Haiyang Wang

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Wang

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Haiyang

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0000-0001-8618-3343

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Publications 1 - 10 of 20

Plausible constraints on the range of bulk terrestrial exoplanet compositions in the Solar neighbourhood
Spaargaren, Rob J.; Wang, Haiyang; Mojzsis, Stephen; et al. (2022)
arXiv
Rocky planet compositions regulate planetary evolution by affecting core sizes, mantle properties, and melting behaviours. Yet, quantitative treatments of this aspect of exoplanet studies remain generally under-explored. We attempt to constrain the range of potential bulk terrestrial exoplanet compositions in the solar neighbourhood (<200 pc). We circumscribe probable rocky exoplanet compositions based on a population analysis of stellar chemical abundances from the Hypatia and GALAH catalogues. We apply a devolatilization model to simulate compositions of hypothetical, terrestrial-type exoplanets in the habitable zones around Sun-like stars, considering elements O, S, Na, Si, Mg, Fe, Ni, Ca, and Al. We further apply core-mantle differentiation by assuming constant oxygen fugacity, and model the consequent mantle mineralogy with a Gibbs energy minimisation algorithm. We report statistics on several compositional parameters and propose a reference set of (21) representative planet compositions for using as end-member compositions in imminent modelling and experimental studies. We find a strong correlation between stellar Fe/Mg and metallic core sizes, which can vary from 18 to 35 wt%. Furthermore, stellar Mg/Si gives a first-order indication of mantle mineralogy, with high-Mg/Si stars leading to weaker, ferropericlase-rich mantles, and low-Mg/Si stars leading to mechanically stronger mantles. The element Na, which modulates crustal buoyancy and mantle clinopyroxene fraction, is affected by devolatilization the most. While we find that planetary mantles mostly consist of Fe/Mg-silicates, core sizes and relative abundances of common minerals can nevertheless vary significantly among exoplanets. These differences likely lead to different evolutionary pathways among rocky exoplanets in the solar neighbourhood.
GiT: Towards Generalist Vision Transformer Through Universal Language Interface
Wang, Haiyang; Tang, Hao; Jiang, Li; et al. (2025)
Lecture Notes in Computer Science ~ Computer Vision – ECCV 2024
This paper proposes a simple, yet effective framework, called GiT, simultaneously applicable for various vision tasks only with a vanilla ViT. Motivated by the universality of the Multi-layer Transformer architecture (e.g., GPT) widely used in large language models (LLMs), we seek to broaden its scope to serve as a powerful vision foundation model (VFM). However, unlike language modeling, visual tasks typically require specific modules, such as bounding box heads for detection and pixel decoders for segmentation, greatly hindering the application of powerful multi-layer transformers in the vision domain. To solve this, we design a universal language interface that empowers the successful auto-regressive decoding to adeptly unify various visual tasks, from image-level understanding (e.g. captioning), over sparse perception (e.g. detection), to dense prediction (e.g. segmentation). Based on the above designs, the entire model is composed solely of a ViT, without any specific additions, offering a remarkable architectural simplification. GiT is a multi-task visual model, jointly trained across five representative benchmarks without task-specific fine-tuning. Interestingly, our GiT builds a new benchmark in generalist performance, and fosters mutual enhancement across tasks, leading to significant improvements compared to isolated training. This reflects a similar impact observed in LLMs. Further enriching training with 27 datasets, GiT achieves strong zero-shot results over various tasks. Due to its simple design, this paradigm holds promise for narrowing the architectural gap between vision and language. Code and models are available at https://github.com/Haiyang-W/GiT.
The interior diversity of terrestrial-type exoplanets: constrained with devolatilized stellar abundances and mass-radius measurements
Wang, Haiyang; Quanz, Sascha Patrick; Yong, David; et al. (2022)
EPSC Abstracts
