Surface temperature and synthetic spectral energy distributions for rotationally deformed stars

The spectral energy distribution (SED) of a non-spherical star could differ significantly from the SED of a spherical star with the same average temperature and luminosity. Calculation of the SED of a deformed star is often approximated as a composite of several spectra, each produced by a plane parallel model of given effective temperature and gravity. The weighting of these spectra over the stellar surface, and hence the inferred effective temperature and luminosity, will be dependent on the inclination of the rotation axis of the star with respect to the observer, as well as the temperature and gravity distribution on the stellar surface. Here we calculate the surface conditions of rapidly rotating stars with a 2D stellar structure and evolution code and compare the effective temperature distribution to that predicted by von Zeipel's law. We calculate the composite spectrum for a deformed star by interpolating within a grid of intensity spectra of plane parallel model atmospheres and integrating over the surface of the star. Using this method, we find that the deduced variation of effective temperature with inclination can be as much as 3000 K for an early B star, depending on the details of the underlying model.Comment: 38 pages, 9 figures (AAStex preprint format). Accepted for publication in the Ap

A NLTE line blanketed model of a solar type star

We present LTE and NLTE atmospheric models of a star with solar parameters, and study the effect of treating many thousands of Iron group lines out of LTE on the computed atmospheric structure, overall absolute flux distribution, and the moderately high resolution spectrum in the visible and near UV bands. Our NLTE modeling includes the first two or three ionization stages of 20 chemical elements, up to and including much of the Fe-group, and includes about 20000 Fe I and II lines. We investigate separately the effects of treating the light metals and the Fe-group elements in NLTE. Our main conclusions are that 1) NLTE line blanketed models with direct multi-level NLTE for many actual transitions gives qualitatively similar results as the more approximate treatment of Anderson (1989) for both the Fe statistical equilibrium and the atmospheric temperature structure, 2) models with many Fe lines in NLTE have a temperature structure that agrees more closely with LTE semi-empirical models based on center-to-limb variation and a wide variety of spectra lines, whereas LTE models agree more with semi-empirical models based only on an LTE calculation of the Fe I excitation equilibrium, 3) the NLTE effects of Fe-group elements on the model structure and flux distribution are much more important than the NLTE effects of all the light metals combined, and serve to substantially increases the violet and near UV flux level as a result of NLTE Fe over-ionization. These results suggest that there may still be important UV opacity missing from the models.Comment: Accepted for publication in The Astrophysical Journa

Numerical Simulations of Magnetoacoustic-Gravity Waves in the Solar Atmosphere

We investigate the excitation of magnetoacoustic-gravity waves generated from localized pulses in the gas pressure as well as in vertical component of velocity. These pulses are initially launched at the top of the solar photosphere that is permeated by a weak magnetic field. We investigate three different configurations of the background magnetic field lines: horizontal, vertical and oblique to the gravitational force. We numerically model magnetoacoustic-gravity waves by implementing a realistic (VAL-C) model of solar temperature. We solve two-dimensional ideal magnetohydrodynamic equations numerically with the use of the FLASH code to simulate the dynamics of the lower solar atmosphere. The initial pulses result in shocks at higher altitudes. Our numerical simulations reveal that a small-amplitude initial pulse can produce magnetoacoustic-gravity waves, which are later reflected from the transition region due to the large temperature gradient. The atmospheric cavities in the lower solar atmosphere are found to be the ideal places that may act as a resonator for various oscillations, including their trapping and leakage into the higher atmosphere. Our numerical simulations successfully model the excitation of such wave modes, their reflection and trapping, as well as the associated plasma dynamics

The impact of non-LTE effects and granulation inhomogeneities on the derived iron and oxygen abundances in metal-poor halo stars

