Thermal Emission Spectroscopy Research Articles

Evolution of BD-14 3065b (TOI-4987b) from giant planet to brown dwarf as possible evidence of deuterium burning at old stellar ages

The present study confirms BD-14\,3065b as a transiting planet-brown dwarf in a triple-star system, with a mass near the deuterium-burning boundary. BD-14\,3065b has the largest radius observed within the sample of giant planets and brown dwarfs around post-main sequence stars. Its orbital period is 4.3 days and it transits a subgiant F-type star with a mass of $M_ odot $, a radius of $R_ odot $, an effective temperature of $T_ eff and a metallicity of $-0.34 By combining TESS photometry with high-resolution spectra acquired with the TRES and Pucheros+ spectrographs, we measured a mass of $M_p=12.37 and a radius of $R_p=1.926 Our discussion of potential processes that could be responsible for the inflated radius led us to conclude that deuterium burning is a plausible explanation for the heating taking place in BD-14\,3065b's interior. Detections of the secondary eclipse with TESS photometry enabled a precise determination of the eccentricity, $e_p=0.066 and reveal that BD-14\,3065b has a brightness temperature of $3520 130$\,K. With its unique characteristics, BD-14\,3065b presents an excellent opportunity to study its atmosphere via thermal emission spectroscopy.

Spherical Harmonics for the 1D Radiative Transfer Equation. II. Thermal Emission

Approximate methods for radiative transfer equations that are fast, reliable, and accurate are essential for the understanding of atmospheres of exoplanets and brown dwarfs. The simplest and most popular choice is the “two-stream method,” which is often used to produce simple yet effective models for radiative transfer in scattering and absorbing media. Toon et al. (hereafter, Toon89) outlined a two-stream method for computing reflected light and thermal spectra that was later implemented in the open-source radiative transfer model PICASO. In Part I of this series, we developed an analytical spherical harmonics method for solving the radiative transfer equation for reflected solar radiation that was implemented in PICASO to increase the accuracy of the code by offering a higher-order approximation. This work is an extension of this spherical harmonics derivation, to study thermal emission spectroscopy. We highlight the model differences in the approach for thermal emission and benchmark the four-term method (SH4) against Toon89 and a high-stream discrete-ordinates method, CDISORT. By comparing the spectra produced by each model, we demonstrate that the SH4 method provides a significant increase in accuracy, compared to Toon89, which can be attributed to the increased order of approximation and to the choice of phase function. We also explore the trade-off between computational time and model accuracy. We find that our four-term method is twice as slow as our two-term method, but is up to five times more accurate, when compared with CDISORT. Therefore, SH4 provides excellent improvement in model accuracy with minimal sacrifice in numerical expense.

Wavelength-selective thermal emission metasurfaces based on synthetic dimensional topological Weyl points

Blackbody emission such as the emission from incandescent sources usually possesses a broadband emission spectrum covering the whole infrared wavelength range. Most of emission energy goes into the unwanted infrared range and consequently causes low emission efficiency. Recently, metasurfaces with two-dimensional subwavelength artificial nanostructures have been widely studied due to their flexibility in modulating optical properties, thus providing an ideal platform for controlling thermal emission. The use of synthetic dimension methods in metasurfaces has opened up new avenues for fine-tuning thermal emission, especially highlighting the physical properties beyond traditional three-dimensional systems and rich topological physics. Although it is theoretically possible to explore physical phenomena through complete three-dimensional structures, such structures are difficult to construct in practice. In contrast, studying one-dimensional system or two-dimensional system is more feasible and efficient. The synthetic dimension approach introduces the possibility of manipulating intrinsic degrees of freedom in photon systems by introducing structural or physical parameters. In this work, we propose utilizing synthetic dimension methods to achieve wavelength-selective thermal emission. Firstly, we construct synthetic Weyl point in a superlattice model and validate it theoretically. Subsequently, experimental characterization of synthetic Weyl cones is conducted by using angle-resolved thermal emission spectroscopy (ARTES). The experimental results demonstrate that we can achieve reasonable wavelength-selective thermal emission while suppressing emission at other wavelengths as much as possible. This is essential for practical infrared applications such as thermalphotovoltaics and thermal management devices.

