KIC 9821622: An interesting lithium-rich giant in the Kepler field

We report the discovery of a new exceptional young lithium-rich giant, KIC 9821622, in the \textit{Kepler} field that exhibits an unusually large enhancement of $\alpha$, Fe-peak, and \textit{r}-process elements. From high-resolution spectra obtained with GRACES at Gemini North, we derived fundamental parameters and detailed chemical abundances of 23 elements from equivalent widths and synthesis analysis. By combining atmospheric stellar parameters with available asteroseismic data, we obtained the stellar mass, radius, and age. The data analysis reveals that KIC 9821622 is a Li-rich (A(Li)$_{NLTE}$ = 1.80 $\pm$ 0.2) intermediate-mass giant star ($M$ = 1.64 $M_{\odot}$) located at the red giant branch near the luminosity bump. We find unexpectedly elevated abundances of Fe-peak and \textit{r}-process elements. In addition, as previously reported, we find that this is a young star (2.37 Gyr) with unusually high abundances of $\alpha$-elements ([$\alpha$/Fe] = 0.31). The evolutionary status of KIC 9821622 suggests that its Li-rich nature is the result of internal fresh Li that is synthesized through the Cameron-Fowler mechanism near the luminosity bump. However, its peculiar enhancement of $\alpha$, Fe-peak, and \textit{r}-process elements opens the possibility of external contamination by material enriched by a supernova explosion. Although it is less likely, planet accretion cannot be ruled out.Comment: Letter, 6 pages, 3 figures, Accepted for publication in A&A. - Some language editing include

Signatures of rocky planet engulfment in HAT-P-4. Implications for chemical tagging studies

Aims. To explore the possible chemical signature of planet formation in the binary system HAT-P-4, by studying abundance vs condensation temperature Tc trends. The star HAT-P-4 hosts a planet detected by transits while its stellar companion does not have any detected planet. We also study the Lithium content, which could shed light on the problem of Li depletion in exoplanet host stars. Conclusions. The exoplanet host star HAT-P-4 is found to be ~0.1 dex more metal rich than its companion, which is one of the highest differences in metallicity observed in similar systems. This could have important implications for chemical tagging studies, disentangling groups of stars with a common origin. We rule out a possible peculiar composition for each star as lambda Boo, delta Scuti or a Blue Straggler. The star HAT-P-4 is enhanced in refractory elements relative to volatile when compared to its stellar companion. Notably, the Lithium abundance in HAT-P-4 is greater than in its companion by ~0.3 dex, which is contrary to the model that explains the Lithium depletion by the presence of planets. We propose a scenario where, at the time of planet formation, the star HAT-P-4 locked the inner refractory material in planetesimals and rocky planets, and formed the outer gas giant planet at a greater distance. The refractories were then accreted onto the star, possibly due to the migration of the giant planet. This explains the higher metallicity, the higher Lithium content, and the negative Tc trend detected. A similar scenario was recently proposed for the solar twin star HIP 68468, which is in some aspects similar to HAT-P-4. We estimate a mass of at least Mrock ~ 10 Mearth locked in refractory material in order to reproduce the observed Tc trends and metallicity.Comment: 5 pages, 6 figures, A&A Letters accepte

Reaching an equilibrium of prices and holdings of goods through direct buying and selling

The Walras approach to equilibrium focuses on the existence of market prices at which the total demands for goods are matched by the total supplies. Trading activities that might identify such prices by bringing agents together as potential buyers and sellers of a good are characteristically absent, however. Anyway, there is no money to pass from one to the other as ordinarily envisioned in buying and selling. Here a different approach to equilibrium -- what it should mean and how it may be achieved -- is offered as a constructive alternative. Agents operate in an economic environment where adjustments to holdings have been needed in the past, will be needed again in a changed future, and money is familiar for its role in facilitating that. Marginal utility provides relative values of goods for guidance in making incremental adjustments, and with money incorporated into utility and taken as num\`eraire, those values give money price thresholds at which an agent will be willing to buy or sell. Agents in pairs can then look at such individualized thresholds to see whether a trade of some amount of a good for some amount of money may be mutually advantageous in leading to higher levels of utility. Iterative bilateral trades in this most basic sense, if they keep bringing all goods and agents into play, are guaranteed in the limit to reach an equilibrium state in which the agents all agree on prices and, under those prices, have no interest in further adjusting their holdings. The results of computer simulations are provided to illustrate how this works

