SORA: Stellar occultation reduction and analysis Gomes-Júnior, A R; Morgado, B E; Benedetti-Rossi, G ...
Monthly Notices of the Royal Astronomical Society,
02/2022, Volume:
511, Issue:
1
Journal Article
Peer reviewed
Open access
ABSTRACT
The stellar occultation technique provides competitive accuracy in determining the sizes, shapes, astrometry, etc., of the occulting body, comparable to in-situ observations by spacecraft. ...With the increase in the number of known Solar system objects expected from the LSST, the highly precise astrometric catalogs, such as Gaia, and the improvement of ephemerides, occultations observations will become more common with a higher number of chords in each observation. In the context of the Big Data era, we developed sora, an open-source python library to reduce and analyse stellar occultation data efficiently. It includes routines from predicting such events up to the determination of Solar system bodies’ sizes, shapes, and positions.
Context.
The Centaur (10199) Chariklo has the first ring system discovered around a small object. It was first observed using stellar occultation in 2013. Stellar occultations allow sizes and shapes ...to be determined with kilometre accuracy, and provide the characteristics of the occulting object and its vicinity.
Aims.
Using stellar occultations observed between 2017 and 2020, our aim is to constrain the physical parameters of Chariklo and its rings. We also determine the structure of the rings, and obtain precise astrometrical positions of Chariklo.
Methods.
We predicted and organised several observational campaigns of stellar occultations by Chariklo. Occultation light curves were measured from the datasets, from which ingress and egress times, and the ring widths and opacity values were obtained. These measurements, combined with results from previous works, allow us to obtain significant constraints on Chariklo’s shape and ring structure.
Results.
We characterise Chariklo’s ring system (C1R and C2R), and obtain radii and pole orientations that are consistent with, but more accurate than, results from previous occultations. We confirm the detection of W-shaped structures within C1R and an evident variation in radial width. The observed width ranges between 4.8 and 9.1 km with a mean value of 6.5 km. One dual observation (visible and red) does not reveal any differences in the C1R opacity profiles, indicating a ring particle size larger than a few microns. The C1R ring eccentricity is found to be smaller than 0.022 (3
σ
), and its width variations may indicate an eccentricity higher than ~0.005. We fit a tri-axial shape to Chariklo’s detections over 11 occultations, and determine that Chariklo is consistent with an ellipsoid with semi-axes of 143.8
−1.5
+1.4
, 135.2
−2.8
+1.4
, and 99.1
−2.7
+5.4
km. Ultimately, we provided seven astrometric positions at a milliarcsecond accuracy level, based on
Gaia
EDR3, and use it to improve Chariklo’s ephemeris.
► Trans fat (TF) consumption can modify the neuronal plasticity causing motor diseases. ► TF-fed rats showed movement disorders, which was intensified by exercise. ► TF and lard decreased catalase ...activity, which was increased by exercise in TF group. ► Exercise increased striatal Na
+K
+-ATPase activity of lard and soybean-fed rats. ► TF inhibited benefits of exercise indicating its critical role in brain neurochemistry.
The influence of
trans fatty acids (FA) on development of orofacial dyskinesia (OD) and locomotor activity was evaluated. Rats were fed with diets enriched with 20% soybean oil (SO;
n
−
6 FA), lard (L; saturated FA) or hydrogenated vegetable fat (HVF;
trans FA) for 60 weeks. In the last 12 weeks each group was subdivided into sedentary and exercised (swimming). Brains of HVF and L-fed rats incorporated 0.33% and 0.20% of
trans FA, respectively, while SO-fed group showed no incorporation of
trans FA. HVF increased OD, while exercise exacerbated this in L and HVF-fed rats. HVF and L reduced locomotor activity, and exercise did not modify. Striatal catalase activity was reduced by L and HVF, but exercise increased its activity in the HVF-fed group. Na
+K
+-ATPase activity was not modified by dietary FA, however it was increased by exercise in striatum of SO and L-fed rats. We hypothesized that movement disorders elicited by HVF and less by L could be related to increased dopamine levels in striatum, which have been related to chronic
trans FA intake. Exercise increased OD possibly by increase of brain dopamine levels, which generates pro-oxidant metabolites. Thus, a long-term intake of
trans FA caused a small but significant brain incorporation of
trans FA, which favored development of movement disorders. Exercise worsened behavioral outcomes of HVF and L-fed rats and increased Na
+K
+-ATPase activity of L and SO-fed rats, indicating its benefits. HVF blunted beneficial effects of exercise, indicating a critical role of
trans FA in brain neurochemistry.