Keck Planet Imager and Characterizer Emission Spectroscopy of WASP-33b

We present Keck Planet Imager and Characterizer (KPIC) high-resolution (R ∼35,000) K-band thermal emission spectroscopy of the ultrahot Jupiter WASP-33b. The use of KPIC’s single-mode fibers greatly improves both blaze and line-spread stabilities relative to slit spectrographs, enhancing the cross-correlation detection strength. We retrieve the dayside emission spectrum with a nested-sampling pipeline, which fits for orbital parameters, the atmospheric pressure–temperature profile, and the molecular abundances. We strongly detect the thermally inverted dayside and measure mass-mixing ratios for CO (), H2O (), and OH (), suggesting near-complete dayside photodissociation of H2O. The retrieved abundances suggest a carbon- and possibly metal-enriched atmosphere, with a gas-phase C/O ratio of , consistent with the accretion of high-metallicity gas near the CO2 snow line and post-disk migration or with accretion between the soot and H2O snow lines. We also find tentative evidence for 12CO/13CO ∼ 50, consistent with values expected in protoplanetary disks, as well as tentative evidence for a metal-enriched atmosphere (2–15 × solar). These observations demonstrate KPIC’s ability to characterize close-in planets and the utility of KPIC’s improved instrumental stability for cross-correlation techniques.

Characteristics of the shortwave-thermal infrared spectra of the Zhuxi superlarge tungsten deposit in Jiangxi Province and their exploration significance

Infrared spectroscopy, as an innovative exploration tool, enables rapid identification of alteration minerals, thus can facilitate an improved understanding of mineralization and enhance prospecting efficiency. This paper specifically applies this methodology to drill core samples from the Zhuxi Deposit, Jiangxi Province, the world's largest tungsten deposit. Using shortwave and thermal infrared spectroscopy, this study aims to identify spectral characteristics of typical altered minerals within the deposit, establish the mineral identification methods and preferred spectrum bands, and discern spectral characteristics of varied altered mineral combinations. The variations observed in the characteristic bands of these isomorphic minerals serve as indicators of changes in the ore-forming environment. Specifically, absorption features around 2190 nm are indicative of paragonite formation in low-temperature environments, while features around 2210–2225 nm signify the presence of phengite in high-pressure, high-temperature conditions. Absorption at 2260 nm is characteristic of Fe-rich chlorite, suggesting a low-temperature, reducing environment, whereas Mg-rich chlorite exhibits absorption at 2250 nm, indicative of a higher-temperature environment. Based on depth, the deposit can be classified into three types of alteration mineralization: greisen, garnet skarn, and diopside skarn. Shortwave infrared spectroscopy proves effective for identifying muscovite in greisen and altered minerals such as serpentine and chlorite in diopside skarn. Thermal infrared spectroscopy, on the other hand, is ideal for quartz identification in greisen and garnet in garnet skarn. Intriguingly, the study finds that the absorption characteristics of garnet can reflect the metal mineralization type of the deposit. The absorption valley wavelength of garnet varies from around 11290–11380 nm in non-mineralized or poorly mineralized samples, to 11230–11290 nm when scheelite mineralization dominates, and to 11180–11230 nm when both scheelite and chalcopyrite are present. These findings contribute significantly to our understanding of the mineralogical characteristics and genetic environment of the Zhuxi deposit. Moreover, they provide valuable insights into the potential application of infrared spectroscopy for skarn zonation and mineral exploration.

