Habitable Planets Research Articles

Reassessing Ocean Retention Rates: The Role of Ocean Formation Time Assumptions in Rocky Exoplanet Studies

Abstract In this work, we aim to model ocean and atmospheric mass loss in exoplanets with varying orbital parameters to assess the impact of simulation assumptions on conclusions on planetary habitability. In particular, we examine how altering the time at which a planet’s ocean is assumed to form may affect long-term inferred ocean retention rates. To study this relationship, we used VPlanet, a modular code that has the ability to model water loss on exoplanets. Using a suite of VPlanet simulations, we found that the stellar age at which a planet is assumed to form its oceans has a noticeable effect on the computed planetary water loss over Gyr timescales. This suggests that future research on ocean loss in exoplanets should account for the variability in the timing of when planets are able to form oceans.

Solar System Migration Points to a Renewed Concept: Galactic Habitable Orbits

Abstract Astrophysical evidence suggests that the Sun was born near 5 kpc from the Galactic center, within the corotation radius of the Galactic bar, around 6–7 kpc. This presents challenges for outward migration due to the Jacobi energy constraint, preventing stars from easily overcoming the corotation barrier. In this study, we use test particle simulations to explore two possible migration pathways for the Sun: a “trapped” scenario, where the Sun's orbit was influenced by a slowing Galactic bar, and an “untrapped” scenario driven by dynamic spiral arms. Our results demonstrate that both mechanisms can explain how the Sun migrated from its birth radius (≈5 kpc) to its current orbital radius around 8.5–9 kpc. Furthermore, we investigate the environmental changes experienced by the Sun along these migration pathways, focusing on variations in radiation hazards and comet fluxes, which may have impacted planetary habitability. These findings highlight the dynamic nature of galactic habitability, emphasizing that the path a star takes within the Milky Way can significantly affect its surrounding environment and the potential for life. We propose a new concept of “Galactic habitable orbits,” which accounts for evolving galactic structures and their effects on stellar and planetary systems. This work contributes to a deeper understanding of the solar system's migration and its implications for habitability within the Milky Way.

Water-Microdroplet-Driven Interface-Charged Chemistries.

Water has made Earth a habitable planet by electrifying the troposphere. For example, the lightning caused by the electrification and discharge of cloudwater microdroplets is closely related to atmospheric chemistry. Recent work has revealed that a high electric field exists at the interface of water microdroplets, which is ∼3 orders of magnitude higher than the electric field that accounts for lightning. A surge of exotic redox reactions that were recently found over water microdroplets can be contributed by such an interfacial electric field. However, the role of net charge in microdroplet redox chemistry should not be ignored. In this Perspective, we show how redox reactions can be driven by electron transfer pathways in the electrification and discharge process of water microdroplets. Understanding and harnessing the origin and evolution of charged microdroplets are likely to lead to a paradigm shift of electrochemistry, which may play an overlooked role in geological and environmental chemistry.

Continuable Weathering of Silicate Minerals Driven by Fungal Plowing

AbstractSilicate weathering acts as a significant carbon sink and sustains ecosystems by supplying essential elements, thus shaping Earth's habitability. However, our understanding the evolution of silicate weathering rates remains incomplete, with most knowledge focusing on rate decreases at solution‐silicate interfaces, while reactivity at fungi‐weathered silicate interfaces is poorly understood. This study shows that the fungus Talaromyces flavus significantly enhances the dissolution of olivine and lizardite covered by Si‐rich layers up to 3.6 μm thick by one to two orders of magnitude compared to abiotic conditions. Initially, fungal hyphae create dissolution channels ∼10–65 nm deep, promoting element release from altered layers and underlying pristine minerals while oxidizing structural Fe(II). Over time, hyphae penetrate these altered layers, exposing and etching the underlying minerals. Our data suggest that fungal etching and penetration degrade the altered layers, leading to increased interdiffusion of weathering agents and released cations, thereby continuously driving silicate weathering.

