Evidence from stellar rotation of enhanced disc dispersal: (I) The case of the triple visual system BD-21 1074 in the β\beta Pictoris association

The early stage of stellar evolution is characterized by a star-disc locking mechanism. The disc-locking prevents the star to spin its rotation up, and its timescale depends on the disc lifetime. Some mechanisms can significantly shorten this lifetime, allowing a few stars to start spinning up much earlier than other stars. In the present study, we aim to investigate how the properties of the circumstellar environment can shorten the disc lifetime. We have identified a few multiple stellar systems, composed of stars with similar masses, which belong to associations with a known age. Since all parameters that are responsible for the rotational evolution, with the exception of environment properties and initial stellar rotation, are similar for all components, we expect that significant differences among the rotation periods can only arise from differences in the disc lifetimes. A photometric timeseries allowed us to measure the rotation periods of each component, while high-resolution spectra provided us with the fundamental parameters, $v\sin{i}$ and chromospheric line fluxes. The rotation periods of the components differ significantly, and the component B, which has a closer companion C, rotates faster than the more distant and isolated component A. We can ascribe the rotation period difference to either different initial rotation periods or different disc-locking phases arising from the presence of the close companion C. In the specific case of BD$-$21 1074, the second scenario seems to be more favored. In our hypothesis of different disc-locking phase, any planet orbiting this star is likely formed very rapidly owing to a gravitational instability mechanism, rather than core accretion. Only a large difference of initial rotation periods alone could account for the observed period difference, leaving comparable disc lifetimes.Comment: Accepted by Astronomy & Astrophysics on July 31, 2014; Pages 12, Figs.

Estimativas de parâmetros genéticos e fenotípicos em nível de indivíduo em populações segregantes de feijoeiro-comum.

O objetivo desse trabalho foi estimar os parâmetros genéticos e fenotípicos, em nível de indivíduo, de populações segregantes de feijoeiro-comum, grupo carioca, para caracteres de escurecimento e produção de grãos.CONAF

Selection of parents and segregating populations of common bean with high agronomic potential and slow seed-coat darkening.

Choosing parents and segregating populations are fundamental steps for the success in plant breeding. For the common bean crop, the development of genotypes that combine favorable agronomic traits and seed quality may increase the chances of adopting new cultivars. This study aimed to select promising parents and segregating populations to develop slow seed-coat darkening lines, together with high grain yield, lodging tolerance and short seed cooking time after storage, as well as to investigate the relationship between seed-coat darkening and seed cooking time after storage. Twenty segregating populations (F3, F4 and F5 generations) and their parents were evaluated. The sum of ranks index for combined traits was used in the selection of superior populations. Genetic and phenotypic correlations between seed-coat darkening and cooking time after storage were estimated. Among the parents, the BRSMG Madrepérola cultivar was the most promising to generate lines with seedcoat darkening. The superior populations were BRSMG Madrepérola x IPR Saracura, BRSMG Madrepérola x BRS Sublime, BRSMG Madrepérola x BRS Estilo and BRSMG Madrepérola x BRS Notável. A linear relationship was not found between seed-coat darkening and seed cooking time after storage, indicating that the first trait is not an adequate indicator to infer about seed cooking time

Giant planets around two intermediate-mass evolved stars and confirmation of the planetary nature of HIP67851 c

Precision radial velocities are required to discover and characterize planets orbiting nearby stars. Optical and near infrared spectra that exhibit many hundreds of absorption lines can allow the m/s precision levels required for such work. However, this means that studies have generally focused on solar-type dwarf stars. After the main-sequence, intermediate-mass stars (former A-F stars) expand and rotate slower than their progenitors, thus thousands of narrow absorption lines appear in the optical region, permitting the search for planetary Doppler signals in the data for these types of stars. We present the discovery of two giant planets around the intermediate-mass evolved star HIP65891 and HIP107773. The best Keplerian fit to the HIP65891 and HIP107773 radial velocities leads to the following orbital parameters: P=1084.5 d; m$_b$sin$i$ = 6.0 M$_{jup}$; $e$=0.13 and P=144.3 d; m$_b$sin$i$ = 2.0 M$_{jup}$; $e$=0.09, respectively. In addition, we confirm the planetary nature of the outer object orbiting the giant star HIP67851. The orbital parameters of HIP67851c are: P=2131.8 d, m$_c$sin$i$ = 6.0 M$_{jup}$ and $e$=0.17. With masses of 2.5 M$_\odot$ and 2.4 M$_\odot$ HIP65891 and HIP107773 are two of the most massive stars known to host planets. Additionally, HIP67851 is one of five giant stars that are known to host a planetary system having a close-in planet ($a <$ 0.7 AU). Based on the evolutionary states of those five stars, we conclude that close-in planets do exist in multiple systems around subgiants and slightly evolved giants stars, but probably they are subsequently destroyed by the stellar envelope during the ascent of the red giant branch phase. As a consequence, planetary systems with close-in objects are not found around horizontal branch stars.Comment: Accepted for publication in A&

Estimation of genetic parameters and selection of high-yielding, upright common bean lines with slow seed-coat darkening.

