(astro-ph.EP Archives

The combined STIS G430L and G750L spectrum of WASP-39 b (top left), WASP-121 b (top right), WASP-69 b (bottom left), and WASP-17 b (bottom right). Each color (common between planets) corresponds to a different systematics detrending technique, either using linear or GP methods and either between 1-10 PCs or the 10 initial input vectors. -- astro-ph.EP

Astronomy & Telescopes, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Status Report, Stellar Cartography

HST SHEL: Enabling Comparative Exoplanetology with HST/STIS

by Keith CowingJune 3, 2024

The Hubble Space Telescope (HST) has been our most prolific tool to study exoplanet atmospheres. As the age of JWST begins, there is a wealth of HST archival data that […]

Top: Residuals (data-model) for single, hemispheric best-fit porosity values for Europa’s leading hemisphere (∼ 90◦ W longitude) from Band 3 (97.5 GHz/3.05 mm; A), Band 6 (233 GHz/1.25 mm; B), and Band 7 (343.5 GHz/0.88 mm; C). All images are aligned with Europa’s north pole along the vertical axis. Bottom: Residual contours are plotted on projected image maps of Europa’s surface from the USGS Voyager and Galileo SSI composite map. Positive temperature contours are shown as redscale, solid lines; negative contours are in bluescale, dashed lines. Contour levels increase in increments of 3σ (RMS noise varies between observation, on the order of 0.1-1 K). The approximate locations of leading hemisphere regiones are denoted for reference in panel D. -- astro-ph.EP

Europa, Icy Worlds, Imaging & Spectroscopy, Jupiter, Status Report

Subsurface Thermophysical Properties of Europa’s Leading and Trailing Hemispheres as Revealed by ALMA

by Keith CowingFebruary 6, 2024February 6, 2024

We present best-fit values of porosity — and the corresponding effective thermal inertiae — determined from three different depths in Europa’s near-subsurface (~1-20 cm). The porosity of the upper ~20 […]

Planetary system architectures in comparison. Left panel: Semi-major axes in planetary systems in comparison. For Teegarden’s Star we show two possible configurations: the three planets as fit by our preferred model and a hypothetical configuration (labeled as Teegarden (h)) with the three planets, the candidate at 7.7 d (light blue) as well as a purely hypothetical planet between planets c and d (light gray). The size of the plot symbols in the left panel are scaled assuming a constant planet density using the masses from Table 4 and G.2. Right panel: Mutual Hill separations in planetary systems in comparison. The light blue line indicates the mutual Hill radius above which the orbital crossing time is larger than 109 orbits. -- astro-ph.EP

Exoplanets, -moons, -comets, Habitable Zones, Status Report

Teegarden’s Star Revisited: A Nearby Planetary System With At Least Three Planets

by Keith CowingFebruary 5, 2024February 5, 2024

The two known planets in the planetary system of Teegarden’s Star are among the most Earth-like exoplanets currently known. Revisiting this nearby planetary system with two planets in the habitable […]

Principal component values for all six meteorites studied at different grain sizes are shown with the “α-line” boundary from DeMeo et al. (2009) that separates the S- and C/X-complexes. Grain size variations can be seen by using the dotted line interconnecting PC values of measurements of the same meteorite at different grain sizes. Marker size increases with grain size which includes values of 45-90 µm, 90-150 µm, 150-300 µm, 300-500 µm, and 500-1,000 µm. The Lunar-style space weathering trend from Binzel et al. (2019) is shown with blue dots and a corresponding arrow showing the direction of increasing space weathering. The carbonaceous space weathering trend from Lantz et al. (2018) is shown with the brown arrow indicating that the measured weathering trend would move in either direction depending on the meteorite composition. It also shows that differentiating between space weathering and grain size effects would be challenging in PC space. -- astro-ph.EP

Astrochemistry, Astrogeology, Comets and Asteroids, Meteorites & Asteroids, Status Report

Grain Size Effects on UV-MIR (0.2-14 micron) Spectra of Carbonaceous Chondrite Groups

by Keith CowingJanuary 22, 2024January 22, 2024

Carbonaceous chondrites are among the most important meteorite types and have played a vital role in deciphering the origin and evolution of our solar system.

Detection of the planet using model templates of the full planet, H2O and CO using cross-correlation (top row) and the likelihood ratio (bottom row). The radial velocity is shown here in the barycentric restframe. In the top panel we also show the cross-correlation value for a reference spectrum, which was taken at the same separation on the other side of the star. In the bottom panels we indicate the location of the star and the planet and the expected velocity of the planet. -- astro-ph.IM

Astrochemistry, Astronomy & Telescopes, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

β Pictoris b Through The Eyes Of The Upgraded CRIRES+

by Keith CowingNovember 24, 2023November 24, 2023

Context: High-resolution spectrographs fed by adaptive optics (AO) provide a unique opportunity to characterize directly imaged exoplanets. Observations with such instruments allow us to probe the atmospheric composition, spin rotation, […]

𝐼 and 𝑄 Stokes parameters for silicate grains measured at 220 GHz at the South magnetic pole (top) and at the equator (bottom) aligned with respect to the solar radiation field (𝑘-alignment). We note that maps at both values of 𝛼 reproduce the spurious patterns seen in the temperature maps in Fig. 6, being the ones in the 𝛼 = −2.0 due to higher opacities and boundary effects, and the strike patterns seen in the 𝛼 = −3.5 maps only due to statistical fluctuations in the spatial generation of the photon packages, resulting in negligible spatial variations in the 𝐼 and 𝑄 magnitudes. Maps for the South magnetic pole are identical to those of the equator, since both configurations are equivalent. Negative values of 𝑄 are due to the linear polarization along the 𝑌 axis of the image. -- astro-ph.EP

Astrochemistry, Astrogeology, Atmospheres, Climate, Weather, Meteorites & Asteroids, Panspermia, Status Report

Polarized Microwave Emission From Space Particles In The Upper Atmosphere Of The Earth

by Keith CowingOctober 17, 2023October 17, 2023

Tons of space particles enter the Earth atmosphere every year, being detected when they produce fireballs, meteor showers, or when they impact the Earth surface.