Development of Gravity Theories in the View of TRAPPIST-1e

Abstract Contrary to the solar system, most exoplanet systems detected hitherto are close-in and compact. One typical system is TRAPPIST-1, which has seven nearly co-planar terrestrial planets all within the orbit of Mercury, including three in the habitable zone.
To evaluate the differences in development of sophisticated gravity theories from the solar system, we use N-body integrations to simulate ephemeris and reproduce some important astronomy phenomena observed on the potentially habitable planet TRAPPIST-1e.
Retrograde motions of other planets last 1–2 orders of magnitude shorter than in the solar system, but occur much more frequently. Transit events of all inner planets can be observed steadily. 
Except Kepler's first law is hard to notice for low eccentricities of planets, the other two laws can then be precisely verified in 102 days, because the areas swept by planets vary by <~ 0.01% and the observed semimajor axes and periods result in constants with theoretical and observation accuracies both <~ 2%. However, the mean motion correlation implies the Great Inequality does not keep apparent between one pair of planets like Jupiter and Saturn.
Furthermore, general relativity can hardly be discovered because it gives rise to perihelion precession of inner planets only ∼0.1% of gravity precession, dozens of times smaller than Mercury. 
Our results supports the possibility of developing part of gravity theories by potential exo-civilizations in compact systems like TRAPPIST-1.

The microbial phosphorus cycle in aquatic ecosystems.

Phosphorus is an essential element for life, and phosphorus cycling is crucial to planetary habitability. In aquatic environments, microorganisms are a major component of phosphorus cycling and rapidly transform the diverse chemical forms of phosphorus through various uptake, assimilation and release pathways. Recent discoveries have revealed a more dynamic and complex aquatic microbial phosphorus cycle than previously understood. Some microorganisms have been shown to use and produce new phosphorus compounds, including those in reduced forms. New findings have also raised numerous unanswered questions that warrant further investigation. There is an expanding influence of human activity on aquatic ecosystems. Advancements in understanding the phosphorus biogeochemistry of evolving aquatic environments offer a unique opportunity to comprehend, anticipate and mitigate the effect of human activities. In this Review, I discuss the wealth of new aquatic phosphorus cycle research, spanning disciplines from omics and physiology to global biogeochemical modelling, with a focus on the current comprehension of how aquatic microorganisms sense, transport, assimilate, store, produce and release phosphorus. Of note, I delve into cellular phosphorus allocation, an underexplored topic with wide-ranging implications for energy and element flux in aquatic ecosystems.

The Search for Exoplanets: Methods and History

The discovery of exoplanets, planets beyond the solar system, has raised key questions about extraterrestrial life and the technology needed to find it. While considerable progress in exoplanet detection has been achieved over the past three decades, the methods currently in use still face notable limitations. Indeed, the detection of exoplanets has come a long way since its first confirmation in 1992. At first, these celestial objects were considered as figment of movies and science fiction, but it is credible today that Radial Velocity, Transit, Gravitational Microlensing, Direct Imaging, and Astrometry approaches have found these planetary bodies. While each of the methods works well, all techniques possess specific systematic errors depending on orbital radius, planetary size, and so on. For the past few decades, missions like Hubble, Spitzer as well as Kepler have delivered the fundamental catalogs and enormously improved the knowledge in the field of exoplanets. Recent developments, specifically with the JWST, have provided new ideas with indications of biosignatures on planet exoplanet K2-18b. The future prospects for exoplanet discovery also look good, for example, with the help of the machine learning for analysis and planned instruments like Nancy Grace Roman Space Telescope and the concept of Habitable Worlds Observatory. These observatories are oriented towards the search of potentially habitable exoplanets and for exploration of other universal enigmatic processes. In this paper, the advancement of technique in identifying exoplanets is outlined with specific focus on significant accomplishments, trends, technologies, and future outlook, which shows a fairly promising field that holds great potential for finding more habitable planets.

The Main Groups of Photosynthetic Bacteria and Photosynthetic Pigments

Photosynthesis is one of the most important process on today’s Earth, which provides most of the energy source of the Earth’s biosphere, changed and shaped the atmosphere and oceans in early days of the Earth. Photosynthetic bacteria are a kind of prokaryotic microorganism that can assimilate or dissimilate by using light energy as an energy source and organic or inorganic matter as the electron donor for assimilation or heterocytosis, which can be divided into Cyanobacteria, Purple bacteria (PB), Green bacteria (GB), Aerobic anoxygenic photosynthesis bacteria (AAPB) and others. In this paper, the literature on photosynthetic bacteria in recent years is reviewed and combined with the latest astrobiology research, revealing the photosynthetic pigment composition of different photosynthetic bacteria. Cyanobacteria contain Chlorophyll (Chl) for the absorption and transfer of light energy including Chl a, CHl b, Chl d, carotenoids and phycobilins, of which chlorophyll b and chlorophyll d are not contained in all types of cyanobacteria, PB contain BChl a or BChl b, GSB contains photopigments BChl a, Chl a, and BChl c, d, or e, GNSB contains photopigments BChl a and/or BChl c, and AAPB mainly contain BChl a. Understanding how Photosynthesis evolves, what kinds of photosynthetic pigments and how do it function could provide a new insight into the origins of life and are beneficial to detection of extraterrestrial life and potential habitable planets.

