The search for atmospheres on rocky planets has been notoriously difficult. While gas giants often show clear spectral fingerprints, habitable-zone super-Earths produce extremely subtle signals. Even with powerful observatories such as NASA’s James Webb Space Telescope, previous observations frequently suggested airless or weakly buffered worlds, leaving open the key question of whether they can hold onto atmospheres long enough to be habitable.

Red dwarf stars offer a practical advantage: their small size makes planetary transits more detectable. By measuring periodic dips in starlight as a planet passes in front of its host star, researchers can perform transmission spectroscopy—splitting the starlight into a spectrum and reading which atmospheric constituents absorb particular wavelengths. In this study, the team targeted a more accessible atmospheric layer by searching for helium in the upper atmosphere.

LHS 1140 b orbits an older, cool red dwarf every 24.7 days. With a mass about 5.6 times Earth’s and a radius roughly 1.7 Earth radii, the planet is consistent with a rocky composition. It receives about 42% of the radiation Earth gets from the Sun, placing it in a temperature range where liquid water could exist, though the presence of an Earth-like surface remains unknown.

Using the WINERED spectrograph on the Magellan Clay telescope at Las Campanas Observatory in Chile, the researchers observed the planet in 2024 and detected spectral evidence of helium escaping from its atmosphere. The result indicates an active gaseous envelope, challenging assumptions that many rocky habitable-zone planets rapidly lose volatiles.

The data show that heating from stellar X-rays and extreme ultraviolet radiation likely drives the escape. In 2025, however, the team found no escaping helium, implying the atmospheric outflow is variable rather than constant. This short-timescale change provides rare real-time evidence that an exoplanet’s atmosphere can evolve quickly under changing stellar forcing.

By combining the observations with models of exoplanet evolution, the team interpreted the atmosphere as highly layered: a helium-dominated, hydrogen-poor upper region, with heavier species such as water trapped at lower altitudes nearer the surface. Such stratification helps explain both the detectability of helium and the lack of signals from deeper atmospheric layers.

The group also examined a second planet in the same system, LHS 1140 c, which is smaller and more strongly irradiated. No atmospheric evidence was found there, suggesting the planets may lie on opposite sides of the “cosmic shoreline,” where some worlds retain atmospheres for billions of years while others lose them quickly.

The study was conducted by scientists across Harvard and Carnegie, including Shreyas Vissapragada, Collin Cherubim, and multiple Carnegie co-authors, and involved prior observations and advanced interpretation. Together, these results strengthen the case that at least some rocky habitable-zone exoplanets can maintain atmospheres—and that helium escape spectroscopy can reveal them.

Subject of Research:
Not applicable

Article Title:
Helium escaping from the atmosphere of a nearby rocky exoplanet orbiting in a habitable zone

News Publication Date:
16-Jul-2026

Web References:
http://dx.doi.org/10.1126/science.aea9708

References:
10.1126/science.aea9708

Image Credits:
Melissa Weiss/Center for Astrophysics | Harvard & Smithsonian

Keywords

exoplanets; rocky worlds; habitable zone; atmospheric escape; helium; transmission spectroscopy; red dwarf stars; LHS 1140 b; WINERED; James Webb Space Telescope

The exoplanet WD 1856 b, located approximately 80 light-years from Earth, orbits the white dwarf star WD 1856+534 in an extraordinarily tight orbit. This system, first identified in 2020 using data from the Transiting Exoplanet Survey Satellite (TESS) and the Spitzer Space Telescope, presents a unique laboratory for astronomers studying stellar death and planetary survival. The close proximity of WD 1856 b to its diminutive host—an Earth-sized white dwarf approximately seven times smaller than the planet—raises profound questions about planetary dynamics and evolution in post-main-sequence star systems.

A team led by Dr. Ryan MacDonald at the University of St Andrews employed the unparalleled capabilities of the James Webb Space Telescope (JWST), a collaborative NASA/ESA/CSA mission, to observe a transit event wherein WD 1856 b passes in front of its faint stellar host. This rare “grazing transit,” where only a portion of the planet overlaps the star, enabled precise measurements of the planet’s mass, thermal emission, and atmospheric constituents—data never before captured for a planet orbiting a white dwarf.

