Red Stars Research Articles

Investigating APOKASC Red Giant Stars with Abnormal Carbon-to-nitrogen Ratios

The success of galactic archeology and the reconstruction of the formation history of our Galaxy relies critically on precise ages for large populations of stars. For evolved stars in the red clump and red giant branch, the carbon-to-nitrogen ratio ([C/N]) has recently been identified as a powerful diagnostic of mass and age that can be applied to stellar samples from spectroscopic surveys such as Sloan Digital Sky Survey/APOGEE. Here, we show that at least 10% of red clump stars and red giant branch stars deviate from the standard relationship between [C/N] and mass. We use the APOGEE–Kepler (APOKASC) overlap sample to show that binary interactions are responsible for the majority of these outliers and that stars with indicators of current or previous binarity should be excluded from galactic archeology analyses that rely on [C/N] abundances to infer stellar masses. We also show that the Data Release 14 APOGEE analysis overestimates the surface gravities for even moderately rotating giants (vsini > 2 km s−1).

K-band Absolute Magnitude Relations of Red Clump Stars Separated by Age

Red clump (RC) stars form a distinguishable clump on the color-magnitude diagram, making it a good distance indicator. Currently, the two main absolute magnitude estimation methods in the I-band (700–900 nm) conflict: one assumes a constant RC magnitude as supported by empirical data and one relates magnitude with other physical characteristics as supported by theoretical models. Studies attribute these discrepancies to population effects, such as dust, and recommend the K-band (2000–2400 nm) to minimize them. Past studies analyzed relations between the K-band magnitude, color, metallicity, and age, including those stratified by age at 2 Gyr. This study aims to investigate these different relations to clarify trends from past studies, discover new trends, and compare them to similar relations in the I-band. After analyzing cluster RC data from Gaia DR3, 2MASS, and Gaia-ESO DR5, K-band magnitude exhibits insignificant correlation in all relations (p>0.05) but has the greatest dependence and the least root mean square error (RMS) with metallicity in the old RC. Significant correlation was found between I-band magnitude and metallicity for all RC and young RC (p<0.05), especially the latter (R2 = 0.804). This consistency with theoretical trends suggests weaker I-band population effects than previously believed. Overall, these three relations yield more accurate predictions than the mean magnitude. Thus, studies cannot solely rely on the mean K-band or I-band magnitude to estimate distance, and magnitude relations stratified by age can potentially lead to more accurate RC distance estimations and a more accurately calibrated distance ladder.

Seismic and spectroscopic analysis of nine bright red giants observed by Kepler

ABSTRACT Photometric time series gathered by space telescopes such as CoRoT and Kepler allow to detect solar-like oscillations in red giant stars and to measure their global seismic constraints, which can be used to infer global stellar properties (e.g. masses, radii, and evolutionary states). Combining such precise constraints with photospheric abundances provides a means of testing mixing processes that occur inside red-giant stars. In this work, we conduct a detailed spectroscopic and seismic analysis of nine nearby (d < 200 pc) red giant stars observed by Kepler. Both seismic constraints and grid-based modelling approaches are used to determine precise fundamental parameters for those evolved stars. We compare distances and radii derived from Gaia Data Release 3 parallaxes with those inferred by a combination of seismic, spectroscopic, and photometric constraints. We find no deviations within errors bars, however the small sample size and the associated uncertainties are a limiting factor for such comparison. We use the period spacing of mixed modes to distinguish between ascending red-giants and red clump stars. Based on the evolutionary status, we apply corrections to the values of Δν for some stars, resulting in a slight improvement to the agreement between seismic and photometric distances. Finally, we couple constraints on detailed chemical abundances with the inferred masses, radii, and evolutionary states. Our results corroborate previous studies that show that observed abundances of lithium and carbon isotopic ratio are in contrast with predictions from standard models, giving robust evidence for the occurrence of additional mixing during the red-giant phase.

