AI insight:
The research on GJ 1132b's thermal emission measurements is significant as it provides evidence suggesting the planet likely lacks a significant atmosphere, supporting the concept of a universal "cosmic shoreline."
📄 JWST Thermal Emission of the Terrestrial Exoplanet GJ 1132b
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Xue, Qiao et al. (2024) · The Astrophysical Journal
Reads: 166 · Citations: 49
DOI: 10.3847/2041-8213/ad72e9
🔗 https://ui.adsabs.harvard.edu/abs/2024ApJ...973L...8X/abstract
#Astronomy #Astrophysics #Exoplanets #PlanetaryScience #ExoplanetAstronomy
JWST Thermal Emission of the Terrestrial Exoplanet GJ 1132b
We present thermal emission measurements of GJ 1132b spanning 5–12 μm obtained with the Mid-Infrared Instrument Low-Resolution Spectrometer on the James Webb Space Telescope. GJ 1132b is an M dwarf rocky planet with T <SUB>eq</SUB> = 584 K and an orbital period of 1.6 days. We measure a white-light secondary eclipse depth of 140 ± 17 ppm, which corresponds to a dayside brightness temperature of T <SUB> p,dayside</SUB> = 709 ± 31 K using improved star and planet parameters. This measured temperature is only 1σ below the maximum possible dayside temperature of a bare rock (i.e., assuming a zero-albedo planet with no heat redistribution, <inline-formula> <mml:math overflow="scroll"><mml:msub><mml:mrow><mml:mi>T</mml:mi></mml:mrow><mml:mrow><mml:mi>max</mml:mi></mml:mrow></mml:msub></mml:math> </inline-formula> = <inline-formula> <mml:math overflow="scroll"><mml:msubsup><mml:mrow><mml:mn>746</mml:mn></mml:mrow><mml:mrow><mml:mo>‑</mml:mo><mml:mn>11</mml:mn></mml:mrow><mml:mrow><mml:mo>+</mml:mo><mml:mn>14</mml:mn></mml:mrow></mml:msubsup></mml:math> </inline-formula> K). The emission spectrum is consistent with a featureless blackbody, which agrees with a wide range of possible surface compositions. By comparing forward models to the dayside emission spectrum, we rule out Earth-thickness (P ∼ 1 bar) atmospheres with at least 1% H<SUB>2</SUB>O, atmospheres of any modeled thickness (10<SUP>‑4</SUP> to 10<SUP>2</SUP> bars) that contain at least 1% CO<SUB>2</SUB>, and thick, Venus-like atmospheres (P ≳ 100 bars) with at least 1 ppm CO<SUB>2</SUB> or H<SUB>2</SUB>O. We therefore conclude that GJ 1132b likely does not have a significant atmosphere. This finding supports the concept of a universal "cosmic shoreline" given the high level of bolometric and extreme ultraviolet (EUV) and X-rays (collectively XUV) irradiation received by the planet.
AI insight:
The UMIST Database for Astrochemistry's latest version includes significant updates and expansions, such as the addition of 23 new species and a comprehensive set of reactions, enhancing its utility for modeling astrophysical environments.
📄 The UMIST database for astrochemistry 2006
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Woodall, J. et al. (2007) · Astronomy and Astrophysics
Reads: 2 · Citations: 506
DOI: 10.1051/0004-6361:20064981
🔗 https://ui.adsabs.harvard.edu/abs/2007A&A...466.1197W/abstract
#Astronomy #Astrophysics #AstroSoftware #MolecularData #MolecularProcesses
The UMIST database for astrochemistry 2006
Aims:We present a new version of the UMIST Database for Astrochemistry, the fourth such version to be released to the public. The current version contains some 4573 binary gas-phase reactions, an increase of 10% from the previous (1999) version, among 420 species, of which 23 are new to the database. <BR />Methods: Major updates have been made to ion-neutral reactions, neutral-neutral reactions, particularly at low temperature, and dissociative recombination reactions. We have included for the first time the interstellar chemistry of fluorine. In addition to the usual database, we have also released a reaction set in which the effects of dipole-enhanced ion-neutral rate coefficients are included. <BR />Results: These two reactions sets have been used in a dark cloud model and the results of these models are presented and discussed briefly. The database and associated software are available on the World Wide Web at www.udfa.net. <P />Tables 1, 2, 4 and 9 are only available in electronic form at http://www.aanda.org
AI insight:
The research presents tightened and robust constraints on cosmological parameters using the Baryon Oscillation Spectroscopic Survey, in agreement with the ΛCDM model and providing insights into dark energy and neutrino mass.
