Sobre la distribución geográfica de los géneros "Monacha" y "Helicigona" "(Mollusca: Pulmonata: Helicidae)" en la Península Ibérica

Hom presenta i comenta la distribució de quatre espècies de mol•luscs pulmonats a la península Ibèrica, a partir de dades bibliogràfiques i no publicades. Es tracta de Monacha cartusiana, M. cantiana, M. (Ashfordia) granulata i Helicigona lapicida. S'assenyalen les primeres localitats segures de la Península, donat que l'única citació coneguda de M. cantiana (San Pedro de Nieva, Asturies, sub Helix (Theba) cantiana) és una identificació errònia, que correspon a Theba pisana. Per a les altres espècies es donen noves dades geogràfiques: les primeres localitats de Castella la Vella per a H. lapicida, les primeres localitats segures d'Andalusia per a M. cartusiana, i la primera citació per a Cantabria de M. (A.) granulata. Per a les quatre espècies s'ofereixen descripcions curtes, amb il•lustracions de les conquilles i dels genitals, així com mapes amb les coordenades UTM.The distribution of four species, Monacha cartusiana, M. cantiana, M. (Ashfordia) granulata and Helicigona lapicida, in the Iberian Peninsula, compiled from both previously recorded and unpublished data, is presented and discussed herein. Confirmed first locatings in the Iberian Peninsula are indicated (the only known citation of M. cantiana in the peninsula —from San Pedro de Nieva, Asturias, sub Helix (Theba) cantiana- is an erroneous identification and corresponds instead to Theba pisana). As regards the other three species, new geographical data are given on the locating of H. lapicida in Old Castile, M. cartusiana in Andalusia and M. (A.) granulata in Cantabria, in each case for the first time. Short descriptions with figures of shell and genitalia, as well as maps with UTM coordinates, are provided for all four species

Elemental Abundance Survey of The Galactic Thick Disk

[Abridged abstract] We have performed an abundance analysis for 176 F- and G- dwarfs of the Galactic thick disk component. Using accurate radial velocities combined with $Hipparcos$ astrometry, kinematics (U, V, and W) and Galactic orbital parameters were computed. We estimate the probability for a star to belong to the thin disk, the thick disk or the halo. Abundances of C, O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Ba, Ce, Nd, and Eu have been obtained. The abundances for thick disk stars are compared with those for thin disk members from Reddy et al. (2003). The ratios of $\alpha$-elements (O, Mg, Si, Ca and Ti) to iron for thick disk disk stars show a clear enhancement compared to thin disk members in the range $-0.3 <$ [Fe/H] $< -1.2$. There are also other elements -- Al, Sc, V, Co, and possibly Zn -- which show enhanced ratios to iron in the thick disk relative to the thin disk. The abundances of Na, Cr, Mn, Ni, and Cu (relative to Fe) are very similar for thin and thick disk stars. The dispersion in abundance ratios [X/Fe] at given [Fe/H] for thick disk stars is consistent with the expected scatter due to measurement errors, suggesting a lack of `cosmic' scatter. The observed compositions of the thin and thick disks seem to be consistent with models of galaxy formation by hierarchical clustering in a $\Lambda$CDM universe. In particular, the distinct abundance patterns observed in the thin and thick disks, and the chemical homogeneity of the thick disk at different galactocentric distances favor a scenario in which the majority of thick-disk stars were formed {\it in situ}, from gas rich merging blocks.Comment: 57 pages (text: 27 pages in MNRAS format + 27 figures) Accepted for publication in MNRA

Hypervelocity Star Candidates in the SEGUE G & K Dwarf Sample

We present 20 candidate hypervelocity stars from the Sloan Extension for Galactic Understanding and Exploration (SEGUE) G and K dwarf samples. Previous searches for hypervelocity stars have only focused on large radial velocities; in this study we also use proper motions to select the candidates. We determine the hypervelocity likelihood of each candidate by means of Monte Carlo simulations, considering the significant errors often associated with high proper motion stars. We find that nearly half of the candidates exceed their escape velocities with at least 98% probability. Every candidate also has less than a 25% chance of being a high-velocity fluke within the SEGUE sample. Based on orbits calculated using the observed six-dimensional positions and velocities, few, if any, of these candidates originate from the Galactic center. If these candidates are truly hypervelocity stars, they were not ejected by interactions with the Milky Way's supermassive black hole. This calls for a more serious examination of alternative hypervelocity-star ejection scenarios.Comment: 8 pages, 5 figures, published in ApJ, this version includes all figures as intende

Cristarmadillidium zaragozai n. sp. (Oniscidea, Armadillidiidae), un nuevo isópodo terrestre de la península ibérica