Objective: Development of a hydrogel containing rutin at 0.025% (w/w) and evaluation of its in vivo efficacy in cutaneous wound healing in rats.
Methods: Hydrogels were prepared using Carbopol ...Ultrez® 10 NF and an aqueous dispersion of rutin in polysorbate 80. Hydrogels were characterized by means of pH measurement, rheological and spreadability analysis and rutin content determination by liquid chromatography. The in vivo healing effect was evaluated through the regression of skin lesions in rats and by analysis of oxidative stress.
Results and discussion: Hydrogels showed adequate pH values (5.50-6.50) and pseudoplastic non-Newtonian behavior. After 5 days of treatment of wounds, hydrogels containing rutin presented a higher decrease in the wound area compared to the control hydrogels. Analysis of the oxidative stress showed a decrease in lipid peroxidation and protein carbonyl content as well as an increase in catalase activity after the treatment with the hydrogel containing rutin. Furthermore, this treatment increased total protein levels.
Conclusion: This study shows for the first time the feasibility of using dermatological formulations containing rutin to improve skin wound healing.
Context. Bright stellar positions are now known with an uncertainty below 1 mas thanks to Gaia DR2. Between 2019–2020, the Galactic plane will be the background of Jupiter. The dense stellar ...background will lead to an increase in the number of occultations, while the Gaia DR2 catalogue will reduce the prediction uncertainties for the shadow path. Aims. We observed a stellar occultation by the Galilean moon Europa (J2) and propose a campaign for observing stellar occultations for all Galilean moons. Methods. During a predicted period of time, we measured the light flux of the occulted star and the object to determine the time when the flux dropped with respect to one or more reference stars, and the time that it rose again for each observational station. The chords obtained from these observations allowed us to determine apparent sizes, oblatness, and positions with kilometre accuracy. Results. We present results obtained from the first stellar occultation by the Galilean moon Europa observed on 2017 March 31. The apparent fitted ellipse presents an equivalent radius of 1561.2 ± 3.6 km and oblatenesses 0.0010 ± 0.0028. A very precise Europa position was determined with an uncertainty of 0.8 mas. We also present prospects for a campaign to observe the future events that will occur between 2019 and 2021 for all Galilean moons. Conclusions. Stellar occultation is a suitable technique for obtaining physical parameters and highly accurate positions of bright satellites close to their primary. A number of successful events can render the 3D shapes of the Galilean moons with high accuracy. We encourage the observational community (amateurs included) to observe the future predicted events.
ABSTRACT
While proper orbital elements are currently available for more than 1 million asteroids, taxonomical information is still lagging behind. Surveys like SDSS-MOC4 provided preliminary ...information for more than 100 000 objects, but many asteroids still lack even a basic taxonomy. In this study, we use Dark Energy Survey (DES) data to provide new information on asteroid physical properties. By cross-correlating the new DES data base with other data bases, we investigate how asteroid taxonomy is reflected in DES data. While the resolution of DES data is not sufficient to distinguish between different asteroid taxonomies within the complexes, except for V-type objects, it can provide information on whether an asteroid belongs to the C- or S-complex. Here, machine learning methods optimized through the use of genetic algorithms were used to predict the labels of more than 68 000 asteroids with no prior taxonomic information. Using a high-quality, limited set of asteroids with data on gri slopes and i − z colours, we detected 409 new possible V-type asteroids. Their orbital distribution is highly consistent with that of other known V-type objects.
The two rings of (50000) Quaoar Pereira, C. L.; Sicardy, B.; Morgado, B. E. ...
Astronomy & astrophysics,
05/2023, Volume:
673
Journal Article
Peer reviewed
Open access
Context.
Quaoar is a classical trans-Neptunian object (TNO) with an area-equivalent diameter of 1100 km and an orbital semi-major axis of 43.3 astronomical units. Based on stellar occultations ...observed between 2018 and 2021, an inhomogeneous ring (Q1R, i.e., Quaoar’s first ring) has been detected around this body.
Aims.