News territorials configurations in the southwestern edge of the City of San Juan as a result of implementing housing policies

En la expansión urbana dispersa hacia el sur-oeste de la Ciudad de San Juan sin un plan integrado de desarrollo y sobre espacios tradicionalmente dedicados a la agricultura intensiva, se destaca por un lado la construcción, desde el año 2005, de barrios con viviendas de interés social, destinados a población socialmente vulnerable erradicada de asentamientos irregulares y por otro, el mejoramiento habitacional a grupos con niveles de ingresos medio - bajos. El objetivo del presente artículo es mostrar las nuevas configuraciones producidas a raíz de la implementación de la política pública de vivienda. Se realizaron sucesivos relevamientos del área de estudio a fin de corroborar las progresivas transformaciones territoriales, complementándose con análisis de bases de datos censales provistos por el Instituto Provincial de la Vivienda. Los resultados muestran la conformación de territorios de borde en los que la producción del uso de suelo residencial es progresiva, lo cual hace prever a mediano plazo una tendencia al cambio de uso del suelo rural a urbano o su transformación en urbanizable. Las nuevas configuraciones territoriales tienen al Estado como actor principal, pero el abordaje sectorial si bien permite el acceso a la vivienda digna, acentúa los problemas de movilidad intraurbana, disponibilidad de equipamientos e infraestructura y provisión de servicios, situaciones que podrían ser evitadas si se lograra integrar las políticas habitacionales con estrategias de desarrollo y ordenamiento territorial, orientadas hacia el crecimiento urbano sostenible.In the urban sprawl towards the southwest of the City of San Juan- without an integrated approach development and spaces traditionally devoted to intensive agriculture it stands out on the one hand the construction from year 2005 of neighborhoods with social interest housing, intended for socially vulnerable population eradicated from irregular settlements and on the other housing improvement for groups with levels of lower middle income. The objectives of this paper is to show the new configurations produced the wake of the implementation housing policy. Successive surveys were done of the study area to corroborate the progressive territorial transformations complemented through analysis of census databases and provided by the Provincial Housing Institute. The results show the conformation of edge of territories where the production of residential land use is progressive, which seems to indicate a medium term trend change of use of rural soil to urban or to urbanize The new territorial configurations have the state as the main actor, but the sectorial approacheven though allows access to decent housing, accentuates the problems o intra-urban mobility availability of equipment and infrastructure and provision of services, situations that could be avoided if it were possible integrate housing policies with development strategies and spatial planning, geared towards sustainable urban growth.Fil: Jofré, R. del Carmen. Universidad Nacional de San JuanFil: Sarracina, Andrea E.. Universidad Nacional de San Jua

High-contrast imaging of HD 29992 and HD 196385 with GPI

Based on high contrast images obtained with the Gemini Planet Imager (GPI), we report the discovery of two point-like sources at angular separations of $\rho\sim0.18''$ and $\rho\sim0.80''$ from the stars HD 29992 and HD 196385. A combined analysis of the new GPI observations and images from the literature indicates that the source close to HD 29992 could be a companion to the star. Concerning HD 196385, the small number of contaminants ($\sim0.5$) suggests that the detected source may be gravitationally bound to the star. For both systems, we discarded the presence of other potential companions with $m>75$ M$_{\rm Jup}$ at $\rho\sim0.3 - 1.3''$. From stellar model atmospheres and low-resolution GPI spectra, we derive masses of $\sim0.2$ - $0.3$ M$_{\odot}$ for these sources. Using a Markov-chain Monte Carlo approach, we performed a joint fit of the new astrometry measurements and published radial velocity data to characterize the possible orbits. For HD 196385B, the median dynamic mass is in agreement with that derived from model atmospheres, whilst for HD 29992B, the orbital fit favors masses close to the brown dwarf regime($\sim0.08$ M$_{\odot}$). HD 29992 and HD 196385 might be two new binary systems with M-type stellar companions. However, new high angular resolution images would help to definitively confirm whether the detected sources are gravitationally bound to their respective stars, and permit tighter constraints on the orbital parameters of both systems

