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Common dynamo scaling in slowly rotating young and evolved stars
Spada, Federico; Lehtinen, Jyri J.; Käpylä, Maarit J. +2 more
One interpretation of the activity and magnetism of late-type stars is that these both intensify with decreasing Rossby number up to a saturation level1-3, suggesting that stellar dynamos depend on both rotation and convective turbulence4. Some studies have claimed, however, that rotation alone suffices to parametrize this sc…
Resolving the Crab pulsar wind nebula at teraelectronvolt energies
H. E. S. S. Collaboration
The Crab nebula is one of the most-studied cosmic particle accelerators, shining brightly across the entire electromagnetic spectrum up to very-high-energy gamma rays1,2. It is known from observations in the radio to gamma-ray part of the spectrum that the nebula is powered by a pulsar, which converts most of its rotational energy losse…
A basin-free spherical shape as an outcome of a giant impact on asteroid Hygiea
Jorda, L.; Lamy, P.; Colas, F. +44 more
(10) Hygiea is the fourth largest main belt asteroid and the only known asteroid whose surface composition appears similar to that of the dwarf planet (1) Ceres1,2, suggesting a similar origin for these two objects. Hygiea suffered a giant impact more than 2 Gyr ago3 that is at the origin of one of the largest asteroid famili…
An eclipsing substellar binary in a young triple system discovered by SPECULOOS
Kunovac Hodžić, Vedad; Triaud, Amaury H. M. J.; Burgasser, Adam J. +18 more
Mass, radius and age are three of the most fundamental parameters for celestial objects, enabling insight into the evolution and internal physics of stars, brown dwarfs and planets. Brown dwarfs are hydrogen-rich objects that are unable to sustain core fusion reactions but are supported against collapse by electron degeneracy pressure1.…
Global helium abundance measurements in the solar corona
Telloni, Daniele; Antonucci, Ester; Fineschi, Silvano +24 more
Solar abundances have been historically assumed to be representative of cosmic abundances. However, our knowledge of the solar abundance of helium, the second most abundant element, relies mainly on models1 and indirect measurements through helioseismic observations2, because actual measurements of helium in the solar atmosph…
A pulsating white dwarf in an eclipsing binary
Hermes, J. J.; Parsons, Steven G.; Breedt, Elmé +8 more
White dwarfs are the burnt-out cores of Sun-like stars and are the fate of 97 per cent of the stars in our Galaxy. The internal structure and composition of white dwarfs are hidden by their high gravities, which causes all elements apart from the lightest ones to settle out of their atmospheres. The most direct method of probing the inner structur…
Infalling gas in a Lyman-α blob
Kohno, Kotaro; Lehnert, Matthew D.; Menten, Karl M. +11 more
Lyman-α blobs (LABs) are spatially extended nebulae of emission in the Lyman-α (Lyα) line of hydrogen, seen at high redshifts1,2, and most commonly found in the dense environment of star-forming galaxies3,4. A recent study showed that nearly 100% of the sky is covered by Lyα emission around high-redshift galaxies5-7
Highlights of exoplanetary science from Spitzer
Deming, Drake; Knutson, Heather A.
Observations of extrasolar planets were not projected to be a substantial part of the Spitzer Space Telescope's mission when it was conceived and designed. Nevertheless, Spitzer was the first facility to detect thermal emission from a hot Jupiter-sized planet, and the range of its exoplanetary investigations grew to encompass transiting planets, m…
A plague of magnetic spots among the hot stars of globular clusters
Gullieuszik, M.; Milone, A. P.; Stetson, P. B. +15 more
For more than six decades, the quest to understand the formation of hot (about 20,000-30,000 K) extreme horizontal branch (EHB) stars in Galactic globular clusters has remained one of the most elusive in stellar evolutionary theory. Here we report on two discoveries that challenge the idea of the stable luminosity of EHB stars. The first mode of E…
Diffuse X-ray emission around an ultraluminous X-ray pulsar
Wolter, Anna; Pintore, Fabio; Mereghetti, Sandro +17 more
Ultraluminous X-ray sources (ULXs) are extragalactic X-ray emitters located off-centre of their host galaxy and with a luminosity in excess of a few 1039 erg s-1, if emitted isotropically1,2. The discovery of periodic modulation revealed that in some ULXs the accreting compact object is a neutron star3-7…