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

Habitat use by smooth snakes on lowland heath managed using 'conservation grazing'

Heathland in the UK, and parts of mainland Europe, is being managed increasingly by landowners and statutory conservation bodies e.g., Natural England, using cattle grazing which is often referred to as 'conservation grazing' in an attempt to justify its use in the absence of any detailed prior research into its actual benefits for wildlife species whose individual habitat requirements are likely to vary. Over four years, between 2010 and 2013, cattle were excluded from six hectares of lowland heath that had been subject to annual summer cattle grazing between May 1997 and autumn 2009 and in which reptile numbers had been monitored annually since 1997. Changes in smooth snake (Coronella austriaca) numbers were recorded annually in the ungrazed area and in a four hectare area of heathland adjacent to it that continued to be grazed. The number of individual smooth snakes, and the total number of smooth snake captures, were significantly higher in the ungrazed heath than the grazed heath and were associated with increased habitat structure, resulting principally from tall heathers and grasses. The results of the study suggest that the use of cattle grazing as a management tool on lowland heath is detrimental to smooth snake populations and that their recovery, following the cessation of grazing, may take many years

The orientation of galaxy pairs with filamentary structures: dependence on morphology

Aims. With the aim of performing an analysis of the orientations of galaxy pair systems with respect to the underlying large-scale structure, we study the alignment between the axis connecting the pair galaxies and the host cosmic filament where the pair resides. In addition, we analyze the dependence of the amplitude of the alignment on the morphology of pair members as well as filament properties. Methods. We build a galaxy pair catalog requiring r_p < 100\kpc and \Delta V < 500 \kms within redshift $z<0.1$ from the Sloan Digital Sky Survey (SDSS). We divided the galaxy pair catalog taking into account the morphological classification by defining three pair categories composed by elliptical-elliptical (E-E), elliptical-spiral (E-S) and spiral-spiral (S-S) galaxies. We use a previously defined catalog of filaments obtained from SDSS and we select pairs located closer than 1\mpc from the filament spine, which are considered as members of filaments. For these pairs, we calculate the relative angle between the axis connecting each galaxy, and the direction defined by the spine of the parent filament. Results. We find a statistically significant alignment signal between the pair axes and the spine of the host filaments consistent with a relative excess of $\sim$ 15\% aligned pairs. We obtain that pairs composed by elliptical galaxies exhibit a stronger alignment, showing a higher alignment signal for pairs closer than 200 \kpc to the filament spine. In addition, we find that the aligned pairs are associated with luminous host filaments populated with a high fraction of elliptical galaxies. The findings of this work show that large scale structures play a fundamental role in driving galactic anisotropic accretion as induced by galaxy pairs exhibiting a preferred alignment along the filament direction.Comment: 8 pages, 6 figures. Accepted for publication in A&

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

KIC~8975515: a fast-rotating (γ\gamma Dor - δ\delta Sct) hybrid star with Rossby modes and a slower δ\delta Sct companion in a long-period orbit

{KIC~8975515 is a \emph{Kepler} double-lined spectroscopic binary system with hybrid pulsations. Two components have similar atmospheric properties (T$_{\rm eff}$ $\sim$ 7400~K), and one of them is a fast rotator ($v\sin i = 162$ versus 32 km/s). Our aim is to study the \emph {Kepler} light curve in great detail in order to determine the frequencies of the pulsations, to search for regular spacing patterns in the Fourier spectrum, if any, and to discuss their origin in the context of binarity and fast rotation. In this paper, we study the properties of the stellar pulsations based on a careful analysis in the low-, intermediate- and high-frequency regions of the Fourier spectrum. This is done by performing repeated frequency-search analyses with successive prewhitenings of all the significant frequencies detected in the spectrum. Moreover, we searched for regular period spacings among the $g$ modes, as well as frequency splitting among the $g$ and $p$ modes. In the low-frequency regime, five regular period spacing patterns including one series of prograde $g$ modes and four series of retrograde $r$ modes were detected. The $r$ modes are well-distributed with respect to the harmonics of the rotational frequency of the fast-rotating star $f_{\rm rot}$ = 1.647 d$^{-1}$. The dominant $g$ mode is $f_{2}$ = 2.37 d$^{-1}$. The strongest p mode, at $f_{1}$ = 13.97 d$^{-1}$, forms a singlet. In the high-frequency region, we identified two multiplets of regularly split $p$ modes with mean frequency spacings of 0.42 d$^{-1}$ and 1.65 d$^{-1}$. We detected some series of retrograde $r$ and prograde $g$ modes as well as two multiplets of $p$ modes with frequency spacings related to the stellar rotation of both components of the twin system KIC~8975515. We identified the fast-rotating component as a hybrid pulsator with $r$ modes and the slowly-rotating component as a $\delta$ Sct pulsator.Comment: Accepted to publish on A \&

Revisiting the 16 Cygni planet host at unprecedented precision and exploring automated tools for precise abundances

The binary system 16 Cygni is key in studies of the planet-star chemical composition connection, as only one of the stars is known to host a planet. This allows us to better assess the possible influence of planet interactions on the chemical composition of stars that are born from the same cloud and thus, should have a similar abundance pattern. In our previous work, we found clear abundance differences for elements with Z$\leq30$ between both components of this system, and a trend of these abundances as a function of the condensation temperature (T$_{c}$), which suggests a spectral chemical signature related to planet formation. In this work we show that our previous findings are still consistent even if we include more species, like the volatile N and neutron capture elements (Z $>$ 30). We report a slope with T$_{c}$ of $1.56 \pm 0.24 \times 10^{-5}$ dex K$^{-1}$, that is good agreement with both our previous work and recent results by Nissen and collaborators. We also performed some tests using ARES and iSpec to automatic measure the equivalent width and found T$_c$ slopes in reasonable agreement with our results as well. In addition, we determine abundances for Li and Be by spectral synthesis, finding that 16 Cyg A is richer not only in Li but also in Be, when compared to its companion. This may be evidence of planet engulfment, indicating that the T$_{c}$ trend found in this binary system may be a chemical signature of planet accretion in the A component, rather than a imprint of the giant planet rocky core formation on 16 Cyg B.Comment: 11 pages, 5 figures, accepted for publication in A&

Innovative strategies to enhance the sensory quality of dry fermented sausages containing lactic ingredients by the addition of exogenous enzymes

This study investigated the impact of the addition of exogenous enzymes (Accelerzyme CPG, Debitrase DBP20) or cellular preparations (FlavoGard), traditionally used in the cheese industry, to accelerate flavour development of dry fermented sausages with 6% of lactic derivatives content. Sausages were fermented to pH 5.0, dried for 32 days and vacuum packed stored under refrigeration for 60 days. Sausages were analysed for physicochemical parameters, technological microbiota and proteolysis after fermentation, drying/ripening and storage. Similar compositional results were obtained in all products (38-39% humidity in the final product; 38.2% fat and 40.7% protein as dry matter throughout the study). Debitrase application positively affected proteolysis by changing the free amino acid profile and increasing non-protein nitrogen and total free amino acids by 2.2 and 11.8-fold, respectively. Accelerzyme increased ripened cheese flavour and overall sensory quality from 5.1 to 5.8; Debitrase increased ripened cheese odour and flavour, bitterness, umami, adhesiveness, pastiness, and overall sensory quality from 5.0 to 5.9, and decreased acid and hardness. This study highlights the effects of adding some exogenous enzyme/bacterial preparations traditionally used in the cheese industry to enhance the flavour of dry fermented sausages with high content of lactic ingredients and increase its sensory quality.info:eu-repo/semantics/acceptedVersio