What they found was truly unexpected: WD 1856 b maintains a temperature of roughly 400 Kelvins (126°C), some 240 degrees hotter than would be supplied by the white dwarf’s luminosity alone. This internal heat signature implies prior episodes of intense heating, a clue to how the planet reached its unusually close orbit. Using sophisticated cooling models and spectral analysis, researchers traced the planet’s thermal history, concluding that the heating event likely occurred between three and five and a half billion years after the host star became a white dwarf.

Two primary hypotheses were considered regarding the planet’s migration. One scenario posits that the planet was engulfed by the progenitor star during its expansive red giant phase and survived this harsh environment within the stellar envelope. Alternatively, the planet may have originally orbited safely at a wide radius, later migrating inward due to gravitational interactions with the white dwarf’s two companion stars in this triple system. The latter explanation gains traction as the heating timeline aligns with a gradual orbital migration induced by complex gravitational dynamics.

Notably, the white dwarf WD 1856+534 is roughly Earth-sized yet hosts a Jupiter-sized planet at a distance fifty times closer than Earth’s orbit around the Sun. This proximity challenges existing models of planetary survivability through the tumultuous red giant phase, during which inner planets like Mercury, Venus, and potentially Earth face obliteration. WD 1856 b’s endurance suggests that gas giants in outer orbits can persist and even settle into tight orbits around their host star remnants, revealing novel pathways in post-stellar planetary evolution.

The JWST’s infrared instruments enabled the team to capture the transmission spectrum of WD 1856 b’s atmosphere as starlight filtered through the planet’s gaseous envelope during the transit. This spectrum revealed the presence of aerosols, small cloud particles, and hydrocarbons such as methane—marking the first detection of atmospheric constituents on a planet orbiting a dead star. These insights pave the way for unprecedented atmospheric characterization of remnant planetary systems and the chemistry of planets enduring extreme stellar evolution.

Dr. Christopher O’Connor from Northwestern University contributed to unraveling the planet’s thermal history, demonstrating that as WD 1856 b spiraled inward, tidal interactions and gravitational forces induced significant heating. This residual heat continues to radiate today, illuminating the complex interplay of dynamics and thermodynamics in post-main-sequence systems. The study’s findings thus bridge stellar astrophysics with planetary science, enhancing understanding of extinct star systems hosting surviving planets.

The authors emphasize that such observations would have been impossible without JWST’s extraordinary sensitivity and rapid imaging capabilities. The white dwarf’s intrinsic dimness, coupled with the brief eight-minute duration of WD 1856 b’s transit, posed formidable observational challenges. However, JWST’s innovative design successfully captured sufficient light to resolve the planet’s spectral signature, underscoring the telescope’s revolutionary potential for advancing exoplanetary research.

Beyond breaking new ground in our understanding of planetary survival around white dwarfs, this research ignites new questions regarding the frequency and diversity of planets orbiting stellar remnants. Ongoing efforts to detect additional white dwarf planets and characterize their atmospheres promise to expand the sample size, deepening scientific knowledge of planetary system lifecycles through to their late evolutionary stages.

In contemplating the fate of our Solar System, the discovery of WD 1856 b offers a tantalizing preview. Billions of years from now, after the Sun becomes a red giant and eventually transitions to a white dwarf, gas giants like Jupiter may endure — migrating closer to the fading ember of our once vibrant star. This celestial resilience highlights the enduring nature of planetary bodies, even after the dramatic transformations of their stellar hosts.

The study, published in the journal Nature, represents a milestone in exoplanetary science and stellar astrophysics, combining cutting-edge observational data with theoretical modeling to illuminate one of the final chapters in the story of planetary systems. As researchers continue to mine JWST data and refine models, our grasp of planetary survival and evolution in extreme post-stellar environments will undoubtedly deepen, reshaping our cosmic perspective.

WD 1856 b stands as a testament to the dynamic and oftentimes surprising fate of worlds orbiting stars after their death, inspiring a fresh wave of inquiry into the longevity and adaptability of planetary systems throughout cosmic history. The insights gained open doors to new explorations of how planetary atmospheres and orbits evolve under the influence of their dramatic stellar pasts, marking a thrilling new frontier in space science.