Thermal infrared spectroscopy studies on skarn minerals for exploration of the Jiama Cu-Mo deposit, Tibet, China

The zonation patterns of skarn minerals, including garnet, diopside, and wollastonite, are important for exploration of skarn deposits. Thermal infrared (TIR) spectroscopy, which covers the wavelength range of 6–14 μm, is a new eco-friendly technology for skarn mineral identification. In this study, the TIR spectra data were collected, using an Agilent 4300 Handheld FTIR Spectrometer from nine drill holes within Jiama Cu-Mo deposit in Tibet, China. This study focuses on the TIR characteristics of grandite-series garnets (i.e., grossular to andradite), which have twin peaks in the 10–13 μm range and a diagnostic absorption valley (T absorption valley) at around 11.5 μm shifting based on the contents of Al2O3 and Fe2O3. The T absorption valley in the zoned garnet sample showed an undulating pattern, shifting towards longer wavelengths from the core to the rim, indicating the increase in Fe2O3 content and a decrease in Al2O3, MnO, and TiO2 content. The mixed spectral features of three significant skarn minerals including garnet, diopside, and wollastonite were used to classify the skarn zonation into garnet skarns, diopside-garnet skarns, and wollastonite-garnet skarns. The results from nine drill holes of the No. 24 exploration line in the cross section showed that the garnet T absorption valley shifted towards shorter wavelengths from the proximal to the distal skarn, as well as from the lower to the upper skarn. Furthermore, intensive copper mineralization occurred in the skarn when the garnet T absorption valley exceeded 11.50 μm. In comparison, the garnet T absorption valley at 11.35–11.50 μm is related to more intense molybdenum mineralization. This study suggests that TIR spectroscopy has the potential to rapidly identify skarn zonation in the field, and providing a suitable vector tool for skarn ore exploration.

Experimental and analytical methods for thermal infrared spectroscopy of complex dust coatings in a simulated asteroid environment

Abstract Airless bodies in the Solar system are commonly dominated by complex regolith mixtures consisting of coarse and fine particulates. These materials often manifest as coatings with the potential to modify or obscure the spectral signatures of underlying substrates. This can make accurate spectral analysis of surface materials challenging, especially for thermal infrared (TIR) techniques of which the spectral properties concurrently depend on grain size and albedo. Further complexity is presented when these coatings occur as discontinuous patterns in which some substrate is exposed and some is masked. Discontinuous patterns are distinguished by scale as having macroscopic or microscopic discontinuity, with the former being patches of homogeneous dust covering portions of the substrate and the latter being randomly distributed individual particles on the substrate. Investigations of asteroid (101955) Bennu’s surface by NASA’s Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer have revealed contradictions between spectral and thermophysical results that are hypothesized to indicate the presence of thin and/or laterally discontinuous dust coatings. To address this, we constructed an environment chamber that enables the controlled deposition of size-regulated dust particles in coatings with varying continuity and thickness. TIR spectra of coated substrates acquired in a simulated asteroid environment are used to investigate the extent to which dust coatings of different thicknesses and arrangements contribute to orbital spectral signatures of airless body surfaces.

Rapid Analysis of Composition of Coal Gangue Based on Deep Learning and Thermal Infrared Spectroscopy

Coal gangue is the main solid waste in coal mining areas, and its annual emissions account for about 10% of coal production. The composition information of coal gangue is the basis of reasonable utilization of coal gangue, and according to the composition information of coal gangue, one can choose the appropriate application scene. The reasonable utilization of coal gangue can not only effectively alleviate the environmental problems in mining areas but also produce significant economic and social benefits. Chemical analysis techniques are the principal ones used in traditional coal gangue analysis; however, they are slow and expensive. Many researchers have used machine learning techniques to analyze the spectral data of coal gangue, primarily random forests (RFs), extreme learning machines (ELMs), and two-hidden-layer extreme learning machines (TELMs). However, these techniques are heavily reliant on the preprocessing of the spectral data. This research suggests a quick analysis approach for coal gangue based on thermal infrared spectroscopy and deep learning in light of the drawbacks of the aforementioned methodologies. The proposed deep learning model is named SR-TELM, which extracts spectral features using a convolutional neural network (CNN) consisting of a spatial attention mechanism and residual connections and implements content prediction with TELM as a regressor, which can effectively overcome the dependence on preprocessing. The usefulness and speed of SR-TELM in coal gangue analysis were demonstrated by comparing several models in order to verify the proposed coal gangue analysis model. The experimental findings show that, for the prediction tasks of moisture, ash, volatile matter, and fixed carbon content, respectively, the SR-TELM model attained an R2 of 0.947, 0.972, 0.967, and 0.981 and an RMSE of 0.274, 4.040, 1.567, and 2.557 with a test time of just 0.03 s. It offers a method for the analysis of coal gangue that is low cost, highly effective, and highly reliable.

