Manuel Esteve Domingo

New experimental sublimation energy measurements for some relevant astrophysical ices

Context. The knowledge of the sublimation energy of ices allows us to better understand the dynamics between surfaces and atmospheres of different environments of astrophysical interest where ices are present. Aims. This work is intended to provide sublimation energy values for a set of pure ices (CO, CH4 ,C O 2 ,N 2 ,a nd NH 3 )u sing an ew experimental procedure. The results were compared to some values obtained by other authors under different conditions and/or methods, to check the reliability of this new method. Methods. We used the frequency variation obtained from a quartz crystal microbalance to calculate the sublimation energy from the Polany-Wigner equation for the first time. Results. The results obtained are relevant since there are few previous values of sublimation energy reported on these molecules in these conditions of pressure and temperature, which are representative of astrophysical regions. These values are needed in models used to interpret dynamics of icy surfaces. In general, our results compare well to other ones obtained by different methods and complement those previously available.

Thermal desorption of CH4 retained in CO2 ice

CO2 ices are known to exist in different astrophysical environments. In spite of this, its physical properties (structure, density, refractive index) have not been as widely studied as those of water ice. It would be of great value to study the adsorption properties of this ice in conditions related to astrophysical environments. In this paper, we explore the possibility that CO2 traps relevant molecules in astrophysical environments at temperatures higher than expected from their characteristic sublimation point. To fulfil this aim we have carried out desorption experiments under High Vacuum conditions based on a Quartz Crystal Microbalance and additionally monitored with a Quadrupole Mass Spectrometer. From our results, the presence of CH4 in the solid phase above the sublimation temperature in some astrophysical scenarios could be explained by the presence of several retaining mechanisms related to the structure of CO2 ice.

Distributed Sensor System for Earthquake Early Warning Based on the Massive Use of Low Cost Accelerometers

This paper presents a different and innovative proposal to detect seismic events, a solution that uses smartphones as opportunistic sensor nodes to obtain real-time knowledge of the community environment through a hierarchical architecture, taking advantage of this growing trend. A distributed low-cost network formed of smartphones capable of detect a seismic-peak with a high accuracy by means of converting accelerometers in accelerographs optimizing distributed calculations in these. A server which considers time and spatial analyses not present in another works, making it more precise and customizable, coupling it to the features of the geographical zone, network and resources. Validated by extensive evaluation, the most relevant results have been the improvement in notifications delivery about a seismic-peak 12 seconds earlier in the epicenter zone, the reduced consumption of mobile battery and the reduction in the number of false positives. In addition, this challenge becomes an great opportunity giving people as much as tens of seconds warning before an earthquake occurs in places far from the epicenter.

Density of Ices of Astrophysical Interest

Density plays an important role in the understanding of chemical and physical evolution of ices in space. It is related with abundances, energetic processing, porosity, buoyancy, etc.

Densities, infrared band strengths, and optical constants of solid methanol

Funds have been provided for this research by the Spanish MINECO, Project FIS2016-77726-C3-1-P and FIS2016-77726-C3-3-P. German Molpeceres acknowledges MINECO PhD grant BES-2014-069355. We are grateful to R. Escribano for helpful discussions. Our skillful technicians C. Santonja, M. A. Moreno, and J. Rodriguez are also gratefully acknowledged.