GJ 273: On the formation, dynamical evolution, and habitability of a planetary system hosted by an M dwarf at 3.75 parsec

Context. Planets orbiting low-mass stars such as M dwarfs are now considered a cornerstone in the search for life-harbouring planets. GJ 273 is a planetary system orbiting an M dwarf only 3.75 pc away, composed of two confirmed planets, GJ 273b and GJ 273c, and two promising candidates, GJ 273d and GJ 273e. Planet GJ 273b resides in the habitable zone. Currently, due to a lack of observed planetary transits, only the minimum masses of the planets are known: Mb sin ib=2.89 M⊕, Mc sin ic=1.18 M⊕, Md sin id=10.80 M⊕, and Me sin ie=9.30 M⊕. Despite being an interesting system, the GJ 273 planetary system is still poorly studied. Aims. We aim at precisely determine the physical parameters of the individual planets, in particular to break the mass–inclination degeneracy to accurately determine the mass of the planets. Moreover, we present thorough characterisation of planet GJ 273b in terms of its potential habitability. Methods. First, we explored the planetary formation and hydration phases of GJ 273 during the first 100 Myr. Secondly, we analysed the stability of the system by considering both the two- and four-planet configurations. We then performed a comparative analysis between GJ 273 and the Solar System, and searched for regions in GJ 273 which may harbour minor bodies in stable orbits, i.e. main asteroid belt and Kuiper belt analogues. Results. From our set of dynamical studies, we obtain that the four-planet configuration of the system allows us to break the mass– inclination degeneracy. From our modelling results, the masses of the planets are unveiled as: 2:89 ≤ Mb ≤ 3:03 M⊕, 1:18 ≤ Mc ≤ 1:24 M⊕, 10:80 ≤ Md ≤ 11:35 M⊕ and 9:30 ≤ Me ≤ 9:70 M⊕. These results point to a system likely composed of an Earth-mass planet, a super-Earth and two mini-Neptunes. From planetary formation models, we determine that GJ 273b was likely an efficient water captor while GJ 273c is probably a dry planet. We found that the system may have several stable regions where minor bodies might reside. Collectively, these results are used to comprehensively discuss the habitability of GJ 273bSpanish Ministry of Science and Education Ramón y Cajal programme ESP2017-87676-2-2 RYC-2012-09913CONICYT- FONDECYT/Chile Postdoctorado 3180405MIT’s Kavli Institut

El Género Eucalyptus (Myrtaceae) en Galicia: Claves y descripción

This review focuses on the species of genus Eucalyptus (Myrtaceae) that are forest interested, planted or naturalized in Galicia, excluding those that only flourish in parks and gardens. Besides using poor herbarium material, we carried out recollections based on data provided by the forest districts, organizations and individuals as well as field trips by different areas of Galicia. Based on the morphological characteristics, 40 taxa (37 species and 3 subspecies), including several hybrids, have been identified. We have also included two keys to help in identification, which are the number of flowers per peduncle and the type of bark. In this review, we provide an overview of the present knowledge on the identification, description and distribution of each of the taxa.Se ha realizado una revisión de las especies de interés forestal, plantadas o asilvestradas, del género Eucalyptus (Myrtaceae) en Galicia, excluyendo aquellas que sólo se desarrollan en parques y jardines. Además del escaso material de herbario, nos hemos basado en herborizaciones basadas en datos aportados por los distritos forestales, organizaciones forestales y particulares, así como recorridos por distintas zonas de Galicia. En base a los caracteres morfológicos, se han identificado 40 taxa (37 especies y 3 subespecies) incluyendo varios híbridos. Se han confeccionado 2 claves de identificación, basadas en el número de flores por pedicelo o por el tipo de corteza. Aportamos una iconografía para facilitar la identificación, así como una descripción de cada uno de los taxa identificados y algunos datos sobre su distribución