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| Open AccessFast rotating blue stragglers prefer loose clusters
Blue Stragglers Stars (BSSs) are anomalously luminous main sequence stars in clusters. Here, the authors show evidence that the fraction of fast rotating BSSs increases for decreasing central density of the host system, suggesting fast spinning BSSs prefer low-density environments.
- Francesco R. Ferraro
- , Alessio Mucciarelli
- & Mario Mateo
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Article
| Open AccessMetal-rich stars are less suitable for the evolution of life on their planets
Low stellar ultraviolet (UV) radiation leads to low ozone abundances, therefore, less planetary UV protection. Here, the authors show that planets in the habitable zones of metal-poor stars, despite their higher UV radiation than metal-rich stars, are the best targets for search for life.
- Anna V. Shapiro
- , Christoph Brühl
- & Jos Lelieveld
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Article
| Open AccessEvidence of structural discontinuities in the inner core of red-giant stars
Red giant stars enter the clump phase as the helium in the cores start fusing. Here, the authors show evidence for large core structural discontinuities in 7% of Kepler satellite clump star data implying that the mixing region beyond the convective core boundary has a radiative thermal stratification.
- Mathieu Vrard
- , Margarida S. Cunha
- & Benoît Mosser
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Article
| Open AccessThe imprint of star formation on stellar pulsations
The classical stellar evolution concept assumes that when the stars arrive on the main sequence, there is no traceable mark remains about their early evolutionary history. Here, the authors show that the accretion history leaves an imprint on the interior structure of the stars that are potentially detectable via asteroseismology.
- Thomas Steindl
- , Konstanze Zwintz
- & Eduard Vorobyov
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Article
| Open AccessNGC1818 unveils the origin of the extended main-sequence turn-off in young Magellanic Clouds clusters
The nature of young star clusters in the Magellanic Clouds is debated. Here, the authors show an alternative approach that exploits data to exclude the presence of age differences greater than a few million years among cluster stars in a very young cluster.
- Giacomo Cordoni
- , Antonino P. Milone
- & Maria V. Legnardi
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| Open AccessSpectroscopic evidence for a large spot on the dimming Betelgeuse
The reason of the dimming of Betelgeuse is debated. Here, the authors show effective temperature decrease that can be explained by a large spot.
- Sofya Alexeeva
- , Gang Zhao
- & Shaoming Hu
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Article
| Open AccessPhosphorus-rich stars with unusual abundances are challenging theoretical predictions
Current models of Galactic chemical evolution under predict the phosphorus we observe in our Solar System. Here, the authors show the discovery of 15 phosphorus-rich stars with a peculiar abundance pattern that challenges the present stellar nucleosynthesis theoretical predictions, but which could explain the missing source of phosphorus in the Galaxy.
- Thomas Masseron
- , D. A. García-Hernández
- & Carlos Dafonte
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Article
| Open AccessMeasuring the ionisation fraction in a jet from a massive protostar
The ionisation fraction of protostellar jets is key to establish their true energetics. Here, the authors determine it in a jet from a high-mass young stellar object, using multi-wavelengths observations, confirming that the ionising mechanism giving rise to the radio emission originates from shocks.
- R. Fedriani
- , A. Caratti o Garatti
- & M. Hoare
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Article
| Open AccessAstrometrically registered maps of H2O and SiO masers toward VX Sagittarii
The red supergiant VX Sagittarii is a strong emitter of H2O and SiO masers, however its mass loss dynamics are still poorly understood. Here, the authors present astrometrically registered, simultaneous maps of SiO and H2O maser regions, and provide observational evidence for a break in spherical symmetry between the SiO and H2O maser zone.
- Dong-Hwan Yoon
- , Se-Hyung Cho
- & Do-Young Byun
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Article
| Open AccessA light carbon isotope composition for the Sun
The Sun’s light stable isotopes compositions can help us understand how our solar system formed. Here, the authors find that solar C is depleted relative to bulk Earth indicating that the 13C enrichment of the terrestrial planets is from CO self-shielding or inheritance from the parent cloud.
- James R. Lyons
- , Ehsan Gharib-Nezhad
- & Thomas R. Ayres
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Article
| Open AccessA peculiar low-luminosity short gamma-ray burst from a double neutron star merger progenitor
A short-duration gamma-ray burst was detected along with a double neutron start merger gravitational wave by LIGO-Virgo on August 17th 2017. Here, the authors show that the fluence and spectral peak energy of this event fall into the lower portion of the distribution of known short-duration gamma-ray bursts.
- B.-B. Zhang
- , B. Zhang
- & E.-W. Liang
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Article
| Open AccessA circular white-light flare with impulsive and gradual white-light kernels
White-light flares are rare solar events entailing emission in the optical continuum. Here, the authors report a nearly circular white-light flare observed on March 10th 2015 that contains simultaneously both impulsive and gradual white-light kernels.