This paper presents the results of a detailed theoretical investigation of the impact of non-LTE effects and of granulation inhomogeneities on the derived iron and oxygen abundances in the metal-poor halo subgiant HD140283. Our analysis is based on both the `classical' one-dimensional (1D) stellar atmosphere models and on the new generation of three-dimensional (3D) hydrodynamical models. We find that the non-LTE effects on the iron abundance derived from Fe {\sc i} lines are very important, amounting to ${\sim}0.9$ dex and to ${\sim}0.6$ dex in the 3D and 1D cases, respectively. On the other hand, we find that non-LTE and 3D effects have to be taken into account for a reliable determination of the iron abundance from weak Fe {\sc ii} lines, because the significant overexcitation of their upper levels in the granular regions tend to produce emission features. As a result such Fe {\sc ii} lines are weaker than in LTE and the abundance correction amounts to ${\sim}0.4$ dex for the 3D case. We derive also the oxygen-to-iron abundance ratio in the metal-poor star HD140283 by using the O {\sc i} triplet at 7772--5 \AA and the forbidden [O {\sc i}] line at 6300 \AA. Interestingly, when both non-LTE and 3D effects are taken into account there still remains significant discrepancies in the iron abundances derived from Fe {\sc i} and Fe {\sc ii} lines, as well as in the oxygen abundances inferred from the O {\sc i} and [O {\sc i}] lines. We conclude that the metalicity of this type of metal-poor stars could be significantly larger than previously thought, which may have far-reaching implications in stellar astrophysics.Comment: The Astrophysical Journal (in press). (35 pages, 5 figures and 4 tables

Permitted Oxygen Abundances and the Temperature Scale of Metal-Poor Turn-Off Stars

We use high quality VLT/UVES published data of the permitted OI triplet and FeII lines to determine oxygen and iron abundances in unevolved (dwarfs, turn-off, subgiants) metal-poor halo stars. The calculations have been performed both in LTE and NLTE, employing effective temperatures obtained with the new infrared flux method (IRFM) temperature scale by Ramirez & Melendez, and surface gravities from Hipparcos parallaxes and theoretical isochrones. A new list of accurate transition probabilities for FeII lines, tied to the absolute scale defined by laboratory measurements, has been used. We find a plateau in the oxygen-to-iron ratio over more than two orders of magnitude in iron abundance (-3.2 < [Fe/H] < -0.7), with a mean [O/Fe] = 0.5 dex (sigma = 0.1 dex), independent of metallicity, temperature and surface gravity. According to the new IRFM Teff scale, the temperatures of turn-off halo stars strongly depend on metallicity, a result that is in excellent qualitative and quantitative agreement with stellar evolution calculations, which predict that the Teff of the turn-off at [Fe/H] = -3 is about 600-700 K higher than that at [Fe/H] = -1.Comment: In press, Ap

Oxygen in the Very Early Galaxy

Oxygen abundances in a sample of ultra-metal-poor subdwarfs have been derived from measurements of the oxygen triplet at 7771--5 A and OH lines in the near UV performed in high-resolution and high signal-to-noise spectra obtained with WHT/UES, KeckI/HIRES, and VLT/UVES. Our Fe abundances were derived in LTE and then corrected for NLTE effects following Thevenin and Idiart (1999). The new oxygen abundances confirm previous findings for a progressive linear rise in the oxygen-to-iron ratio with a slope -0.33+-0.02 from solar metallicity to [Fe/H] -3. A slightly higher slope would be obtained if the Fe NLTE corrections were not considered. Below [Fe/H]= -2.5 our stars show [O/Fe] ratios as high as ~ 1.17 (G64-12), which can be interpreted as evidence for oxygen overproduction in the very early epoch of the formation of the halo, possibly associated with supernova events with very massive progenitor stars. We show that the arguments against this linear trend given by Fulbright and Kraft (1999), based on the LTE Fe analysis of two metal-poor stars cannot be sustained when an NLTE analysis is performed. Using 1-D models our analysis of three oxygen indicators available for BD +23 3130 gives consistent abundances within 0.16 dex and average [O/Fe] ratio of 0.91.Comment: 45 pages, 11 figures, accepted for publication in The Astrophysical Journa

