NIRSpec G395H Archives

JWST GO time allocation for exoplanet science on different Cycles. Representation of the total General Observer (GO) allocated time for exoplanet science on JWST Cycle 1 (released on March, 2021, i.e., pre-launch), Cycle 2 (released on May 2023), Cycle 3 (released on February, 2024) and Cycle 4 (released on March, 2025). The percentage of all telescope time spent on exoplanet science for a given Cycle is indicated on top of this illustration (e.g., Cycle 1 comprised 23% of time on the telescope devoted to exoplanet science). The purple shading corresponds to the share allocated to transiting exoplanet science while the orange shading corresponds to highcontrast exoplanet science performed with JWST. -- astro-ph.EP

Astrochemistry, Astrogeology, Astronomy & Telescopes, Atmospheres, Climate, Weather, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Gas Giants, Status Report

Highlights from Exoplanet Observations by the James Webb Space Telescope

by Keith CowingMay 28, 2025May 28, 2025

The James Webb Space Telescope (JWST) has started a revolution in exoplanetary science.

Masses and radii of well-constrained small planets (0.2 ≤ Mp ≤ 30 M⊕). This catalog is a subset of the NASA Exoplanet Archive showing planets with consistently measured masses (RV or TTV) and measured radii (transit). The points are color-coded by composition: On the left, as bulk water mass fraction (Aguichine et al. 2021) and on the right, as bulk H2/He mass fraction (Lopez & Fortney 2014). Composition lines are shown for an equilibrium temperature of 500 K; rocky and Earth-like predictions are from Zeng et al. (2016). Bold and labeled circle symbols show planets with published JWST transmission spectra, and bold and labeled star symbols show other published COMPASS targets. TOI-776 c (the subject of this paper) is shown in larger font/symbol. -- astro-ph.EP

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

JWST COMPASS: NIRSpec/G395H Transmission Observations of TOI-776 c, a 2 Rearth [Earth radius] M Dwarf Planet

by Keith CowingMarch 4, 2025March 4, 2025

The atmospheres of planets between the size of Earth and Neptune at short orbital periods have been under intense scrutiny.

The average Eureka! transmission spectrum of L 98-59 b from the four JWST NIRSpec/G395H transits compared against the 98% SO2 model predicted in Seligman et al. (2024) and a self-consistent photochemical model assuming an SO2 -dominated atmosphere. We also show the best-fit flat line and atmosphere models retrieved with Aurora on the ∆λ = 0.01 µm data and the corresponding 2σ uncertainty bands. All models include an offset between the two detectors. -- astro-ph.EP

Astrogeology, Astronomy & Telescopes, Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Status Report

Evidence For A Volcanic Atmosphere On The Sub-Earth L98-59b

by Keith CowingFebruary 5, 2025February 5, 2025

Assessing the prevalence of atmospheres on rocky planets around M-dwarf stars is a top priority of exoplanet science. High-energy activity from M-dwarfs can destroy the atmospheres of these planets, which […]

Allowed parameter space in terms of opaque pressure level (either a cloud top or surface pressure, bar) versus log metallicity for the ExoTiC-JEDI (top, pinks) and Eureka! (middle, blues) reductions for Visits 1 (left) and 2 (right). In all cases, we are able to rule out metallicities of at least 100× solar (i.e., mean molecular weights of ∼5.5) with an opaque pressure of 1 millibar by 3σ. The exact limits of each reduction and visit differ (see Table 4). -- astro-ph.EP

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

JWST COMPASS: NIRSpec/G395H Transmission Observations of the Super-Earth TOI-776b

by Keith CowingJanuary 27, 2025January 27, 2025

We present two transit observations of the ∼520K, 1.85R⊕, 4.0M⊕ super-Earth TOI-776b with JWST NIRSpec/G395H, resulting in a 2.8-5.2μm transmission spectrum.