Optical Sensing by Metamaterials and Metasurfaces: From Physics to Biomolecule Detection

AbstractMetasurfaces are planar or 2D forms of metamaterials made up of arrays of antennas with a subwavelength thickness. They have been rapidly developed in the recent years due to their ability to manipulate light–matter interaction in both linear and non‐linear regimes at the nanoscale. Various metasurfaces display remarkable optical features, such as acute resonance, significant near‐field enhancement, and suitable capacity to support electric and magnetic modes, on account of the strong light–matter interaction and the low optical loss. Due to these important properties, they can be used in several advanced optoelectronic applications, like surface‐enhanced spectroscopy, photocatalysis, and sensing. This review reports on the recent progress of metamaterials and metasurfaces in molecular optical sensors. The principles that govern plasmonic and dielectric metasurfaces along with their features are outlined, supported by numerous examples. Then, the factors that result in a high Q‐factor are presented in order to show that metamaterials and metasurfaces can be used for label‐free sensing in a variety of detection mechanisms, including surface‐enhanced spectroscopy, refractometric sensing, and surface‐enhanced thermal emission spectroscopy via infrared absorption and Raman scattering, as well as chiral sensing. Finally, the challenges for future development are outlined.

Thermal-Infrared Spectral Feature Analysis and Spectral Identification of Monzonite Using Feature-Oriented Principal Component Analysis

Rock spectral analysis is an important research field in hyperspectral remote sensing information processing. Compared with the spectra in the short-wave infrared and visible–near-infrared regions, the emittance spectrum of rocks in the thermal infrared (TIR) region is highly significant for identifying some major rock-forming minerals, including feldspar, biotite, pyroxene and hornblende. Even for the same rock type, slight differences in mineral composition generally result in varying spectral signatures, undoubtedly increasing the difficulty in discriminating rock types on the Earth’s surface via TIR spectroscopy. In this study, amounts of monzonite samples from different regions were collected in the central part of Hunan Province, China, and emission spectra at 8–14 μm were measured using a portable thermal infrared spectrometer. The experimental result illustrates 13 remarkable feature positions for all the monzonite samples from different geological environments. Furthermore, by combining the extracted features with the principal component analysis (PCA) method, feature-oriented PCA was applied to establish a model for identifying monzonite accurately and quickly without performing spectral library matching and spectral deconvolution. This study provides an important method for rock type identification in the TIR region that is helpful for the rock spectral analysis, geological mapping and pixel unmixing of remote sensing images.

Iron Ore Tailing Composition Estimation Using Fused Visible–Near Infrared and Thermal Infrared Spectra by Outer Product Analysis

