A candidate super-Earth planet orbiting near the snow line of Barnard’s star

Barnard’s star is a red dwarf, and has the largest proper motion (apparent motion across the sky) of all known stars. At a distance of 1.8 parsecs, it is the closest single star to the Sun; only the three stars in the α Centauri system are closer. Barnard’s star is also among the least magnetically active red dwarfs known and has an estimated age older than the Solar System. Its properties make it a prime target for planetary searches; various techniques with different sensitivity limits have been used previously, including radial-velocity imaging, astrometry and direct imaging, but all ultimately led to negative or null results. Here we combine numerous measurements from high-precision radial-velocity instruments, revealing the presence of a low-amplitude periodic signal with a period of 233 days. Independent photometric and spectroscopic monitoring, as well as an analysis of instrumental systematic effects, suggest that this signal is best explained as arising from a planetary companion. The candidate planet around Barnard’s star is a cold super-Earth, with a minimum mass of 3.2 times that of Earth, orbiting near its snow line (the minimum distance from the star at which volatile compounds could condense). The combination of all radial-velocity datasets spanning 20 years of measurements additionally reveals a long-term modulation that could arise from a stellar magnetic-activity cycle or from a more distant planetary object. Because of its proximity to the Sun, the candidate planet has a maximum angular separation of 220 milliarcseconds from Barnard’s star, making it an excellent target for direct imaging and astrometric observations in the future. © 2018, Springer Nature Limited.The results are based on observations made with the CARMENES instrument at the 3.5-m telescope of the Centro Astronomico Hispano-Aleman de Calar Alto (CAHA, Almeria, Spain), funded by the German Max-Planck-Gesellschaft (MPG), the Spanish Consejo Superior de Investigaciones Cientificas (CSIC), the European Union and the CARMENES Consortium members; the 90-cm telescope at the Sierra Nevada Observatory (Granada, Spain) and the 40-cm robotic telescope at the SPACEOBS observatory (San Pedro de Atacama, Chile), both operated by the Instituto de Astrofisica de Andalucia (IAA); and the 80-cm Joan Oro Telescope (TJO) of the Montsec Astronomical Observatory (OAdM), owned by the Generalitat de Catalunya and operated by the Institute of Space Studies of Catalonia (IEEC). This research was supported by the following institutions, grants and fellowships: Spanish MINECO ESP2016-80435-C2-1-R, ESP2016-80435-C2-2-R, AYA2016-79425-C3-1-P, AYA2016-79245-C3-2-P, AYA2016-79425-C3-3-P, AYA2015-69350-C3-2-P, ESP2014-54362-P, AYA2014-56359-P, RYC-2013-14875; Generalitat de Catalunya/CERCA programme; Fondo Europeo de Desarrollo Regional (FEDER); German Science Foundation (DFG) Research Unit FOR2544, project JE 701/3-1; STFC Consolidated Grants ST/P000584/1, ST/P000592/1, ST/M001008/1; NSF AST-0307493; Queen Mary University of London Scholarship; Perren foundation grant; CONICYT-FONDECYT 1161218, 3180405; Swiss National Science Foundation (SNSF); Koshland Foundation and McDonald-Leapman grant; and NASA Hubble Fellowship grant HST-HF2-51399.001. J.T. is a Hubble Fellow

Extrasolar enigmas: from disintegrating exoplanets to exoasteroids

Thousands of transiting exoplanets have been discovered to date, thanks in great part to the {\em Kepler} space mission. As in all populations, and certainly in the case of exoplanets, one finds unique objects with distinct characteristics. Here we will describe the properties and behaviour of a small group of `disintegrating' exoplanets discovered over the last few years (KIC 12557548b, K2-22b, and others). They evaporate, lose mass unraveling their naked cores, produce spectacular dusty comet-like tails, and feature highly variable asymmetric transits. Apart from these exoplanets, there is observational evidence for even smaller `exo-'objects orbiting other stars: exoasteroids and exocomets. Most probably, such objects are also behind the mystery of Boyajian's star. Ongoing and upcoming space missions such as {\em TESS} and PLATO will hopefully discover more objects of this kind, and a new era of the exploration of small extrasolar systems bodies will be upon us.Comment: Accepted for publication in the book "Reviews in Frontiers of Modern Astrophysics: From Space Debris to Cosmology" (eds Kabath, Jones and Skarka; publisher Springer Nature) funded by the European Union Erasmus+ Strategic Partnership grant "Per Aspera Ad Astra Simul" 2017-1-CZ01-KA203-03556

Male performance in pistachio (Pistacia vera)

This research was performed in order to select male performance with good criteria in the Pistachio Research Institute. The study was conducted on 10 genotype until flowering time, pollen quantity and pollen quality were evaluated. The results indicated that flowering times P1, P2 male genotypes were simultaneous with Kallehghochi female genotype; P3, P4, P5 male genotypes with female Ahmad Aghaii genotype; P6 and P7 male genotypes with femal Ohadi genotype and P8, P9, P10 male genotypes with femal Akbari genotype. Inflorescence density showed big differences between male genotypes, ranging from 4.5g for P6 to 1.66 g for P8, the average being 3.138g. The amount of pollen per inflorescence also showed big differences, ranging from 0.071g for P2 and 0.267g for P5, the average being 0.168g. Inflorescence density and pollen per in florescence are not related and there are clones with a good inflorescence density and a poor amount of pollen per inflorescence and vice versa. In order to determine the percentages of pollen germination, a medium consisted of sucrose, agar and boric acid was used. The results of percentages of germinated pollen showed significant differences between experimental samples: ranging from 30% for P3 and P4 to 85% for P10, the average was 56%. Medium culture without boric acid was lower in compare to other treatment. The viability of pollen collected from cutting inflorescences kept in water bottle was higher than dried inflorescences maintained at room condition.Peer reviewe

Salt response of seeds and pollen of pistacia species

5 Pags. The definitive version is available at: http://www.actahort.org/The salt response of five Pistacia species at the germination stage has been investigated and we have evaluated if the germination capability of seeds and pollen under salt stress parallel to each other. Seeds of P. atlantica, P. terebinthus, P, palaestina, P. vera and inter P. atlantica et P. terebinthus were germinated in six saline solutions with electrical conductivities (EC) ranging from 7 to 42 dS/m. Similarly, pollen was germinated in vitro in twelve saline solutions with ECs ranging from 0.5 to 11.5 dS/m. The EC50, EC at which germination capacity was 50% of the control, was used as the salinity-tolerance parameter. Germination decreased with increasing salinities in the five species. The ranking in salinity tolerance for seed germination, as given by the EC50 (dS/m) in parenthesis, decreased in the order: P. atlantica (26.9) > inter P. atlantica et P. terebinthus (23.2) > P. terebinthus (22.5) > P. palaestina (19.8) > P. vera (18.4). Decreases of pollen germination with increasing salinities were much larger, indicating that the pollen is much more sensitive to salinity. The corresponding ranking for pollen germination was: P: terebinthus (7.3) > inter P. atlantica et P. terebinthus (7.0) > P. atlantica (6.2) > P. vera (3.1) > P. palaestina (2.9). The results suggest a certain parallelism between the salinity tolerance at the gametophytic (pollen) and sporophytic (seed) phases. If this conclusion is substantiated with a larger number of Pistacia species, it will offer a potential for selection at the gametophytic phase and therefore, for facilitating and speeding up the screening for salt tolerance.We acknowledge INIA for the award of a scholarship lo E.M-P. Financial support carne from projects INIA 9123 and CICYT AGR 92- 0739.Peer reviewe