Ghost-Stitching American Politics

Ghost-Stitching American Politics

Warp and flare of the old Galactic disc as traced by the red clump stars

ABSTRACT Our study aims to investigate the outer disc structure of the Milky Way Galaxy using the red clump (RC) stars. We analysed the distribution of the largest sample of RC stars to date, homogeneously covering the entire Galactic plane in the range of 40° ≤ ℓ ≤ 340° and −10° ≤ b ≤ +10°. This sample allows us to model the RC star distribution in the Galactic disc to better constrain the properties of the flare and warp of the Galaxy. Our results show that the scale length of the old stellar disc weakly depends on azimuth, with an average value of 1.95 ± 0.26 kpc. On the other hand, a significant disc flaring is detected, where the scale height of the disc increases from 0.38 kpc in the solar neighbourhood to ∼2.2 kpc at R ≈15 kpc. The flare exhibits a slight asymmetry, with ∼1 kpc more scale height below the Galactic plane as compared to the Northern flare. We also confirm the warping of the outer disc, which can be modelled with Zw = (0.0057 ± 0.0050) [R − (7358 ± 368)(pc)]1.40 ± 0.09sin (ϕ − (− 2${_{.}^{\circ}}$03 ± 0${_{.}^{\circ}}$18)). Our analysis reveals a noticeable north–south asymmetry in the warp, with a greater amplitude observed in the southern direction compared to the northern. Comparing our findings with younger tracers from the literature, we observe an age dependency of both the flare and warp. An increase in flare strength with age suggests the secular evolution of the disc as the preferred mechanism for forming the flare. The increase of the maximum warp amplitude with age indicates that the warp dynamics could be the possible cause of the variation in the warp properties with age.

Spectroscopy and Photochemistry of Aluminum-Bearing Species in the Universe.

ConspectusMetal-bearing molecules impact the chemical and physical environment of many astronomical sources such as the circumstellar envelopes of large asymptotic giant branch and red supergiant stars, the interstellar medium, and planetary atmospheres (e.g., ablation of ∼20 tons per day into the Earth's upper atmosphere). In recent decades, the number of successfully detected metal-containing molecules has increased via rotational spectroscopic observations, which are driven by theoretical and experimental investigations. Following formation, the ultimate fate of each species (stabilization, dissociation, etc.) is determined by its electronic structure and electronic spectroscopic properties as it encounters the pervasive radiation fields in the vacuum of space. Studying these properties can evince the possibility of detection and predict the impact each molecule has on its surrounding environment. Aluminum, one of the most abundant elements and metals, is distributed throughout the universe as a constituent of gas-phase molecules (e.g., AlO, AlOH, AlCl, etc.) as well as condensed onto solid dust grains such as Al2O3. Free gas-phase aluminum-bearing molecules are synthesized by nonthermal equilibrium processes such as shocks and pulsations near the stellar photosphere or via the reaction of molecules on the surface of dust grains. Recent investigations in our research group utilizing quantum chemical methods, such as coupled cluster (CCSD(T) and CCSD(T)-F12) and multireference configuration interaction (MRCI) with large basis sets, have explored a wide breadth of spectroscopy and photochemistry of small (triatomic and tetratomic) aluminum-bearing molecules, including Al-H, Al-C, Al-N, Al-O, Al-Si, Al-P, and Al-S bonds, among others. The ground-state spectroscopy (rotational and vibrational) of various aluminum-bearing molecules is discussed in the context of experimental and observational detection potentials. These detection potentials depend on various factors, such as the magnitude of the permanent dipole moment (PDM) and the population of states yielding transition frequencies in detectable ranges. Many aluminum-bearing molecules possess large PDMs and may be prime candidates for astronomical and laboratory detection. Within this discussion, interesting aspects of the ground-state molecular orbital configuration of OAlNO are shown to lead to an uncommon triplet ground state. Additionally, the electronic absorption spectrum of the quasi-isoenergetic ground-state isomers of AlOSO is discussed as a sensitive method for detecting this species and differentiating between the two isomers. Finally, photochemical mechanisms key to the production of AlO and AlOH in low-density regions and the destruction of AlCO and AlOC are also discussed in order to understand the radiation-induced formation and destruction of these molecules.