Caracteres epidérmicos foliares de latifoliadas herbáceas del chaco occidental, San Luis

The leaf epidermis of the following forbs from the Westem Chaco region (San Luis Province, Argentina) are analized and lIIustrated: Conyza bonariensis, Schkuria pinnata, Xanthium spinosum, Cryptantha mendocina, Evolvulus seticeus, Cucurbitella asperata, Ibicella parodii, Clematis denticulata, Solanum juvenale y Tribulus terrestris. The characteres used for taxonomíc determination are those useful for the identification of small fragments such as: cell walls, trichomas, stomata and cuticular omamentatlon. A key for the identification of these species is presented.Se analiza e ilustra la epidermis foliar de las siguientes latifoliadas herbáceas de la región Chaquena Occidental, San Luis, Argentina: Conyza bonariensis, Schkuria pinnata, Xanthium spinosum, Cryptantha mendocina, Evolvulus sericeus, Cucurbitella asperata, Ibicella parodii, Clematis denticulata, Solanum juvenale y Tribulus terrestris. Los caracteres considerados de valor diagnóstico en la determinación de estas especies son aquellos útiles para la identificación de fragmentos pequeños tales como: las formas de la pared anticlinal de las células epld6rmicas propiamente dichas, los tricomas, los complejos estomáticos y la ornamentación cuticular. Se presenta una clave para la identificación de estas especies

Fundamental stellar parameters of benchmark stars from CHARA interferometry. I. Metal-poor stars

Benchmark stars are crucial as validating standards for current as well as future large stellar surveys of the Milky Way. However, the number of suitable metal-poor benchmarks is currently limited. We aim to construct a new set of metal-poor benchmarks, based on reliable interferometric effective temperature ($T_\text{eff}$) determinations and a homogeneous analysis with a desired precision of $1\%$ in $T_\text{eff}$. We observed ten late-type metal-poor dwarf and giants: HD2665, HD6755, HD6833, HD103095, HD122563, HD127243, HD140283, HD175305, HD221170, and HD224930. Only three of the ten stars (HD103095, HD122563, and HD140283) have previously been used as benchmarks. For the observations, we used the high angular resolution optical interferometric instrument PAVO at the CHARA array. We modelled angular diameters using 3D limb darkening models and determined $T_\text{eff}$ directly from the Stefan-Boltzmann relation, with an iterative procedure to interpolate over tables of bolometric corrections. Surface gravities ($\log(g)$) were estimated from comparisons to Dartmouth stellar evolution model tracks. We collected spectroscopic observations from the ELODIE and FIES spectrographs and estimated metallicities ($\mathrm{[Fe/H]}$) from a 1D non-LTE abundance analysis of unblended lines of neutral and singly ionized iron. We inferred $T_\text{eff}$ to better than $1\%$ for five of the stars (HD103095, HD122563, HD127243, HD140283, and HD224930). The $T_\text{eff}$ of the other five stars are reliable to between $2-3\%$; the higher uncertainty on the $T_\text{eff}$ for those stars is mainly due to their having a larger uncertainty in the bolometric fluxes. We also determined $\log(g)$ and $\mathrm{[Fe/H]}$ with median uncertainties of $0.03\,\mathrm{dex}$ and $0.09\,\mathrm{dex}$, respectively. These ten stars can, therefore, be adopted as a new, reliable set of metal-poor benchmarks.Comment: 13 pages, 7 figures, 8 tables + 10 online tables, abstract shortened to meet arXiv requirements, accepted in A&