Spectroscopic Study of IRAS 19285+0517(PDS 100): A Rapidly Rotating Li-Rich K Giant

We report on photometry and high-resolution spectroscopy for IRAS 19285+0517. The spectral energy distribution based on visible and near-IR photometry and far-IR fluxes shows that the star is surrounded by dust at a temperature of $T_{\rm {d}}$ $\sim$ 250 K. Spectral line analysis shows that the star is a K giant with a projected rotational velocity $v sin i$ = 9 $\pm$ 2 km s$^{-1}$. We determined the atmospheric parameters: $T_{\rm {eff}}$ = 4500 K, log $g$ = 2.5, $\xi_{t}$ = 1.5 km s$^{-1}$, and [Fe/H] = 0.14 dex. The LTE abundance analysis shows that the star is Li-rich (log $\epsilon$(Li) = 2.5$\pm$0.15), but with essentially normal C, N, and O, and metal abundances. Spectral synthesis of molecular CN lines yields the carbon isotopic ratio $^{12}$C/$^{13}$C = 9 $\pm$3, a signature of post-main sequence evolution and dredge-up on the RGB. Analysis of the Li resonance line at 6707 \AA for different ratios $^{6}$Li/$^{7}$Li shows that the Li profile can be fitted best with a predicted profile for pure $^{7}$Li. Far-IR excess, large Li abundance, and rapid rotation suggest that a planet has been swallowed or, perhaps, that an instability in the RGB outer layers triggered a sudden enrichment of Li and caused mass-loss.Comment: To appear in AJ; 40 pages, 9 figure

Assessing the Impact of Mpas on Recreational Uses of A Marine Ecosystem: the Case of the Côte Bleue Marine Park (France)

Though the basic purpose of MPAs is marine ecosystem conservation, the question of their influence on the local economy is often critical since it governs their social acceptability. This paper addresses the problem of measuring the consequences of creating a marine protected area (MPA) on recreational extractive and non-extractive uses of the ecosystem (scuba diving, snorkelling, sport fishing). In the first part, we analyse the results of several field surveys dedicated to scuba diving and recreational fishing activities in the Côte Bleue Marine Park, along the French Mediterranean coast. These surveys have been performed in 2006-2009, within the framework of two multidisciplinary research projects on MPAs (EMPAFISH project, funded by the EU and PAMPA project, funded by the French Environment Ministry). Its aim was to characterize the behaviour of recreational users, their attitude towards the marine park, and to provide information for an assessment of its economic value. More than 2,500 answers of recreational users were collected. On the basis of these results, the second part of the paper proposes a simple illustrative model of demand for recreational uses of the MPA, taking into account both environmental and congestion effects

Ultraviolet Imaging of the z=0.23 Cluster Abell 2246

We present deep ultraviolet observations of a field containing the cluster Abell 2246 (z=0.225) which provide far-ultraviolet (FUV) images of some of the faintest galaxies yet observed in that bandpass. Abell 2246 lies within the field of view of Ultraviolet Imaging Telescope (UIT) observations of the quasar HS1700+64, which accumulated over 7100 seconds of UIT FUV exposure time during the Astro-2 mission in March 1995. For objects found on both the FUV and ground-based V-band images, we obtain FUV (l ~ 1520 A) photometry and V-band photometry, as well as mid-UV (l ~ 2490 A) photometry from UIT Astro-1 observations and ground-based I-band photometry. We find five objects in the images which are probably galaxies at the distance of Abell 2246, with FUV magnitudes (m(FUV)) between 18.6 and 19.6, and V magnitudes between 18.4 and 19.6. We find that their absolute FUV fluxes and colors imply strongly that they are luminous galaxies with significant current star formation, as well as some relatively recent, but not current, (> 400 Myr ago) star formation. We interpret the colors of these five objects by comparing them with local objects, redshift-corrected template spectra and stellar population models, finding that they are plausibly matched by 10-Gyr-old population models with decaying star formation, with decay time constants in the range 3 Gyr < t < 5 Gyr, with an additional color component from a single burst of moderate ( ~ 400-500 Myr) age. From derived FUV luminosities we compute current star formation rates. We compare the UV properties of Abell 2246 with those of the Coma cluster, finding that Abell 2246 has significantly more recent star formation, consistent with the Butcher-Oemler phenomenon.Comment: Accepted for publication in the Astronomical Journal, June 1998. 17 Pages AAS latex, includes 4 bitmap .jpg format images and 4 other figures. PDF, Embedded Gzipped PS version (1.9Mb) TeX source and figures available at http://www.astro.virginia.edu/~bd4r/galaxies.htm