Red Star over Seoul: Facts and the Myths of the Ninety-Day-Long Communist Rule over the South Korean Capital in 1950

During its long history, the city of Seoul has suffered three major sieges and occupations. The first happened in 1592, the second occupation of the capital was in 1636, and the third occasion when the city was besieged and occupied by an enemy army was during the first phase of the Korean War. The main goal of this study is to describe facts and myths about the ninety-day-long communist rule over the South Korean capital in 1950. During my research, I compared all available documentary sources with recollections and memoirs to ascertain how the city and its citizens survived that difficult period. I collected impressions about the North Korean invaders to examine everyday life in the occupied city. I also attempted to determine if there is any truth to the myth that the North Korean leader Kim Il Sung visited occupied Seoul. The main primary sources used here are the contemporary newspapers of the DPRK: the Rodong Sinmun, which published several news items about occupied Seoul, and the Haebang Ilbo (Liberation Daily), which was published in Seoul during the North Korean occupation. The documentation about the ninety-day-long occupation of Seoul began right after the liberation of the capital in fall 1950. The first book, which collected the experiences of some elite members of South Korean society, was published by the Soodo Munhwasa company, under the title Konan ŭi 90 il (90 days of suffering).1 The reminiscences of the authors—university professor Yu Chin-oh, poet Mo Yun-suk, lawyer-scholar Yi Geon-ho, and news reporter Ku Chul-hoi—were published in English soon after the Korean version. The Reds Take a City was the first non-Korean book that collected available pieces of infor- mation about the occupation.2 In the second year of the Korean War, another important collection titled Chok Hwa Sam Sak Kuinjip (赤禍三朔九人集, Three Months under the Reds) was published.3 The book contained nine recollections from those who experienced communist rule and were forced to collaborate with the North Koreans regarding minor matters. Its publisher was the anti-communist Podo yŏnmaeng (보도연맹, Podo League) organization, which was established before the Korean War to “erase” citizens’ leftist ideologies.4 Some other important sources of the ninety-day-long occupation of Seoul are the personal recollections, written by well-known South Korean intellectuals. Park Wan-suh’s popular novel Ku manhtŏn shinga nun nuga ta mŏgŏssŭlkka? (그 많던 싱아는 누가 다 먹었을까? Who Ate up all the Shinga?) and Kim Seong-chil’s famous diary, Yŏksa ap’ eso (역 사 앞에서 In Front of History), included important observations about that period. Kim Won-Il’s reminiscences, which are particularly meaningful because his father had been involved in the developments, also provide useful information.5 To add more North Korean elements to the puzzle of the ninety-day-long occupation, one important source is the novel 50 nyŏn yŏrŭm (50년 여름, Summer of the year 50), which contains details about Kim Il Sung’s alleged trip to Seoul at that time.6 In my capacity as the Ambassador for Hungary to the DPRK, I also studied the local publications available in Pyongyang. Often, Central and Eastern European sources proved to be most beneficial as the archives of these former communist states proved to be far more accessible than North Korean archives, which are very restricted. At that time, the party organs of the Soviet bloc countries published daily about the developments, and their journalists reported personally from the battlefield of Korea. These include archive diplomatic reports from the Hungarian legation in Pyongyang, which are available now in the Ministry of Foreign Affairs’ Directory at the National Archives of Hungary.

S.K. "RUS'" UZHHOROD – TEAM "FLYING TEACHERS" AND OTHER UKRAINIAN CLUBS OF THE SILVER LAND: NAMES OF ZAKARPATTIAN [TRANSCARPATHIAN] FOOTBALL TEAMS

