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Astrometric view of companions in the inner dust cavities of protoplanetary discs
No full textContext. Protoplanetary discs with inner dust cavities (often referred to as ‘transition discs’) are potential signposts of planet formation. However, few companions have been identified within these cavities, and the role of companions in shaping them remains unclear.
Aims. We used Gaia astrometry to search for planetary and stellar companions in a sample of 98 transition discs, assessing the occurrence rate of such companions and their potential influence on cavity formation.
Methods. For the 98 young stellar objects (YSOs) with inner dust cavities, we computed Gaia proper motion anomalies, which together with the renormalised unit weight error (RUWE), identify companions with mass ratios q ≳0.01 at ∼0.1−30 au. We assessed the impact of disc gravity, accretion, disc-scattered light, dippers, starspots, jets, and outflows on the measured proper motion anomalies, concluding that these effects are unlikely to affect our analyses and that astrometric techniques such as the one of this work can be robustly applied to YSOs.
Results. Significant proper motion anomalies are found in 31 transition discs (32% of the sample), indicative of companions. We recovered 85% of the known companions within our sensitivity range. Assuming that the astrometry of each system is dominated by a single companion, we modelled the semi-major axis and mass required to reproduce the observed astrometric signals. Most inferred companions have M>30 MJ, placing many within or near the stellar mass regime. Seven sources host companions compatible with a planetary mass (M<13 MJ, HD 100453, J04343128+1722201, J16102955-3922144, MHO6, MP Mus, PDS 70, and Sz 76). For the non-detections, we provide the companion masses and semi-major axes that can be excluded in future searches. About half (53%) of detected companions cannot be reconciled with having carved the observed dust cavities.
Conclusions. We have gathered evidence of the presence of companions in a large sample of transition discs. However, we find that the population of transition discs cannot be fully described as a circumbinary population. Transition discs host as many companions within our sensitivity range as do randomly sampled groups of YSOs and main-sequence stars. If dust cavities are shaped by companions, such companions must reside at larger orbital separations than those of the companions detected here, and we predict them to be of planetary mass
Integrating Coral Reef and Reef Fish Community Data to Support Sustainable Ecotourism Management in Lihaga Island, North Sulawesi, Indonesia
No full textCoral reef ecosystems and reef-fish communities underpin essential ecosystem services in tropical seas, particularly for small-island ecotourism. Lihaga Island in North Sulawesi, Indonesia, is experiencing increasing ecological pressure as marine ecotourism expands, highlighting the need for integrated ecological assessments to support sustainable management. This study evaluates coral reef condition, reef-fish assemblages, and the presence of hawksbill turtles to assess their implications for sustainable ecotourism management. Field surveys were conducted from August to September 2023 at two marine stations surrounding the approximately 8-hectare island, quantifying live and dead coral cover, coral life-form composition, and reef-fish species richness and abundance using underwater visual census and benthic surveys, supported by multivariate analyses and spatial visualization. The coral reefs exhibited moderate overall condition, with mean live coral cover of 38.58 percent and dead coral cover of 40.32 percent. A total of 1,152 reef fishes representing 15 families and 72 species were recorded, dominated by Pomacentridae, Labridae, and Chaetodontidae. The presence of the Critically Endangered hawksbill turtle (Eretmochelys imbricata) indicated the persistence of functional nesting habitat. Sites with higher live coral cover supported greater reef-fish diversity, demonstrating strong ecological coupling between habitat complexity and community structure. The findings indicate that habitat degradation, shifts in trophic composition, and spatial overlap between tourism activities and turtle nesting zones pose risks to long-term ecosystem stability. Adaptive spatial zoning, visitor regulation, and ecologically informed governance are therefore essential to support sustainable small-island ecotourism at Lihaga Island
Effect of Black Rice Enrichment on the Quality of Fermented Milk Produced with