Position of TOI-1685 b in a mass-radius diagram. Internal composition models of rocky planets from Zeng et al. (2016). The change in radius from the highest precision of JWST observations compared to TESS makes the density of TOI-1685 b even more consistent with Earth than previously reported. -- astro-ph.EP

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

A Dark, Bare Rock For TOI-1685 b From A JWST NIRSpec G395H Phase Curve

by Keith CowingDecember 5, 2024

We report JWST NIRSpec/G395H observations of TOI-1685 b, a hot rocky super-Earth orbiting an M2.5V star, during a full orbit.

This plot shows the retrieved spectra from the main retrieval scenarios of stellar inhomogeneities with planetary atmospheres and stellar inhomogeneities only extended to the 0.6 - 12 µm JWST wavelength range. The gas contributions for H2S and SO2 are highlighted. The available wavelength ranges for different JWST instruments are marked on the top of the plot. Several H2S features in the NIRISS SOSS range, combined H2S and SO2 features in NIRSpec G395H range, and SO2 features in the MIRI LRS range may be detectable in future observations. -- astro-ph.EP

Astrochemistry, Astronomy & Telescopes, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Lava / magma ocean / Volcanic Worlds, Status Report

Atmospheric Retrievals Suggest The Presence of a Secondary Atmosphere and Possible Sulfur Species on L 98-59 d from JWST NIRSpec G395H Transmission Spectroscopy

by Keith CowingNovember 4, 2024November 4, 2024

L 98-59 d is a Super-Earth planet orbiting an M-type star. We performed retrievals on the transmission spectrum of L 98-59 d obtained using NIRSpec G395H during a single transit, […]

Transmission spectra of L98-59 d obtained using transitspectroscopy (pink) and FIREFLy (blue) pipelines. The spectral light curves from the two indepedent reductions were fitted using juliet with a similar parametrization at pixel resolution and then binned to R ∼ 100. The residuals between the two reductions show a global offset between the two reductions for the NRS2 detector. -- astro-ph.EP

Astrochemistry, Astrogeology, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

Hints Of A Sulfur-rich Atmosphere Around the 1.6 R⊕ Super-Earth L98-59 d from JWST NIRSpec G395H Transmission Spectroscopy

by Keith CowingAugust 30, 2024August 29, 2024

Detecting atmospheres around planets with a radius below 1.6 R⊕, commonly referred to as rocky planets (Rogers_2015, Rogers_2021), has proven to be challenging. However, rocky planets orbiting M-dwarfs are ideal […]

Broadband and spectroscopic light-curve fits of the NIRISS/SOSS (left) and NIRSpec/G395H (right) transits of TOI-270 d. For both instruments, examples of 10 normalized and systematics-corrected light curves are shown (colored points) along with their best-fitting transit models (black lines) and labelled with the central wavelength of the spectroscopic channel. Broadband light-curve fits (white) are also shown at the top for Order 1 in the NIRISS/SOSS case, and for NRS1 in the NIRSpec/G395H case. For clarity, the spectroscopic light curves are plotted with a relative flux offset. For NIRSpec/G395H, light curves with wavelengths below 3.8 µm are from the NRS1 detector and the remaining from NRS2. For visual purposes, the light curves are also binned in time in groups of 10 (NIRISS/SOSS) and 20 (NIRSpec/G395H) data points, resulting in 3.6 minute bins. A full transit of planet b occurs at the start of the NIRSpec/G395H exposure, with both transits overlapping shortly as planet d starts transiting. All light curves are well-behaved, with no signs of spot-crossing events or Hα flares. -- astro-ph.EP

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

JWST Reveals CH4, CO2, and H2O in a Metal-rich Miscible Atmosphere on a Two-Earth-Radius Exoplanet

by Keith CowingMarch 7, 2024March 7, 2024

Even though sub-Neptunes likely represent the most common outcome of planet formation, their natures remain poorly understood.