Iron ore tailings are mainly composed of SiO2 and iron, whose content determines the potential reuse strategy of the tailings. Compared with the traditional wet chemistry approach, spectroscopy has proven its superior effectiveness in characterizing and predicting minerals, such as iron oxides, clay, and SiO2. This study aims to estimate the content of SiO2 and TFe in iron ore tailings based on visible–near infrared (VIS–NIR, 350–2500 nm) and thermal infrared (TIR, 8–14 μm) spectroscopy. The outer product analysis (OPA) method is used to combine VIS–NIR and TIR spectral domains, from which an outer product matrix of fusion data can be generated. The study area is the iron ore tailing dam from Waitoushan, which is one of the super-large iron deposits in the Anshan–Benxi iron cluster of northeastern China. The spectral analysis results demonstrated the following: (1) The reflectance feature at 1163–2499 nm in the VIS–NIR range correlates with TFe and the emissivity feature at 8–9.4 and 10.7–12 μm in the TIR range correlates with SiO2. (2) Compared with the original absorbance spectra, the correlation coefficients of fusion spectra improve from 0.66 to 0.87 for TFe and from 0.64 to 0.84 for SiO2. (3) The partial least squares regression, random forest (RF), and extreme learning machine exploiting particle swarm optimization modeling methods are established for SiO2 and TFe estimation. The prediction accuracy results indicate that the prediction model with OPA-fused spectra performs significantly better than with individual VIS–NIR and TIR spectra. The RF model with input-fused spectra provides the highest accuracy with the coefficients of determination of 0.95 and 0.91, root mean square errors of 0.97% and 0.96%, and ratios of performance to interquartile distance of 6.49 and 2.31 for SiO2 and TFe content estimation, respectively. These outcomes provide a theoretical basis and technical support for tailing composition estimation using spectroscopy.

Detection of iron emission lines and a temperature inversion on the dayside of the ultra-hot Jupiter KELT-20b

Ultra-hot Jupiters (UHJs) are gas giants with very high equilibrium temperatures. In recent years, multiple chemical species, including various atoms and ions, have been discovered in their atmospheres. Most of these observations have been performed with transmission spectroscopy, although UHJs are also ideal targets for emission spectroscopy due to their strong thermal radiation. We present high-resolution thermal emission spectroscopy of the transiting UHJ KELT-20b/MASCARA-2b. The observation was performed with the CARMENES spectrograph at orbital phases before and after the secondary eclipse. We detected atomic Fe using the cross-correlation technique. The detected Fe lines are in emission, which unambiguously indicates a temperature inversion on the dayside hemisphere. We furthermore retrieved the temperature structure with the detected Fe lines. The result shows that the atmosphere has a strong temperature inversion with a temperature of 4900 ± 700 K and a pressure of 10−4.8−1.1+1.0 bar at the upper layer of the inversion. A joint retrieval of the CARMENES data and the TESS secondary eclipse data returns a temperature of 2550−250+150 K and a pressure of 10−1.5−0.6+0.7 bar at the lower layer of the temperature inversion. The detection of such a strong temperature inversion is consistent with theoretical simulations that predict an inversion layer on the dayside of UHJs. The joint retrieval of the CARMENES and TESS data demonstrates the power of combing high-resolution emission spectroscopy with secondary eclipse photometry in characterizing atmospheric temperature structures.

Spectral introductions of typical minerals during the periods of skarn formation and evolution at Zhuxi tungsten polymetallic deposit in Jiangxi Province