No full textThe incorporation of plant-based ingredients into fermented dairy products can enhance their functional value while maintaining product quality. This study investigated the effects of black rice powder enrichment (0-12% w/v) on the key characteristics of fermented milk produced using Lactiplantibacillus plantarum. Increasing the black rice concentration resulted in a significant decrease in pH from 4.98 to 3.81, indicating enhanced acidification. Viscosity and water-holding capacity showed a significant decrease from 2869.33 to 241.33 cP and from 100% to 50%, respectively, reflecting the disruption of the milk protein gel structure. Colour attributes were significantly affected, with lightness (L*) decreasing from 84.09 to 38.15 and a shift toward reddish-purple hues associated with anthocyanin pigments. The probiotic viability remained consistently high across all formulations (8.45-8.81 log CFU/mL), confirming successful fermentation. Sensory evaluation revealed significant differences among treatments, with moderate black rice enrichment (3-6% w/v) achieving the highest overall acceptability, whereas higher substitution levels negatively affected texture and flavour. These findings demonstrate, for the first time, that black rice powder can be effectively incorporated into fermented milk to enhance its functional properties while preserving probiotic viability and consumer acceptance
Impact of Climate Change on the Hydrological Conditions of The Noelmina Watershed, East Nusa Tenggara, Indonesia
No full textClimate change is a phenomenon that has become a real threat to human life and the environment. Over the past 40 years, climate parameters in the Noelmina River Watershed, East Nusa Tenggara, have undergone changes. This has undoubtedly caused significant changes in the hydrological conditions of the watershed, which covers an area of 1,965,71.39 hectares. Due to the limited climate data available from the Meteorology, Climatology, and Geophysics Agency (BMKG) at the study site, Climate data from the National Aeronautics and Space Administration Prediction of Worldwide Energy Resources (POWER NASA) were used. In the last 40 years, the average air temperature at the study site has increased by 0.19 0C, relative air humidity has increased by 2.1 %, and annual rainfall has increased by 430 mm.There has also been a shift in the climate types in the watershed. Based on the criteria of Smith and Ferguson, Oldeman, and Mohr. Changes in watershed water balance were observed using the Thornwaite-Matter method. The water surplus in the Noelmina sub-watershed increased by 51.06%. The surplus period occurred between December and March. The base flow also increased by 45.8%
Les brumes de Titan : des grains organiques formés dans la haute atmosphère ionisée
No full textLe système climatique de la lune de Saturne, Titan, est gouverné par la production intense d’aérosols organiques dans sa haute atmosphère, sous l’effet de rayonnements UV et de particules énergétiques. Ce phénomène s’est aussi certainement produit sur Terre au moment de l’apparition de la vie, avant la Grande Oxygénation. Ces deux points motivent fortement les recherches sur les processus de formation et d’évolution des aérosols dans l’atmosphère de Titan
Capture and escape from the 2:1 resonance between Ariel and Umbriel in a fast-migration scenario of the Uranian system
No full textRecent measurements and theoretical developments suggest that Uranus may exhibit a higher tidal dissipation than previously assumed. This enhanced dissipation leads to a faster orbital migration of its five major moons: Miranda, Ariel, Umbriel, Titania, and Oberon. Consequently, when studying their orbital evolution, resonant encounters that were always discarded in previous works need to be included. In particular, Ariel’s fast migration implies that the crossing of the 2:1 mean motion resonance with Umbriel is extremely likely and it could have occurred in recent times (within the last one billion years). Capture into this strong resonance would have induced significant tidal heating within Ariel, possibly explaining its resurfacing. Therefore, for this work, we explored the orbital history of the Uranian moons in a context of fast tidal migration, including the crossing of the 2:1 mean motion resonance between Ariel and Umbriel. For low initial eccentricities, we confirm that the moons are always captured into this resonance, which can potentially persist indefinitely. As the system is not currently involved in any mean motion resonance, we investigated possible dynamical mechanisms for exiting the 2:1 resonance. We show that the resonance could have been broken by a further resonant encounter with Titania. We analyzed the crossing of the 4:2:1 and 3:2:1 resonant chains, and looked for the parameter space where