A major goal in the discovery and characterization of exoplanets is to identify terrestrial-type worlds that are similar to (or otherwise distinct from) our Earth. The combination of mass-radius measurements and host stellar abundances has been proposed to constrain the interiors of small (rocky) exoplanets. In this work, we advocate the importance of using devolatilized stellar abundances, instead of uncorrected stellar abundances, to further reduce degeneracies in modelling the interiors of rocky exoplanets. We apply an empirical devolatilization model to a selected sample of 13 planet-hosting Sun-like stars, for which high-precision photospheric abundances have been available. With the resultant devolatilized stellar composition (i.e. the model planetary bulk composition), as well as other constraints including mass and radius, we model the detailed mineralogy and interior structure of hypothetical, habitable-zone terrestrial planets (‘exo-Earths’) around these stars. Model output shows that most of these exo-Earths are expected to have broadly Earth-like composition and interior structure, consistent with conclusions derived independently from analysis of polluted white dwarfs. Investigating the empirical devolatilization model at its extremes as well as varying planetary mass and radius (within the terrestrial regime) reveals potential diversities in the interiors of terrestrial planets. By considering (i) high-precision stellar abundances, (ii) devolatilization, and (iii) planetary mass and radius holistically, this work represents essential steps to explore the detailed mineralogy and interior structure of terrestrial-type exoplanets, which in turn are fundamental for a quantitative understanding of planetary long-term evolution including the interior-atmosphere interactions.
Large Interferometer for Exoplanets: VIII. Where Is the Phosphine? Observing Exoplanetary PH3 with a Space Based Mid-Infrared Nulling Interferometer
Angerhausen, Daniel; Ottiger, Maurice; Dannert, Felix; et al. (2023)
Astrobiology
Phosphine could be a key molecule in the understanding of exotic chemistry that occurs in (exo)planetary atmospheres. While phosphine has been detected in the Solar System's giant planets, it has not been observed in exoplanets to date. In the exoplanetary context, however, it has been theorized to be a potential biosignature molecule. The goal of our study was to identify which illustrative science cases for PH3 chemistry are observable with a space-based mid-infrared nulling interferometric observatory like the Large Interferometer for Exoplanets (LIFE) concept. We identified a representative set of scenarios for PH3 detections in exoplanetary atmospheres that vary over the whole dynamic range of the LIFE mission. We used chemical kinetics and radiative transfer calculations to produce forward models of these informative, prototypical observational cases for LIFEsim, our observation simulator software for LIFE. In a detailed, yet first order approximation, it takes a mission like LIFE: (i) about 1 h to find phosphine in a warm giant around a G star at 10 pc, (ii) about 10 h in H-2 or CO2 dominated temperate super-Earths around M star hosts at 5 pc, (iii) and even in 100 h it seems very unlikely that phosphine would be detectable in a Venus-Twin with extreme PH3 concentrations at 5 pc. Phosphine in concentrations previously discussed in the literature is detectable in 2 out of the 3 cases, and it is detected about an order of magnitude faster than in comparable cases with James Webb Space Telescope. We show that there is a significant number of objects accessible for these classes of observations. These results will be used to prioritize the parameter range for the next steps with more detailed retrieval simulations. They will also inform timely questions in the early design phase of a mission like LIFE and guide the community by providing easy-to-scale first estimates for a large part of detection space of such a mission.
No universal devolatilization trend has been found for the solar system rocky bodies
Lin, Wen-Jou; Wang, Haiyang; Hunt, Alison; et al. (2022)
EPSC Abstracts
Rocky planets formed at different heliocentric distances from the Sun are thought to experience different and systematic devolatilization (i.e. depletion of volatile elements) with respect to the solar composition. The canonical empirical model of devolatilization is calibrated based on the bulk compositional difference between the Sun and Earth as a function of 50% condensation temperature of elements (TC). The quantification of the volatility trends for other solar system rocky bodies, with a goal of formulating a general devolatilization model, has been expected to be useful for estimating the bulk compositions of rocky exoplanets orbiting at different distances to the central star in a planetary system. To do so, we compiled an enormous set of literature data for the bulk compositions of a wide range of rocky bodies in our Solar System, including the terrestrial planets, asteroids, and chondritic bodies. Following the previous studies on quantifying Earth’s volatility trends, we adopted two relationship forms: one is in the log-log space (log (f) = α log (TC) + β, where f is the bulk compositional ratio of a rocky body relative to the Sun; α and β are the model coefficients); and the other is in the linear space (f = 1/(1+e-k(T-T0)), where T is the mid-plane temperature assuming the in-situ formation of these planetary bodies; and k and T0 are the model coefficients). Based on the best literature data that have been compiled, we did not find any statistically robust trend of devolatilization for these rocky bodies, except for Earth and Mars. If we arbitrarily increase the uncertainties of the coefficients of the poorly quantified volatility trends for Venus and Mercury by a factor of 3, the best possible general