X-Ray Emission of Nearby Low-mass and Sunlike Stars with Directly Imageable Habitable Zones

Stellar X-ray and UV radiation can significantly affect the survival, composition, and long-term evolution of the atmospheres of planets in or near their host star’s habitable zone (HZ). Especially interesting are planetary systems in the solar neighborhood that may host temperate and potentially habitable surface conditions, which may be analyzed by future ground- and space-based direct-imaging surveys for signatures of habitability and life. To advance our understanding of the radiation environment in these systems, we leverage ∼3 Ms of XMM-Newton and Chandra observations in order to measure three fundamental stellar properties at X-ray energies for 57 nearby FGKM stellar systems: the shape of the stellar X-ray spectrum, the luminosity, and the timescales over which the stars vary (e.g., due to flares). These systems possess HZs that will be directly imageable to next-generation telescopes such as the Habitable Worlds Observatory and ground-based Extremely Large Telescopes. We identify 29 stellar systems with L X/L bol ratios similar to (or less than) that of the Sun; any potential planets in the HZs of these stars therefore reside in present-day X-ray radiation environments similar to (or less hostile than) modern Earth, though a broader set of these targets could host habitable planets. An additional 19 stellar systems have been observed with the Swift X-ray Telescope; in total, only ∼30% of potential direct imaging target stars has been observed with XMM-Newton, Chandra, or Swift. The data products from this work (X-ray light curves and spectra) are available via a public Zenodo repository (doi:10.5281/zenodo.11490574).

Spacecraft design for interstellar travel

This paper endeavours to introduce and elucidate potential mechanisms aimed at the development of a spacecraft that is not only sustainable but also optimized for interstellar travel to the Andromeda galaxy, with the primary objective of scouting for potentially habitable exoplanets suitable for human colonization. The conceptual framework encompasses a comprehensive analysis of various critical components essential for the functionality and longevity of the spacecraft, including but not limited to propulsion systems, attitude control mechanisms, and advanced navigation systems. In addition, habitable areas which are also called Goldilocks zones refer to the areas around stars where planetary conditions are conducive to foster lives. As the existence of liquid water is known as the fundamental prerequisite for supporting life, the basic criteria for a habitable planet is temperature appropriate for water sustaining. The final analysis shows that space immigration is a determined consequence of human being and people should take effective measures to investigate future possible ways of immigrating to another planet.

RedDots: Limits on habitable and undetected planets orbiting nearby stars GJ 832, GJ 674, and Ross 128

Context. The nearby (d < 5 pc) M dwarfs GJ 832, GJ 674, and Ross 128 each host a single exoplanet, with Ross 128 b located within the optimistic habitable zone. Due to their low mass and close proximity, these three systems are prime candidates for further characterization studies. Aims. Using HARPS spectroscopic data obtained by the RedDots campaign, as well as archival data from HARPS and CARMENES, supplemented with ASH2 and T90 photometry, we aim to search for additional planets in the three systems. We also aim to determine limits on possible undetected, habitable planets. We investigate (i) the reliability of the recovered orbital eccentricities and (ii) the reliability of Bayesian evidence as a diagnostic for selecting the best model. Methods. We employed Markov-chain Monte Carlo, nested sampling, and Gaussian process (GP) analyses to fit a total of 20 different models comprising 0–2 Keplerian signals and three different GP kernels for stellar activity. We used the residuals to create grids for injection-recovery simulations to obtain detection limits on potentially undiscovered planets. Results. Our refined orbital elements for GJ 832 b, GJ 674 b, and Ross 128 b confirm (GJ 832, GJ 674) or increase (Ross 128) prior eccentricity determinations. No additional planets were found in any of the systems. The detection limits obtained for all three systems are between 30 and 50 cm s−1 for orbital periods in the range of 1–10 000 days. This corresponds to habitable planet masses of <1.5M⊕for GJ 832 and < 1M⊕ for GJ 674 and Ross 128. Using N-body simulations, we find that undiscovered secondary planets are unlikely (Ross 128) or incapable (GJ 674) of having caused the observed eccentricities of the known planets. We find that the eccentricity of GJ 832b is not significantly different from zero. Conclusions. GJ 832 b, GJ 674 b, and Ross 128 b retain their status as hosting lonely and (for the latter two) eccentric planets (e = 0.04, 0.24, 0.21; respectively). This is unexpected in classical planet formation scenarios, which favor circular orbits and multiplanet configurations, demonstrating that planet formation in these cases is more complicated than traditionally thought. Additionally, the eccentricity of Ross 128 indicates that it spends some of its orbit outside of the optimistic habitable zone. Finally, our results show that Bayesian evidence, when used in conjunction with GP, is not a robust diagnostic for selecting the best model in cases of low- activity stars. In such cases, we advise an inspection of the shapes of the posterior distributions and to ensure that relevant simulations are performed to assess the validity of the perceived best model.