Differences sustained between diffuse and limited forms of juvenile systemic sclerosis in expanded international cohort. www.juvenile-scleroderma.com

OBJECTIVES: To evaluate the baseline clinical characteristics of juvenile systemic sclerosis (jSSc) patients in the international Juvenile SSc Inception Cohort (jSScC), compare these characteristics between the classically defined diffuse (dcjSSc) and limited cutaneous (lcjSSc) subtypes, and among those with overlap features. METHODS: A cross-sectional study was performed using baseline visit data. Demographic, organ system evaluation, treatment, and patient and physician reported outcomes were extracted and summary statistics applied. Comparisons between dcjSSc and lcSSc subtypes and patients with and without overlap features were performed using Chi-square and Mann Whitney U-tests. RESULTS: At data extraction 150 jSSc patients were enrolled across 42 centers, 83% were Caucasian, 80% female, dcjSSc predominated (72%), and 17% of the cohort had overlap features. Significant differences were found between dcjSSc and lcjSSc regarding the modified Rodnan Skin Score, presence of Gottron's papules, digital tip ulceration, 6 Minute walk test, composite pulmonary and cardiac involvement. All more frequent in dcSSc except for cardiac involvement. DcjSSc patients had significantly worse scores for physician rated disease activity and damage. A significantly higher occurrence of Gottron's papules, musculoskeletal involvement and composite pulmonary involvement, and significantly lower frequency of Raynaud's phenomenon, were seen in those with overlap features. CONCLUSION: Results from a large international jSSc cohort demonstrate significant differences between dcjSSc and lcjSSc patients including more globally severe disease and increased frequency of ILD in dcjSSc patients, while those with lcSSc have more frequent cardiac involvement. Those with overlap features had an unexpected higher frequency of interstitial lung disease

Defining criteria for disease activity states in systemic juvenile idiopathic arthritis based on the systemic Juvenile Arthritis Disease Activity Score

Objective To develop and validate cutoff values in the systemic Juvenile Arthritis Disease Activity Score 10 (sJADAS10) that distinguish the states of inactive disease (ID), minimal disease activity (MiDA), moderate disease activity (MoDA), and high disease activity (HDA) in children with systemic juvenile idiopathic arthritis (sJIA), based on subjective disease state assessment by the treating pediatric rheumatologist. Methods The cutoffs definition cohort was composed of 400 patients enrolled at 30 pediatric rheumatology centers in 11 countries. Using the subjective physician rating as an external criterion, 6 methods were applied to identify the cutoffs: mapping, calculation of percentiles of cumulative score distribution, Youden index, 90% specificity, maximum agreement, and ROC curve analysis. Sixty percent of the patients were assigned to the definition cohort and 40% to the validation cohort. Cutoff validation was conducted by assessing discriminative ability. Results The sJADAS10 cutoffs that separated ID from MiDA, MiDA from MoDA, and MoDA from HDA were ≤ 2.9, ≤ 10, and > 20.6. The cutoffs discriminated strongly among different levels of pain, between patients with or without morning stiffness, and between patients whose parents judged their disease status as remission or persistent activity/flare or were satisfied or not satisfied with current illness outcome. Conclusion The sJADAS cutoffs revealed good metrologic properties in both definition and validation cohorts, and are therefore suitable for use in clinical trials and routine practice

NLRP12 -ассоциированный периодический синдром: описание собственного наблюдения и анализ данных литературы

Autoinflammatory diseases (AIDs) are a group of rare disorders characterized by persistent or recurrent inflammation caused by the hyperactivation of mediators and innate immune cells (neutrophils, monocytes/macrophages). The paper describes the authors' own case of NLRP12-associated AIDs and the efficiency of canakinumab therapy and reviews a series of cases of the similar disease, which are given in the literature. Аутовоспалительные заболевания (АВЗ) – это группа редких заболеваний, характеризующихся персистирующим или возвратным воспалением, обусловленным гиперактивацией медиаторов и клеток врожденного иммунитета (нейтрофилов, моноцитов/макрофагов). В статье приводятся описание собственного наблюдения NLRP12-ассоциированного АВЗ, эффективности терапии канакинумабом, а также обзор серии случаев аналогичного заболевания, представленных в литературе.