- Q. Hao
- , K. Yang
- & Z. Li
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Article
| Open AccessImaging spectroscopy of solar radio burst fine structures
Radio observations of the solar atmosphere provide a unique view on the non-thermal processes in the outer atmosphere. Here the authors use LOFAR observations to demonstrate that the observed radio burst characteristics are dominated by propagation effects rather than underlying emission variations.
- E. P. Kontar
- , S. Yu
- & P. Subramanian
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Article
| Open AccessBuildup of a highly twisted magnetic flux rope during a solar eruption
Solar eruptions provide opportunities to study magnetic flux ropes, a structure of fundamental importance for both plasma physics and space weather. Here the authors reveal the dynamic formation of a flux rope through its footprint on the solar surface, revealing a highly twisted core structure.
- Wensi Wang
- , Rui Liu
- & Chunming Zhu
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| Open AccessA Solar cycle correlation of coronal element abundances in Sun-as-a-star observations
The Sun’s elemental composition is a vital part of understanding the processes that transport energy from the interior to the outer atmosphere. Here, the authors show that if the Sun is observed as a star, then the variation of coronal composition is highly correlated with the F10.7cm radio flux.
- David H. Brooks
- , Deborah Baker
- & Harry P. Warren
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| Open AccessEvidence from stable isotopes and 10Be for solar system formation triggered by a low-mass supernova
One hypothesis for solar system formation is gas compression by a nearby supernova, whose traces should be found in isotopic anomalies. Here the authors show that this mechanism is viable only if the triggering event was a low-mass supernova, looking at short-lived 10Be and lack of anomalies in stable isotopes.
- Projjwal Banerjee
- , Yong-Zhong Qian
- & W C Haxton
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Article
| Open AccessOptical analogues of the Newton–Schrödinger equation and boson star evolution
In the weak field limit, boson star evolution is governed by the Newton-Schrödinger equation. Here the authors report an optical setup that provides a formal analogue of such dynamics via the interaction between vortex beams and a medium with positive thermo-optical nonlinearity.
- Thomas Roger
- , Calum Maitland
- & Daniele Faccio
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| Open AccessThe Macronova in GRB 050709 and the GRB-macronova connection
A macronova is a clear signature that a short gamma-ray burst has been emitted by a compact-binary merger, but evidence of these events is so far scarce. Here, the authors report signs of a macronova in the optical afterglow of GRB050709, and find similar evidence in other three short bursts.
- Zhi-Ping Jin
- , Kenta Hotokezaka
- & Tsvi Piran
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Article
| Open AccessLaboratory analogue of a supersonic accretion column in a binary star system
Stationary radiative shocks are expected to form above the surface of highly-magnetized white dwarves in binary systems, but this cannot be resolved by telescopes. Here, the authors report a laboratory experiment showing the evolution of a reverse shock when both ionization and radiative losses are important.
- J. E. Cross
- , G. Gregori
- & É. Falize
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| Open AccessA low pre-infall mass for the Carina dwarf galaxy from disequilibrium modelling
The cold dark matter paradigm predicts that Milky Way-like galaxies should have dwarf galaxies with dark matter halos as satellites. Ural et al.present a new model, independent of cosmological simulations, that constrains the pre-infall mass of the Milky Way satellite Carina to a value lower than expected.
- Uğur Ural
- , Mark I. Wilkinson
- & Matthew G. Walker
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| Open AccessA possible macronova in the late afterglow of the long–short burst GRB 060614
The gamma-ray burst GRB 060614 was an unusual astrophysical event whose origins are still unclear. This study re-examines the burst’s afterglow data and finds an excess in the spectrum that appears to be consistent with a weak macronova, suggesting that GRB 060614 originated from a compact binary merger.
- Bin Yang
- , Zhi-Ping Jin
- & Da-Ming Wei
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Article |
Discovery of X-ray pulsations from a massive star
Optical light from many stars is known to pulsate and degenerate objects, like neutron stars, are known to emit pulses of X-rays, but X-ray pulsations have yet to be associated with non-degenerate objects. Here, Oskinova et al. find X-ray pulsations from a non-degenerate object: the massive B-type star ξ1CMa.
- Lidia M. Oskinova
- , Yael Nazé
- & Wolf-Rainer Hamann
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Review Article |
Type Ia supernovae as stellar endpoints and cosmological tools
Type Ia supernovae are thought to result from the explosion of white dwarf stars but a full understanding of their formation is lacking. In this review, Howell describes how large surveys are generating sufficient data to challenge and refine existing theories.
- D. Andrew Howell