The Feasibility of Asynchronous Rotation via Thermal Tides for Diverse Atmospheric Compositions

The equilibrium rotation rate of a planet is determined by the sum of torques acting on its solid body. For planets with atmospheres, the dominant torques are usually the gravitational tide, which acts to slow the planet’s rotation rate, and the atmospheric thermal tide, which acts to spin up the planet. Previous work demonstrated that rocky planets with thick atmospheres may produce strong enough thermal tides to avoid tidal locking, but a study of how the strength of the thermal tide depends on atmospheric properties has not been done. In this work, we use a combination of simulations from a global climate model and analytic theory to explore how the thermal tide depends on the shortwave and longwave optical depth of the atmosphere, the surface pressure, and the absorbed stellar radiation. We find that for planets in the habitable zones of M stars only high-pressure but low-opacity atmospheres permit asynchronous rotation owing to the weakening of the thermal tide at high longwave and shortwave optical depths. We conclude that asynchronous rotation may be very unlikely around low-mass stars, which may limit the potential habitability of planets around M stars.

The erosion of large primary atmospheres typically leaves behind substantial secondary atmospheres on temperate rocky planets

Exoplanet exploration has revealed that many—perhaps most—terrestrial exoplanets formed with substantial H2-rich envelopes, seemingly in contrast to solar system terrestrials, for which there is scant evidence of long-lived primary atmospheres. It is not known how a long-lived primary atmosphere might affect the subsequent habitability prospects of terrestrial exoplanets. Here, we present a new, self-consistent evolutionary model of the transition from primary to secondary atmospheres. The model incorporates all Fe-C-O-H-bearing species and simulates magma ocean solidification, radiative-convective climate, thermal escape, and mantle redox evolution. For our illustrative example TRAPPIST-1, our model strongly favors atmosphere retention for the habitable zone planet TRAPPIST-1e. In contrast, the same model predicts a comparatively thin atmosphere for the Venus-analog TRAPPIST-1b, which would be vulnerable to complete erosion via non-thermal escape and is consistent with JWST observations. More broadly, we conclude that the erosion of primary atmospheres typically does not preclude surface habitability, and frequently results in large surface water inventories due to the reduction of FeO by H2.

Closeby Habitable Exoplanet Survey (CHES). II. An Observation Strategy for the Target Stars

The Closeby Habitable Exoplanet Survey (CHES) constitutes a mission intricately designed to systematically survey approximately 100 solar-type stars located within the immediate proximity of the solar system, specifically within a range of 10 pc. The core objective of this mission is the detection and characterization of potentially habitable Earth-like planets or super-Earths within the habitable zone of these stars. The CHES mission obtains high-precision astrometric measurements of planets orbiting the target stars by observing angular distance variations between the target star and reference stars. As a result, we surveyed the relevant parameters of both target and reference stars in detail, conducting a thorough analysis and calculation of the required observation accuracy, the number of observations, and the priority assigned to each target star. Observational emphasis will be concentrated on targets considered of higher priority, ensuring the effectiveness of their observation capabilities. Through this approach, we formulate a 5 yr observation strategy that will cover all the target stars within a 6 month time frame. The strategy not only fulfills the required observing capability but also exhibits high efficiency simultaneously, providing an executable program for future mission. Over the span of the mission’s 5 yr duration, a cumulative observation time of 29,220 hr will be available. Approximately 86% of this, totaling 25,120 hr, is allocated for the observation of target stars. This allocation leaves approximately 4100 hr for extended scientific observation programs. We have also performed simulated observations based on this strategy and verified its observational capability for exoplanets.

