Testing Evolutionary Models with Red Supergiant and Wolf–Rayet Populations

Despite the many successes that modern massive star evolutionary theory has enjoyed, reproducing the apparent trend in the relative number of red supergiants (RSGs) and Wolf–Rayet (WR) stars has remained elusive. Previous estimates show the RSG/WR ratio decreasing strongly with increasing metallicity. However, the evolutionary models have always predicted a relatively flat distribution for the RSG/WR ratio. In this paper we reexamine this issue, drawing on recent surveys for RSGs and WRs in the Magellanic Clouds, M31, and M33. The RSG surveys have used Gaia astrometry to eliminate foreground contamination and have separated RSGs from asymptotic giant branch stars using near-infrared colors. The surveys for WRs have utilized interference-filter imaging, photometry, and image subtraction techniques to identify candidates, which have then been confirmed spectroscopically. After carefully matching the observational criteria to the models, we now find good agreement in both the single-star Geneva and binary BPASS models with the new observations. The agreement is better when we shift the RSG effective temperatures derived from J − Ks photometry downwards by 200 K in order to agree with the Levesque TiO effective temperature scale. In an appendix we also present a source list of RSGs for the SMC which includes effective temperatures and luminosities derived from near-infrared 2MASS photometry, in the same manner as used for the other galaxies.

30-year cone production dynamics in Siberian stone pine (Pinus sibirica) in the southern boreal zone: a causal interpretation

Background and aims – Siberian stone pine is a keystone species for Siberia, and numerous studies have analyzed Siberian stone pine seeding dynamics in connection with the dynamics of weather conditions. However, all studies were based on observations before 1990. The aim of the study was to expand our knowledge about the balance of weather and climatic factors in the regulation of cone production to enable conclusions about the current reproductive function in Siberian stone pine.Material and methods – We monitored Siberian stone pine cone production in the southeastern region of the Western Siberian Plain, in association with climatic factors, over a period of 30 years. To analyze the relationship with weather conditions, we used the trait mature cone number per tree and weather data obtained from the weather station in Tomsk.Key results – During this period, cone production decreased by about one-third, mainly caused by the complete absence of high yields. The main factor negatively affecting cone production was late spring frost: severe frost occurring with a large accumulated sum of effective temperatures resulted in full cone loss, and light frost substantially reduced cone number. A less important but significant climatic factor was September temperature: as the temperature increased, the cone number decreased in the following year. Over the last 30 years, the sum of the effective temperatures at which the last spring frost occurs, as well as the average September temperature, increased considerably, resulting in reduced cone production.Conclusion – If the current climatic trend is maintained, and especially if it is strengthened, Siberian stone pine cone production in the southern boreal forest zone on the Western Siberian Plane is unlikely to provide for the effective renewal of the species.

Assessment of Weather and Climate-Related Risks to Human Health in Different Areas of the Krasnoyarsk Region

Introduction: Extreme climate conditions have a negative impact on human health. Purpose: The study aimed to assess weather and climate-related risks to human health in different areas of the Krasnoyarsk Region by effective temperatures estimated during two long-term observation periods. Materials and methods: We analyzed ambient temperatures (average monthly and minimum), wind speed (average and maximum), and relative humidity in the subarctic and temperate continental zones estimated during the periods of determining climatic norms in 1961–1990 and 1991–2020. The health risk was assessed on the basis of effective temperatures. Results: In the subarctic zone, the wind strength (average and maximum values) decreased, the duration of such periods increased just like the ambient temperature while the relative humidity did not change. In temperate climates, all indicators have changed. In the subarctic zone, in the second observation period, frostbite was possible within 20–30 minutes during two months (versus 3 in the first). In the temperate climate, there was no such risk to humans. At the minimum temperature and maximum wind speed in the subarctic zone, the risk of frostbite is possible during 5 months (versus 6): after 10–15 minutes during two months and after 20–30 minutes – during three months of the year. In temperate climates, frostbite is possible within 20–30 minutes during two months (versus 3 in the first period). Conclusions: In the interval of establishing climatic norms (1991–2020), a significant increase in effective temperatures was determined: in the subarctic zone with the average wind strength and temperature in February–April and June, with maximum wind and minimum temperature – in March–July; in temperate climates, in April and June, respectively. The duration of periods of health risks posed by cold temperature exposures in the subarctic climate with average wind and temperature values equaled two months (I–II), with maximum wind speed and minimum temperatures – five months (XI–III); in the temperate climate, it was null and 2 (3) months (I, II, and XII), respectively.

