Articles in 2019

Star DMPP-1 hosts a compact, four-planet system comprising three irradiated super-Earth-mass planets and one Neptune-mass planet, discovered through radial velocity measurements and the star’s anomalously low chromospheric emission.

This Article provides an overview of the Dispersed Matter Planet Project, a programme to discover close-in exoplanets being ablated by their host stars by means of the stars’ anomalously low chromospheric emission. One example is presented here: DMPP-2 hosts a sub-Jupiter-mass planet around a γ Doradus pulsator.

The third target of the Dispersed Matter Planet Project, DMPP-3, is an unusual binary system containing a solar-type star ablating a super-Earth-mass planet, along with a very low mass secondary.

Dust in the Solar System originates primarily in two locations: the interstellar medium and stellar outflows. On the basis of measurements of palladium isotopes in iron meteorites, Ek et al. suggest that the interstellar component was destroyed in the inner Solar System, revealing an enhancement of s-process isotopes from stardust.

Coupling a global surface hydrology model to an existing atmospheric model of Titan reproduces the observed variable climate and distribution of surface liquid, with possible implications for an unobserved methane reservoir on Titan.

The large-scale spatial distribution of local active galactic nuclei can constrain the black hole–stellar mass relation and their mean radiative efficiency to 10–20%, suggesting moderate to high spins for the vast majority of supermassive black holes.

16 out of 17 spectral observations of Europa, spanning from February 2016 to May 2017, did not see anything, but the one on 26 April 2016 shows evidence of a direct detection of water vapour, compatible with a column density of 1.4 ± 0.4 × 10¹⁹ H₂O m⁻². Whatever water activity there is on Europa, it is very sporadic.

On its departure from the heliosphere, the plasma experiment on Voyager 2 observed changes corresponding to a 1.5-au-wide boundary region, followed by a much thinner boundary layer, before reaching the heliopause. Outside the heliopause, the very local interstellar medium is found to be hotter than expected. [The summary that originally appeared was incorrect and has been updated.]

This paper reports measurements of the magnetic fields and energetic particles detected by the Voyager 2 spacecraft as it passed from the heliosphere, through the heliosheath and heliopause, to the interstellar medium. As predicted by models, Voyager 2 encountered a ‘magnetic barrier’ before reaching the heliopause.

This Article reports measurements from the plasma wave instruments of the Voyager spacecraft as they passed from the heliosphere into interstellar space. The Voyager 2 instrument recorded an electron density jump of a factor of 20, similar to that from Voyager 1 several years previously.

As it crossed the heliopause, Voyager 2 observed a sharp decrease in measurements of the low-energy ions that originate within the heliosphere, and an increase in the cosmic rays from the Milky Way, without any of the precursor flux tubes that Voyager 1 experienced. Outside the heliopause, a boundary layer exists.

Measurements of energetic ions and electrons with the Low-Energy Charged Particle instrument on Voyager 2 are presented from the boundary of the heliosphere and from the interstellar medium. Voyager 2’s heliopause crossing bears some similarity to that of Voyager 1, despite differing solar wind conditions.

The standard cosmological model assumes a flat Universe, but some model inconsistencies appear when curvature is allowed, as supported by the latest Planck Legacy 2018 power spectra. Is it time to consider new physics?

Using an atomic gas aggregation process in the laboratory to simulate the conditions in the inner regions of a carbon-rich evolved star, Martínez, Santoro, Merino and colleagues. show that aromatic species and fullerenes form surprisingly inefficiently, and that amorphous carbon nanograins and aliphatic clusters dominate.

A series of four storms appeared on Saturn’s northern polar region in 2018, unusually close to each other in space and time. By their dimension and the energy needed to form them, they appear to be a hitherto unobserved kind of storm at Saturn, intermediate between the regional- and the global-sized ones.

Graur et al. present near-infrared light curves of five type Ia supernovae based on Hubble Space Telescope data that show plateaux at late times (>150 days) rather than the expected ‘infrared catastrophe’. The authors suggest that the year-long plateaux are produced by the scattering of ultraviolet photons.

Asteroid families created by collisions in the last ~100 Myr have a higher fraction of subfamilies than older ones. The impact produces highly rotating fragments that generate such subfamilies by fission and subsequently disperse. The final appearance of an asteroid family is thus the product of a drawn-out evolution.

The range of sizes of old star clusters in the LMC does not necessarily imply the presence of binary black holes within them; the spread can be explained as a consequence of internal dynamical evolution and formation conditions. Looking at five old LMC clusters, Ferraro et al. find signs of dynamical youth.

An extensive survey to search for members of the only known Kuiper belt family, named after the parent body Haumea, found no family members fainter than absolute magnitude H_r = 7.9, significantly brighter than the detection limit (H_r = 9.5). This lack of small members is inconsistent with a catastrophic disruption as the origin of the Haumea family.

Radial velocity data of the young β Pictoris system acquired by HARPS and spanning 15 years show evidence of β Pic c, a gas giant of ~9 Jupiter masses orbiting on an eccentric orbit at ~2.4 au from the star, near the theoretical snowline. Both β Pic b and c, located close to the star, may have formed in situ by core accretion.