We assess the prospects for exoplanet transit observations in the 10-year Wide Fast Deep (WFD) and Deep Drilling Field (DDF) surveys within the Legacy Survey of Space and Time (LSST) mission of the Vera C. Rubin Observatory. We construct a framework for systematic assessment of expected exoplanet yields, highlighting the principal limitations imposed by the survey observing strategy and cadence. We simulate light curves with a wide range of exoplanetary system models derived from planet occurrence rates developed with data from the Kepler mission. Transit counts for the stellar population are calculated using the TRILEGAL Galactic structure model, incorporating telescope sensitivity and survey cadences. We apply the constraints that the full duration of at least three transits must be observed and that the signal-to-noise ratio will support detectability. The observations were then validated using the Transit Least Squares periodogram. Our findings indicate a limited potential for exoplanet confirmations under the current survey design. Only a small number of hot planets orbiting faint M class main sequence stars will be confirmed in the DDF fields. The WFD survey is projected to produce no confirmations. These findings underscore the constraints imposed by the sparse, multi-band observing strategy, which prioritizes cosmology and extragalactic science over the continuous photometric coverage required for confirmations.

Most young stars and therefore planetary systems form in high-mass star forming regions and are exposed to ultraviolet radiation, affecting the protoplanetary disk. These regions are located at large distances and only now with JWST become accessible to study the inner disks surrounding young stars. We present the eXtreme UV Environments (XUE) program, which provides the first detailed characterization of the physical and chemical properties of the inner disks around young intermediate-mass stars exposed to external irradiation from nearby massive stars. We present high signal to noise MIRI-MRS spectroscopy of 12 disks located in three sub-clusters of the high-mass star-forming region NGC 6357. Based on their mid-infrared spectral energy distribution, we classify the XUE sources into Group I and II based on the Meeus scheme. We analyze their molecular emission features, and compare their spectral indices and 10 μm silicate emission profiles to those of nearby Herbig and intermediate T Tauri disks. Despite being more massive, the XUE stars host disks with molecular richness comparable to isolated T Tauri systems. The 10 μm silicate features show lower F_11.3/F_9.8 ratios at a given F_peak, but current uncertainties prevent conclusions about their inner disk properties. Most disks display water emission from the inner disk, suggesting that even in these extreme environments rocky planets can form in the presence of water. The absence of strong line fluxes and other irradiation signatures suggests that the XUE disks have been truncated by external UV photons. However, this truncation does not appear to significantly impact the chemical richness of their inner regions. These findings indicate that even in extreme environments, IMTT disks can retain the ingredients necessary for rocky planet formation.

Context. Our knowledge of the initial conditions of terrestrial planet formation is mainly based on the study of protoplanetary disks around nearby isolated low-mass stars. However, most young stars and therefore planetary systems form in high-mass star-forming regions and are exposed to ultraviolet radiation, affecting the protoplanetary disk. These regions are located at large distances and only now with JWST has it become accessible to study the inner disks surrounding young stars. Aims. We present the eXtreme UV Environments (XUE) program, which provides the first detailed characterization of the physical and chemical properties of the inner disks around young intermediate-mass (1-4 M-circle dot) stars exposed to external irradiation from nearby massive stars. We present high-signal-to-noise MIRI-MRS spectroscopy of 12 disks located in three subclusters of the high-mass star-forming region NGC 6357 (d similar to 1690 pc). Methods. Based on their mid-infrared spectral energy distribution, we classified the XUE sources into Group I and II based on the Meeus scheme. We analyzed their molecular emission features, and compared their spectral indices and 10 mu m silicate emission profiles to the ones of nearby Herbig and intermediate T Tauri (IMTT) disks. Results. The XUE program provides the first detailed characterization of the rich molecular inventory in IMTT disks, including water, CO, CO2, HCN, and C2H2. In the XUE sample, the detected emission likely originates from within 10 au, although this inner disk origin may not be typical for all externally irradiated disks. Despite being more massive, the XUE stars host disks with a molecular richness comparable to isolated T Tauri systems. The spectral indices are also consistent with similar-mass stars in nearby regions. The 10 mu m silicate features in the XUE sample exhibit lower F-11.3/F-9.8 ratios at a given F-peak, suggesting that the disk surfaces may be dominated by smaller grains compared to nearby disks. However, uncertainties in extinction prevent us from drawing firm conclusions about their inner disk properties. The majority of disks display water emission from the inner disk, suggesting that even in these extreme environments rocky planets can form in the presence of water. Only one object shows PAH emission, contrasting with the higher PAH detection rates in IMTT surveys from lower-UV environments. Conclusions. The absence of strong line fluxes and other irradiation signatures suggests that the XUE disks have been truncated by external UV photons. However, this truncation does not appear to significantly impact the chemical richness of their inner regions. These findings indicate that even in extreme environments, IMTT disks can retain the ingredients necessary for rocky planet formation, comparable to the ones of lower-mass T Tauri disks in low-mass star-forming regions.