trend that we can quantify as a function of heliocentric distance (d) is α = (3.773 ± 0.202)/d3/4 and β = (-11.832 ± 0.613)/d3/4. However, Mercury is still statistically deviated (towards a larger slope and thus severer devolatilization) from the general trend. We find the similar behaviour if we adopt the alternative sigmoid function. This may imply a more violent thermal history that Mercury experienced during its formation, beyond what can be constrained with the assumptions of the in-situ formation and stellar-irradiation-relevant-only devolatilization. Furthermore, Vesta and ordinary and carbonaceous chondrites do not follow this nominal general trend, either. We therefore report here that no universal devolatilization trend has been found (empirically) for the solar system rocky bodies. This null result warrants the future efforts in advancing this field on two fundamental aspects. One is to further improve the measurements of the compositions of the solar system objects through various missions. The other is to launch a comprehensive investigation of nebular condensation, disc evolution, hydrodynamic escape, accretionary dynamics, and impacts towards establishing a sophisticated planet formation model of both dynamics and chemistry.
The PLATO Mission
Rauer, Heike; Aerts, Conny; Cabrera, Juan; et al. (2024)
arXiv
PLATO (PLAnetary Transits and Oscillations of stars) is ESA's M3 mission designed to detect and characterise extrasolar planets and perform asteroseismic monitoring of a large number of stars. PLATO will detect small planets (down to <2 R_(Earth)) around bright stars (<11 mag), including terrestrial planets in the habitable zone of solar-like stars. With the complement of radial velocity observations from the ground, planets will be characterised for their radius, mass, and age with high accuracy (5 %, 10 %, 10 % for an Earth-Sun combination respectively). PLATO will provide us with a large-scale catalogue of well-characterised small planets up to intermediate orbital periods, relevant for a meaningful comparison to planet formation theories and to better understand planet evolution. It will make possible comparative exoplanetology to place our Solar System planets in a broader context. In parallel, PLATO will study (host) stars using asteroseismology, allowing us to determine the stellar properties with high accuracy, substantially enhancing our knowledge of stellar structure and evolution.
Towards characterising rocky worlds: Trends in chemical make-ups of M dwarfs versus GK dwarfs
Wang, Haiyang; Quanz, Sascha Patrick; Mahadevan, Suvrath; et al. (2024)
Astronomy & Astrophysics
Context: Elemental abundances of Sun-like stars have been shown to be crucial for understanding the detailed properties of planets surrounding them. However, accurately measuring elemental abundances of M stars, the most abundant class of stars in the solar neighbourhood, is challenging due to their faintness and pervasive molecular features in optical photospheric spectra. As a result, elemental abundances of Sun-like stars have been proposed to constrain those of M stars, particularly by scaling [X/H] given measured [Fe/H]. Aims: This work aims to test the robustness of this convenient practice based on two selected sets of M- and GK-dwarf stellar abundances and a set of rigorous statistical methods. Methods: We compiled the elemental abundances of a sample of up to 43 M dwarfs for ten major rock-forming elements (Fe, C, O, Mg, Si, Al, Ca, Na, Ni, and Ti) from high-resolution near-infrared stellar surveys including APOGEE, CARMENES, and Subaru. We carried out bootstrap-based linear regressions on the selected sample of M dwarfs to constrain the statistical trends of [X/H] versus [Fe/H] and then compare them with those of GK dwarfs (sampled from the GALAH database). We then applied a two-sample, multivariate Mahalanobis Distance test to assess the significance of the differences in the [X/H]-[Fe/H] trends for individual elemental pairs between M and GK dwarfs. Results: We find that the null hypothesis – that is, no significant difference in the chemical trends of [X/H] versus [Fe/H] between M and GK dwarfs – is strongly rejected for all elements except for Si, for which the rejection is marginal (p-value close to 0.05), and Na and Ni, for which the results are inconclusive. This finding suggests that assuming no difference may result in biased results, and thus inaccurate constraints on characterising rocky planets around M dwarfs by scaling the (unmeasured) chemical abundances of planet-hosting M dwarfs from the chemical trends of [X/H]–[Fe/H] determined by GK dwarfs. Conclusions: It is therefore crucial for both the stellar and exoplanet communities to be aware of these observed differences. To better understand these differences, we advocate for dedicated modelling techniques for M-dwarf atmospheres and an increasing set of benchmark, homogeneous abundance analyses. Intermediately, our statistically constrained trends of [X/H]–[Fe/H] for M dwarfs provide a new constraint on estimating M-dwarf elemental abundances given measured [Fe/H] and further on characterising the detailed properties of M-dwarf-hosted rocky worlds.
