Search

The Cosmic Gems arc is among the brightest and highly magnified galaxies observed at redshift z ≈ 10.2 (ref.  1 ). However, it is an intrinsically ultraviolet faint galaxy, in the range of those now thought to drive the reionization of the Universe 2-4 . Hitherto the smallest features resolved in a galaxy at a comparable redshift are between a few hundreds and a few tens of parsecs (pc) 5,6 . Here we report JWST observations of the Cosmic Gems. The light of the galaxy is resolved into five star clusters located in a region smaller than 70 pc. They exhibit minimal dust attenuation and low metallicity, ages younger than 50 Myr and intrinsic masses of about 10 6 M ⊙ . Their lensing-corrected sizes are approximately 1 pc, resulting in stellar surface densities near 10 5 M ⊙  pc -2 , three orders of magnitude higher than typical young star clusters in the local Universe 7 . Despite the uncertainties inherent to the lensing model, they are consistent with being gravitationally bound stellar systems, that is, proto-globular clusters. We conclude that star cluster formation and feedback likely contributed to shaping the properties of galaxies during the epoch of reionization., (© 2024. The Author(s).)

Galaxy clusters magnify background objects through strong gravitational lensing. Typical magnifications for lensed galaxies are factors of a few but can also be as high as tens or hundreds, stretching galaxies into giant arcs 1,2 . Individual stars can attain even higher magnifications given fortuitous alignment with the lensing cluster. Recently, several individual stars at redshifts between approximately 1 and 1.5 have been discovered, magnified by factors of thousands, temporarily boosted by microlensing 3-6 . Here we report observations of a more distant and persistent magnified star at a redshift of 6.2 ± 0.1, 900 million years after the Big Bang. This star is magnified by a factor of thousands by the foreground galaxy cluster lens WHL0137-08 (redshift 0.566), as estimated by four independent lens models. Unlike previous lensed stars, the magnification and observed brightness (AB magnitude, 27.2) have remained roughly constant over 3.5 years of imaging and follow-up. The delensed absolute UV magnitude, -10 ± 2, is consistent with a star of mass greater than 50 times the mass of the Sun. Confirmation and spectral classification are forthcoming from approved observations with the James Webb Space Telescope., (© 2022. The Author(s), under exclusive licence to Springer Nature Limited.)

A fundamental quest of modern astronomy is to locate the earliest galaxies and study how they influenced the intergalactic medium a few hundred million years after the Big Bang 1-3 . The abundance of star-forming galaxies is known to decline 4,5 from redshifts of about 6 to 10, but a key question is the extent of star formation at even earlier times, corresponding to the period when the first galaxies might have emerged. Here we report spectroscopic observations of MACS1149-JD1 6 , a gravitationally lensed galaxy observed when the Universe was less than four per cent of its present age. We detect an emission line of doubly ionized oxygen at a redshift of 9.1096 ± 0.0006, with an uncertainty of one standard deviation. This precisely determined redshift indicates that the red rest-frame optical colour arises from a dominant stellar component that formed about 250 million years after the Big Bang, corresponding to a redshift of about 15. Our results indicate that it may be possible to detect such early episodes of star formation in similar galaxies with future telescopes.

The physical properties and elemental abundances of the interstellar medium in galaxies during cosmic reionization are important for understanding the role of galaxies in this process. We report the Atacama Large Millimeter/submillimeter Array detection of an oxygen emission line at a wavelength of 88 micrometers from a galaxy at an epoch about 700 million years after the Big Bang. The oxygen abundance of this galaxy is estimated at about one-tenth that of the Sun. The nondetection of far-infrared continuum emission indicates a deficiency of interstellar dust in the galaxy. A carbon emission line at a wavelength of 158 micrometers is also not detected, implying an unusually small amount of neutral gas. These properties might allow ionizing photons to escape into the intergalactic medium., (Copyright © 2016, American Association for the Advancement of Science.)

This study is the first to examine a large group of children born after in-vitro fertilization (IVF) who were old enough at the time of the investigation to make it possible to draw conclusions about the outcome. The aim of the study was to assess the cognitive, behavioural and social development of the children. The study comprised 99 IVF children, 33-85 months of age, from the University Hospitals of Lund and Malmö, Sweden. The children's development was assessed with the Griffiths' scales of mental development. The children's behaviour was delineated through semi-structured interviews with their mothers, covering 50 different behaviours. The mothers also filled in Achenbach's Child Behaviour Checklist (CBCL). All children were examined by a paediatric neurologist. The results were compared to Swedish population groups. Of the children born, 66% were singletons, 22% were twins, 12% were triplets and 28% were born prematurely in gestational weeks 32-36. The cognitive development of the IVF children was excellent, and their behaviour was normal when compared with two Swedish population groups. Our conclusion was that the development, behaviour and social adaptation of the children was very satisfactory.