Subject of Research: Not applicable
Article Title: ‘Aerosol and hydrocarbons in the atmosphere of a white dwarf planet’
News Publication Date: 1-Jul-2026
References: [1] Grazing transit observations using JWST; [2] Transmission spectrum analysis revealing atmospheric composition
Image Credits: European Space Agency

Keywords

White dwarf planet, exoplanet, WD 1856 b, James Webb Space Telescope, planetary migration, stellar evolution, planetary atmosphere, hydrocarbons, methane, red giant phase, planetary survival, infrared spectroscopy

WASP-121 b belongs to a class of exoplanets known as hot Jupiters, gas giants orbiting perilously close to their stars. Its proximity results in tidal locking—the synchronous rotation where one hemisphere permanently faces the star while the opposite side remains shrouded in near-freezing darkness. This unique dynamic creates sharply defined day/night hemispheres with temperature differentials reaching thousands of degrees Celsius. Daytime skies on WASP-121 b blaze at nearly 2770 Kelvin (approx. 2500°C), while the nightside cools dramatically to about 1000 Kelvin (approx. 725°C), a difference capable of fundamentally shaping atmospheric dynamics and chemistry.

The research team, led by Cyril Gapp of the Max Planck Institute for Astronomy (MPIA), leveraged JWST’s Near Infrared Spectrograph (NIRSpec) to analyze the planet as it passed in front of its star. By measuring variations in the starlight filtered through the planet’s atmosphere along a transit and correlating them with the planet’s rotation, the scientists discerned more than mere average brightness dips. Instead, they detected distinct asymmetries in infrared absorption between the morning and evening terminators—boundaries marking the transitions between day and night sides—as the planet rotated about 30 degrees during the transit.

Detailed spectral analyses revealed that the evening terminator’s atmosphere absorbs significantly more stellar infrared radiation than the morning side. This bespoke absorption pattern aligns precisely with expectations from robust eastward winds that transport intense daytime heat toward the night hemisphere. These winds elevate atmospheric temperatures on the evening side, causing its gaseous layers to expand and increase its effective cross-sectional area occulting the star. This expanded atmosphere thus filters more infrared light, resulting in the observed enhanced absorption signature.

Interestingly, while the carbon monoxide (CO) absorption feature intensifies towards the evening terminator, the researchers attribute this to temperature-related shifts in molecular excitation rather than an increase in CO molecule abundance. Conversely, the water vapor (H₂O) signature diminishes markedly on the evening side, indicating genuine molecular depletion. Scientists interpret this as photodissociation driven by extreme temperatures breaking water molecules into hydrogen and oxygen, a hallmark of ultra-hot planetary atmospheres subjected to relentless stellar irradiation.

The innovative approach exploited the planet’s tidally locked nature to parse atmospheric composition with longitudinal specificity—a refined spectroscopic “longitude scan” rarely attainable for exoplanets. Traditionally, transit observations amalgamate data over ingress to egress, masking subtle spatial differences. Here, accounting for the planet’s rotation mid-transit provided richer insights and improved model fits, affirming genuine asymmetries due to localized physical phenomena rather than observational noise.

However, when researchers compared these observations to advanced atmospheric circulation models simulating heat distribution, some discrepancies arose. Specifically, the observed amplitude of variation surpassed theoretical predictions, hinting at missing or underestimated mechanisms modulating the atmospheric properties. One plausible explanation relates to the presence of mineral clouds—composed of silicates and other condensates—that preferentially form on the cooler morning terminator. Clouds can efficiently absorb or scatter infrared radiation, complicating measurements by masking hotter, deeper layers and suppressing apparent emission. Incorporating these cloud effects into models brought simulations into closer harmony with JWST’s unprecedented data.

The study exemplifies the extraordinary capabilities of the JWST in unveiling detailed atmospheric physics in distant exoplanets, heralding a new era of precision exoplanetology. By characterizing longitudinal structure across terminator zones, scientists can now probe global circulation patterns, chemistry, and cloud formation in worlds vastly different from those in our solar system. These insights shed light not only on atmospheric dynamics under extreme irradiation but also on planetary formation and evolution processes.

