diffraction in the near and far fields to simulate the propagation of the complex electromagnetic wavefront through the Ariel optical chain and deliver the realistic PSFs vs. lambda at the intermediate and focal planes.
PAOS is written with a full Python 3 stack and comes with an installer, documented examples, and an exhaustive guide. PAOS is meant to be easy to use, generic and versatile for POP simulations of optical systems other than Ariel’s, thanks to its generic input system and built-in GUI providing a seamless user interface and simulations
Data analysis Pipeline for EChO end-to-end simulations
Full text linkAtmospheric spectroscopy of extrasolar planets is an intricate business. Atmospheric signatures typically require a photometric precision of in flux over several hours. Such precision demands high instrument stability as well as an understanding of stellar variability and an optimal data reduction and removal of systematic noise. In the context of the EChO mission concept, we here discuss the data reduction and analysis pipeline developed for the EChO end-to-end simulator EChOSim. We present and discuss the step by step procedures required in order to obtain the final exoplanetary spectrum from the EChOSim`raw data' using a simulated observation of the secondary eclipse of the hot-Neptune 55 Cnc e
Molecular detectability in exoplanetary emission spectra
No full textAbstractOf the many recently discovered worlds orbiting distant stars, very little is yet known of their chemical composition. With the arrival of new transit spectroscopy and direct imaging facilities, the question of molecular detectability as a function of signal-to-noise (SNR), spectral resolving power and type of planets has become critical. In this paper, we study the detectability of key molecules in the atmospheres of a range of planet types, and report on the minimum detectable abundances at fixed spectral resolving power and SNR. The planet types considered—hot Jupiters, hot super-Earths, warm Neptunes, temperate Jupiters and temperate super-Earths—cover most of the exoplanets characterisable today or in the near future. We focus on key atmospheric molecules, such as CH4, CO, CO2, NH3, H2O, C2H2, C2H6, HCN, H2S and PH3. We use two methods to assess the detectability of these molecules: a simple measurement of the deviation of the signal from the continuum, and an estimate of the level of confidence of a detection through the use of the likelihood ratio test over the whole spectrum (from 1 to 16μm). We find that for most planetary cases, SNR=5 at resolution R=300 (λ<5μm) and R=30 (λ>5μm) is enough to detect the very strongest spectral features for the most abundant molecules, whereas an SNR comprised between 10 and 20 can reveal most molecules with abundances 10−6 or lower, often at multiple wavelengths. We test the robustness of our results by exploring sensitivity to parameters such as vertical thermal profile, mean molecular weight of the atmosphere and relative water abundances. We find that our main conclusions remain valid except for the most extreme cases. Our analysis shows that the detectability of key molecules in the atmospheres of a variety of exoplanet cases is within realistic reach, even with low SNR and spectral resolving power
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