The article analyzes the names of Zakarpattian [Transcarpathian] football teams in different periods of the more than century-long history of the development of Ukrainian football in Zakarpattia [Transcarpathia]. The motivation of the collected names of Ukrainian football teams was clarified, and they were differentiated into homonymous and appellative names (common names). Naming trends during three periods of the history of the formation of Ukrainian football in Zakarpattia [Transcarpathia], caused by social and political, social and cultural factors, are traced. It was revealed that during the first third of the 20th century, when Zakarpattian [Transcarpathian] lands belonged to various foreign states, and the Ukrainians of Zakarpattia [Transcarpathia] sought to demonstrate their national identity in various ways, the names of football clubs reflected associations with the historical, geographical and cultural realities of Ukraine (the ancient name of the state was Rus'; anthroponym – Dukhnovych; toponyms – Korolevo nad Tysoyu, Strypa; oronym – Carpathians) and contained important ethno-cultural connotations. In the Soviet period (40–80s of the 20 th century), along with names with national and cultural semantics, nominations appeared in which colonial influences on the naming system were noticeable, which were manifested in the uniformity of the names of football teams and in the tendency to reflect in the names Soviet realities and communist values (names of all-Union sports associations – Dynamo, Spartak, Kolos, Avanhard, Burevisnyk; names of individuals by occupation – ceramicist, cooperator, furniture maker, motorist, woodworker, chemist, miner, metallurgist, builder, kolhospnyk; names of enterprise products – andesite, plastic; ideological names – red star, Bolshevik, spark). In the period after the restoration of Ukrainian independence, a noticeable increase in the number of football team names was recorded, reflecting the geographical realities of the ethnographic region of Zakarpattia [Transcarpathia] (toponyms – Mynai, Mukachevo, Perechyn, Seredne, Tyachiv, Khust; oronyms – Borzhava, Buzhora, Hoverla; hydronym – Tysa; relief names, flora and fauna – highlands, skala [mountain rock], spruce, berkut [eagle of prey]), but for more than thirty years in football nomenclature it was not possible to completely get rid of totalitarian influences.

Images of Betelgeuse with VLTI/MATISSE across the Great Dimming

ABSTRACT From Nov. 2019 to May 2020, the red supergiant star Betelgeuse experienced an unprecedented drop of brightness in the visible domain called the Great Dimming event (GDE). Large atmospheric dust clouds and large photospheric convective features are suspected to be responsible for it. To better understand the dimming event, we used mid-infrared long-baseline spectro-interferometric measurements of Betelgeuse taken with the Very Large Telescope Interferometer/Multi AperTure mid-Infrared SpectroScopic Experiment (VLTI/MATISSE) instrument before (Dec. 2018), during (Feb. 2020), and after (Dec. 2020) the GDE. We present data in the 3.98–4.15 µm range to cover SiO spectral features molecules as well as adjacent continuum. We have employed geometrical models, image reconstruction, as well as radiative transfer models to monitor the spatial distribution of SiO over the stellar surface. We find a strongly inhomogeneous spatial distribution of SiO that appears to be looking very different between our observing epochs, indicative of a vigorous activity in the stellar atmosphere. The contrast of our images is small in the pseudo-continuum for all epochs, implying that our MATISSE observations support both cold spot and dust cloud model.

Yellow Star, Red Star: Response to Critiques

There is no greater honor for an author than to respond to such generous and thoughtful engagement with one’s work such as the two commentaries by Mila Dragojević and Tamara Trošt. These commentaries are that much more appreciated as both Dragojević and Trošt have contributed tremendous scholarship on memory politics and historical narratives in the Western Balkans and in many ways Yellow Star, Red Star builds on their own work.

Measurements of visual double stars with PISCO2 at the Nice 76‐cm refractor in 2013–2014 (new data) and in 2015

AbstractWe present relative astrometric and photometric measurements of visual double stars made in 2013–2015, with PISCO2 installed at the 76‐cm refractor of Côte d'Azur Observatory in Nice (France). Our observing list contains orbital couples as well as double stars whose motion is still uncertain. Most of the observations were done in 2015, but some other observations of wide couples were done in 2013–2014 (0.3% of the total of the observations). Three different techniques were used for obtaining measurements: lucky imaging, speckle interferometry and the direct vector autocorrelation method. From our observations of 2837 multiple stars, we obtained 5182 new measurements with angular separations in the range of 0.1–32 and an average accuracy of . The mean error on the position angles is 0°.8. Most of the position angles were determined without the usual 180° ambiguity with the application of the direct vector autocorrelation technique and/or by inspection of the Lucky images or the long integration files. We managed to routinely monitor faint systems () with large magnitude difference (up to ). We have thus been able to measure 21 systems containing red dwarf stars that had been poorly monitored since their discovery, from which we estimated the stellar masses thanks to Gaia measurements. We also measured the magnitude difference of the two components of 1079 double stars with an estimated error of 0.2 mag. Except for a few objects that are discussed, our measurements are in good agreement with the ephemerides computed with published orbital elements, even for the double stars whose separation is smaller than the diffraction limit. Thanks to good seeing images and with the use of high‐contrast numerical filters, we have also been able to obtain 196 measurements with an angular separation smaller than the diffraction limit of our instrumentation, and consistent with those obtained with larger telescopes. We also report measurements of the 164 new double stars that we found in the files obtained during the observations. Finally, from a study of the DR3 Gaia release, it is shown that all the objects of the Tycho Double Star Catalog that we did not resolve in 2015 are probably false detections by Tycho.