朱溪是近年来在江西塔前-赋春成矿带发现的一个世界级超大型钨铜矿床。本文采用短波红外+热红外光谱技术对矿区13个钻孔进行了光谱测量，结合岩石-矿物地球化学分析，探讨了朱溪矿床矽卡岩中典型蚀变矿物的形成与演化过程，厘定了矽卡岩形成不同阶段矿物组合的光谱特征，构建了朱溪矿床的短波红外+热红外光谱勘查模型。研究发现:（1）区内不同矿物组合形成了明显的蚀变分带，由内向外依次为绢云母（富Si）+长石（岩体顶层蚀变，多期流体叠加综合作用）→外矽卡岩:钙铝榴石+透辉石+（绢云母）→透辉石+蛇纹石+绿泥（帘）石+滑石→绢云母（富Al）+绿泥（帘）石（基底不整合面蚀变）；（2）Al-OH波长的移动可指示成矿流体压力、温度及pH值的变化；（3）研究区透辉石的形成、演化与矿体之间关系密切，虽然富矿体赋存于矽卡岩形成早期的透辉石-石榴子石蚀变带，但大量矿体则赋存于矽卡岩退蚀变阶段的蛇纹石-绿泥石蚀变带；（4）矿体的形成与流体的混合作用关系极大，伊利石光谱吸收特征能够指示外部冷水（大气降水或地下水）的灌入轨迹。;The Zhuxi tungsten polymetallic giant deposit is located in the Taqian- Fuchun metallogenic belt, Jiangxi Province. By measuring 13 drill cores with SWIR and TIR spectroscopy combined with geochemical analysis, we discussed the formation and evolution process of typical skarn minerals in the Zhuxi deposit, summarized their spectral characteristics, and constructed a spectral exploration model. It was found that:(1) different mineral assemblages form obvious alteration zones, i.e., sericite+feldspar (the top layer of the rock mass, caused by multistage fluid superposition probably) → grossular+diopside+(sericite) → diopside+serpentine+chlorite (epidote+talc) → sericite+chlorite (epidote) (alteration on the basement); (2) the shift of the Al-OH wavelength 2200nm can indicate the changes in pressure, temperature, and pH value of the ore-forming fluid; (3) diopside formation and evolution have a close relationship with ore bodies. Bonanza occurs in the grossular+diopside alteration zone, and a large number of ore bodies occur in the serpentine+chlorite alteration zone. It evidenced the importance of the fluid mixing and cooling for mineralization. The ore body emerged in the early stage of skarn formation, but the real enrichment stages occurred in the retrograde alteration stage; (4) the mixing fluid plays a key role in forming the deposit, and the illite spectrum can indicate the trace of the external cold water (atmospheric precipitation or groundwater).

Probing mid-infrared surface interface states based on thermal emission.

Probing mid-infrared surface wave radiation remains a big challenge for a long time. The lack of convenient and quick mid-infrared surface wave radiation probing methods limits the development of the integrated mid-infrared materials and devices. In this work, we propose a scheme to construct and probe the mid-infrared surface wave radiation of interface state in the waveguide through thermal emission. A superlattice composed of alternately placed periodic meta-crystals is designed to construct an array of interfaces to realize the interface states through the transverse electrical waveguide modes with a tolerance in structural parameters. By heating the structure, we employ angular resolved thermal emission spectroscopy to directly and quickly verify the dispersion of mid-infrared interface states, which have specific frequencies, angles, and polarizations. Moreover, we establish a thermal imaging microscopy to probe the local waveguide interface state directly for the first time. This proposed infrared probing method based on thermal emission can be generalized to probe the mid-infrared surface wave in other systems, such as surface plasmon waves in graphene or surface phonon waves in two-dimensional materials in the mid-infrared range.

Quantitative Thermal Emission Spectroscopy at High Temperatures: A Laboratory Approach for Measurement and Calibration

AbstractAcquiring accurate high temperature laboratory‐based infrared emission spectra of geologic samples is important to constrain their radiative and spectral properties. This is important in calculations of lava flow cooling, crust formation, and ultimately lava flow propagation modeling. However, measuring accurate emission at high temperatures remains a challenge. A new micro‐furnace design was created to integrate with a Fourier transform infrared spectrometer, replacing the previous furnace and improving the performance and error metrics. Importantly, this approach accounts for all significant error sources and uses only one spectrometer to acquire sample and calibration emission data over greater temperature (473–1,573 K) and spectral (4,000–500 cm−1, 2.5–20 μm) ranges. Emissivity spectra of forsterite and quartz samples were acquired to test the calibration procedure. Forsterite, with no expected phase transitions over the temperature range, showed spectral change above ∼1140 K, potentially due to amorphization–a process not well described in past studies. The quartz results revealed the expected polymorph transformations at ∼846 and ∼1323 K. A Hawaiian basalt sample served as a representative rock test and showed an increase in emissivity (∼25%) with decreasing temperature. The greatest emissivity increase (∼60%) occurred in the middle infrared region (3,333–2,000 cm−1, 3–5 μm). This is significant for thermal/mass flux calculations using satellite data in this spectral region, which rely on emissivity to derive accurate temperatures. All results are consistent with our previous investigations, but with improved mean accuracy (<2%), uncertainty (<4%), and spectral contrast (<20%). The improved metrics were achieved by constraining the sample measurement geometry, sample temperature stability, and environmental contamination within the experiment.