A new stellar occultation by Quaoar was observed on August 9, 2022, with the aim of improving Quaoar’s shape models and the physical parameters of Q1R, while searching for additional material around the body.
Methods.
The occultation provided nine effective chords across Quaoar, pinning down its size, shape, and astrometric position. Large facilities, such as Gemini North and the Canada-France-Hawaii Telescope (CFHT), were used to obtain high acquisition rates and signal-to-noise ratios. The light curves were also used to characterize the Q1R ring (radial profiles and orbital elements).
Results.
Quaoar’s elliptical fit to the occultation chords yields the limb with an apparent semi-major axis of 579.5 ± 4.0 km, apparent oblateness of 0.12 ± 0.01, and area-equivalent radius of 543 ± 2 km. Quaoar’s limb orientation is consistent with Q1R and Weywot orbiting in Quaoar’s equatorial plane. The orbital radius of Q1R is refined to a value of 4057 ± 6 km. The radial opacity profile of the more opaque ring profile follows a Lorentzian shape that extends over 60 km, with a full width at half maximum (FWHM) of ∼5 km and a peak normal optical depth of 0.4. Besides the secondary events related to the already reported rings, new secondary events detected during the August 2022 occultation in three different data sets are consistent with another ring around Quaoar with a radius of 2520 ± 20 km, assuming the ring is circular and co-planar with Q1R. This new ring has a typical width of 10 km and a normal optical depth of ∼0.004. Just as Q1R, it also lies outside Quaoar’s classical Roche limit.
Abstract Here we evaluated the influence of physical exercise on behavior parameters and enzymatic status of rats supplemented with different dietary fatty acids (FA). Male Wistar rats fed diets ...enriched with soybean oil (SO), lard (L), or hydrogenated vegetable fat (HVF) for 48 weeks were submitted to swimming (30 min/d, five times per week) for 90 days. Dietary FA per se did not cause anxiety-like symptoms in the animals, but after physical exercise, SO group showed a better behavioral performance than L and the HVF groups in elevated plus maze (EPM). In Barnes maze, HVF group showed impaired memory acquisition as compared to L group, and exercise reversed this effect. SO-fed rats showed an improvement in memory acquisition after 1 day of training, whereas lard caused an improvement of memory only from day 4. HVF-fed rats showed no improvement of memory acquisition, but this effect was reversed by exercise in all training days. A lower activity of the Na+ K+ -ATPase in brain cortex of rats fed lard and HVF was observed, and this effect was maintained after exercise. Similarly, the HVF diet was related to lower activity of hippocampal Na+ K+ -ATPase, and exercise reduced activity of this enzyme in the SO and L groups. Our findings show influences of dietary FA on memory acquisition, whereas regular exercise improved this function and was beneficial on anxiety-like symptoms. As FA are present in neuronal membrane phospholipids and play a critical role in brain function, our results suggest that low incorporation of trans FA in neuronal membranes may act on cortical and hippocampal Na+ K+ -ATPase activity, but this change appears to be unrelated to the behavioral parameters primarily harmed by consumption of trans and less so by saturated FA, which were reversed by exercise.
Abstract Myrtle rust, caused by Austropuccinia psidii , has been associated with more than 480 plant species belonging to the family Myrtaceae . Intraspecific variability in pathogenicity has been ...reported among isolates of A . psidii from different hosts. However, there are few studies that have comparatively quantified the disease in guava ( Psidium guajava ) and rose apple ( Syzygium jambos ). The objective of this work was to quantify the pathogenic variability of A . psidii isolates collected from guava and rose apple in Brazil and to investigate the mechanisms of infection and colonization of the pathogen at the cellular level. The monocyclic components of the rust disease were evaluated on young leaves of rose apple and guava plants cross‐inoculated with isolates from rose apple and guava. Pathogenic specialization of both A . psidii isolates for their respective hosts was confirmed in this work. The guava A . psidii isolate was able to infect and colonize rose apple leaf tissues but no sporulation occurred. Similarly, the rose apple A . psidii isolate infected guava plants but did not sporulate. Confocal laser scanning microscopy revealed that lobed haustoria were present within rose apple leaves at 2 days post‐inoculation (dpi) with both isolates, which resulted in intense mesophyll colonization for both interactions at 9 dpi. The latter is remarkable because infection of rose apple with the guava A . psidii isolate did not result in mature rust pustules.
PDF