Photosynthesis under a red Sun: predicting the absorption characteristics of an extraterrestrial light-harvesting antenna

ABSTRACT Here, we discuss the feasibility of photosynthesis on Earth-like rocky planets in close orbit around ultracool red dwarf stars. Stars of this type have very limited emission in the photosynthetically active region of the spectrum (400–700 nm), suggesting that they may not be able to support oxygenic photosynthesis. However, photoautotrophs on Earth frequently exploit very dim environments with the aid of highly structured and extremely efficient antenna systems. Moreover, the anoxygenic photosynthetic bacteria, which do not need to oxidize water to source electrons, can exploit far-red and near-infrared light. Here, we apply a simple model of a photosynthetic antenna to a range of model stellar spectra, ranging from ultracool (2300 K) to Sun-like (5800 K). We assume that a photosynthetic organism will evolve an antenna that maximizes the rate of energy input while also minimizing fluctuations. The latter is the noise cancelling principle recently reported by Arp et al. Applied to the solar spectrum, this predicts optimal antenna configurations in agreement with the chlorophyll Soret absorption bands. Applied to cooler stars, the optimal antenna peaks become redder with decreasing stellar temperature, crossing to the typical wavelength ranges associated with anoxygenic photoautotrophs at ∼3300 K. Lastly, we compare the relative input power delivered by antennae of equivalent size around different stars and find that the predicted variation is within the same order of magnitude. We conclude that low-mass stars do not automatically present light-limiting conditions for photosynthesis, but they may select for anoxygenic organisms.

Jet-powered Turbulence in Common Envelope Evolution

We conduct a three-dimensional hydrodynamical simulation of common envelope evolution (CEE) where a neutron star (NS) spirals in inside the envelope of a red supergiant star in a predetermined orbit. We find that the jets shed pairs of vortices in an expanding spiral pattern, inflate two expanding spirally shaped low-density bubbles, one above and one below the equatorial plane, and deposit angular momentum to the envelope. In the simulation we do not include the gravity of the NS such that all effects we find are solely due to the jets that the spiraling-in NS launches. The angular momentum that the jets deposit into the envelope is of the same order of magnitude as the orbital angular momentum and has the same direction. The turbulence that the jets induce in the common envelope might play a role in transporting energy and angular momentum. The jet-deposited energy that is radiated away (a process not studied here) leads to a transient event that is termed a common envelope jets supernova (CEJSN) and might mimic an energetic core collapse supernova. The turbulence and the spiral pattern that we explore here might lead to bumps in the late light curve of the CEJSN when different segments of the ejected envelope collide with each other. This study emphasizes the roles that jets can play in CEE (including jets launched by black hole companions) and adds to the rich variety of processes in CEJSN events.

