Volume 4 Issue 8, August 2020

During the last 15 years the number of astronomy-related papers published by scientists in Venezuela has been continuously decreasing, mainly due to emigration. If rapid corrective actions are not implemented, professional astronomy in Venezuela could disappear.

Long believed to be a primitive body, Ceres is now an ocean world with deep brines at a regional and potentially global scale. Further studies at Ceres’s conditions and — above all — a follow-up mission are needed to study its evolution and potential habitability.

The LIGO/Virgo collaboration recently announced the detection of an unusual compact binary merger including either the most massive neutron star or the least massive black hole known. The formation path of such a binary system is still up for debate.

Secondary gas disks around main sequence stars may regenerate planetary atmospheres, potentially transforming desiccated rocky worlds into gas-enveloped sub-Neptunes that feature high metallicities and enhanced atmospheric C/O ratios.

In the event of accidental transmission of microbes to other planets, we must consider whether the local conditions would allow their proliferation. Whereas temperatures on Mars are usually hostile to life, liquid water is available from deliquescing salts.

High-resolution data of Ceres’s bright spots (faculae), obtained by Dawn’s second extended mission, suggest the existence of a deep brine-rich reservoir that emerged to the surface through long-lived cryovolcanic activity as a consequence of the impact that created Occator crater.

High-resolution gravity data from Dawn’s second extended mission could probe the global and local structure of Ceres’s crust. The results show significant spatial and vertical variations of crustal density and porosity, associated with ice features and ice-related processes driven from the interior, and impacts.

A map of the stability of brines on Mars, obtained by combining thermodynamic and climate modelling, shows that some brines can stay liquid for longer than previously thought, particularly at high northern latitudes. However, they are not habitable to known terrestrial life, and can be explored without risk of biological contamination from Earth.

The abundances of isotopes in presolar grains are presumed to reflect their nucleosynthetic generation in stars. However, here Robert et al. report experimentally detected evidence of mass-independent fractionation of titanium, implying that titanium isotopic abundances in presolar grains may not be as representative as once thought.

The exoplanet atmospheres we study may not be primary atmospheres. Models show that the accretion of gas late in a planetary system’s formation may completely replace the primary atmospheres of terrestrial planets. These secondary atmospheres are likely to have high metallicities and high C/O ratios.

Simultaneous optical and gamma-ray observations of nova V906 Carinae reveal correlated flares in both wavelength ranges that can be linked to shocks in the nova ejecta. Weak X-ray emission suggests that the shocks are deeply embedded, but they contribute substantially to the luminosity of the nova.

Methane ice has been presumed to form via the sequential hydrogenation of carbon atoms on dust grains for many years, but now Qasim et al. have performed the experiment, with and without the presence of water. Methane forms more rapidly in the polar ice phase.

Spectroscopic data obtained at high spatial resolution from Dawn detected the presence of fresh chloride salts at Cerealia Facula on Ceres. The spatial distribution of the hydration level of these salts suggests that they surfaced a maximum of a few centuries ago and that the upwelling of salty fluids may still be active.

High-spatial-resolution images of the bright points at Occator crater on Ceres, taken during the second extended Dawn mission, allowed reconstruction of the chronology of their formation. The area experienced extensive cryovolcanism less than nine million years ago that lasted several million years, indicating recent geological activity.

Escherichia coli bacteria and yeast cultures (representative prokaryotes and eukaryotes) have been tested under laboratory conditions in a 100% H₂ atmosphere. They can reproduce normally, with lower growth rates, producing a range of biosignature gases. Exoplanets with a H₂-dominated atmosphere might thus not be totally hostile to some forms of life.

In its second extended mission at Ceres, the Dawn spacecraft returned a harvest of high-resolution data on the intriguing Occator crater, a landmark for understanding the role of impacts in shaping ice-rich bodies, explain Project Scientist Julie Castillo-Rogez and Chief Engineer Marc Rayman.