Moreover, this approach provides a blueprint for future investigations targeting similar ultra-hot gas giants within optimal temperature and rotation regimes. Expanding such longitudinal studies to a broader exoplanet sample will enable comparative atmospheric climatology, revealing whether WASP-121 b’s asymmetries are unique or reflect widespread characteristics among tidally locked hot Jupiters. Unlocking this diversity will advance understanding of atmospheric escape, chemistry, and heat transport mechanisms under conditions alien to our own planetary neighborhood.

WASP-121 b’s case also spotlights challenges in exoplanet atmospheric modeling, emphasizing the importance of incorporating cloud microphysics and non-equilibrium chemistry alongside thermal and dynamical factors. Robust, multi-dimensional models capturing these intricacies are necessary to interpret forthcoming JWST data accurately and to unravel the interplay of radiative transfer, chemical kinetics, and fluid dynamics shaping these extreme atmospheres. Future observational campaigns supported by enhanced modeling will ultimately refine our ability to reconstruct exoplanet atmospheric compositions with confidence.

In summary, this compelling research not only confirms predicted asymmetrical atmospheric structures on a tidally locked ultra-hot Jupiter but also highlights the nuanced complexity of exoplanet atmospheres revealed through state-of-the-art infrared transit spectroscopy. The successful detection and characterization of the dawn-dusk differences on WASP-121 b showcase cutting-edge exoplanet science propelled by JWST’s capabilities, affirming its vital role in decoding the secrets of distant worlds and their climates.

Subject of Research: Not applicable

Article Title: Atmospheric asymmetries in WASP-121 b revealed by rotational transits detected with JWST

News Publication Date: 10-Jun-2026

Web References: http://dx.doi.org/10.1038/s41550-026-02887-6

References: Nature Astronomy journal, DOI: 10.1038/s41550-026-02887-6

Image Credits: Patricia Klein and MPIA

Keywords: WASP-121 b, ultra-hot Jupiter, exoplanet atmosphere, atmospheric asymmetry, JWST, NIRSpec, tidally locked, infrared transit spectroscopy, atmospheric dynamics, hot Jupiters

The field of exoplanet research has evolved rapidly since the mid-1990s, initially focused on the detection of exoplanets through indirect methods, like transit photometry and radial velocity. Early observations revealed fundamental properties such as mass and radius but provided little insight into atmospheric composition or weather phenomena. The launch and operation of the James Webb Space Telescope (JWST) in 2022 initiated a transformative second phase, offering high-resolution spectroscopic capabilities that allow precise atmospheric characterization of numerous exoplanets. However, direct study of Jupiter analogs—gas giants with low atmospheric temperatures akin to those within our own Solar System—remained elusive due to observational constraints.

The study of Epsilon Indi Ab marks a significant departure from prior methods by exploiting the JWST’s mid-infrared instrument (MIRI) for direct imaging. This gas giant, orbiting the star Epsilon Indi A approximately 12 light years away in the southern constellation Indus, resides at a distance about four times that of Jupiter from our Sun. Its considerable mass, fixed at 7.6 times that of Jupiter, is offset by an unexpectedly similar radius, suggestive of dense, complex atmospheric layers that attenuate radius expansion despite the higher mass.

Epsilon Indi Ab’s relatively low equilibrium temperature, ranging between 200 and 300 Kelvin, is slightly warmer than Jupiter’s 140 Kelvin, primarily due to residual heat from its formation. Over geological timescales, the planet is expected to cool and eventually become colder than its solar counterpart. This thermal regime provides a unique laboratory to study atmospheric chemistry and dynamics in conditions markedly different from those of the typical hot Jupiters often discovered closer to their host stars.