Unveiling the physical structure of protoplanetary disks is crucial for interpreting the diversity of the exoplanet population. Until recently, the census of the physical properties of protoplanetary disks probed by mid-infrared observations was limited to the solar neighborhood ( d ≲ 250 pc). However, nearby star-forming regions (SFRs) such as Taurus—where no O-type stars reside—are not representative of the environments where the majority of the planet formation occurs in the Galaxy. The James Webb Space Telescope (JWST) now enables observations of disks in distant high-mass SFRs, where strong external far-ultraviolet radiation is expected to impact those disks. Nevertheless, a detailed characterization of the population of externally irradiated disks is still lacking. We use the thermochemical code ProDiMo to model JWST/MIRI spectroscopy and archival visual/near-infrared photometry aiming to constrain the physical structure of the irradiated disk around the solar-mass star XUE 1 in NGC 6357 ( d ≈ 1690 pc). Our findings are as follows. (1) Mid-infrared dust emission features are explained by amorphous and crystalline silicates with compositions similar to nearby disks. (2) The molecular features detected with MIRI originate within the first ∼1 au, consistent with results from slab models. (3) Our model favors a disk truncated at 10 au with a gas-to-dust ratio of unity in the outskirts. (4) Comparing models of the same disk structure under different irradiation levels, we find that strong external irradiation raises gas temperature tenfold and boosts water abundance beyond 10 au by a factor of 100.

We explore the empirical power-law relationship between X-ray luminosity ( L X ) and total surface magnetic flux (Φ), established across solar magnetic elements, time- and disk-averaged emission from the Sun, older active stars, and pre-main-sequence (PMS) stars. Previous models of large PMS X-ray flares, lacking direct magnetic field measurements, showed discrepancies from this baseline law, which MHD simulations attribute to unusually strong magnetic fields during flares. To test this, we used nearly simultaneous Chandra X-ray and HET-HPF near-infrared observations of four young Orion stars, measuring surface magnetic fields during or just after powerful PMS X-ray flares. We also modeled these PMS X-ray flares, incorporating their measured magnetic field strengths. Our findings reveal magnetic field strengths at the stellar surface typical of nonflaring PMS stars, ruling out the need for abnormally strong fields during flares. Both PMS and solar flares deviate from the L X –Φ law, with PMS flares exhibiting a more pronounced deviation, primarily due to their much larger active regions on the surface and larger flaring loop volumes above the surface compared to their solar counterparts. These deviations likely stem from the fact that powerful flares are driven by magnetic reconnection, while baseline X-ray emission may involve less efficient mechanisms like Alfvén wave heating. Our results also indicate a preference for dipolar magnetic loops in PMS flares, consistent with Zeeman–Doppler imaging of fully convective stars. This requirement for giant dipolar loops aligns with MHD predictions of strong dipoles supported by polar magnetic surface active regions in fast-rotating, fully convective stars.

