The origin of young star clusters represents a major challenge for modern stellar astrophysics. While stellar rotation partially explains the colour spread observed along main-sequence turn-offs, i.e. where stars leave the main-sequence after the exhaustion of hydrogen in their core, and the multiple main sequences in the colour-magnitude diagrams of stellar systems younger than approximately 2 Gyr, it appears that an age difference may still be required to fulfill the observational constraints. Here we introduce an alternative approach that exploits the main-sequence turn-on, i.e. the point alongside the colour-magnitude diagram where pre-main-sequence stars join the main-sequence, to disentangle between the effects of stellar rotation and age to assess the presence, or lack thereof, of prolonged star formation in the approximately 40-Myr-old cluster NGC1818. Our results provide evidence for a fast star formation, confined within 8 Myr, thus excluding age differences as responsible for the extended main-sequence turn-offs, and leading the way to alternative observational perspectives in the exploration of stellar populations in young clusters.
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http://dx.doi.org/10.1038/s41467-022-31977-y | DOI Listing |
Environ Health Insights
November 2024
Department of Medical Microbiology, University of Ghana Medical School, Korle Bu, Accra, Ghana.
Background: Antibiotic resistance (ABR) poses a critical global health challenge, necessitating its surveillance across both human and animal health sectors. This study evaluated ABR in bacteria harboured in reared inland fishes sold in Accra and the pond water from which they originated.
Method: The study was cross-sectional, involving fishes and water sampled from 80 ponds.
Open Res Eur
July 2024
Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, CA 91125, USA.
Observations at (sub-)millimeter wavelengths offer a complementary perspective on our Sun and other stars, offering significant insights into both the thermal and magnetic composition of their chromospheres. Despite the fundamental progress in (sub-)millimeter observations of the Sun, some important aspects require diagnostic capabilities that are not offered by existing observatories. In particular, simultaneously observations of the radiation continuum across an extended frequency range would facilitate the mapping of different layers and thus ultimately the 3D structure of the solar atmosphere.
View Article and Find Full Text PDFNat Astron
July 2023
Center for Computational Astrophysics, Flatiron Institute, New York, New York USA.
Massive stars die in catastrophic explosions that seed the interstellar medium with heavy elements and produce neutron stars and black holes. Predictions of the explosion's character and the remnant mass depend on models of the star's evolutionary history. Models of massive star interiors can be empirically constrained by asteroseismic observations of gravity wave oscillations.
View Article and Find Full Text PDFInfect Drug Resist
August 2023
Department of Clinical Laboratory, The First Affiliated Hospital of Ningbo University, Ningbo, People's Republic of China.
Purpose: The objectives of this study are to determine the differences in clonality, virulence gene (VG) content and phylogenetic group between non extended-spectrum beta-lactamase-producing (non-ESBL-EC) and ESBL-EC isolates from urine.
Patients And Methods: This study characterized a total of 100 clinical isolates consecutively obtained from the inpatients hospitalized in The First Affiliated Hospital of Ningbo University in China by polymerase-chain reaction (PCR).
Results: Phylogenetic group B2 was found to be the most prevalent in both ESBL-EC and non-ESBL-EC group.
Nature
June 2023
Department of Physics and Astronomy, University of Notre Dame, Notre Dame, IN, USA.
When main-sequence stars expand into red giants, they are expected to engulf close-in planets. Until now, the absence of planets with short orbital periods around post-expansion, core-helium-burning red giants has been interpreted as evidence that short-period planets around Sun-like stars do not survive the giant expansion phase of their host stars. Here we present the discovery that the giant planet 8 Ursae Minoris b orbits a core-helium-burning red giant.
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