the probability of escaping the resonance is maximized. In particular, taking a dissipative parameter of Ariel k2,2/Q2 < 10−3, the passage through the 3:2:1 resonance succeeds in disrupting the 2:1 mean motion resonance between Ariel and Umbriel in more than 60% of our numerical experiments. While the crossing of the three-body resonant chain produces a general excitation of the orbital elements of all moons, a fraction of our simulations results in final low eccentricities and inclinations, which can eventually match the current orbital features of the system. As the proposed orbital history requires specific ranges of the dissipative parameters for the system, it will be possible to validate (or disprove) this scenario with the data of the next space mission to Uranus
Asymptotic analysis for waiting time in a retrial queue with multiple input streams
No full textUnder the classical retrial policy, we consider a single-server M/G/1 queue with multiple input streams and orbits. Different types of customers have corresponding arrival rates, general distributions of service time and retrial rates. Assume that the retrial rates for different types of customers linearly converge to zero. We firstly derive the first-order asymptotics of the orbit queue lengths. Subsequently, we find that the joint asymptotic distribution of the number of retrials follows a multidimensional geometric distribution. Finally, we obtain the joint asymptotic distribution of waiting times, which follows a multidimensional exponential distribution. This result indicates that the waiting times for different types of customers are independent of each other
Estimating the cross-sectional sizes of potential solar triggers of near-Sun magnetic switchbacks
No full textContext. The discovery of near-Sun magnetic switchbacks (SBs) represents a key result of the Parker Solar Probe (PSP) mission.
Aims. Several theories and models suggest that near-Sun SBs may be triggered by small-scale transient phenomena occurring in the low solar atmosphere. Therefore, estimating the cross-sectional sizes of potential triggers that are consistent with near-Sun SB observations could place tighter constraints on related theories and models.
Methods. We propose a simple method based on the conservation of magnetic flux in flux tubes connecting near-Sun SBs with their potential triggers in the low solar atmosphere. This method combines inferences of SB diameters and their magnetic fields from PSP in situ observations and estimates of the low-solar atmosphere magnetic fields, calculated at heights pertinent to proposed solar triggers of near-Sun SBs, from magnetic field extrapolations in areas on the Sun that are magnetically connected with PSP. The application of our method provides estimates of the radii of the cross-sections of potential near-Sun SB triggers taking place in the low solar atmosphere.
Results. We applied our method to the SBs observed during the first solar encounter of PSP, when the spacecraft was connected to a small equatorial coronal hole. The inferred radii of the cross-sections of potential triggers of near-Sun SBs in the low solar atmosphere take values in the range ≈10–26 000 km; a more compressed range of ≈125–3500 km corresponds to the most representative SB diameters values.
Conclusions. The latter range of potential solar near-Sun SB trigger radii is fully accessible by contemporary extreme UV (EUV) and UV instrumentation, with its lowest end of around 125 km being reachable by the Extreme Ultraviolet Imager on board the Solar Orbiter mission. This range is also consistent with the spatial scales of proposed near-Sun SB triggers in the low solar atmosphere. The smallest SB diameters we considered give rise to potential near-Sun SB solar trigger radii below ≈100 km, which are inaccessible with current EUV and UV instrumentation. Given that the inferred cross-sections sizes of the potential solar triggers of near-Sun SBs are significantly smaller than the respective errors in establishing their actual locations via magnetic connectivity tools, it is more appropriate to compare statistics of near-Sun SBs and their potential solar triggers on scales commensurate with the cross-sections inferred here, rather than with the entire connected region for encounter 1. Our simple method, paired with magnetic connectivity studies, is a step towards more refined assessments of potential solar triggers of near-Sun SBs
Theoretical investigation of fluorescence turn-on mechanism for cysteine detection by quinazolinone-based probe HTPQC