Evidence for limited compositional and particle size variation on asteroid (101955) Bennu from thermal infrared spectroscopy

Context.Asteroid (101955) Bennu is the target of NASA’s Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer (OSIRIS-REx) mission. The spacecraft’s instruments have characterized Bennu at global and local scales to select a sampling site and provide context for the sample that will be returned to Earth. These observations include thermal infrared spectral characterization by the OSIRIS-REx Thermal Emission Spectrometer (OTES).Aims.To understand the degree of compositional and particle size variation on Bennu, and thereby predict the nature of the returned sample, we studied OTES spectra, which are diagnostic of these properties.Methods.We created and mapped spectral indices and compared them with the distribution of geomorphic features. Comparison to laboratory spectra of aqueously altered carbonaceous chondrites constrains the amount of compositional variability that is observable.Results.The OTES spectra exhibit two end-member shapes (or types), and compositional variability appears limited at the spatial resolution of the observations. The global distribution of these spectral types corresponds with the locations of regions composed of (i) large, dark, relatively rough boulders and (ii) relatively smooth regions lacking large boulders.Conclusions.The two spectral types appear to be diagnostic primarily of particle size variations, with contributions from other properties. The spectra resemble experimental data of solid substrates with very thin accumulations (a few to tens of microns) of fine particles (<~65–100 μm). The dustier surfaces commonly correspond with rougher rocks that may produce and/or act as traps for the particles. Anhydrous silicates are limited in abundance, and the bulk mineralogy is consistent with the most aqueously altered carbonaceous chondrites. We expect the returned samples to include these physical and mineralogical characteristics.

An ultra-short-period transiting super-Earth orbiting the M3 dwarf TOI-1685

Dynamical histories of planetary systems, as well as the atmospheric evolution of highly irradiated planets, can be studied by characterizing the ultra-short-period planet population, which the TESS mission is particularly well suited to discover. Here, we report on the follow-up of a transit signal detected in the TESS sector 19 photometric time series of the M3.0 V star TOI-1685 (2MASS J04342248+4302148). We confirm the planetary nature of the transit signal, which has a period ofPb= 0.6691403−0.0000021+0.0000023d, using precise radial velocity measurements taken with the CARMENES spectrograph. From the joint photometry and radial velocity analysis, we estimate the following parameters for TOI-1685 b: a mass ofMb= 3.78−0.63+0.63M⊕, a radius ofRb= 1.70−0.07+0.07R⊕, which together result in a bulk density ofρb= 4.21−0.82+0.95g cm−3, and an equilibrium temperature ofTeq= 1069−16+16K. TOI-1685 b is the least dense ultra-short-period planet around an M dwarf known to date. TOI-1685 b is also one of the hottest transiting super-Earth planets with accurate dynamical mass measurements, which makes it a particularly attractive target for thermal emission spectroscopy. Additionally, we report with moderate evidence an additional non-transiting planet candidate in the system, TOI-1685 [c], which has an orbital period ofPc= 9.02−0.12+0.10d.