A new species of terrestrial isopod belonging to Armadillidiidae family from eastern Spain, C. Zaragozai n. sp., is described. Its diagnostic characteristics are discussed, and also its similarity with the other two species of the genus are discussed.En este trabajo se describe una nueva especie de isópodo terrestre de la familia Armadillidiidae del levante español, C. Zaragozai n. sp. Se discuten sus caracteres diagnósticos que permiten separarla de las otras dos especies del género. urn:lsid:zoobank.org:pub:3BB0B30E-BEA9-4024-981D-641D0438576

sMILES SSPs: A Library of Semi-Empirical MILES Stellar Population Models with Variable [α\alpha/Fe] Abundances

We present a new library of semi-empirical stellar population models that are based on the empirical MILES and semi-empirical sMILES stellar libraries. The models span a large range of age and metallicity, in addition to an [$\alpha$/Fe] coverage from $-$0.2 to $+$0.6 dex, at MILES resolution (FWHM=2.5$\mathring {\mathrm A}$) and wavelength coverage (3540.5-7409.6$\mathring {\mathrm A}$). These models are aimed at exploring abundance ratios in the integrated light from stellar populations in star clusters and galaxies. Our approach is to build SSPs from semi-empirical stars at particular [$\alpha$/Fe] values, thus producing new SSPs at a range of [$\alpha$/Fe] values from sub-solar to super-solar. We compare these new SSPs with previously published and well-used models and find similar abundance pattern predictions, but with some differences in age indicators. We illustrate a potential application of our new SSPs, by fitting them to the high signal-to-noise data of stacked SDSS galaxy spectra. Age, metallicity and [$\alpha$/Fe] trends were measured for galaxy stacks with different stellar velocity dispersions and show systematic changes, in agreement with previous analyses of subsets of those data. These new SSPs are made publicly available.Comment: 21 pages, 18 figures plus Supplementary Material. Accepted for publication in MNRA

The Chemical Compositions of Galactic Disk F and G Dwarfs

Photospheric abundances are presented for 27 elements from carbon to europium in 181 F-G dwarfs from a differential LTE analysis of high-resolution and high signal-to-noise spectra. Stellar $T_{\rm eff}$ were adopted from an infrared flux method calibration of Str\"{o}mgren photometry. Stellar log $g$ were calculated from {\it Hipparcos} parallaxes and stellar evolutionary tracks. Stellar space motions ($U, V, W$) and a Galactic potential were used to estimate Galactic orbital parameters. Results of $\alpha$-elements -- O, Mg, Si, Ca, and Ti -- show [$\alpha$/Fe] to increase slightly with decreasing [Fe/H]. Heavy elements with dominant contributions at solar metallicity from the $s$-process show [$s$/Fe] to decrease slightly with decreasing [Fe/H]. Scatter in [X/Fe] at a fixed [Fe/H] is entirely attributable to the small measurement errors, after excluding the few thick disc stars and the $s$-process enriched CH subgiants. Tight limits are set on `cosmic' scatter. By combining our sample with published studies, thick disc stars are identified by their $V_{LSR}$ in the range $- 40$ to -100 km s$^{-1}$. These are very old stars with origins in the inner Galaxy and metallicities [Fe/H] $\leq -0.4$. At the same [Fe/H], the sampled thin disc stars have $V_{LSR} \sim 0$ km s$^{-1}$, and are generally younger with a birthplace at about the Sun's Galactocentric distance. In the range $-$0.35 $\geq$ [Fe/H] $\geq$ $-$0.70, well represented by present thin and thick disc samples, [X/Fe] of the thick disc stars is greater than that of thin disc stars for Mg, Al, Si, Ca, Ti, and Eu. [X/Fe] is very similar for the thin and thick disc for -- notably -- Na, and iron-group elements.Comment: 51 pages (includes 19 figures and 6 tables). To appear in MNRAS (paper has been replaced: typos added, In Table~1, [Fe/H]phot has been replaced by spectroscopic [Fe/H] that are used in the plots) (Table1, photometric[Fe/H] values are replaced by spectroscopically derived [Fe/H] that are used in the plots

Descripción de dos nuevas especies cavernícolas de Trichoniscinae Verhoeff, 1908 de la Cordillera Cantábrica (Crustacea: Isopoda: Trichoniscidae)

