Study Findings: Atmospheric Carbon Depletion as a Tracer of Water Oceans and Biomass on Temperate Terrestrial Exoplanets

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Credit: NASA/JPL-Caltech

Nature Astronomy abstract of the study findings:

The conventional observables to identify a habitable or inhabited environment in exoplanets, such as an ocean glint or abundant atmospheric O2, will be challenging to detect with present or upcoming observatories. Here we suggest a new signature. A low carbon abundance in the atmosphere of a temperate rock`y planet, relative to other planets of the same system, traces the presence of a substantial amount of liquid water, plate tectonics and/or biomass. Here we show that JWST can already perform such a search in some selected systems such as TRAPPIST-1 via the CO2 band at 4.3 μm, which falls in a spectral sweet spot where the overall noise budget and the effect of cloud and/or hazes are optimal. We propose a three-step strategy for transiting exoplanets: detection of an atmosphere around temperate terrestrial planets in about 10 transits for the most favourable systems; assessment of atmospheric carbon depletion in about 40 transits; and measurements of O3 abundance to disentangle between a water- versus biomass-supported carbon depletion in about 100 transits. The concept of carbon depletion as a signature for habitability is also applicable for next-generation direct-imaging telescopes.

Citation: Triaud, A.H.M.J., de Wit, J., Klein, F. et al. Atmospheric carbon depletion as a tracer of water oceans and biomass on temperate terrestrial exoplanets. Nat Astron (2023).
https://doi.org/10.1038/s41550-023-02157-9

Study-related stories:

NASA Had a Busy Year

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Image (Credit): The introduction of the Artemis II crew, just one of many items highlighted in NASA’s new video summarizing 2023. (NASA)

This is the time of year for lists, so I wanted to highlight one of the more important lists, at least in the opinion of this writer. That’s right, we need to remember the important space milestones from this year.

Fortunately, NASA recently summed up its successes in 2023 with a new video titled NASA 2023: Nothing is Beyond Our Reach. The video highlights many of the Agency’s accomplishments this year, including the launch of the Psyche mission, the announcement of a crew for the Artemis II mission, and the OSIRIS-REx capsule retrieval.

It is quite a list. Luckily, NASA provided a list of links so you can read more about the various efforts:

Time to read up on 2023 before we dive into more activities in 2024.

Note: You can read a more detailed list of accomplishments at this NASA site.

Pic of the Week: Supernova Remnant Cassiopeia A

Posted on by onespaceman2000
Image (Credit): Supernova Remnant Cassiopeia A. (NASA, ESA, CSA, STScI; D. Milisavljevic (Purdue University), T. Temim (Princeton University), I. De Looze (University of Gent))

This week’s image captured by the James Webb Space Telescope is both violent yet beautiful. It is also NASA’s Astronomy Picture of the Day for today.

Here are some details about the image from NASA:

Massive stars in our Milky Way Galaxy live spectacular lives. Collapsing from vast cosmic clouds, their nuclear furnaces ignite and create heavy elements in their cores. After only a few million years for the most massive stars, the enriched material is blasted back into interstellar space where star formation can begin anew. The expanding debris cloud known as Cassiopeia A is an example of this final phase of the stellar life cycle. Light from the supernova explosion that created this remnant would have been first seen in planet Earth’s sky about 350 years ago, although it took that light 11,000 years to reach us. This sharp NIRCam image from the James Webb Space Telescope shows the still hot filaments and knots in the supernova remnant. The whitish, smoke-like outer shell of the expanding blast wave is about 20 light-years across. Light echoes from the massive star’s cataclysmic explosion are also identified in Webb’s detailed image of supernova remnant Cassiopeia A.

Study Findings: A Resonant Sextuplet of Sub-Neptunes Transiting the Bright Star HD 110067

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Image (Credit): Neptune as captured by the James Webb Space Telescope’s near-infrared camera. (NASA, ESA, CSA, and STScI)

Nature abstract of the study findings:

Planets with radii between that of the Earth and Neptune (hereafter referred to as ‘sub-Neptunes’) are found in close-in orbits around more than half of all Sun-like stars. However, their composition, formation and evolution remain poorly understood. The study of multiplanetary systems offers an opportunity to investigate the outcomes of planet formation and evolution while controlling for initial conditions and environment. Those in resonance (with their orbital periods related by a ratio of small integers) are particularly valuable because they imply a system architecture practically unchanged since its birth. Here we present the observations of six transiting planets around the bright nearby star HD 110067. We find that the planets follow a chain of resonant orbits. A dynamical study of the innermost planet triplet allowed the prediction and later confirmation of the orbits of the rest of the planets in the system. The six planets are found to be sub-Neptunes with radii ranging from 1.94R⊕ to 2.85R⊕. Three of the planets have measured masses, yielding low bulk densities that suggest the presence of large hydrogen-dominated atmospheres.

Citation: Luque, R., Osborn, H.P., Leleu, A. et al. A resonant sextuplet of sub-Neptunes transiting the bright star HD 110067. Nature 623, 932–937 (2023).
https://doi.org/10.1038/s41586-023-06692-3

Study-related stories:

Pic of the Week: The Core of Our Galaxy

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Image (Credit): JWST’s view of the Milky Way. (NASA)

With the Thanksgiving holiday almost over, you may be thinking of Christmas lights after seeing the image above. Think larger, such as the size of a galaxy. You are looking at approximately 500,000 stars at the center of the Milky Way galaxy as seen by the James Webb Space Telescope (JWST), and it is pretty amazing.

The Webb telescope site has this to say about the image (and even more to say at the linked site):

A bright field of gas sweeps around the edge of a dark, dense cloud where young stars are bursting out to take their place in the universe. They join an estimated 500,000 other stars in the scene, of various ages, sizes, and colors. It’s the hub of our Milky Way galaxy, a city center at rush hour, making our solar system’s calm corner a frontier outpost by comparison. Discover the new features – and mysteries – NASA’s James Webb Space Telescope has revealed with its unprecedented infrared-light view of the chaotic region, and what it means for astronomy.