Тяжелые грибковые инфекции у детей с ревматическими заболеваниями

Introduction. In children with rheumatic diseases, severe fungal infections (invasive mycoses – IM) are not well understood.Objectives. To analyze risk factors, disease course of IM in children with systemic rheumatic diseases.Materials and methods. For diagnosis of IM were used criteria EORTC/MSGERC, 2019. We reviewed the literature over the past 15 years on IM in children with rheumatic diseases from the international databases Pubmed and Web of Science.Results. In retrospective multicenter study were included 8 children with IM and systemic rheumatic diseases: ANCA-associated vasculitis (n=4), systemic lupus erythematosus (n=3), juvenile rheumatoid arthritis (n=1). Median age was 13,5 (8-17) y., boys – 67%. Invasive aspergillosis was diagnosed in 5 patients and invasive candidiasis – 3. The risk factors of invasive mycoses were high rheumatic disease activity (100%), corticosteroids (prednisolone ≥ 0,3 mg/kg/d) use for ≥21 d (87,5%), immunosuppressive therapy (87,5%), recent (≤ 2 weeks) pulse steroid therapy (75%), hemophagocytic lymphohistiocytosis (62,5%), prolonged (≥ 10 days) severe neutropenia (≤ 0,5х109/l) (62,5%), and prolonged (≥10 days lymphopenia (≤ 1,0х109/l) (37,5%). In patients with invasive aspergillosis the involved organ was the lung, in patients with invasive candidiasis a candidemia was diagnoses. All patients received antifungal therapy. The overall 30 days survival rate was 37,5%.Сonclusions. Children with high rheumatic diseases activity and intensive treatment with immunosuppressive agents should be considered as patients with a high risk of invasive mycoses with a high mortality. Введение. У детей с ревматическими заболеваниями тяжелые грибковые инфекции (инвазивные микозы) изучены недостаточно.Цель. Проанализировать факторы риска, клинические проявления и результаты лечения инвазивных микозов у детей с ревматическими заболеваниями.Материалы и методы. Диагностику и оценку результатов лечения инвазивных микозов проводили на основании критериев EORTC/MSGERS, 2019. Провели обзор литературы из международных баз данных Pubmed и Web of Science за последние 15 лет.Результаты. При ретроспективном мноогоцентровом исследовании выявили 8 детей с ИМ и ревматическими заболеваниями: АНЦА-ассоциированный васкулит (n=4), системная красная волчанка (n=3), ювенильный ревматоидный артрит (n=1). Медиана возраста составила 13,5 лет (8–17), мальчики – 67%. Инвазивный аспергиллез диагностировали у 5 пациентов, инвазивный кандидоз – у 3. Установлены факторы риска развития инвазивных микозов: высокая активность ревматологического заболевания (100%), применение системных глюкокортикостероидов (преднизолон ≥ 0,3 мг/кг/сут) более 21 дня (87,5%), применение иммунодепрессантов (87,5%), недавняя (≤ 2 недель) пульс-терапия системными глюкокортикостероидами (75%), гемофагоцитарный синдром (62,5%), выраженная нейтропения (≤ 0,5×109 /л) более 10 дней (62,5%), лимфоцитопения (≤1,0×109 /л) более 10 дней (37,5%). При инвазивном аспергиллезе у всех пациентов выявили поражение легких, при инвазивном кандидозе – кандидемию. Антифунгальную терапию получали 100% пациентов. Общая выживаемость больных в течение 30 дней от диагностики ИМ составила 37,5%.Вывод. Детей с высокой активностью ревматических заболеваний и интенсивной иммуносупрессивной терапией следует отнести к группе риска развития ИМ с возможной высокой летальностью.