Two new cavernicolous species of the Iberian Peninsula, belonging to the sub-family Trichoniscinae Verhoeff, 1908, have been discovered through the study of the terrestrial isopods present in the “Colección de Fauna Cavernícola de la Universidad del País Vasco”. Trichoniscoides cantabricus n. sp. is described from Miera-Asón river system cavities, being present in another 3 karstic environments in Cantabria, and another cavity in the north of Burgos. Troglonethes fonsocalvoi n. sp. is described in the Montes de Triano cavities (Bizkaia) and it is also present at Sierra Salvada and the Jorrios-Alén and Gorbea massifs.Dos nuevas especies cavernícolas de la Península Ibérica pertenecientes a la subfamilia Trichoniscinae Verhoeff, 1908, han sido descubiertas gracias al estudio de los isópodos terrestres de la Colección de Fauna Cavernícola de la Universidad del País Vasco. Trichoniscoides cantabricus n. sp. se describe de las cavidades del Miera-Asón, estando presente también en otras tres áreas kársticas de Cantabria y una cavidad del norte de Burgos. Troglonethes fonsocalvoi n. sp. se describe de las cavidades de Montes de Triano (Bizkaia) y está presente también en Sierra Salvada y los macizos de Jorrios-Alén, Gorbea. http://zoobank.org/urn:lsid:zoobank.org:pub:5DE67D90-805E-458D-BBFA-04DF244FBD6

Sobre la presència d’Otala xanthodon (Anton, 1838) (Gastropoda: Helicidae) a la península Ibèrica

In this article, the first known established population of Otala xanthodon (Helicidae) is given for the Iberian Peninsula. Some few thousands of live specimens were found at the Sierra de Callosa de Segura mountain system (Baix Segura, Alicante province). The specimens were found preferably in sunny environments at an altitude above 400m, mainly on Macrochloa and Asphodelus plants or hidden in crevices. This is a species native to north Africa and is apparently already cited in the south of France. Its presence in an environment of high ecological value could endanger some endemic snails present in these mountains, particularly those of the genus IberusA la present nota es recull la primera població establerta coneguda d’Otala xanthodon (Helicidae) a la penín-sula Ibèrica. Es van trobar milers d’exemplars vius en un punt de la serra de Callosa de Segura (el Baix Segura, província d’Alacant). Els espècimens trobats habiten preferentment en ambients assolellats per sobre del 400 m d’altitud, principalment sobre espart i Asphodelus, o amagats en esquerdes. Es tracta d’una espècie originària del nord d’Àfrica, però aparentment ja citada al sud de França. La seva presència en un lloc d’alt valor ambiental podria posar en risc poblacions de cargols endèmics, fonamentalment del gènere Iberus, present en aquesta serralada

Rapid Orbital Decay in the 12.75-Minute Binary White Dwarf J0651+2844

We report the detection of orbital decay in the 12.75-minute, detached binary white dwarf (WD) SDSS J065133.338+284423.37 (hereafter J0651). Our photometric observations over a 13 month baseline constrain the orbital period to 765.206543(55) s and indicate that the orbit is decreasing at a rate of (-9.8 +/- 2.8) x 10(-12) s s(-1) (or -0.31 +/- 0.09 ms yr(-1)). We revise the system parameters based on our new photometric and spectroscopic observations: J0651 contains two WDs with M-1 = 0.26 +/- 0.04 M-circle dot and M-2 = 0.50 +/- 0.04 M-circle dot. General relativity predicts orbital decay due to gravitational wave radiation of (-8.2 +/- 1.7) x 10(-12) s s(-1) (or -0.26 +/- 0.05 ms yr(-1)). Our observed rate of orbital decay is consistent with this expectation. J0651 is currently the second-loudest gravitational wave source known in the milli-Hertz range and the loudest non-interacting binary, which makes it an excellent verification source for future missions aimed at directly detecting gravitational waves. Our work establishes the feasibility of monitoring this system's orbital period decay at optical wavelengths.NSF AST-0909107, AST-1008734Norman Hackerman Advanced Research Program 003658-0252-2009Astronom

The Shortest Period Detached Binary White Dwarf System

We identify SDSS J010657.39-100003.3 (hereafter J0106-1000) as the shortest period detached binary white dwarf (WD) system currently known. We targeted J0106-1000 as part of our radial velocity program to search for companions around known extremely low-mass (ELM, ~ 0.2 Msol) WDs using the 6.5m MMT. We detect peak-to-peak radial velocity variations of 740 km/s with an orbital period of 39.1 min. The mass function and optical photometry rule out a main-sequence star companion. Follow-up high-speed photometric observations obtained at the McDonald 2.1m telescope reveal ellipsoidal variations from the distorted primary but no eclipses. This is the first example of a tidally distorted WD. Modeling the lightcurve, we constrain the inclination angle of the system to be 67 +- 13 deg. J0106-1000 contains a pair of WDs (0.17 Msol primary + 0.43 Msol invisible secondary) at a separation of 0.32 Rsol. The two WDs will merge in 37 Myr and most likely form a core He-burning single subdwarf star. J0106-1000 is the shortest timescale merger system currently known. The gravitational wave strain from J0106-1000 is at the detection limit of the Laser Interferometer Space Antenna (LISA). However, accurate ephemeris and orbital period measurements may enable LISA to detect J0106-1000 above the Galactic background noise.Comment: MNRAS Letters, in pres