15 research outputs found
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 Ă 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(BâV) = 0.30 ± 0.05, E(VâI) = 0.40 ± 0.05 and VâMV= 12.20 ± 0.25 for log t= 8.70 (t= 500+130â100 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 sâ1 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 Ă 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 colourâmagnitude diagrams with isochrones of the Padova group yields E(B â V) = 0.30 ± 0.05, E(V â I) = 0.40 ± 0.05 and V â MV = 12.20 ± 0.25 for log t = 8.70 (t = 500+130 â100 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 sâ1 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 InvestigaciĂłnes CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Ciudad Universitaria. Instituto de AstronomĂa y FĂsica del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de AstronomĂa y FĂsica del Espacio; ArgentinaFil: Claria Olmedo, Juan Jose. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; 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 CientĂficas y TĂ©cnicas; ArgentinaFil: Ahumada, Andrea Veronica. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentin
Quelle R&D Mener pour le DĂ©veloppement Des RĂ©seaux D'Ă©nergie De Demain ? Les Propositions de L'ancre en 2015
Feuille de route sur les rĂ©seaux Ă©lectriques et stockage Ă©laborĂ©e par le GP10 RĂ©seaux et Stockages de l'Energie de l'ANCRECette feuille de route concerne les rĂ©seaux dâĂ©nergie Ă©lectrique, de chaleur et de froid, les rĂ©seaux de gaz (hydrogĂšne, gaz naturel), leurs stockages associĂ©s, ainsi que leurs couplages Ă venir dans le cadre de la transition Ă©nergĂ©tique et des Ă©volutionsqui lâaccompagneront, que ce soit sur les modes de production dâĂ©nergie ou sur lâĂ©volution des usages.Le focus est portĂ© sur les rĂ©seaux Ă©lectriques qui seront les premiers impactĂ©s par cette transition Ă©nergĂ©tique. Hormisquelques Ă©lĂ©ments trĂšs spĂ©cifiques aux rĂ©seaux Ă©lectriques (et qui seront notĂ©s dans le texte par une couleur diffĂ©rente)il est Ă souligner que la quasi-totalitĂ© des considĂ©rations et axes de R&D Ă©voquĂ©s pour les rĂ©seauxĂ©lectriques et le dĂ©veloppement de leur « intelligence » et/ou de leur flexibilitĂ© sâappliquentĂ©galement aux autres rĂ©seaux dâĂ©nergie. Par ailleurs, si le groupe programmatique« RĂ©seaux et Stockage » de lâANCRE (GP10) sâest largement appuyĂ© sur les nombreuses feuilles de route Ă©mises tant au niveau national, dont celles de lâADEME, quâeuropĂ©en, il a Ă©galement souhaitĂ© sâen dĂ©marquer en insistantlargement et en dĂ©taillant les recherches scientifiques et technologiques Ă mener face aux verrous actuellement identifiĂ©s
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 ž 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 (ž 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's absolute visual magnitude is-3.67 \Sigma 0.36 mag, whose..