The radius distribution of M dwarf-hosted planets and its evolution

Abstract M dwarf stars are the most promising hosts for detection and characterization of small and potentially habitable planets, and provide leverage relative to solar-type stars to test models of planet formation and evolution. Using Gaia astrometry, adaptive optics imaging, and calibrated gyrochronologic relations to estimate stellar properties and filter binaries we refined the radii of 117 Kepler Objects of Interest (confirmed or candidate planets) transiting 74 single late K- and early M-type stars, and assigned stellar rotation-based ages to 113 of these. We constructed the radius distribution of 115 small (<4R⊕) planets and assessed its evolution. As for solar-type stars, the inferred distribution contains distinct populations of ‘super-Earths’ (at ∼1.3R⊕) and ‘sub-Neptunes’ (at ∼2.2 R⊕) separated by a gap or ‘valley’ at ≈1.7R⊕that has a period dependence that is significantly weaker (power law index of -0.03$^{+0.01}_{-0.03}$) than for solar-type stars. Sub-Neptunes are largely absent at short periods (<2 days) and high irradiance, a feature analogous to the ‘Neptune desert’ observed around solar-type stars. The relative number of sub-Neptunes to super-Earths declines between the younger and older halves of the sample (median age 3.86 Gyr), although the formal significance is low (p = 0.08) because of the small sample size. The decline in sub-Neptunes appears to be more pronounced on wider orbits and low stellar irradiance. This is not due to detection bias and suggests a role for H2O as steam in inflating the radii of sub-Neptunes and/or regulating the escape of H/He from them.

Biomimetic CO2 Capture Unlocked through Enzyme Mining: Discovery of a Highly Thermo- and Alkali-Stable Carbonic Anhydrase.

Taking immediate action to combat the urgent threat of CO2-driven global warming is crucial for ensuring a habitable planet. Decarbonizing the industrial sector requires implementing sustainable carbon-capture technologies, such as biomimetic hot potassium carbonate capture (BioHPC). BioHPC is superior to traditional amine-based strategies due to its eco-friendly nature. This innovative technology relies on robust carbonic anhydrases (CAs), enzymes that accelerate CO2 hydration and endure harsh industrial conditions like high temperature and alkalinity. Thus, the discovery of highly stable CAs is crucial for the BioHPC technology advancement. Through high-throughput bioinformatics analysis, we identified a highly thermo- and alkali-stable CA, termed CA-KR1, originating from a metagenomic sample collected at a hot spring in Kirishima, Japan. CA-KR1 demonstrates remarkable stability at high temperatures and pH, with a half-life of 24 h at 80 °C and retains activity and solubility even after 30 d in a 20% (w/v) K2CO3/pH 11.5 solution─a standard medium for HPC. In pressurized batch reactions, CA-KR1 enhanced CO2 absorption by >90% at 90 °C, 20% K2CO3, and 7 bar. To our knowledge, CA-KR1 constitutes the most resilient CA biocatalyst for efficient CO2 capture under HPC-relevant conditions, reported to date. CA-KR1 integration into industrial settings holds great promise in promoting efficient BioHPC, a potentially game-changing development for enhancing carbon-capture capacity toward industrial decarbonization.

Frank Drake is Alive! (Rethinking the Drake Equation for the Search For Biological Life)

In 1961, astronomer Frank Drake formulated the Drake Equation as a cornerstone for scientific discourse regarding the prevalence of communicative extraterrestrial civilizations within the Milky Way galaxy. This equation, often referred to as the “Classic Drake Equation”, outlines the key factors influencing the number of potential civilizations with which we might establish communication. This article submerges into the Drake Equation and proposes a simplified version focused on the broader detection of extraterrestrial non-intelligent life. The established terms of the equation, such as the rate of stellar formation, the fraction of stars harboring planetary systems, and the probability of such systems containing habitable planets, are re-examined and discussed. Additionally, a reevaluation of other factors is presented. Based on this revised framework, various scenarios are explored. As our technological capabilities continue to advance, the detection of biosignatures on exoplanets (incorporated into the suggested new version of the equation) is anticipated to offer insights into the search for life beyond Earth. Keywords: Drake Equation, Extraterrestrial Life, Exoplanetology, Habitability, Biomarkers, Communicative Civilizations

Exoplanet Detection Using Machine Learning : A Comparative Study Using Kepler Mission Data