Asteroseismology and Next Generation Stellar Models - EES2014

International audienc

Asteroseismology and Next Generation Stellar Models - EES2014

International audienc

Gerbert l'européen

International audienc

La chapelle de la commanderie Saint-Jean-des-Prés à Montbrison (Loire). Étude préliminaire: Campagne de fouilles 2005

Rapport de fouille archéologique programméeLa première intervention archéologique sur le site de la commanderie hospitalière de Saint-Jean-des-Prés à Montbrison (Loire) a été consacrée à la réalisation d’un état des lieux de la chapelle, seul bâtiment conservé de l’ensemble architectural, et à une évaluation du potentiel archéologique du site, dont la construction remonte aux années 1170-1180. Plusieurs axes ont été privilégiés lors de cette opération.Une analyse du bâti de l’extérieur de l’édifice et d’une partie de ses élévations internes a permis de mettre en évidence la présence d’une galerie pouvant appartenir à un cloître du côté sud de la chapelle et d’une porte rapidement murée destinée à desservir l’édifice depuis la galerie, ces deux éléments prenant part au projet architectural primitif, ainsi que de réaliser une première analyse des décors peints successifs de l’intérieur de la chapelle. Si la nef romane est conservée en totalité, à l’exception de sa voûte, dont la date d’effondrement est encore incertaine, le chœur de l’édifice apparaissait partiellement reconstruit en première analyse, mais semblait conserver le plan roman dans sa partie basse, construite en pierres de taille de granite comme la nef, tandis que la partie haute et les contreforts semblaient résulter d’une reconstruction gothique. Les irrégularités des chaînages et des assises de la partie basse en granite laissait cependant douter de l’appartenance de ces parties de l’édifice à la construction primitive. Deux sondages réalisés dans le chœur et à la jonction du chœur et de la nef de l’édifice ont confirmé ces soupçons, grâce à la découverte de parties romanes du chœur en place dans le sous-sol ainsi que l’arrachement du mur du chevet, montrant nettement que celui-ci possédait non pas un plan quadrangulaire à chœur et chevet plats, mais une abside semi-circulaire. Les parties en granite de l’élévation du chevet reposent en outre sur une fondation en petits blocs irréguliers, elle-même assise sur la fondation romane en moellons de granite équarris à tête dressée.C’est donc bien la totalité du chœur qui a été reconstruit, probablement au XIVe ou au XVe s., avec un remploi des pierres de taille romanes pour la partie basse. Ces éléments conduisent à revoir également notre compréhension de l’organisation primitive de la chapelle ; si le chœur gothique occupe une seule travée, les trois autres travées romanes servant de nef, il semble du fait de la taille de l’abside romane (d’un diamètre interne d’environ 6,60 m) que l’organisation romane ne comprenait probablement que deux travées de nef, et une travée droite de chœur avant l’abside. En l’état des recherches, aucun sol à mettre en relation avec l’édifice roman n’a pu être découvert. En revanche, des traces d’une barrière du chœur gothique et d’une partie d’un sol en tommettes glaçurées polychromes ont pu être retrouvées.Les fonctions funéraires de l’édifice ont pu être approchées à travers la découverte de cinq sépultures dans la nef, dont l’état de conservation s’avère satisfaisant sans être exceptionnel, et à travers l’étude des négatifs de deux enfeus de la fin du XIIIe s., et notamment du décor peint de l’un de ces enfeus, appartenant au tombeau d’un prêtre de l’Hôpital nommé Aténulphe, commandeur de Saint-Jean-des-Prés de 1215 à 1248. Le site s’avère dans l’ensemble dans un bon état de conservation, même si les constructions des XIXe et XXe s. nuisent à la lecture de l’ensemble