We investigate the James Webb Space Telescope (JWST) MIRI MRS gas molecular content of an externally irradiated Herbig disk, the F-type XUE 10 source, in the context of the eXtreme UV Environments (XUE) program. XUE 10 belongs to the massive star cluster NGC 6357 (1.69 kpc), where it is exposed to an external far-ultraviolet (FUV) radiation ≈ 10^3 times stronger than in the Solar neighborhood. We modeled the molecular features in the mid-infrared spectrum with Local Thermodynamic Equilibrium (LTE) 0D slab models. We derived basic parameters of the stellar host from a VLT FORS2 optical spectrum using PHOENIX stellar templates. We detect bright CO2 gas with the first simultaneous detection (> 5σ) of four isotopologues (12CO2, 13CO2, 16O12C18O, 16O12C17O) in a protoplanetary disk. We also detect faint CO emission (2σ) and the HI Pfα line (8σ). We also place strict upper limits on the water content, finding a total column density ≲ 10^18 cm^-2. The CO2 species trace low gas temperatures (300-370 K) with a range of column densities of 7.4 × 10^17 cm^-2 (16O12C17O)-1.3 × 10^20 cm^-2 (12CO2) in an equivalent emitting radius of 1.15 au. The emission of 13CO2 is likely affected by line optical depth effects. 16O12C18O and 16O12C17O abundances may be isotopically anomalous compared to the 16O/18O and 16O/17O ratios measured in the interstellar medium and the Solar System. We propose that the mid-infrared spectrum of XUE 10 is explained by H2O removal either via advection or strong photo-dissociation by stellar UV irradiation, and enhanced local CO2 gas-phase production. Outer disk truncation supports the observed CO2-H2O dichotomy. A CO2 vapor enrichment in 18O and 17O can be explained by means of external UV irradiation and early on (10^4-5 yr) delivery of isotopically anomalous water ice to the inner disk.

Aims. We investigate the James Webb Space Telescope (JWST) MIRI MRS gas molecular content of an externally irradiated Herbig disk, the F-type XUE 10 source, in the context of the eXtreme UV Environments (XUE) program. XUE 10 belongs to the massive star cluster NGC 6357 (1.69 kpc), where it is exposed to an external far-ultraviolet (FUV) radiation approximate to 10(3) times stronger than in the solar neighborhood. Methods. We modeled the molecular features in the mid-infrared spectrum with local thermodynamic equilibrium (LTE) 0D slab models. We derived basic parameters of the stellar host from a VLT FORS2 optical spectrum using PHOENIX stellar templates. Results. We detected bright CO2 gas with the first simultaneous detection (>5 sigma) of four isotopologues ((CO2)-C-12, (CO2)-C-13, (OCO)-O-16-C-12-O-18, (OCO)-O-16-C-12-O-17) in a protoplanetary disk. We also detected faint CO emission (2 sigma) and the HI Pf alpha line (8 sigma). We placed strict upper limits on the water content, finding a total column density of less than or similar to 10(18) cm(-2). The CO2 species trace low gas temperatures (300-370 K) with a range of column densities of 7.4 x 10(17) cm(-2) ((OCO)-O-16-C-12-O-17)-1.3 x 10(20) cm(-2) ((CO2)-C-12) in an equivalent emitting radius of 1.15 au. The emission of (CO2)-C-13 is likely affected by line optical depth effects. The (OCO)-O-16-C-12-O-18 and (OCO)-O-16-C-12-O-17 abundances may be isotopically anomalous compared to the O-16/O-18 and O-16/O-17 ratios measured in the interstellar medium and the Solar System. Conclusions. We propose that the mid-infrared spectrum of XUE 10 is explained by H2O removal either via advection or strong photo-dissociation by stellar UV irradiation and enhanced local CO2 gas phase production. Outer disk truncation supports the observed CO2-H2O dichotomy. A CO2 vapor enrichment in O-18 and O-17 can be explained by means of external UV irradiation and early (10(4-5) yr) delivery of isotopically anomalous water ice to the inner disk.

The most powerful stellar flares driven by magnetic energy occur during the early pre-main-sequence (PMS) phase. The Orion Nebula represents the nearest region populated by young stars, showing the greatest number of flares accessible to a single pointing of Chandra. This study is part of a multi-observatory project to explore stellar surface magnetic fields (with the Hobby-Eberly Telescope Habitable-zone Planet Finder, HET-HPF), particle ejections (with the Very Long Baseline Array, VLBA), and disk ionization (with the Atacama Large Millimeter/submillimeter Array, ALMA) immediately following the detection of PMS superflares with Chandra. In 2023 December, we successfully conducted such a multi-telescope campaign. Additionally, by analyzing Chandra data from 2003, 2012, and 2016, we examine the multi-epoch behavior of PMS X-ray emission related to PMS magnetic cyclic activity and ubiquitous versus sample-confined megaflaring. Our findings are as follows. (1) We report detailed stellar quiescent and flare X-ray properties for numerous HET/ALMA/VLBA targets, facilitating ongoing multiwavelength analyses. (2) For numerous moderately energetic flares, we report correlations (or lack thereof) between flare energies and stellar mass/size (presence/absence of disks) for the first time. The former is attributed to the correlation between convection-driven dynamo and stellar volume, while the latter suggests the operation of solar-type flare mechanisms in PMS stars. (3) We find that most PMS stars exhibit minor long-term baseline variations, indicating the absence of intrinsic magnetic dynamo cycles or observational mitigation of cycles by saturated PMS X-rays. (4) We conclude that X-ray megaflares are ubiquitous phenomena in PMS stars, which suggests that all protoplanetary disks and nascent planets are subject to violent high-energy emission and particle irradiation events.