The search for habitable planets outside our solar system has captivated scientists throughout the centuries. Discovery and characterization of exoplanets have been one of the most important endeavors of modern astronomy. With various space missions, we have significantly expanded our observational capacity, resulting in an abundance of information about the universe. The influx of more data necessitates the development of techniques that can aid astronomers in processing all the information more efficiently and in an automated manner. Machine learning in recent years has become an indispensable paradigm to automate complex tasks that are possible only by humans. This work explores the application of machine learning to detect exoplanets from NASA’s Kepler mission. Our dataset comprises Kepler Objects of Interest (KOIs), encompassing their characteristic features and confirmed exoplanet status. We experiment with multiple supervised classification techniques including classical, tree-based, and neural methods. The best-performing model Histogram Gradient Boosting achieves a strong performance of 94.6% precision and 94.1% recall on a held-out dataset demonstrating the strong potential of integrating machine learning techniques into astronomy, potentially leading to new insights into planetary systems outside the solar system.

Large Interferometer For Exoplanets (LIFE)

Context. Following the recommendations to NASA (in the Astro2020 Decadal survey) and ESA (through the Voyage2050 process), the search for life on exoplanets will be a priority in the next decades. Two concepts for direct imaging space missions are being developed for this purpose: the Habitable Worlds Observatory (HWO) and the Large Interferometer for Exoplanets (LIFE). These two concepts operate in different spectral regimes: HWO is focused on reflected light spectra in the ultraviolet, visible, and near-infrared (UV/VIS/NIR), while LIFE will operate in the mid-infrared (MIR) to capture the thermal emission of temperate exoplanets. Aims. In this study, we aim to assess the potential of HWO and LIFE to characterize a cloud-free Earth twin orbiting a Sun-like star at a distance of 10 pc, both as separate missions and in synergy with each other. We aim to quantify the increase in information that can be gathered by joint atmospheric retrievals on a habitable planet. Methods. We performed Bayesian retrievals on simulated data obtained by an HWO-like mission and a LIFE-like one separately, then jointly. We considered the baseline spectral resolutions currently assumed for these concepts and used two increasingly complex noise simulations, obtained using state-of-the-art noise simulators. Results. An HWO-like concept would allow one to strongly constrain H2O, O2, and O3 in the atmosphere of a cloud-free Earth twin, while the atmospheric temperature profile is not well constrained (with an average uncertainty ≈100 K). LIFE-like observations would strongly constrain CO2, H2O, and O3 and provide stronger constraints on the thermal atmospheric structure and surface temperature (down to ≈10 K uncertainty). For all the investigated scenarios, both missions would provide an upper limit on CH4. A joint retrieval on HWO and LIFE data would accurately define the atmospheric thermal profile and planetary parameters. It would decisively constrain CO2, H2O, O2, and O3 and find weak constraints on CO and CH4. The significance of the detection is in all cases greater than or equal to the single-instrument retrievals. Conclusions. Both missions provide specific information that is relevant for the characterization of a terrestrial habitable exoplanet, but the scientific yield can be maximized by considering synergistic studies of UV/VIS/NIR+MIR observations. The use of HWO and LIFE together will provide stronger constraints on biosignatures and life indicators, with the potential to be transformative for the search for life in the Universe.

Statistics and Habitability of F-type Star–Planet Systems

F-type star–planet systems represent an intriguing case for habitability studies. Although F-type stars spend considerably less time on the main sequence (MS) than G-, K-, and M-type stars, they still offer a unique set of features, allowing for the principal possibility of exolife. Examples of these features include the increased widths of stellar habitable zones as well as the presence of enhanced UV flux, which in moderation may have added to the origin of life in the Universe. In this study, we pursue a detailed statistical analysis of the currently known planet-hosting F-type stars by making use of the NASA Exoplanet Archive. After disregarding systems with little or no information on the planet(s), we identify 206 systems of interest. We also evaluate whether the stars are on the MS based on various criteria. In one approach, we use the stellar evolution code MESA. Depending on the adopted criterion, about 60–80 stars have been identified as MS stars. In 18 systems, the planet spends at least part of its orbit within the stellar habitable zone. In one case, i.e., HD 111998, known as 38 Vir, the planet is situated in the habitable zone at all times. Our work may serve as a basis for future studies, including studies on the existence of Earth-mass planets in F-type systems, as well as investigations of possibly habitable exomoons hosted by exo-Jupiters, as the lowest-mass habitable zone planet currently identified has a mass estimate of 143 Earth masses.