Monitoring of the artificial reef fish assemblages of golfe juan marine protected area (France, North-Western Mediterranean)

Artificial reefs were deployed within the Golfe-Juan marine protected area (Alpes-Maritimes coast, France, Northwestern Mediterranean) created in 1981. This no-take area is fully protected since its establishment, except in 2004 when some anthropic activities were, exceptionally, authorized. Moreover, no park rangers to prevent poaching since 2002 occur. In order to carry out a long term monitoring of the artificial reef fish assemblages, underwater visual censuses (UVC) were carried out in 1988, 1998 and 2008, according to a traditional standardized visual census method that taken into account all fish species. The complexification of some large reefs built with wide voide spaces called Bonna reefs appear to be a good solution to increase species richness and density. Species richness and density of the fish assemblages showed significant increase between 1988 and 1998. However the fast increasing was stopped from 1998 and 2008 probably due to a lack of law enforcement and poaching. Despite artificial reefs were deployed in MPA since at least 20 years, they did not show a real positive impact on fish assemblages. These results could be explained (i) by a lack of law enforcement patrol within the protected areas during the last decade, and (ii) by the one-year opening to fishing activities within MPA. The real effectiveness of the artificial reefs in sustaining fish assemblages is discussed and the necessity of a regular and efficient control by park rangers is highlighted.<br>Recifes artificiais foram implantados na área protegida Golfe-Juan (costa dos Alpes-Maritimes, Noroeste do Mediterraneo) criada em 1981. Esta área NTZ (Area de Restrição da Pesca ) é inteiramente protegida, desde seu estabelecimento, exceto em 2004, quando algumas atividades antropicas foram excepcionalmente autorizadas. Além disso, desde 2002, não houve nenhuma patrulha florestal para impedir a caça e pesca ilegais. . A fim realizar um monitoramento a longo prazo das assembléias artificiais dos peixes do recife, recenseamentos visuais subaquáticos (UVC) foram realizados em 1988, 1998 e 2008, de acordo com um método visual tradicional de recenseamento, que leva em consideração todas as espécies de peixes. A complexidade de alguns recifes grandes, construídos com amplos espaços vagos, chamados recifes Bonna parece ser uma boa solução para aumentar a riqueza e a densidade das espécies. A riqueza das espécies e a densidade das assembléias de peixes mostraram um aumento significativo entre 1988 e 1998. Entretanto esse aumento rápido parou entre 1998 e 2008 provavelmente devido à falta da aplicação da lei contra a caça e pesca ilegal. . Apesar dos recifes artificiais terem sido instalados em MPAs pelo menos há 20 anos atrás, eles não apresentaram um impacto positivo real nas assembléias de peixes. Estes resultados podem ser explicados (i) por uma falta de patrulhamento da aplicação da lei dentro das áreas protegidas durante a última década, e (ii) pela abertura de um ano de atividades de pesca dentro das MPAs. A eficiência real dos recifes artificiais para sustentar assembléias de peixes é discutida, destacando-se a necessidade de um controle regular e de um patrulhamento regular e eficiente dos parques

Position and Attitude Model-Based Thruster Fault Diagnosis: A Comparison Study

International audienceThis paper deals with performance and reliability evaluation of a fault diagnosis scheme based on two distinct models to detect and isolate a single thruster fault affecting a chasing spacecraft during rendezvous with a passive target in a circular orbit. The analysis is conducted in the frame of a terminal rendezvous sequence of the Mars Sample Return mission. A complete description of a robust residual generation design approach based on eigenstructure assignment is presented. Unknown time-varying delays, induced by the thruster drive electronics and uncertainties on thruster rise times, are considered as unknown inputs. Particular novelty of the work is a new method for estimating the unknown input directions used to enhance the robustness properties of the diagnosis scheme. Monte Carlo results from a high-fidelity industrial simulator and carefully selected performance and reliability indices allows us to evaluate the effectiveness of both schemes. The obtained results reveal that the proposed fault diagnosis scheme based on a position model is a justified competitor to the conventionally used attitude model-based scheme