Impact of Water-latent Heat on the Thermal Structure of Ultra-cool Objects: Brown Dwarfs and Free-floating Planets

Brown dwarfs are essential targets for understanding planetary and sub-stellar atmospheres across a wide range of thermal and chemical conditions. As surveys continue to probe ever deeper and as observing capabilities continue to improve, the number of known Y dwarfs—the coldest class of sub-stellar objects, with effective temperatures below about 600 K—is rapidly growing. Critically, this class of ultra-cool objects has atmospheric conditions that overlap with solar-system worlds and, as a result, tools and ideas developed from studying Earth, Jupiter, Saturn, and other nearby worlds are well suited for application to sub-stellar atmospheres. To that end, we developed a one-dimensional (vertical) atmospheric structure model for ultra-cool objects that includes moist adiabatic convection, as this is an important process for many solar-system planets. Application of this model across a range of effective temperatures (350, 300, 250, 200 K), metallicities ([M/H] of 0.0, 0.5, 0.7, 1.5), and gravities (log g of 4.0, 4.5, 4.7, 5.0) demonstrates strong impact of water-latent heat release on simulated temperature-pressure profiles. At the highest metallicities, water-vapor mixing ratios reach an Earth-like 3% with associated major alterations to the thermal structure in the atmospheric regions where water condenses. Spectroscopic and photometric signatures of metallicity and moist convection should be readily detectable at near- and mid-infrared wavelengths, especially with James Webb Space Telescope observations, and can help indicate the formation history of an object.

Features of seasonal growth of Arundo donax var. versicolor Mill. (Stokes) in the conditions of the M. M. Gryshko National Botanical Garden of the National Academy of Sciences of Ukraine

Purpose. To define of phenological and morphological features of A. donax var. versicolor growth during the introduction in the M. M. Gryshko National Botanical Garden of the National Academy of Sciences of Ukraine (NBG). Methods. The object of research was the plants of A. donax var. versicolor in the collection of ornamental grasses of the department of flower and ornamental plants of NBG. The plants were grown on a sunny experimental area during 2014–2020. Since under NBG conditions, A. donax var. versicolor did not enter the flowering phase, the beginning of the phases of spring regrowth, leaf unfolding, and the end of the growing season were recorded. Morphometric parameters and shoot-forming ability were investigated for 3–5 years of cultivation. Results. The beginning and duration of the phases of shoot spring regrowth and the unfolding of leaves of A. donax var. versicolor as well as their dependence on the sum of effective temperatures was established. Thus, spring regrowth begins with renewal buds on May 11 ± 5 days at the effective temperature sums of 226.6 ± 19.7 °С. The phase of leaf development in plants occurred on May 20 ± 7 days. The effective temperature sum at the beginning of this phase was 309.45 ± 11.66 °C. The productivity of shoot formation (1.6 ± 0.3 shoot per plant) under the conditions of introduction was determined. Conclusions. A. donax var. versicolor plants did not have a full cycle of seasonal development in the conditions of the NBG. Plants formed vegetative monocyclic shoots 240–260 cm tall. The duration of their vegetation was 182–189 days. The optimal period for the growth of the ground mass of plants fell on July-August. During this period, the leaves were quickly formed, the number of which was 28.8 ± 6.68 on the shoot. The correlation between the rate of accumulation of effective temperatures and the rate of regrowth of plant shoots was recorded.

Unifying fluctuation-dissipation temperatures of slow-evolving nonequilibrium systems from the perspective of inherent structures

For nonequilibrium systems, how to define temperature is one of the key and difficult issues to solve. Although effective temperatures have been proposed and studied to this end, it still remains elusive what they actually are. Here, we focus on the fluctuation-dissipation temperatures and report that such effective temperatures of slow-evolving systems represent characteristic temperatures of their equilibrium counterparts. By calculating the fluctuation-dissipation relation of inherent structures, we obtain a temperature-like quantity TIS. For monocomponent crystal-formers, TIS agrees well with the crystallization temperature Tc, while it matches with the onset temperature Ton for glass-formers. It also agrees with effective temperatures of typical nonequilibrium systems, such as aging glasses, quasi-static shear flows, and quasi-static self-propelled flows. From the unique perspective of inherent structures, our study reveals the nature of effective temperatures and the underlying connections between nonequilibrium and equilibrium systems and confirms the equivalence between Ton and Tc.

Comparative characteristics of the weather and climate health risk in the Arctic belt of the Krasnoyarsk region

The average for 2009–2019 was determined. monthly indicators of temperature, speed of movement and air humidity in the open area according to the data of meteorological stations at Cape Chelyuskin and Dikson Island. Monthly wind-cold indices (VHI) and equivalent effective temperatures (EET) were calculated, and the assessment of the risk of cold influences on humans was compared. In the Arctic zone of the Krasnoyarsk Territory, thermal discomfort has been established due to low air temperatures, wind strength (from weak to moderate), and humidity (moderate to highly humid) air. Bioclimatic conditions differed in the lower temperatures for 6 months at Cape Chelyuskin and the strength of the wind (1 month); on about. Dixon — higher humidity for 7 months. and wind strength for 2 months. On about Dikson compared with M. Chelyuskin identified less uncomfortable conditions. Average monthly daily temperatures in the open area prove the presence of a cold environment. This suggests that VHI indicates the presence of a potential (4 months) and probable cold health risk (8 months). EET showed the presence of year-round cold risk. At Cape Chelyuskin, the habitat was assessed as «cold» (4 months) and «threat of frostbite» (8 months). Dixon — as «moderately cold» (3 months), «cold» (1 month), «very cold» (1 month) and «threat of frostbite» (7 months).