Transmission spectrum of TOI-270 d observed with JWST/NIRSpec G395H and HST/WFC3. The NIRSpec G395H spectrum between 2.7 - 5.2 µm, from this work, is shown in dark red, binned to R ≈ 55 for visual clarity. The WFC3 spectrum is shown in orange and spans 1.1 - 1.6 µm, reported by Mikal-Evans et al. (2023). The retrieval is performed using the native resolution NIRSpec G395H spectrum (R ∼ 2700) and the WFC3 spectrum. The NIRSpec spectrum is vertically offset by −84 ppm, corresponding to the median retrieved offset in the canonical one-offset case. The blue curve shows the median retrieved model spectrum, while the medium- and lighter-blue contours denote the 1σ and 2σ intervals, respectively. Yellow points correspond to the median spectrum binned to match the observations. The prominent molecules responsible for the features in different spectral regions are labelled. -- astro-ph.EP

Astrochemistry, Astrogeology, Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report, Water/Hycean Worlds & Oceanography

Possible Hycean Conditions In The sub-Neptune TOI-270 d

by Keith CowingMarch 7, 2024March 7, 2024

The JWST has ushered in a new era in atmospheric characterisations of temperate low-mass exoplanets with recent detections of carbon-bearing molecules in the candidate Hycean world K2-18 b.

Transmission spectra of GJ 1132 b from all three data reduction pipelines and both visits. Upper panel: the Eureka! (yellow), FIREFLy (pink), and ExoTiC-JEDI (blue) reductions are shown for both visits at R∼100. Also shown are the differences between reductions (solid, dashed, and dotted gray lines) in units of σ, demonstrating the agreement between pipelines within a single visit. A ±1σ shaded region is overlaid. Bottom panel: the Eureka! reduction for both visits, with the NIRSpec detector gap denoted by the shaded gray region. The shaded yellow regions show two important wavelength ranges that differ the most between the visits (see Sections 4.1 and 4.4.1 for further discussion on these differences). -- astro-ph.EP

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

Double Trouble: Two Transits of the Super-Earth GJ 1132 b Observed with JWST NIRSpec G395H

by Keith CowingOctober 19, 2023October 19, 2023

The search for rocky planet atmospheres with JWST has focused on planets transiting M dwarfs. Such planets have favorable planet-to-star size ratios, enhancing the amplitude of atmospheric features. Since the […]

NIRSpec G395H

Highlights from Exoplanet Observations by the James Webb Space Telescope

JWST COMPASS: NIRSpec/G395H Transmission Observations of TOI-776 c, a 2 Rearth [Earth radius] M Dwarf Planet

Evidence For A Volcanic Atmosphere On The Sub-Earth L98-59b

JWST COMPASS: NIRSpec/G395H Transmission Observations of the Super-Earth TOI-776b

A Dark, Bare Rock For TOI-1685 b From A JWST NIRSpec G395H Phase Curve

Atmospheric Retrievals Suggest The Presence of a Secondary Atmosphere and Possible Sulfur Species on L 98-59 d from JWST NIRSpec G395H Transmission Spectroscopy

Hints Of A Sulfur-rich Atmosphere Around the 1.6 R⊕ Super-Earth L98-59 d from JWST NIRSpec G395H Transmission Spectroscopy

JWST Reveals CH4, CO2, and H2O in a Metal-rich Miscible Atmosphere on a Two-Earth-Radius Exoplanet

Possible Hycean Conditions In The sub-Neptune TOI-270 d

Double Trouble: Two Transits of the Super-Earth GJ 1132 b Observed with JWST NIRSpec G395H

Tricorder Tech: New Handheld Device Maps Chemical Composition Using Infrared Light

No Statistically Significant Evidence For A Correlation Between Stellar And planetary Composition

Water Planet Recon: How Accurately Can We Measure Earth Ocean’s Deepest Point?

Webb Reveals A Stunning Panorama Of Star Formation

Deep Learning of SHERLOC Raman Spectra For Facilitating Mars Astromaterial Identification