To isolate the exoplanet’s faint infrared signatures from the overwhelming glare of its parent star, the research team utilized MIRI’s coronagraphic capability. This technology blocks starlight, enabling direct imaging in a narrow spectral window centered at 11.3 micrometers, near but distinct from the 10.6 micrometer emission feature of ammonia (NH3). By comparing these observations with earlier images captured in 2024 at the 10.6 micrometer wavelength, Matthews and colleagues derived the ammonia content in the planet’s atmosphere with unprecedented precision.

Unexpectedly, the photometric data revealed a lower-than-predicted abundance of ammonia gas. Instead, the best-fitting models indicate the presence of thick, patchy clouds composed of water ice in the upper atmosphere—analogous to the cirrus clouds observed high in Earth’s atmosphere. This finding is a critical deviation from traditional atmospheric models, which typically exclude clouds due to the complex and computationally expensive modeling required to simulate their formation, distribution, and radiative properties.

This discovery signals a pressing need for theorists to revise common atmospheric modeling approaches to incorporate clouds and their multifaceted roles. Co-author James Mang of the University of Texas at Austin remarked that such detections expose new layers of atmospheric complexity that were previously invisible, underscoring the enhanced sensitivity and capability of JWST to probe the weather patterns and structures of cold, distant worlds.

The study also heralds promising opportunities for upcoming observatories. NASA’s Nancy Grace Roman Space Telescope, planned for launch in the mid-2020s with participation from MPIA, will have the capability to directly detect reflected light from high-altitude water-ice clouds on similar exoplanets. This prospect opens a complementary avenue to infrared characterization, providing a multi-wavelength view crucial for comprehensive atmospheric modeling.

In parallel, Matthews and her team are pursuing additional JWST observation time to extend their survey to other cold Jupiter-like exoplanets. These efforts are not only crucial for understanding the diversity of gas giant atmospheres but also provide vital methodological stepping stones toward the more ambitious goal of characterizing Earth analogs. Such characterization is necessary for the long-sought detection of biosignatures—chemical markers that could signal the presence of life.

This research epitomizes the evolutionary trajectory of exoplanet atmospheric science, moving from mere detection to rich chemical, physical, and meteorological understanding. As Matthews noted, JWST affords astronomers an unprecedented opportunity to approach Jupiter-like planets as if they were looking back at our own Solar System from remote vantage points. Yet, replicating such scrutiny for smaller, terrestrial-type planets will demand still more advanced space telescopes.

As humanity edges closer to unveiling the detailed atmospheric structures of truly Earth-like worlds, the discovery of water-ice clouds on Epsilon Indi Ab marks a key milestone. It validates the efficacy of sophisticated direct imaging and spectral analysis techniques, highlights the limitations of earlier theoretical frameworks, and anticipates an era when the search for life beyond our planet moves from hopeful speculation to data-driven exploration.

The full results of this study have been published under the title “A second visit to Eps Ind Ab with JWST: new photometry confirms ammonia and suggests thick clouds in the exoplanet atmosphere of the closest super-Jupiter” in The Astrophysical Journal Letters. Researchers involved include Elisabeth Matthews and Bhavesh Rajpoot from MPIA, alongside James Mang and Caroline Morley from the University of Texas at Austin, and collaborators from the Space Telescope Science Institute.

This exciting work stands as a testament to the remarkable progress enabled by the James Webb Space Telescope and ongoing international collaboration, heralding a new era in our quest to understand the atmospheric complexities of planets beyond our own, and ultimately, to find life in the cosmos.

Subject of Research: Not applicable

Article Title: A second visit to Eps Ind Ab with JWST: new photometry confirms ammonia and suggests thick clouds in the exoplanet atmosphere of the closest super-Jupiter

News Publication Date: 22-Apr-2026

References: E. C. Matthews et al., “A second visit to Eps Ind Ab with JWST: new photometry confirms ammonia and suggests thick clouds in the exoplanet atmosphere of the closest super-Jupiter,” The Astrophysical Journal Letters.

Image Credits: E. C. Matthews, MPIA / T. Müller, HdA

Keywords

Exoplanets, Epsilon Indi Ab, Jupiter analogs, water-ice clouds, ammonia, James Webb Space Telescope, mid-infrared imaging, coronagraphy, gas giants, planetary atmospheres, direct imaging, exoplanet clouds, next-generation telescopes