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1. SMART: Speedy Measurement of Arabidopsis Rosette Traits

   https://doi.org/10.1002/ppj2.70061  

   Liu, Suxing; Harris, Allison E; Li, Jiamei; Goggin, Fiona L; Mendoza‐Cozatl, David G; Bucksch, Alexander (January 2026, The Plant Phenome Journal)

   Abstract Most computer vision‐ and machine learning‐based plant phenotyping systems compute traits such as shape and size rather than the color distribution of the plant surface, even though color can provide important insights into plant physiology. Therefore, we developedSpeedy Measurement of Arabidopsis Rosette Traits(SMART), an open‐source plant phenotyping pipeline that analyzes a red–green–blue (RGB) top‐view image captured by any imaging device to compute color traits as well as shape and size. SMART combines a pretrained U2‐Net machine learning model and a color clustering method to segment plants from their background and compute basic morphological traits. SMART showed a good average accuracy of 95% for morphological traits using a public benchmark dataset. Uniquely, SMART also analyzes the color of plant surfaces by calculating a normalized color difference index and comparing plant surface colors with reference colors in the L*a*b* color space, which are converted from the RGB color space. The color difference index also showed good correlation with independent measurements of the chlorophyll fluorescence parameterF_v/F_m(maximum quantum yield of photosystem II) (R² > 0.71), chlorophyll content (R² > 0.73), and leaf temperature (R² > 0.76) in our experimental conditions. Therefore, we show that SMART is not only an affordable, open‐source tool for calculating morphological traits such as shape and size but also it is also useful for exploring relationships between color traits and physiological traits. SMART represents a promising new approach to low‐cost, high‐throughput phenotyping, thus benefiting the entire plant science community. 

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2. Li Evolution among Stars of Low/Intermediate Mass: the Metal-deficient Open Cluster NGC 2204

   https://doi.org/10.3847/1538-3881/ad5a99  

   Anthony-Twarog, Barbara J; Deliyannis, Constantine P; Steinhauer, Aaron; Sun, Qinghui; Twarog, Bruce A (August 2024, The Astronomical Journal)

   Abstract We have analyzed high-dispersion spectra in the Li 6708 Å region for 167 stars within the anticenter cluster NGC 2204. From 105 probable members, abundance analysis of 45 evolved stars produces [Fe/H] = −0.40 ± 0.12, [Si/Fe] = 0.14 ± 0.12, [Ca/Fe] = 0.29 ± 0.07, and [Ni/Fe] = −0.12 ± 0.10, where quoted errors are standard deviations. WithE(B−V) = 0.07 and (m−M)₀= 13.12, appropriate isochrones provide an excellent match from the main sequence through the tip of the giant branch for an age of 1.85 ± 0.05 Gyr. Li spectrum synthesis producesA(Li) below 1.4 at the base of the red giant branch to a detectable value of −0.4 at the tip. Six probable asymptotic giant branch stars and all but one red clump star have only Li upper limits. A rapidly rotating red giant is identified as a possible Li-rich giant, assuming it is a red clump star. Main-sequence turnoff stars have a well-definedA(Li) = 2.83 ± 0.03 (sem) down to the Li-dip wall at the predicted mass of 1.29M_☉. Despite having the same isochronal age as the more metal-rich NGC 2506, the luminosity distribution of red giants reflects a younger morphology similar to NGC 7789, possibly indicating a deeper impact of metallicity on stellar structure andA(Li) than previously assumed. As in NGC 2506 and NGC 7789, the NGC 2204 turnoff exhibits a broad range of rotation speeds, making abundance estimation impossible for some stars. The place of the cluster within GalacticA(Li) evolution is discussed. 

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3. White Dwarf Binaries across the H-R Diagram

   https://doi.org/10.3847/1538-3881/ac8357  

   Anguiano, Borja; Majewski, Steven R.; Stassun, Keivan G.; Badenes, Carles; Daher, Christine Mazzola; Dixon, Don; Allende Prieto, Carlos; Schneider, Donald P.; Price-Whelan, Adrian M.; Beaton, Rachael L. (September 2022, The Astronomical Journal)

