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The most massive and shortest-lived stars dominate the chemical evolution of the pre-galactic era. On the basis of numerical simulations, it has long been speculated that the mass of such first-generation stars was up to several hundred solar masses 1-4 . The very massive first-generation stars with a mass range from 140 to 260 solar masses are predicted to enrich the early interstellar medium through pair-instability supernovae (PISNe) 5 . Decades of observational efforts, however, have not been able to uniquely identify the imprints of such very massive stars on the most metal-poor stars in the Milky Way 6,7 . Here we report the chemical composition of a very metal-poor (VMP) star with extremely low sodium and cobalt abundances. The sodium with respect to iron in this star is more than two orders of magnitude lower than that of the Sun. This star exhibits very large abundance variance between the odd- and even-charge-number elements, such as sodium/magnesium and cobalt/nickel. Such peculiar odd-even effect, along with deficiencies of sodium and α elements, are consistent with the prediction of primordial pair-instability supernova (PISN) from stars more massive than 140 solar masses. This provides a clear chemical signature indicating the existence of very massive stars in the early universe., (© 2023. The Author(s).)

Proposed mechanisms for the production of calcium in the first stars (population III stars)—primordial stars that formed out of the matter of the Big Bang—are at odds with observations1. Advanced nuclear burning and supernovae were thought to be the dominant source of the calcium production seen in all stars2. Here we suggest a qualitatively different path to calcium production through breakout from the ‘warm’ carbon–nitrogen–oxygen (CNO) cycle through a direct experimental measurement of the 19F(p, γ)20Ne breakout reaction down to a very low energy point of 186 kiloelectronvolts, reporting a key resonance at 225 kiloelectronvolts. In the domain of astrophysical interest2, at around 0.1 gigakelvin, this thermonuclear 19F(p, γ)20Ne rate is up to a factor of 7.4 larger than the previous recommended rate3. Our stellar models show a stronger breakout during stellar hydrogen burning than previously thought1,4,5, and may reveal the nature of calcium production in population III stars imprinted on the oldest known ultra-iron-poor star, SMSS0313-67086. Our experimental result was obtained in the China JinPing Underground Laboratory7, which offers an environment with an extremely low cosmic-ray-induced background8. Our rate showcases the effect that faint population III star supernovae can have on the nucleosynthesis observed in the oldest known stars and first galaxies, which are key mission targets of the James Webb Space Telescope9.Observation of a new resonance in the 19-fluorine to 20-neon thermonuclear reaction at the China JinPing Underground Laboratory (over 2 km below ground) may provide clues to observed discrepancies in calcium production in the evolution of the first stars. [ABSTRACT FROM AUTHOR]

Proposed mechanisms for the production of calcium in the first stars (population III stars)-primordial stars that formed out of the matter of the Big Bang-are at odds with observations 1 . Advanced nuclear burning and supernovae were thought to be the dominant source of the calcium production seen in all stars 2 . Here we suggest a qualitatively different path to calcium production through breakout from the 'warm' carbon-nitrogen-oxygen (CNO) cycle through a direct experimental measurement of the 19 F(p, γ) 20 Ne breakout reaction down to a very low energy point of 186 kiloelectronvolts, reporting a key resonance at 225 kiloelectronvolts. In the domain of astrophysical interest 2 , at around 0.1 gigakelvin, this thermonuclear 19 F(p, γ) 20 Ne rate is up to a factor of 7.4 larger than the previous recommended rate 3 . Our stellar models show a stronger breakout during stellar hydrogen burning than previously thought 1,4,5 , and may reveal the nature of calcium production in population III stars imprinted on the oldest known ultra-iron-poor star, SMSS0313-6708 6 . Our experimental result was obtained in the China JinPing Underground Laboratory 7 , which offers an environment with an extremely low cosmic-ray-induced background 8 . Our rate showcases the effect that faint population III star supernovae can have on the nucleosynthesis observed in the oldest known stars and first galaxies, which are key mission targets of the James Webb Space Telescope 9 ., (© 2022. The Author(s), under exclusive licence to Springer Nature Limited.)

Doppler spectroscopy has detected 152 planets around nearby stars. A major puzzle is why many of their orbits are highly eccentric; all planets in our Solar System are on nearly circular orbits, as is expected if they formed by accretion processes in a protostellar disk. Several mechanisms have been proposed to generate large eccentricities after planet formation, but so far there has been little observational evidence to support any particular model. Here we report that the current orbital configuration of the three giant planets around upsilon Andromedae (?And) probably results from a close dynamical interaction with another planet, now lost from the system. The planets started on nearly circular orbits, but chaotic evolution caused the outer planet (?And d) to be perturbed suddenly into a higher-eccentricity orbit. The coupled evolution of the system then causes slow periodic variations in the eccentricity of the middle planet (?And c). Indeed, we show that?And c periodically returns to a very nearly circular state every 6,700 years. [ABSTRACT FROM AUTHOR]

The early Universe had a chemical composition consisting of hydrogen, helium and traces of lithium; almost all other elements were subsequently created in stars and supernovae. The mass fraction of elements more massive than helium, Z, is known as 'metallicity'. A number of very metal-poor stars has been found, some of which have a low iron abundance but are rich in carbon, nitrogen and oxygen. For theoretical reasons and because of an observed absence of stars with Z??5, it has been suggested that low-mass stars cannot form from the primitive interstellar medium until it has been enriched above a critical value of Z, estimated to lie in the range 1.5?×?10?8 to 1.5?×?10?6 (ref. 8), although competing theories claiming the contrary do exist. (We use 'low-mass' here to mean a stellar mass of less than 0.8 solar masses, the stars that survive to the present day.) Here we report the chemical composition of a star in the Galactic halo with a very low Z (??6.9?×?10?7, which is 4.5?×?10?5 times that of the Sun) and a chemical pattern typical of classical extremely metal-poor stars-that is, without enrichment of carbon, nitrogen and oxygen. This shows that low-mass stars can be formed at very low metallicity, that is, below the critical value of Z. Lithium is not detected, suggesting a low-metallicity extension of the previously observed trend in lithium depletion. Such lithium depletion implies that the stellar material must have experienced temperatures above two million kelvin in its history, given that this is necessary to destroy lithium. [ABSTRACT FROM AUTHOR]