Stellar variability in Gaia DR3

Context. The unparalleled characteristics of Gaia photometry in terms of calibration, stability, time span, dynamic range, full-sky coverage, and complementary information make it an excellent choice to study stellar variability. Aims. We aim to measure the photometric dispersion in the G, GBP, and GRP bands of the 145 677 450 third Gaia data release (DR3) five-parameter sources with G ≤ 17 mag and GBP – GRP between −1.0 and 8.0 mag. We will use that unbiased sample to analyze stellar variability in the Milky Way (MW), Large Magellanic Cloud (LMC), and Small Magellanic Cloud (SMC). Methods. For each band we convert from magnitude uncertainties to observed photometric dispersions, calculate the instrumental component as a function of apparent magnitude and color, and use it to transform the observed dispersions into the astrophysical ones: sG, SGBP, and SGRP. We give variability indices in the three bands for the whole sample indicating whether the objects are non-variable, marginally variable, or clearly so. We use the subsample established by Rimoldini and collaborators with light curves and variability types to calibrate our results and establish their limitations. Results. The position of an object in the dispersion-dispersion planes can be used to constrain its variability type, a direct application of these results. We use information from the MW, LMC, and SMC color-absolute magnitude diagrams (CAMDs) to discuss variability across the Hertzsprung-Russell diagram. White dwarfs and B-type subdwarfs are more variable than main sequence (MS) or red clump (RC) stars, with a flat distribution in sG up to 10 mmag and with variability decreasing for the former with age. The MS region in the Gaia CAMD includes a mixture of populations from the MS itself and from other evolutionary phases. Its sG distribution peaks at low values (~1–2 mmag) but it has a large tail dominated by eclipsing binaries, RR Lyrae stars, and young stellar objects. RC stars are characterized by little variability, with their sG distribution peaking at 1 mmag or less. The stars in the pre-main-sequence (PMS) region are highly variable, with a power law distribution in sG with slope 2.75 and a cutoff for values lower than 7 mmag. The luminous red stars region of the Gaia CAMD has the highest variability, with its extreme dominated by AGB stars and with a power law in sG with slope ~2.2 that extends from there to a cutoff of 7 mmag. We show that our method can be used to search for LMC Cepheids. We analyze four stellar clusters with O stars (Villafranca O-016, O-021, O-024, and O-026) and detect a strong difference in sG between stars that are already in the MS and those that are still in the PMS.

ALMA Reveals Hidden Morphologies in the Molecular Envelope of VY Canis Majoris

The J = 2 → 1 transition of CO near 230 GHz and the J = 3 → 2 line of HCN at 265 GHz have been imaged in the envelope of the red hypergiant star, VY Canis Majoris (VY CMa), using the Atacama Large Millimeter Array (ALMA) with angular resolutions 0.″2–1.″5; single-dish data were added to provide sensitivity up to 30″. These images reveal a far more complex envelope, with previously unseen outflows extending 4″–9″ from the star. These new structures include an arc-like outflow with an angular separation of ∼9″ northeast from the stellar position (“NE Arc”), twin fingerlike features approximately 4″ to the north/northeast (“NE Extension”), and a roughly spherical region observed ∼7″ E of the star (“E Bubble”). The NE Arc appears to be decelerating from base (V LSR ∼ 7 km s−1) to tip (V LSR ∼ 18 km s−1), while the NE Extension is blueshifted with V LSR ∼ −7 km s−1. Among the new features, HCN is only detected in the NE Arc. In addition, known structures Arc 1, Arc 2, and NW Arc, as well as other features closer to the star, are closely replicated in CO, suggesting that the gas and dust are well mixed. The CO spectra are consistent with the kinematic picture of VY CMa derived from HST data. Arc 2, however, has added complexity. Preliminary results from CO suggest 12C/13C ∼ 22–38 across the envelope. The additional presence of at least three major episodic mass ejection events significantly broadens the current perspective of the envelope structure and mass-loss history of VY CMa.

Investigating Gaia EDR3 parallax systematics using asteroseismology of Cool Giant Stars observed by Kepler, K2, and TESS

Gaia EDR3 has provided unprecedented data that has generated a great deal of interest in the astrophysical community, even though systematics affect the reported parallaxes at the level of ∼10 μas. Independent distance measurements are available from asteroseismology of red-giant stars with measurable parallaxes, whose magnitude and colour ranges more closely reflect those of other stars of interest. In this paper we determine distances to nearly 12 500 red-giant-branch and red clump stars observed by Kepler, K2, and TESS. This was done via a grid-based modelling method, where global asteroseismic observables, and constraints on the photospheric chemical composition and on the unreddened photometry are used as observational inputs. This large catalogue of asteroseismic distances allows us to provide a first comparison with Gaia EDR3 parallaxes. Offset values estimated with asteroseismology show no clear trend with ecliptic latitude or magnitude, and the trend whereby they increase (in absolute terms) as we move towards redder colours is dominated by the brightest stars. The correction model proposed by Lindegren et al. (2021a) is not suitable for all the fields considered in this study. We find a good agreement between asteroseismic results and model predictions of the red clump magnitude. We discuss possible trends with the Gaia scan law statistics, and show that two magnitude regimes exist where either asteroseismology or Gaia provides the best precision in parallax.

