JWST Archives

Optical depth spectra of the YSOs in our sample, shifted vertically for clarity. For illustration purposes, the red lines correspond to a linear combination of four ice mixtures selected from LIDA (3000 monolayers of pure H2O at a temperature of 15 K, H2O:CO2 in the ratio 10:1 at 10 K, CO:CO2 in the ratio 2:1 at 15 K, and pure OCS at 17 K) and provide a reasonable fit to the observations. The corresponding column densities are listed in Table 4. The legend at the top of each panel indicates the ice features discussed in the text and the corresponding wavelengths, to guide the eye. -- astro-ph.GA

Astrochemistry, Astronomy & Telescopes, Biosignatures & Paleobiology, Icy Worlds, Imaging & Spectroscopy, Interstellar, Status Report

First Detection Of Ices In Intermediate-mass Young Stellar Objects Beyond The Milky Way

by Keith CowingSeptember 27, 2025September 27, 2025

Using NIRSpec on JWST, we studied a sample of 15 intermediate-mass (1.8-4.1 Msun) young stellar objects (YSOs) previously identified with MIRI photometry in the low-metallicity NGC 346 star-forming cluster in […]

Extractions regions on images (blue = NRC-F210M, green = NRC-F335M, red = MIR-F770W) of NGC 7023 (left) and the Horsehead (right). The exciting star is off the top of the image in both cases. The color used to designate the regions here will be used in spectral plots for those regions, the remainder of the text. The white dashed rectangles define the minimum (NIRSpec) and maximum (MIRI channel 4) IFU mosaic coverage. -- astro-ph.GA

Astrogeology, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biophysics, Biosignatures & Paleobiology, Imaging & Spectroscopy, Interstellar, Press Release

JWST Observations Of Photo-dissociation Regions. II. Aliphatic/Aromatic Carbonaceous Dust, Ices, And Gas Phase Spectral Line Inventory

by Keith CowingSeptember 26, 2025September 26, 2025

This paper provides an overview of the spectroscopic data obtained by the JWST Guaranteed Time Observations (GTO) program 1192, “The Physics and Chemistry of PDR Fronts”, including an inventory of […]

A classification scheme for volatile-rich sub-Neptunes. The schematic compares different types of sub-Neptunes with H2 and H2O dominated atmospheres as a function of the equilibrium temperature and H2 content. Ice worlds: Cold subNeptunes where any water is frozen in a layer of ice atop high-pressure ice, with a thin H2-dominated atmosphere (65). Hycean worlds: Warmer than ice worlds, hycean worlds have a thin H2-rich atmosphere overlying an ocean of liquid water, which itself is above a layer of high-pressure ices. These planets have the potential to support habitable conditions (9). Mini-Neptunes: Sub-Neptunes with a deep H2-rich atmosphere followed by a mixed H2O-H2 supercritical layer below before reaching a layer of high-pressure ice and then a core (17, 65). Steam worlds: Water worlds with H2O dominated atmospheres. At equilibrium temperatures above Tcrit, a high proportion of H2O exists in the atmosphere, with a supercritical mixed-envelope at higher pressures. Supercritical mini-Neptunes: These planets are hotter than Tcrit, and contain interiors where H2 gas is highly soluble in supercritical H2O (46, 65). This mixed-envelope would lie over a layer of high-pressure ice above the core. Legend: The legend at the top shows the different compositions corresponding to the colors in the schematic, including the core, different phases of H2O and envelope composition; high-P ice refers to high-pressure ice. Note that the core has further distinct layers but we do not label them here. Sharp phase transitions are shown for ice-atmosphere and ocean-atmosphere transitions. Other phase transitions are marked by a gradient, as they may not be sharp phase transitions (83). -- astro-ph.EP

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

Exploring The Sub-Neptune Frontier With JWST

by Keith CowingSeptember 25, 2025September 25, 2025

Sub-Neptune planets, with sizes and masses between those of Earth and Neptune, dominate the exoplanet population.

Raw B band polarization measurements of HD 189733 obtained at Gemini North on UT 1 to 7 Aug 2018, which are dominated by observations on the last night (gold points). Top left: Stokes q (linear polarization) modulation as a function of parallactic angle. Telescope linear polarization is modulated by parallactic angle with amplitude ∆(qTP, uTP) = 0.2620±0.0034% (Wiktorowicz et al. 2023), where the best fit curve from Equation 2a is shown in black. Uncertainties in most data points are smaller than the size of the data points. Top right: Same as at top left but for Stokes u (linear polarization, Equation 2b). Bottom left: Same as at top left but for Stokes v (circular polarization, Equation 2c). Bottom right: Temporal variation of parallactic angle, which rotates rapidly as the target crosses the meridian (black dashed lines) around 20:00 LST. This rapid meridian crossing provides the bulk of the telescope polarization modulation necessary for accurate calibration. -- astro-ph.EP

Astronomy & Telescopes, Atmospheres, Climate, Weather, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

A Scatter of Light from a Polarized World

by Keith CowingSeptember 25, 2025

Many known exoplanets harbor clouds, which lead to degeneracies in spectroscopic models between particle composition and size. Polarimetry, however, provides independent assessment.

Observed spectra after dividing by the out-of-transit spectrum (residuals), shown in the stellar rest frame. Vertical orange and green dotted lines indicate the positions of the Na D2 and D1 lines, respectively. The region between the two horizontal dotted lines corresponds to in-transit observations, while regions outside represent out-of-transit data. The tilted red lines at the positions of Na D2 and D1 indicate the expected shift of the planetary absorption signal. -- astro-ph.EP

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

An Initial Assessment Of The Hanle Echelle Spectrograph For Exoplanet Atmosphere Studies

by Keith CowingSeptember 24, 2025September 24, 2025

Transmission spectroscopy is an effective technique for probing exoplanetary atmospheres.