Nebular condensation of different stellar compositions and its influence on planetary chemistry
Wang, Haiyang; Sossi, Paolo A.; Quanz, Sascha Patrick (2020)
EPSC Abstracts
The volatility of an element is defined by its 50% condensation temperature (Tc50) from a canonical nebular gas of Solar composition at 10-4 bar [1, 2]. However, the variability in metallicity and metal/oxygen ratios of extrasolar systems inferred from the spectroscopic measurements of their parent stars [3, 4] implies that the identity, abundance and sequence of condensation may deviate from that of our solar system. As such, planets formed at similar heliocentric distances may be expected to have distinct compositions from those of the terrestrial planets in our solar system. Here we investigate the degree to which nebular composition influences the condensation process by taking nine sets of stellar compositions with variable metallicities that span the range from -0.4 to +0.4 dex and performing Gibbs free energy minimisation calculations with FactSage, including treatment of mineral solid-solutions, over the temperature range 1723 K to 473 K. We find that, although the general order of condensation is similar, absolute values of Tc50 are shifted to higher temperatures at higher dex, where Tc50(S), in particular, increases relative to those of other elements. Condensing nebulae with high metallicities (and also high metal/oxygen ratios) also exhibit the following features: (i) the appearance of reduced assemblages (e.g. CaS oldhamite, forsterite-rich olivine and graphite) in the condensates, (ii) increased fractions of oxygen (relative to its total abundance) locked in the silicate condensates, and (iii) lower fO2 in the gas phase. As a result, these characteristics will lead to significant differences in the chemistry of planetary building blocks, which are then accreted to form telluric planetary bodies. References[1] Lodders 2003. ApJ 591:1220-1247. [2] Wood, B. J., Smythe, D. J., & Harrison, T. 2019. Ame. Miner. 104:844-856.[3] Buder, S., Asplund, M., Duong, L. et al. 2018. MNRAS 478:4513:4552.[4] Delgado Mena, E., Moya, A., Adibekyan, V., et al. 2019. A&A 624:A78.
From Stars to Diverse Mantles, Melts, Crusts, and Atmospheres of Rocky Exoplanets
Guimond, Claire Marie; Wang, Haiyang; Seidler, Fabian; et al. (2024)
Reviews in Mineralogy and Geochemistry
Large Interferometer For Exoplanets (LIFE)
Cesario, Lorenzo; Lichtenberg, Tim; Alei, Eleonora; et al. (2024)
Astronomy & Astrophysics
Context: The increased brightness temperature of young rocky protoplanets during their magma ocean epoch makes them potentially amenable to atmospheric characterization at distances from the Solar System far greater than thermally equilibrated terrestrial exoplanets, offering observational opportunities for unique insights into the origin of secondary atmospheres and the near surface conditions of prebiotic environments. Aims: The Large Interferometer For Exoplanets (LIFE) mission will employ a space-based midinfrared nulling interferometer to directly measure the thermal emission of terrestrial exoplanets. In this work, we seek to assess the capabilities of various instrumental design choices of the LIFE mission concept for the detection of cooling protoplanets with transient high-temperature magma ocean atmospheres at the tail end of planetary accretion. In particular, we investigate the minimum integration times necessary to detect transient magma ocean exoplanets in young stellar associations in the Solar neighborhood. Methods: Using the LIFE mission instrument simulator (LIFEsim), we assessed how specific instrumental parameters and design choices, such as wavelength coverage, aperture diameter, and photon throughput, facilitate or disadvantage the detection of protoplan-ets. We focused on the observational sensitivities of distance to the observed planetary system, protoplanet brightness temperature (using a blackbody assumption), and orbital distance of the potential protoplanets around both G- and M-dwarf stars. Results: Our simulations suggest that LIFE will be able to detect (S/N ≥ 7) hot protoplanets in young stellar associations up to distances of 100 pc from the Solar System for reasonable integration times (up to a few hours). Detection of an Earth-sized protoplanet orbiting a Solar-sized host star at 1 AU requires less than 30 minutes of integration time. M-dwarfs generally need shorter integration times. The contribution from wavelength regions smaller than 6 µm is important for decreasing the detection threshold and discriminating emission temperatures. Conclusions: The LIFE mission is capable of detecting cooling terrestrial protoplanets within minutes to hours in several local young stellar associations hosting potential targets. The anticipated compositional range of magma ocean atmospheres motivates further architectural design studies to characterize the crucial transition from primary to secondary atmospheres.

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Haiyang Wang

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