A Catalog of Stellar Evolution Profiles and the Effects of Variable Composition on Habitable Systems

Truitt, Amanda; Young, Patrick; Spacek, Alexander; Probst, L. W.; Dietrich, Jennifer E.

doi:10.1088/0004-637x/804/2/145

Cited by 19 publications

(32 citation statements)

References 68 publications

(80 reference statements)

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“…We used the stellar evolution code Tycho (Young & Arnett 2005) to create the catalog of evolutionary tracks discussed in detail in Truitt et al (2015) and Truitt & Young (2017), which are the basis for the model priors discussed here. The database currently contains models between 0.5-1.2 solar masses, with metallicities that fall between 0.1 − 1.5 of solar Z-value, so this is the parameter space we analyze here.…”

Section: Methodsmentioning

confidence: 99%

A Flexible Bayesian Framework for Assessing Habitability with Joint Observational and Model Constraints

Truitt

Young

Walker

et al. 2020

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The catalog of stellar evolution tracks discussed in our previous work is meant to help characterize exoplanet host-stars of interest for follow-up observations with future missions like JWST. However, the utility of the catalog has been predicated on the assumption that we would precisely know the age of the particular host-star in question; in reality, it is unlikely that we will be able to accurately estimate the age of a given system. Stellar age is relatively straightforward to calculate for stellar clusters, but it is difficult to accurately measure the age of an individual star to high precision. Unfortunately, this is the kind of information we should consider as we attempt to constrain the long-term habitability potential of a given planetary system of interest. This is ultimately why we must rely on predictions of accurate stellar evolution models, as well a consideration of what we can observably measure (stellar mass, composition, orbital radius of an exoplanet) in order to create a statistical framework wherein we can identify the best candidate systems for follow-up characterization. In this paper we discuss a statistical approach to constrain long-term planetary habitability by evaluating the likelihood that at a given time of observation, a star would have a planet in the 2 Gy continuously habitable zone (CHZ 2 ). Additionally, we will discuss how we can use existing observational data (i.e. data assembled in the Hypatia catalog and the Kepler exoplanet host star database) for a robust comparison to the catalog of theoretical stellar models.

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Section: Methodsmentioning

confidence: 99%

A Flexible Bayesian Framework for Assessing Habitability with Joint Observational and Model Constraints

Truitt

Young

Walker

et al. 2020

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“…The minimum time for elementary life to significantly alter a planet's atmosphere (biomarkers) up to detectable levels from another planetary system has been estimated at 2 Gyr (Truitt et al, 2015). Therefore, the planetary dynamo must protect life efficiently, for at least these 2 Gyr, so that it can develop and become detectable.…”

Section: The Ideal Referencementioning

confidence: 99%

A fuzzy Multi-Criteria Decision Making approach for Exo-Planetary Habitability

Sánchez-Lozano

Moya

Rodríguez-Mozos

2021

Astronomy and Computing

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Nowadays, we know thousands of exoplanets, some of them potentially habitable. Next technological facilities (JWST, for example) have exoplanet atmosphere analysis capabilities, but they also have limits in terms of how many targets can be studied.Therefore, there is a need to rank and prioritize these exoplanets with the aim of searching for biomarkers. Some criteria involved, such as the habitability potential of a dry-rock planet versus a water-rich planet, or a potentially-locked planet versus a tidally-locked planet, are often vague and the use of the fuzzy set theory is advisable.We have applied a combination of Multi-Criteria Decision-Making methodologies with fuzzy logic, the Fuzzy Reference Ideal Method (FRIM), to this problem. We have analyzed the habitability potential of 1798 exoplanets from TEPCat database based on a set of criteria (composition, atmosphere, energy, tidal locking, type of planet and liquid water), in terms of their similarity to the only ideal alternative, The Earth. Our results, when compared with the probability index SEPHI, indicate that Kepler-442b, Kepler-062e/f, and LHS_1140b are the best exoplanets for searching for biomarkers, regardless its technical difficulty. If we take into account current technical feasibility, the best candidate is TRAPPIST-1e.

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“…Deprioritize exoplanets outside their star's HZ (e.g., Kopparapu et al 2014), as well as those planets that have not spent a minimum time (e.g., ~1 Gyr) in the HZ (Truitt et al 2015), so that the planet has had a sufficiently long time to develop oxygenic photosynthesis, or similar time-dependent habitability considerations. This requires determining a host star's minimum possible age to 0.1 Gyr accuracy, coupled with stellar and HZ modelling that relies on the measured stellar and planetary parameters.…”

Section: An Observational Procedures For Observing Exoplanetsmentioning

confidence: 99%

A Geologically Robust Procedure for Observing Rocky Exoplanets to Ensure that Detection of Atmospheric Oxygen Is a Modern Earth-like Biosignature

Lisse

Desch

Unterborn

et al. 2020

ApJL

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In the next decades, the astrobiological community will debate whether the first observations of oxygen in an exoplanet’s atmosphere signify life, so it is critical to establish procedures now for collection and interpretation of such data. We present a step-by-step observational strategy for using oxygen as a robust biosignature to prioritize exoplanet targets and design future observations. It is premised on avoiding planets lacking subaerial weathering of continents, which would imply geochemical cycles drastically different from modern Earth’s, precluding use of oxygen as a biosignature. The strategy starts with the most readily obtained data: orbital semimajor axis and stellar luminosity to ensure residence in the habitable zone and stellar X-ray/ultraviolet flux to ensure an exoplanet can retain a secondary (outgassed) atmosphere. Next, high-precision mass and radius information should be combined with high-precision stellar abundance data to constrain the exoplanet’s water content; those incompatible with <0.1 wt% H2O can be deprioritized. Then, reflectance photometry or low-resolution transmission spectroscopy should confirm an optically thin atmosphere. Subsequent long-duration, high-resolution transmission spectroscopy should search for oxygen and ensure that water vapor and CO2 are present only at low (∼102–104 ppm levels). Assuming oxygen is found, attribution to life requires the most difficult step, acquisition of a detailed, multispectral light curve of the exoplanet, to ensure both surface land and water. Exoplanets failing some of these steps might be habitable, even have observable biogenic oxygen, but should be deprioritized because oxygen could not be attributed unambiguously to life, and life therefore would not be detectable on such planets. Finally, we show how to use this scheme for the solar system, the 55 Cnc system, and the TRAPPIST-1 system, in which only the Earth and TRAPPIST-1e successfully pass through our procedure.

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A Catalog of Stellar Evolution Profiles and the Effects of Variable Composition on Habitable Systems

Cited by 19 publications

References 68 publications

A Flexible Bayesian Framework for Assessing Habitability with Joint Observational and Model Constraints

A Flexible Bayesian Framework for Assessing Habitability with Joint Observational and Model Constraints

A fuzzy Multi-Criteria Decision Making approach for Exo-Planetary Habitability

A Geologically Robust Procedure for Observing Rocky Exoplanets to Ensure that Detection of Atmospheric Oxygen Is a Modern Earth-like Biosignature

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