The DIAmante TESS AutoRegressive Planet Search (DTARPS) project seeks to identify photometric transiting planets from 976,814 southern hemisphere stars observed in Year 1 of the TESS mission. This paper follows the methodology developed by Melton et al. (Paper I) using light curves extracted and pre-processed by the DIAmante project (Montalto et al. 2020). Paper I emerged with a list of 7,377 light curves with statistical properties characteristic of transiting planets but dominated by False Alarms and False Positives. Here a multistage vetting procedure is applied including: centroid motion and crowding metrics, False Alarm and False Positive reduction, photometric binary elimination, and ephemeris match removal. The vetting produces a catalog of 462 DTARPS Candidates across the southern ecliptic hemisphere and 310 objects in a spatially incomplete Galactic Plane list. Fifty-eight percent were not previously identified as transiting systems. Candidates are flagged for possible blending from nearby stars based on Zwicky Transient Facility data and for possible radial velocity variations based on Gaia satellite data. Orbital periods and planetary radii are refined using astrophysical modeling; the resulting parameters closely match published values for Confirmed Planets. Their properties are discussed in Paper III.

The DIAmante Transiting Exoplanet Sky Survey (TESS) AutoRegressive Planet Search (DTARPS) project, using novel statistical methods, has identified several hundred candidates for transiting planetary systems obtained from 0.9 million full-frame Image light curves obtained in the TESS Year 1 southern-hemisphere survey. Ten lines of evidence including limited reconnaissance spectroscopy indicate that approximately half are true planets rather than false positives. Here various population properties of these candidates are examined. Half of the DTARPS-S candidates are hot Neptunes, populating the “Neptune desert” found in Kepler-planet samples. The DTARPS-S samples also identify dozens of ultrashort-period planets with orbital periods down to 5 hr, high-priority systems for atmospheric transmission spectroscopy, and planets orbiting low-mass M stars. DTARPS-S methodology is sufficiently well characterized at each step so that preliminary planet occurrence rates can be estimated. Except for the increase in hot Neptunes, DTARPS-S planet occurrence rates are consistent with Kepler rates. Overall, DTARPS-S provides one of the most reliable and useful catalogs of TESS exoplanet candidates that can be used to to improve our understanding of various exoplanetary populations and astrophysical processes.

Nearly one million light curves from the TESS Year 1 southern hemisphere extracted from Full Frame Images with the DIAmante pipeline are processed through the AutoRegressive Planet Search statistical procedure. ARIMA models remove trends and lingering autocorrelated noise, the Transit Comb Filter identifies the strongest periodic signal in the light curve, and a Random Forest machine learning classifier is trained and applied to identify the best potential candidates. Classifier training sets include injections of both planetary transit signals and contaminating eclipsing binaries. The optimized classifier has a True Positive Rate of 92.8% and a False Positive Rate of 0.37% from the labeled training set. The result of this DIAmante TESS autoregressive planet search (DTARPS) analysis is a list of 7,377 potential exoplanet candidates. The classifier has a False Positive Rate of 0.3%, a 64% recall rate for previously confirmed exoplanets, and a 78% negative recall rate for known False Positives. The completeness map of the injected planetary signals shows high recall rates for planets with 8 - 30 R(Earth) radii and periods 0.6-13 days and poor completeness for planets with radii < 2 R(Earth) or periods < 1 day. The list has many False Alarms and False Positives that need to be culled with multifaceted vetting operations (Paper II).