This chart shows, on the top row, artist concepts of the seven planets of TRAPPIST-1 with their orbital periods, distances from their star, radii, masses, densities and surface gravity as compared to those of Earth. Credit: NASA/JPL-Caltech (larger image)

Analog Studies, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Desert Worlds, Exoplanets, -moons, -comets, Habitable Zones, Icy Worlds, Imaging & Spectroscopy, Status Report, TRAPPIST-1

Born Dry or Born Wet? A Palette of Water Growth Histories in TRAPPIST-1 Analogs and Compact Planetary Systems

by Keith CowingSeptember 23, 2025September 23, 2025

It is still unclear whether exoplanets in compact multiplanet systems such as TRAPPIST-1 are able to accrete large quantities of volatiles, grow to sufficient mass, and maintain robust atmospheres and […]

Conferences and Meetings, Courses, Education and Outreach, Status Report

JWST 2025 Summer School Materials Are Now Available

by Keith CowingSeptember 23, 2025

All materials of the inaugural JWST Summer school, including presentations, notes, exercises and videos, are now publicly available on the event page.

Alpha Centauri, Astronomy & Telescopes, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Gas Giants, Habitable Zones, Imaging & Spectroscopy, Status Report, Stellar Cartography

Seeking The Worlds Of Avatar: Prospects for Detecting Moons Orbiting a Giant Planet in Alpha Centauri A’s Habitable Zone

by Keith CowingSeptember 22, 2025September 22, 2025

Nearby giant exoplanets offer an opportunity to search for moons (exomoons) orbiting them. Here, we present a simulation framework for investigating the possibilities of detecting exomoons via their astrometric signal […]

PAH fraction anti-correlates with log([S iii]/[S ii]) (ionization parameter tracer) for thousands H ii regions in 42 PHANGS-JWST galaxies. Panel (a, b) shows all ∼ 17200 analyzed H ii regions, while ∼ 5600 brightest “resolved” H ii regions are shown on Panels (c, d). The dashed red line shows the best-fit linear regression to the “resolved” sample defined by Eq. 4. Histograms on panels (b, d) show how the logarithmic residuals after subtracting this linear trend depend on metallicity. Color on panels (a, c) denotes gas-phase oxygen abundance; red contours show the probability density of the high-metallicity (12 + log(O/H) > 8.2) points (levels correspond to 50, 65, 80, 95 and 99 percentile intervals). The Spearman correlation coefficient (ρ) and RMS scatter around the linear fit are reported on panels (a, c). -- astro-ph.GA

Astrochemistry, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biophysics, Biosignatures & Paleobiology, Imaging & Spectroscopy, Interstellar, Status Report

Polycyclic Aromatic Hydrocarbons Destruction In Star-forming Regions Across 42 Nearby Galaxies

by Keith CowingSeptember 22, 2025September 22, 2025

Polycyclic aromatic hydrocarbons (PAHs) are widespread in the interstellar medium (ISM) of Solar metallicity galaxies, where they play a critical role in ISM heating, cooling, and reprocessing stellar radiation.

Observed spectrum of CT Cha b. top-left: Calibrated JWST/MIRI MRS data of the CT Cha system, showcasing the stellar point-spread function dominating the image at 13.3 − 15.6 µm. Bottom left: A spectral cross-correlation map of the same field of view revealing the companion. A gray star marks the location of the host star. Right: continuum-subtracted spectrum of CT Cha b (black) compared to a total model (red shaded area) composed of molecular emission from C2H6, C2H2, 13CCH2, HCN, C6H6, CO2, C3H4 and C4H2, shown with models in the colors below. The four panels on top show selected wavelength regions that contain important molecular features. -- astro-ph.EP

Astrochemistry, Astrogeology, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Gas Giants, Imaging & Spectroscopy, Status Report

A Carbon-rich Disk Surrounding A Planetary-mass Companion

by Keith CowingSeptember 21, 2025September 21, 2025

During the final assembly of gas giant planets, circumplanetary disks (CPDs) of gas and dust form due to the conservation of angular momentum, providing material to be accreted onto the […]

JWST

First Detection Of Ices In Intermediate-mass Young Stellar Objects Beyond The Milky Way

JWST Observations Of Photo-dissociation Regions. II. Aliphatic/Aromatic Carbonaceous Dust, Ices, And Gas Phase Spectral Line Inventory

Exploring The Sub-Neptune Frontier With JWST

A Scatter of Light from a Polarized World

An Initial Assessment Of The Hanle Echelle Spectrograph For Exoplanet Atmosphere Studies

Born Dry or Born Wet? A Palette of Water Growth Histories in TRAPPIST-1 Analogs and Compact Planetary Systems

JWST 2025 Summer School Materials Are Now Available

Seeking The Worlds Of Avatar: Prospects for Detecting Moons Orbiting a Giant Planet in Alpha Centauri A’s Habitable Zone

Polycyclic Aromatic Hydrocarbons Destruction In Star-forming Regions Across 42 Nearby Galaxies

A Carbon-rich Disk Surrounding A Planetary-mass Companion

How High-pressure Ices On Large Ocean Worlds Can Support Habitability: The Compatibility Of Amino Acids Into Ice VI And VII

Ice Drives The Emergence Of Functional Protocells

Chemical Abundance Patterns at z=1-7: Carbon, Nitrogen, Neon, Sulphur, and Argon Abundances From JWST Spectroscopy

Optimization of Petal-Shaped Occulters for Exo-Earth Observation

Topographically Forced Stationary Waves Can Explain The Near-Surface Zonal Winds Observed By Huygens On Titan