Investigation of the Praesepe cluster. III. Radial velocity and binarity of the F5-K0 Klein-Wassink stars

Coravel observations of 103 F5-K0 stars in the Praesepe cluster yielded 24 spectroscopic binaries (3 are non-members), and 20 orbits were determined, with periods from 4 to 7400 days. Based on a complete sample in the colour range 0.40 < B-V < 0.80 (80 stars, including KW 244 = TX Cnc), the companion star fraction CSF = 0.45. The percentage of spectroscopic binaries with P < 1000d is 20% (16/80). The combined photometric and spectroscopic analysis showed that 12 among 18 single-lined spectroscopic binaries are located within the "single" star sequence in the (V,B-V) diagram and cannot be detected by the photometric analysis in the UBV system. In addition, seven photometrically analysed binaries were not detected with the radial velocity observations, but are confirmed members. The number of single:binary:triple stars is 47:30:3.Comment: 10 pages, 3 tables, 7 eps figures. Accepted for A&A. LaTe

CCD BVI photometry and Coravel observations of stars in the open cluster NGC 2489

We present CCD BVI photometry for the southern open cluster NGC 2489 and its surrounding field. The sample consists of 2182 stars measured in an area of 13.6 × 13.6 arcmin2, extending down to V∼ 21.5. These data are supplemented with CORAVEL radial-velocity observations for seven red giant candidates. A cluster angular radius of 6.7 ± 0.6 arcmin, equivalent to 3.5 ± 0.3 pc, is estimated from star counts carried out inside and outside the cluster region. The comparison of the cluster colour-magnitude diagrams with isochrones of the Padova group yields E(B−V) = 0.30 ± 0.05, E(V−I) = 0.40 ± 0.05 and V−MV= 12.20 ± 0.25 for log t= 8.70 (t= 500+130−100 Myr) and Z= 0.019. NGC 2489 is then located at 1.8 ± 0.3 kpc from the Sun and 25 pc below the Galactic plane. The analysis of the kinematical data allowed us to confirm cluster membership for six red giants, one of them being a spectroscopic binary. A mean radial velocity of 38.13 ± 0.33 km s−1 was derived for the cluster red giants. The properties of a sample of open clusters aligned along the line of sight of NGC 2489 are examine

CCD BVI photometry and Coravel observations of stars in the open cluster NGC 2489

We present CCD BVI photometry for the southern open cluster NGC 2489 and its surrounding field. The sample consists of 2182 stars measured in an area of 13.6 × 13.6 arcmin2, extending down to V ∼ 21.5. These data are supplemented with CORAVEL radial-velocity observations for seven red giant candidates. A cluster angular radius of 6.7 ± 0.6 arcmin, equivalent to 3.5 ± 0.3 pc, is estimated from star counts carried out inside and outside the cluster region. The comparison of the cluster colour–magnitude diagrams with isochrones of the Padova group yields E(B − V) = 0.30 ± 0.05, E(V − I) = 0.40 ± 0.05 and V − MV = 12.20 ± 0.25 for log t = 8.70 (t = 500+130 −100 Myr) and Z = 0.019. NGC 2489 is then located at 1.8 ± 0.3 kpc from the Sun and 25 pc below the Galactic plane. The analysis of the kinematical data allowed us to confirm cluster membership for six red giants, one of them being a spectroscopic binary. A mean radial velocity of 38.13 ± 0.33 km s−1 was derived for the cluster red giants. The properties of a sample of open clusters aligned along the line of sight of NGC 2489 are examined.Fil: Piatti, Andres Eduardo. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Claria Olmedo, Juan Jose. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mermilliod, Jean Claude. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; ArgentinaFil: Parisi, Maria Celeste. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ahumada, Andrea Veronica. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Quelle R&D Mener pour le Développement Des Réseaux D'énergie De Demain ? Les Propositions de L'ancre en 2015

Feuille de route sur les réseaux électriques et stockage élaborée par le GP10 Réseaux et Stockages de l'Energie de l'ANCRECette feuille de route concerne les réseaux d’énergie électrique, de chaleur et de froid, les réseaux de gaz (hydrogène, gaz naturel), leurs stockages associés, ainsi que leurs couplages à venir dans le cadre de la transition énergétique et des évolutionsqui l’accompagneront, que ce soit sur les modes de production d’énergie ou sur l’évolution des usages.Le focus est porté sur les réseaux électriques qui seront les premiers impactés par cette transition énergétique. Hormisquelques éléments très spécifiques aux réseaux électriques (et qui seront notés dans le texte par une couleur différente)il est à souligner que la quasi-totalité des considérations et axes de R&D évoqués pour les réseauxélectriques et le développement de leur « intelligence » et/ou de leur flexibilité s’appliquentégalement aux autres réseaux d’énergie. Par ailleurs, si le groupe programmatique« Réseaux et Stockage » de l’ANCRE (GP10) s’est largement appuyé sur les nombreuses feuilles de route émises tant au niveau national, dont celles de l’ADEME, qu’européen, il a également souhaité s’en démarquer en insistantlargement et en détaillant les recherches scientifiques et technologiques à mener face aux verrous actuellement identifiés

INDEPENDENT DISTANCE DETERMINATIONS TO MILKY WAY CEPHEIDS IN OPEN CLUSTERS AND ASSOCIATIONS. III. CV Mon IN ANON VAN DEN BERGH

As part of a program to derive distances of galactic cluster Cepheids independent of cluster ZAMS-fitting, we have used new, high-quality light and radial velocity curves of the Cepheid CV Mon supposed to be a member of the sparse cluster Anon van den Bergh to obtain its distance and mean radius from the visual surface brightness method. We find the distance to CV Mon to be 2160 \Sigma 160 pc which is ¸ 20 percent larger than the ZAMS-fitting distance to the cluster determined by Turner (1978), but cluster membership of CV Mon is still possible given the relatively large uncertainty (¸ 25%) of the ZAMS-based distance. We have measured the radial velocities of three giants in the field near CV Mon and find for one of them a value similar to that of the Cepheid, arguing for a possible membership of both stars in Anon van den Berg. Our surface brightness analysis yields a mean radius of 53.5 \Sigma 3.9 R fi for CV Mon. The Cepheid&apos;s absolute visual magnitude is-3.67 \Sigma 0.36 mag, whose..