   Abstract We created the APOGEE-GALEX-Gaia catalog to study white dwarf (WD) binaries. This database aims to create a minimally biased sample of WD binary systems identified from a combination of GALEX, Gaia, and APOGEE data to increase the number of WD binaries with orbital parameters and chemical compositions. We identify 3414 sources as WD binary candidates, with nondegenerate companions of spectral types between F and M, including main-sequence stars, main-sequence binaries, subgiants, sub-subgiants, red giants, and red clump stars. Among our findings are (a) a total of 1806 systems having inferred WD radii R < 25 R ⊕ , which constitute a more reliable group of WD binary candidates within the main sample; (b) a difference in the metallicity distribution function between WD binary candidates and the control sample of most luminous giants ( M H < −3.0); (c) the existence of a population of sub-subgiants with WD companions; (d) evidence for shorter periods in binaries that contain WDs compared to those that do not, as shown by the cumulative distributions of APOGEE radial velocity shifts; (e) evidence for systemic orbital evolution in a sample of 252 WD binaries with orbital periods, based on differences in the period distribution between systems with red clump, main-sequence binary, and sub-subgiant companions and systems with main-sequence or red giant companions; and (f) evidence for chemical enrichment during common envelope (CE) evolution, shown by lower metallicities in wide WD binary candidates ( P > 100 days) compared to post-CE ( P < 100 days) WD binary candidates. 

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4. APOKASC-3: The Third Joint Spectroscopic and Asteroseismic Catalog for Evolved Stars in the Kepler Fields

   https://doi.org/10.3847/1538-4365/ad9fef  

   Pinsonneault, Marc H; Zinn, Joel C; Tayar, Jamie; Serenelli, Aldo; García, Rafael A; Mathur, Savita; Vrard, Mathieu; Elsworth, Yvonne P; Mosser, Benoit; Stello, Dennis; et al (February 2025, The Astrophysical Journal Supplement Series)

   Abstract In the third APOKASC catalog, we present data for the complete sample of 15,808 evolved stars with APOGEE spectroscopic parameters and Kepler asteroseismology. We used 10 independent asteroseismic analysis techniques and anchor our system on fundamental radii derived from GaiaLand spectroscopicT_eff. We provide evolutionary state, asteroseismic surface gravity, mass, radius, age, and the data used to derive them for 12,418 stars. This includes 10,036 exceptionally precise measurements, with median fractional uncertainties in ${\nu }_{\max }$, Δν, mass, radius, and age of 0.6%, 0.6%, 3.8%, 1.8%, and 11.1%, respectively. We provide more limited data for 1624 additional stars that either have lower-quality data or are outside of our primary calibration domain. Using lower red giant branch (RGB) stars, we find a median age for the chemical thick disk of 9.14 ± 0.05(ran) ± 0.9(sys) Gyr with an age dispersion of 1.1 Gyr, consistent with our error model. We calibrate our red clump (RC) mass loss to derive an age consistent with the lower RGB and provide asymptotic GB and RGB ages for luminous stars. We also find a sharp upper-age boundary in the chemical thin disk. We find that scaling relations are precise and accurate on the lower RGB and RC, but they become more model dependent for more luminous giants and break down at the tip of the RGB. We recommend the use of multiple methods, calibration to a fundamental scale, and the use of stellar models to interpret frequency spacings. 

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5. Extremely precise age and metallicity of the open cluster NGC 2506 using detached eclipsing binaries

   https://doi.org/10.1093/mnras/staa2855  

   Knudstrup, E; Grundahl, F; Brogaard, K; Slumstrup, D; Orosz, J A; Sandquist, E L; Jessen-Hansen, J; Lund, M N; Arentoft, T; Tronsgaard, R; et al (October 2020, Monthly Notices of the Royal Astronomical Society)

   null (Ed.)

   ABSTRACT Accurate stellar parameters of stars in open clusters can help constrain models of stellar structure and evolution. Here, we wish to determine the age and metallicity content of the open cluster NGC 2506. To this end, we investigated three detached eclipsing binaries (DEBs; V2032, V4, and V5) for which we determined their masses and radii, as well as four red giant branch stars for which we determined their effective temperatures, surface gravities, and metallicities. Three of the stars in the DEBs have masses close to the cluster turn-off mass, allowing for extremely precise age determination. Comparing the values for the masses and radii of the binaries to BaSTI (a Bag of Stellar Tracks and Isochrones) isochrones, we estimated a cluster age of 2.01 ± 0.10 Gyr. This does depend on the models used in the comparison, where we have found that the inclusion of convective core-overshooting is necessary to properly model the cluster. From red giant branch stars, we determined values for the effective temperatures, the surface gravities, and the metallicities. From these we find a cluster metallicity of −0.36 ± 0.10 dex. Using this value and the values for the effective temperatures, we determine the reddening to be E(b − y) = 0.057 ± 0.004 mag. Furthermore, we derived the distance to the cluster from Gaia parallaxes and found 3.101 ± 0.017 kpc, and we have performed a radial velocity membership determination for stars in the field of the cluster. Finally, we report on the detection of oscillation signals in γ Dor and δ Scuti members in data from the Transiting Exoplanet Survey Satellite (TESS) mission, including the possible detection of solar-like oscillations in two of the red giants. 

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