No full textThe fluorescence turn-on mechanism of the quinazolinone-based probe HTPQC for selective cysteine (Cys) detection has been theoretically investigated. Electron–hole analysis indicates that HTPQC has a charge transfer distance (D-index) of 4.86 Å, suggesting significant intramolecular charge transfer (ICT). Additionally, the energy levels of the frontier molecular orbitals (FMOs) for both the donor and acceptor components do not support the occurrence of a photoinduced electron transfer (PET) process. These results illustrate that the weak fluorescence of the probe is mainly attributed to ICT, rather than the PET mechanism proposed in previous studies. Upon reaction with Cys, the product HTPQ shows a reduced D-index (4.59 Å) in its enol form, resulting in enhanced fluorescence at 534 nm. Subsequently, the enol form transforms into the keto form via excited-state intramolecular proton transfer (ESIPT), with a low energy barrier of 1.951 kcal mol−1. In the keto form, complete charge separation occurs (D-index = 7.17 Å), and FMO analysis shows that the highest occupied molecular orbital (HOMO) of the acceptor is higher in energy than that of the donor, indicating PET-induced fluorescence quenching of HTPQ. This study provides a novel theoretical explanation for the photophysical mechanism of cysteine detection via the HTPQC probe, offering insights that diverge from previously established explanations
Comparing the data-reduction pipelines of FRIPON, DFN, WMPL, and AMOS: Case study of the Geminids
No full textContext. The number of meteor observation networks has expanded rapidly due to declining hardware costs, enabling professional and amateur groups to contribute substantial datasets. An accurate data reduction remains challenging, however, because variations in processing methods can significantly affect the trajectory reconstructions and orbital interpretations.
Aims. Our goal is to thoroughly compare four professionally produced meteor data-reduction pipelines (FRIPON, DFN, WMPL, and AMOS) by reprocessing FRIPON Geminid observations. This analysis can be used for a comparison with other data-reduction methods.
Methods. We processed a dataset of 5 84 Geminid fireballs observed by FRIPON between 2016 and 2023. The single-station astrometric data were converted into the global fireball exchange (GFE) standard format for uniform processing. We assessed variations in trajectory, velocity, and radiant and orbital element calculations in the pipelines and compared them to previously published Geminid measurements.
Results. The radiant and velocity solutions provided by the four data-reduction pipelines are all within the range of previously published values, with some nuances. Particularly, the radiants estimated by WMPL, DFN, and AMOS are nearly identical, but FRIPON reports a systematic shift in right ascension (−0.3°) that is caused by an improper handling of the precession. Additionally, the FRIPON data-reduction pipeline also tends to overestimate the initial velocity (+0.3 km s−1), which is due to the deceleration model used as the velocity solver. The FRIPON velocity method relies on a well-constrained deceleration profile, but for the Geminids, many are low-deceleration events, which leads to an overestimation of the initial velocity. At the other end of the spectrum, the DFN tends to predict lower velocities, in particular, for poorly observed events. This velocity shift vanishes for the DFN when we considered Geminids alone with at least three observations or more, however. The primary difference identified in the analysis concerns the velocity uncertainties. Although all four pipelines achieved similar residuals between their trajectories and observations, their velocity uncertainties varied systematically. WMPL outputs the lowest values, followed by AMOS, FRIPON, and DFN.
Conclusions. From this Geminid case study, we find that the default FRIPON data-reduction methods, while adequate for meteoritedropping events, are not optimal for all cases. Specifically, FRIPON tends to overestimate velocities for low-deceleration events because the fit is less strongly constrained, and the nominal radiants are not correctly output in J2000. On the other hand, the other data-reduction pipelines (DFN, WMPL, and AMOS) produce consistent results, provided that the observational data are sufficiently robust, that is, more than ∼50 data points from at least three observers. A key takeaway is that we need to reevaluate how the velocity uncertainties are estimated. Our results show that the uncertainty estimates vary systematically in different pipelines, even though the goodness-of-fit statistics is generally similar. The increasing availability of impact observations from varying sources (radar, video, photo, seismic, infrasound, satellite, telescopic, etc.) calls for greater collaboration and transparency in data-reduction practices