The sensitivities of two periodograms are compared for weak signal planet detection in transit surveys: the widely used Box Least Squares (BLS) algorithm following light curve detrending and the Transit Comb Filter (TCF) algorithm following autoregressive ARIMA modeling. Small depth transits are injected into light curves with different simulated noise characteristics. Two measures of spectral peak significance are examined: the periodogram signal-to-noise ratio (S/N) and a false alarm probability (FAP) based on the generalized extreme value distribution. The relative performance of the BLS and TCF algorithms for small planet detection is examined for a range of light curve characteristics, including orbital period, transit duration, depth, number of transits, and type of noise. We find that the TCF periodogram applied to ARIMA fit residuals with the S/N detection metric is preferred when short-memory autocorrelation is present in the detrended light curve and even when the light curve noise had white Gaussian noise. BLS is more sensitive to small planets only under limited circumstances with the FAP metric. BLS periodogram characteristics are inferior when autocorrelated noise is present due to heteroscedastic noise and false period detection. Application of these methods to TESS light curves with known small exoplanets confirms our simulation results. The study ends with a decision tree that advises transit survey scientists on procedures to detect small planets most efficiently. The use of ARIMA detrending and TCF periodograms can significantly improve the sensitivity of any transit survey with regularly spaced cadence.

We present the first results of the eXtreme UV Environments (XUE) James Webb Space Telescope (JWST) program, that focuses on the characterization of planet forming disks in massive star forming regions. These regions are likely representative of the environment in which most planetary systems formed. Understanding the impact of environment on planet formation is critical in order to gain insights into the diversity of the observed exoplanet populations. XUE targets 15 disks in three areas of NGC 6357, which hosts numerous massive OB stars, among which some of the most massive stars in our Galaxy. Thanks to JWST we can, for the first time, study the effect of external irradiation on the inner (< 10 au), terrestrial-planet forming regions of proto-planetary disks. In this study, we report on the detection of abundant water, CO, CO_2, HCN and C_2H_2 in the inner few au of XUE 1, a highly irradiated disk in NGC 6357. In addition, small, partially crystalline silicate dust is present at the disk surface. The derived column densities, the oxygen-dominated gas-phase chemistry, and the presence of silicate dust are surprisingly similar to those found in inner disks located in nearby, relatively isolated low-mass star-forming regions. Our findings imply that the inner regions of highly irradiated disks can retain similar physical and chemical conditions as disks in low-mass star-forming regions, thus broadening the range of environments with similar conditions for inner disk rocky planet formation to the most extreme star-forming regions in our Galaxy.

Stars exhibit a bewildering variety of rapidly variable behaviors ranging from explosive magnetic flares to stochastically changing accretion to periodic pulsations or rotation. The principal Rubin Observatory Legacy Survey of Space and Time (LSST) surveys will have cadences too sparse and irregular to capture many of these phenomena. We propose here an LSST microsurvey to observe a single Galactic field, rich in unobscured stars, in a continuous sequence of 30 s exposures for one long winter night in a single photometric band. The result will be a unique data set of ∼1 million regularly spaced stellar light curves. The light curves will constitute a comprehensive collection of late-type stellar flaring, but also other classes like short-period binary systems and cataclysmic variables, young stellar objects, and ultrashort-period exoplanets. An unknown variety of anomalous solar system, Galactic, and extragalactic variables and transients may also be present. A powerful array of statistical procedures can be applied to individual light curves from the long-standing fields of time series analysis, signal processing, and econometrics. Dozens of “features” describing the variability can be extracted and the ensemble of light curves can be subject to advanced machine-learning clustering procedures. This will give a unique, authoritative, objective taxonomy of the rapidly variable sky derived from identically cadenced light curves. This microsurvey is best performed early in the Rubin Observatory program, and the results can inform the wider community on the best approaches to variable star identification and classification from the sparse, irregular cadences that dominate the planned surveys.