Slow seed coat darkening is desirable in common bean cultivars and genetic parameters are important to define breeding strategies. The aims of this study were to estimate genetic parameters for plant architecture, grain yield, grain size, and seed-coat darkening in common bean; identify any genetic association among these traits; and select lines that associate desirable phenotypes for these traits. Three experiments were set up in the winter 2012 growing season, in Santo Antônio de Goiás and Brasília, Brazil, including 220 lines obtained from four segregating populations and five parents. A triple lattice 15 x 15 experimental design was used. The traits evaluated were plant architecture, grain yield, grain size, and seed-coat darkening. Analyses of variance were carried out and genetic parameters such as heritability, gain expected from selection, and correlations, were estimated. For selection of superior lines, a ?weight-free and parameter-free? index was used. The estimates of genetic variance, heritability, and gain expected from selection were high, indicating good possibility for success in selection of the four traits. The genotype x environment interaction was proportionally more important for yield than for the other traits. There was no strong genetic correlation observed among the four traits, which indicates the possibility of selection of superior lines with many traits. Considering simultaneous selection, it was not possible to join high genetic gains for the four traits. Forty-four lines that combined high yield, more upright plant architecture, slow darkening grains, and commercial grade size were selected

Relação entre o escurecimento dos grãos de feijão carioca e o tempo de cocção.

Objetivo deste trabalho foi verificar a associação entre o retardamento do escurecimento dos grãos de feijão carioca e o seu tempo de cocção.CONAFE

Prediction of genetic potential of common bean segregant populations for slow seed-coat darkening.

The objective of this study was to predict the genetic potential of common bean segregant populations for slow seed-coat darkening

Induction of seed coat darkening in common beans (Phaseolus vulgaris L.) and the association with cooking time after storage.

Carioca is the most important edible dry bean (Phaseolus vulgaris L.) grown in Brazil. It represents the largest dry bean market class in the world. The seed coat of carioca beans will darken under adverse harvest conditions and with the increasing of storage time. In general, darkened seeds are associated with older seeds that suffer from prolonged cooking times. A relatively new 'slow darkening' trait is available in carioca that delays seed coat darkening under storage. However, its effect on cooking time is unknown. The objective of this work was to evaluate two induction methods of seed coat darkening and to examine the effect of slow darkening trait on cooking time after storage. Lines derived from four segregating populations resulting from crossings between cultivar BRSMG Madrepérola with slow seed coat darkening, and the parents BRS Estilo, BRS Cometa, BRS Notável and BRS Sublime with normal darkening were evaluated. An experiment inlcuding 220 lines, 55 per population and the five parents, in a 15x15 triple lattice was conducted in the winter growing season in Brasilia. Seed coat darkening and cooking time traits were evaluated. Two methods for inducing seed coat darkening were compared: an accelerated aging test using UV light for 72 hours, and an extended storage for 90 days under ambient conditions. The correlation between the induction methods ranged from 0.77 to 0.85 for the different populations indicating either method could be used to discriminate lines with normal versus slow darkening trait. The percentage of light-colored grain lines was identified by both induction methods of seed coat darkening ranged from 75 to 85.7% in the populations. The genetic correlation between seed coat darkening and cooking time varied from -0.06 to -0.48, indicating that in some populations there is no significant genetic correlation between seed coat darkening and cooking time. Thus, light colored grains are not indicative of low cooking time, when they are considered genotypes with genetic variation for the seed coat darkening

Caracterização da rede de avaliação final de linhagens de feijoeiro-comum da Embrapa Arroz e Feijão no período de1993 a 2008.

O objetivo desse trabalho foi caracterizar a etapa de avaliação final de linhagens elite de feijoeiro-comum da Embrapaquanto à distribuição dos ensaios por região geográfica, épocas de semeadura e tipo comercial de grão, no período de 1993 a 2008.CONAFE