Gamma-rays from radioactive 26Al (half-life ∼7.2 × 105 years) provide a ‘snapshot’ view of continuing nucleosynthesis in the Galaxy. The Galaxy is relatively transparent to such γ-rays, and emission has been found concentrated along its plane. This led to the conclusion that massive stars throughout the Galaxy dominate the production of 26Al. On the other hand, meteoritic data show evidence for locally produced 26Al, perhaps from spallation reactions in the protosolar disk. Furthermore, prominent γ-ray emission from the Cygnus region suggests that a substantial fraction of Galactic 26Al could originate in localized star-forming regions. Here we report high spectral resolution measurements of 26Al emission at 1808.65 keV, which demonstrate that the 26Al source regions corotate with the Galaxy, supporting its Galaxy-wide origin. We determine a present-day equilibrium mass of 2.8 (± 0.8) solar masses of 26Al. We use this to determine that the frequency of core collapse (that is, type Ib/c and type II) supernovae is 1.9 (± 1.1) events per century. [ABSTRACT FROM AUTHOR]

The chemically most primitive stars provide constraints on the nature of the first stellar objects that formed in the Universe; elements other than hydrogen, helium and traces of lithium present within these objects were generated by nucleosynthesis in the very first stars. The relative abundances of elements in the surviving primitive stars reflect the masses of the first stars, because the pathways of nucleosynthesis are quite sensitive to stellar masses. Several models have been suggested to explain the origin of the abundance pattern of the giant star HE0107-5240, which hitherto exhibited the highest deficiency of heavy elements known. Here we report the discovery of HE1327-2326, a subgiant or main-sequence star with an iron abundance about a factor of two lower than that of HE0107-5240. Both stars show extreme overabundances of carbon and nitrogen with respect to iron, suggesting a similar origin of the abundance patterns. The unexpectedly low Li and high Sr abundances of HE1327-2326, however, challenge existing theoretical understanding: no model predicts the high Sr abundance or provides a Li depletion mechanism consistent with data available for the most metal-poor stars. [ABSTRACT FROM AUTHOR]

Griffith and Montgomerie question our finding that extra-pair parentage in shorebirds correlates with the genetic similarity of social mates, on the grounds that band-sharing coefficients (calculated by comparing bands on DNA fingerprints) are unreliable for determining the degree of genetic similarity between two individuals. [ABSTRACT FROM AUTHOR]

Female birds often copulate with males that are not their social partner, but why they do this is unclear. Blomqvist et al. present evidence from three wader species showing that extra-pair fertilizations are more likely when social mates are genetically closely related. We argue, however, that their conclusions are undermined on technical and theoretical grounds, and that there is still no convincing evidence that extra-pair copulation in birds is influenced by the relatedness between partners. [ABSTRACT FROM AUTHOR]

Focuses on the definition of the term right kiss. Illustration of a right kiss which corresponds to a position in which the nose of each participant is to the right of the nose of the other; Incorporation of a turn and tilt with the head to the right side in the right kiss.

The signature of [sup.60]Fe in deep-sea crusts indicates that one or more supernovae exploded in the solar neighbourhood about 2.2 million years ago (1-4). Recent isotopic analysis is consistent with a core-collapse or electron-capture supernova that occurred 60 to 130 parsecs from the Sun (5). Moreover, peculiarities in the cosmic ray spectrum point to a nearby supernova about two million years ago (6). The Local Bubble of hot, diffuse plasma, in which the Solar System is embedded, originated from 14 to 20 supernovae within a moving group, whose surviving members are now in the Scorpius-Centaurus stellar association (7,8). Here we report calculations of the most probable trajectories and masses of the supernova progenitors, and hence their explosion times and sites. The [sup.60]Fe signal arises from two supernovae at distances between 90 and 100 parsecs. The closest occurred 2.3 million years ago at present-day galactic coordinates l = 327°, b = 11°, and the second-closest exploded about 1.5 million years ago at l = 343°, b = 25°, with masses of 9.2 and 8.8 times the solar mass, respectively. The remaining supernovae, which formed the Local Bubble, contribute to a smaller extent because they happened at larger distances and longer ago ([sup.60]Fe has a half-life of 2.6 million years (9,10)). There are uncertainties relating to the nucleosynthesis yields and the loss of [sup.60]Fe during transport, but they do not influence the relative distribution of [sup.60]Fe in the crust layers, and therefore our model reproduces the measured relative abundances very well., It has been shown that supernovae from a moving stellar group, whose surviving members are now in the Sco-Cen association, were able to generate the Local Bubble (7,11). This hypothesis [...]

The rate of supernovae in our local Galactic neighbourhood within a distance of about 100 parsecs from Earth is estimated to be one every 2-4 million years, based on the [...]

Author(s): Roland Diehl (corresponding author) [1]; Hubert Halloin [1]; Karsten Kretschmer [1]; Giselher G. Lichti [1]; Volker Schönfelder [1]; Andrew W. Strong [1]; Andreas von Kienlin [1]; Wei Wang [1]; [...]

Author(s): Timothy C. Beers (corresponding author) Late last year, the discovery of the most iron-deficient star yet identified, HE0107-5240, was announced. This star has a measured abundance of iron less [...]