📄 The clustering of galaxies in the completed SDSS-III Baryon Oscillati…
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Alam, Shadab et al. (2017) · Monthly Notices of the Royal Astronomical Society
Reads: 588 · Citations: 2978
DOI: 10.1093/mnras/stx721
🔗 https://ui.adsabs.harvard.edu/abs/2017MNRAS.470.2617A/abstract
#Astronomy #Astrophysics #Cosmology #DistanceScale #LargescaleStructureOfUniverse
The clustering of galaxies in the completed SDSS-III Baryon Oscillation Spectroscopic Survey: cosmological analysis of the DR12 galaxy sample
We present cosmological results from the final galaxy clustering data set of the Baryon Oscillation Spectroscopic Survey, part of the Sloan Digital Sky Survey III. Our combined galaxy sample comprises 1.2 million massive galaxies over an effective area of 9329 deg<SUP>2</SUP> and volume of 18.7 Gpc<SUP>3</SUP>, divided into three partially overlapping redshift slices centred at effective redshifts 0.38, 0.51 and 0.61. We measure the angular diameter distance D<SUB>M</SUB> and Hubble parameter H from the baryon acoustic oscillation (BAO) method, in combination with a cosmic microwave background prior on the sound horizon scale, after applying reconstruction to reduce non-linear effects on the BAO feature. Using the anisotropic clustering of the pre-reconstruction density field, we measure the product D<SUB>M</SUB>H from the Alcock-Paczynski (AP) effect and the growth of structure, quantified by fσ<SUB>8</SUB>(z), from redshift-space distortions (RSD). We combine individual measurements presented in seven companion papers into a set of consensus values and likelihoods, obtaining constraints that are tighter and more robust than those from any one method; in particular, the AP measurement from sub-BAO scales sharpens constraints from post-reconstruction BAOs by breaking degeneracy between D<SUB>M</SUB> and H. Combined with Planck 2016 cosmic microwave background measurements, our distance scale measurements simultaneously imply curvature Ω<SUB>K</SUB> = 0.0003 ± 0.0026 and a dark energy equation-of-state parameter w = -1.01 ± 0.06, in strong affirmation of the spatially flat cold dark matter (CDM) model with a cosmological constant (ΛCDM). Our RSD measurements of fσ<SUB>8</SUB>, at 6 per cent precision, are similarly consistent with this model. When combined with supernova Ia data, we find H<SUB>0</SUB> = 67.3 ± 1.0 km s<SUP>-1</SUP> Mpc<SUP>-1</SUP> even for our most general dark energy model, in tension with some direct measurements. Adding extra relativistic species as a degree of freedom loosens the constraint only slightly, to H<SUB>0</SUB> = 67.8 ± 1.2 km s<SUP>-1</SUP> Mpc<SUP>-1</SUP>. Assuming flat ΛCDM, we find Ω<SUB>m</SUB> = 0.310 ± 0.005 and H<SUB>0</SUB> = 67.6 ± 0.5 km s<SUP>-1</SUP> Mpc<SUP>-1</SUP>, and we find a 95 per cent upper limit of 0.16 eV c<SUP>-2</SUP> on the neutrino mass sum.
AI insight:
The paper provides an overview of approximate methods for large scale matter clustering which have become increasingly relevant due to precision cosmology, tracing developments from foundational techniques through pioneering efforts up to recent advancements and applications in…
📄 Approximate Methods for the Generation of Dark Matter Halo Catalogs i…
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Monaco, Pierluigi et al. (2016) · Galaxies
Reads: 99 · Citations: 62
DOI: 10.3390/galaxies4040053
🔗 https://ui.adsabs.harvard.edu/abs/2016Galax...4...53M/abstract
#Astronomy #Astrophysics #Cosmology #DarkMatterHalos #LargescaleStructureOfTheUniverse
Approximate Methods for the Generation of Dark Matter Halo Catalogs in the Age of Precision Cosmology
Precision cosmology has recently triggered new attention on the topic of approximate methods for the clustering of matter on large scales, whose foundations date back to the period from the late 1960s to early 1990s. Indeed, although the prospect of reaching sub-percent accuracy in the measurement of clustering poses a challenge even to full N-body simulations, an accurate estimation of the covariance matrix of clustering statistics, not to mention the sampling of parameter space, requires usage of a large number (hundreds in the most favourable cases) of simulated (mock) galaxy catalogs. Combination of few N-body simulations with a large number of realizations performed with approximate methods gives the most promising approach to solve these problems with a reasonable amount of resources. In this paper I review this topic, starting from the foundations of the methods, then going through the pioneering efforts of the 1990s, and finally presenting the latest extensions and a few codes that are now being used in present-generation surveys and thoroughly tested to assess their performance in the context of future surveys.
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This paper provides a detailed review of solar flare mechanisms based on magnetohydrodynamic processes, emphasizing their explosive nature and impacts across various atmospheric layers due to rapid energy release from coronal electric currents.
📄 Solar Flares: Magnetohydrodynamic Processes
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Shibata, Kazunari et al. (2011) · Living Reviews in Solar Physics
Reads: 26 · Citations: 734
DOI: 10.12942/lrsp-2011-6
🔗 https://ui.adsabs.harvard.edu/abs/2011LRSP....8....6S/abstract
#Astronomy #Astrophysics #SolarPhysics #MagneticReconnection #ParticleAcceleration
Solar Flares: Magnetohydrodynamic Processes
This paper outlines the current understanding of solar flares, mainly focused on magnetohydrodynamic (MHD) processes responsible for producing a flare. Observations show that flares are one of the most explosive phenomena in the atmosphere of the Sun, releasing a huge amount of energy up to about 10<SUP>32</SUP> erg on the timescale of hours. Flares involve the heating of plasma, mass ejection, and particle acceleration that generates high-energy particles. The key physical processes for producing a flare are: the emergence of magnetic field from the solar interior to the solar atmosphere (flux emergence), local enhancement of electric current in the corona (formation of a current sheet), and rapid dissipation of electric current (magnetic reconnection) that causes shock heating, mass ejection, and particle acceleration. The evolution toward the onset of a flare is rather quasi-static when free energy is accumulated in the form of coronal electric current (field-aligned current, more precisely), while the dissipation of coronal current proceeds rapidly, producing various dynamic events that affect lower atmospheres such as the chromosphere and photosphere. Flares manifest such rapid dissipation of coronal current, and their theoretical modeling has been developed in accordance with observations, in which numerical simulations proved to be a strong tool reproducing the time-dependent, nonlinear evolution of a flare. We review the models proposed to explain the physical mechanism of flares, giving an comprehensive explanation of the key processes mentioned above. We start with basic properties of flares, then go into the details of energy build-up, release and transport in flares where magnetic reconnection works as the central engine to produce a flare.