Exoplanets, -moons, -comets, Press Release, Proxima Centauri

Stable Orbits in the Feeding Zone of the Planet Proxima Centauri c

by Keith CowingSeptember 5, 2023September 5, 2023

Estimates of the size of the feeding zone of the planet Proxima Centauri c have been made at initial orbital eccentricities of planetesimals equal to 0.02 or 0.15.

Variations of photometric flux (top panel), airmass (panel 2), Geocentric-to-stellar rest frame RV correction (panel 3) and peak SNR per velocity bin during the two simulated transits of the HD 189733 b analog. On panels 1 and 4, the two different transits are respectively shown as blue dots and pink crosses. The vertical gray band indicates the primary transit of the simulated planet. The horizontal gray dashed line on the bottom panel indicates the average value of the peak S/N for the observed spectra -- astro-ph.IM

Astronomy & Telescopes, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

ATMOSPHERIX: II- Characterising Exoplanet Atmospheres Through Transmission Spectroscopy With SPIRou

by Keith CowingAugust 31, 2023September 18, 2025

In a companion paper, we introduced a publicly-available pipeline to characterise exoplanet atmospheres through high-resolution spectroscopy.

Monte Carlo icy grain model for grain sizes randomly sampled from the size frequency distribution governed by the α=-5.989 power law. All particles are subject to gravitational force from the comet nucleus, pressure from the expanding coma gas (assumed to be H2O), and solar radiation pressure at 1 au. The plot is 15000 km by 15000 km and shown in a logarithmic scale to match the top row of images shown in Figure 1. The model results have been rotated to match the Earth viewing geometry at the time of observation, a phase angle of 18 degrees and a orbital difference angle of -16 degrees. The general morphology of the model is in agreement with observations shown in in Figure 1. -- astro-ph.EP

Astrochemistry, Astrogeology, Comets and Asteroids, Status Report

Ice, Ice, Maybe? Investigating 46P/Wirtanen’s Inner Coma For Icy Grains

by Keith CowingMay 21, 2023May 21, 2023

The release of volatiles from comets is usually from direct sublimation of ices on the nucleus, but for very or hyper-active comets other sources have to be considered to account […]

Top: Abundance and temperature-pressure profiles for a 3 M⊕, 600 K equilibrium temperature planet, with 0.1% soot, orbiting an M-dwarf star. Even under the harsh UV irradiation environment of the host star, high abundances of methane (thick brown line) persist to high altitude and low pressure. A combination of methane photolysis in the upper atmosphere, vertical mixing, and thermochemistry give rise to significant quantities of higher-order hydrocarbons such as C2H2, C2H4, and C2H6, Subsequent photolysis and polymerization reactions result in the formation of hydrocarbon haze (thick dashed red line). Bottom: The resulting transmission spectrum (orange line) of this planet is shaped considerably by haze with some strong methane features permeating through the haze at longer wavelengths. The teal line shows the transmission spectrum of the same planet but with the haze opacity artificially removed, while the transparent colored line shows these data at a spectral resolution of R=1,000. -- astro-ph.EP

Astrochemistry, Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Status Report, Water/Hycean Worlds & Oceanography

Exoplanet Volatile Carbon Content as a Natural Pathway for Haze Formation

by Keith CowingMay 9, 2023May 9, 2023

We explore terrestrial planet formation with a focus on the supply of solid-state organics as the main source of volatile carbon.

(astro-ph.EP

HST SHEL: Enabling Comparative Exoplanetology with HST/STIS

Subsurface Thermophysical Properties of Europa’s Leading and Trailing Hemispheres as Revealed by ALMA

Teegarden’s Star Revisited: A Nearby Planetary System With At Least Three Planets

Grain Size Effects on UV-MIR (0.2-14 micron) Spectra of Carbonaceous Chondrite Groups

β Pictoris b Through The Eyes Of The Upgraded CRIRES+

Polarized Microwave Emission From Space Particles In The Upper Atmosphere Of The Earth

Stable Orbits in the Feeding Zone of the Planet Proxima Centauri c

ATMOSPHERIX: II- Characterising Exoplanet Atmospheres Through Transmission Spectroscopy With SPIRou

Ice, Ice, Maybe? Investigating 46P/Wirtanen’s Inner Coma For Icy Grains

Exoplanet Volatile Carbon Content as a Natural Pathway for Haze Formation

Juice Astrobiology Mission To Fly Past Earth For Third Gravity Assist

Planetary Health Check 2026 Finds Mounting Pressures Across Earth’s Life Support Systems – Reports And Proceedings

Prebiotic Peptide Formation Triggered By Urea-rich Warm Little Ponds On Early Earth

Thyles Rupes Region Of Mars

Do Himalayan-style Mountains Lie Under The Antarctic ice: Implication For The Gondwana Supermountains, The Rise Of Oxygen And The Cambrian Explosion?