The Mars Orbiter for Resources, Ices, and Environments (MORIE) Science Goals and Instrument Trades in Radar, Imaging, and Spectroscopy

Abstract The Mars Orbiter for Resources, Ices, and Environments (MORIE) was selected as one of NASA’s 2019 Planetary Mission Concept Studies. The mission builds upon recent discoveries and current knowledge gaps linked to two primary scientific questions: (1) when did elements of the cryosphere form and how are ice deposits linked to current, recent, and ancient climate, and (2) how does the crust record the evolution of surface environments and their transition through time? Addressing these questions has emerged in numerous recent reports as a high priority in investigating the evolution of Mars as a habitable world. A subsidiary goal of the mission concept is to provide information relevant to the eventual human exploration of Mars, specifically helping to locate and quantify near-surface water ice and hydrated mineral resources. The proposed instrument suite includes polarimetric synthetic aperture radar imaging, radar sounding, high-resolution visible and infrared imaging, both short-wave and thermal-infrared spectroscopy, and multichannel wide-angle imaging. MORIE would provide novel measurements of Mars expected to lead to significant new discoveries by the first radar imaging from orbit, radar sounding directly over the poles, and mineral mapping at spatial scales that will unravel geologic sequence stratigraphy through time. The final report of the mission concept provides details on the spacecraft, orbital design, technological maturity, results from systems-level integration studies, and costs. This article is intended to expand upon the science motivation for the mission, the measurement goals and objectives, and the instrument trade space that was examined in detail during the concept study.

Fluorellestadite from burned coal dumps: crystal structure refinement, vibrational spectroscopy data and thermal behavior

Nine different samples of fluorellestadite from Chelyabinsk, Kizel and Kuznetsk coal basins were studied by single-crystal X-ray diffraction analysis, thermal X-ray diffraction (25–800 °C), Infrared (IR) and Raman spectroscopy. Fluorellestadite is hexagonal, space group P63/m, the unit-cell parameters for the nine samples studied vary within rather small ranges: a = 9.415(5) – 9.4808(7) A, c = 6.906(2) – 6.938(8) A, V = 530.3(4) – 538.41(9) A3. The mineral is isotypic with apatite, the structure is based upon isolated TO4 tetrahedra, where the T position is statistically occupied by Si4+ and S6+ with the ideal ratio Si:S equal to 1:1. The fluorine atoms are located in channels of the Ca4[(S,Si)O4]6 framework oriented parallel to the c axis. The thermal expansion of fluorellestadite is almost isotropic in the temperature range 25–800 °C (for ambient temperature: αa = 12.0·10−6 °C−1, αc = 11.9·10−6 °C−1; for 800 °C: αa = 18.2·10−6 °C−1, αc = 18.6·10−6 °C−1). A similar thermal behavior had been observed for fluorapatite. Despite the same structure motifs and close conditions of formation, the samples of fluorellestadite show different S/Si/P occupancies for T site and the F/Cl/OH (X-position) ratios.

Compositional Mapping of the Nili Patera Feldspathic Unit: Extent and Implications for Formation

AbstractDecades of study of the igneous martian crust concluded that it was primarily basaltic, but a range of new investigations find evidence of evolved compositions. Foremost of these is a highly feldspathic unit within the Nili Patera caldera of Syrtis Major, the only detection with preserved volcanic context but which nonetheless remains ambiguous in exact composition and formation. We conduct compositional mapping of this feldspathic unit via near‐infrared spectroscopy from the Compact Reconnaissance Imaging Spectrometer for Mars instrument and find that the unit occupies at minimum 104 km2 at high confidence and an additional 41 km2 at moderately high confidence, meaning the unit is locally significant. We compare our mapping with that inferred from geomorphology and find that while texture and albedo are useful proxies, they are not perfectly reliable as substitutes for thorough compositional investigation. Study of the boundary between the feldspathic unit and surrounding mafic rock indicates the former formed early and may extend locally in the subsurface. We consider what compositional mixtures could explain the conflicting interpretations derived from visible/near‐infrared and thermal infrared spectroscopy, concluding it is likely due to thermophysical differences between the light‐toned feldspathic unit and the infilling dark mafic sand. We discuss proposed plutonic and volcanic formation scenarios for the feldspathic unit, considering Earth analogs and implications for the parent magmatic system, and offer observations in rock texture and composition that would clarify.