A brightness gap exposes the inner lives of red dwarf stars

A brightness gap exposes the inner lives of red dwarf stars

A cool runaway greenhouse without surface magma ocean.

Water vapour atmospheres with content equivalent to the Earth's oceans, resulting from impacts1 or a high insolation2,3, were found to yield a surface magma ocean4,5. This was, however, a consequence of assuming a fully convective structure2-11. Here, we report using a consistent climate model that pure steam atmospheres are commonly shaped by radiative layers, making their thermal structure strongly dependent on the stellar spectrum and internal heat flow. The surface is cooler when an adiabatic profile is not imposed; melting Earth's crust requires an insolation several times higher than today, which will not happen during the main sequence of the Sun. Venus's surface can solidify before the steam atmosphere escapes, which is the opposite of previous works4,5. Around the reddest stars (Teff < 3,000 K), surface magma oceans cannot form by stellar forcing alone, whatever the water content. These findings affect observable signatures of steam atmospheres and exoplanet mass-radius relationships, drastically changing current constraints on the water content of TRAPPIST-1 planets. Unlike adiabatic structures, radiative-convective profiles are sensitive to opacities. New measurements of poorly constrained high-pressure opacities, in particular far from the H2O absorption bands, are thus necessary to refine models of steam atmospheres, which are important stages in terrestrial planet evolution.

Coupling in Sport

China’s rise in recent years to become an economic superpower has been accompanied by active policies to promote sport and culture. Once chosen by the Olympic Committee in 2015 to host the 2022 Winter Olympics, China faced a problem since its hockey team was not strong and could potentially be humiliated in the climax events of the Games. The Chinese Ice Hockey Association (CIHA) decided on a strategic coupling with Canadian hockey expertise to create credible men’s and women’s hockey teams, including hiring Canadian coaches, taking teams to Canada for extended professional training, playing exhibition games against Canadian teams, inviting Canadian hockey teams and players to China, and recruiting Canadian hockey players with Chinese heritage to play professionally in China on the HC Kunlun Red Star team (men) and the KRS Vanke Rays (women). We label this relationship a global player production network. However, the strict Covid lockdown in China and the froideur that developed in Canada-China geopolitical relations after the detention in Vancouver of Meng Wanzhou and the arrest in China of Michael Spavor and Michael Kovrig, was followed by a decoupling of the Canada-China hockey relationship. But by granting national status to Canadian-born “heritage” players, and by selecting at the eleventh hour the Kunlun Red Star and Vanke Ray teams as their Olympic teams, China effectively re-coupled with Canada and was thereby able to field two credible hockey teams.

Evaluation of the Dietary Profile of Footballers in Ligue 2 in the Department of Brazzaville

This exploratory study aimed to assess the dietary profile of 2nd division footballers in the departmental league of Brazzaville. Our sample was made up of 120 subjects divided into 3 clubs and aged on average 17.86 ± 1.39 years. Through the standardized and extended nutritional survey (SENS) and food frequency questionnaire (FFQ), we used the 24-hours recall method to assess nutritional status, respect for meal times, types of food consumed, quantity of food and variation of breakfast, lunch, snack and dinner foods. The results obtained showed that the nutritional status was normal at the level of the three (03) clubs (19.95 ± 2.12 kg/m2 for Gothia club, 21.60 ± 1.61 kg/m2 for Marakana club and 21.31 ± 1.88 kg/m2 for Red Star club. However, we first noted a lack of respect for meal times in 52.2% of Gothia players, 72.2% of Marakana players and 81.6% of Red Star players respectively. Similarly, dissatisfaction with competition meals was then noticed in 60.9%, 83.3% and 55.3% of Gothia, Marakana and Red Star players respectively. An insufficient number of meals taken during the day and no dietary variation in 60.9%, 58.3% and 57.9% of the players of the three respective clubs. Similarly, these results showed the intake of an insufficient amount of food respectively in 60.9%, 55.6% and 44.7% of the players of the three respective clubs. In the end, it was revealed an under-information in terms of sports nutrition in 100%, 77.78%, and 68.42% of the players of the three respective clubs. In conclusion, the food profile of footballers was inadequate and not controlled by nutritionists. This profile is associated with a nutritional imbalance, which is a factor in poor athletic performance.