We study the four-dimensional relationships between magnetic activity, rotation, mass and age for solar-type stars in the age range 5-25Myr. This is the late-pre-main sequence (l-PMS) evolutionary phase when rapid changes in star's interior may lead to the changes in magnetic dynamo mechanisms. We carefully derive rotational periods and spot sizes for 471 members of several l-PMS open clusters using photometric light curves from the Zwicky Transient Facility. Magnetic activity was measured in our previous Chandra-based study, and additional rotational data were obtained from other work. Several results emerge. Mass-dependent evolution of rotation through the l-PMS phase agrees with astrophysical models of stellar angular momentum changes, although the data point to a subpopulation of stars with slower initial rotations than commonly assumed. There is a hint of the onset of unsaturated tachoclinal dependency of X-ray activity on rotation, as reported by Argiroffi et al. (2016), but this result is not confidently confirmed. Both X-ray luminosity and star spot area decrease approximately as t^{-1} for solar mass stars suggesting that spot magnetic fields are roughly constant and l-PMS stars follow the universal solar-scaling law between the X-ray luminosity and surface magnetic flux. Assuming convective dynamos are dominant, theoretical magnetic fluxes fail to reveal the universal law for l-PMS stars that enter late Henyey tracks. Altogether we emerge with a few lines of evidence suggesting that the transition from the turbulent to solar-type dynamo occurs at the later stages of l-PMS evolution as stars approach the Zero-Age Main Sequence.

We review the iid2022 workshop on statistical methods for X-ray and γ -ray astronomy and high–energy astrophysics event data in astronomy, held in Guntersville, AL, on Nov. 15–18 2022. New methods for faint source detection, spatial point processes, variability and spectral analysis, and machine learning are discussed. Ideas for future developments of advanced methodology are shared.

The DIAmante TESS AutoRegressive Planet Search (DTARPS) project, using novel statistical methods, has identified several hundred candidates for transiting planetary systems obtained from 0.9 million Full Frame Image light curves obtained in the TESS Year 1 southern hemisphere survey (Melton et al. 2022a and 2022b). Several lines of evidence, including limited reconnaissance spectroscopy, indicate that at least half are true planets rather than False Positives. Here various population properties of these objects are examined. Half of the DTARPS candidates are hot Neptunes, populating the 'Neptune desert' found in Kepler planet samples. The DTARPS samples also identify dozens of Ultra Short Period planets with orbital periods down to 5 hours, high priority systems for atmospheric transimssion spectroscopy, and planets orbiting low-mass M stars. DTARPS methodology is sufficiently well-characterized at each step that preliminary planet occurrence rates can be estimated. Except for the increase in hot Neptunes, DTARPS planet occurrence rates are consistent with Kepler rates. Overall, DTARPS provides one of the largest and most reliable catalog of TESS exoplanet candidates that can be tapped to improve our understanding of various exoplanetary populations and astrophysical processes.

Measuring the evolution of X-ray emission from pre-main-sequence (PMS) stars gives insight into two issues: the response of magnetic dynamo processes to changes in the interior structure, and the effects of high-energy radiation on protoplanetary disks and primordial planetary atmospheres. We present a sample of 6003 stars with ages 7–25 Myr in 10 nearby open clusters from Chandra X-ray and Gaia-EDR3 surveys. Combined with previous results in large samples of younger (≲5 Myr) stars in MYStIX and SFiNCs star-forming regions, mass-stratified activity-age relations are derived for the early phases of stellar evolution. X-ray luminosity ( L X ) is constant during the first few Myr, possibly due to the presence of extended X-ray coronas insensitive to temporal changes in stellar size. L X then decays during the 7–25 Myr period, more rapidly as stellar mass increases. This decay is interpreted as decreasing efficiency of the α 2 dynamo as radiative cores grow and a solar-type α Ω dynamo emerges. For more massive 3.5–7 M ⊙ fully radiative stars, the X-ray emission plummets—indicating the lack of an effective magnetic dynamo. The findings provide improved measurements of high-energy radiation effects on circumstellar material, first for the protoplanetary disk and then for the atmospheres of young planets. The observed X-ray luminosities can be so high that an inner Earth-mass rocky, unmagnetized planet around a solar-mass PMS star might lose its primary and secondary atmospheres within a few (several) million years. PMS X-ray emission may thus have a significant impact on the evolution of early-planetary atmospheres and the conditions promoting the rise of habitability.

Dark matter simulations require statistical techniques to properly identify and classify their halos and structures. Nonparametric solutions provide catalogs of these structures but lack the additional learning of a model-based algorithm and might misclassify particles in merging situations. With mixture models, we can simultaneously fit multiple density profiles to the halos that are found in a dark matter simulation. In this work, we use the Einasto profile to model the halos found in a sample of the Bolshoi simulation, and we obtain their location, size, shape, and mass. Our code is implemented in the R statistical software environment and can be accessed on https://github.com/LluisHGil/darkmix.