Browsing by Author "FOUQUE, P"
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- ItemCOMPARISON OF THE OPEN CLUSTER AND SURFACE-BRIGHTNESS DISTANCE SCALES FOR GALACTIC CLASSICAL CEPHEIDS(1993) GIEREN, WP; FOUQUE, PWe have derived a new period-luminosity (PL) relation for galactic Cepheids in open clusters and associations from the Zero-Age Main-Sequence (ZAMS)-fitting method, using the most reliable cluster photometric data and Cepheid reddening data available, and homogeneous treatment of absorption corrections. For about half of the cluster Cepheid sample (17 stars) we also derive distances and absolute magnitudes from the surface-brightness method. From a comparison we find that the surface-brightness PL relation has a zero point about 0.15 mag brighter than the cluster ZAMS-fitting PL relation, but in view of the sources of systematic error involved in both methods, this discrepancy is clearly not significant. Rather, we conclude from our results that the two currently most important methods to derive distances to galactic Cepheids produce consistent results, and that neither of the two methods contain systematic errors in excess of approximately 0. 10 mag. The results of this paper imply a distance to the Large Magellanic Cloud of mu0 (LMC) = 18.65 +/- 0.10 mag. We identify four stars in our cluster/association Cepheid sample for which the discrepancies between ZAMS-fitting and surface brightness M(V) are so large ( > 0.6 mag) that serious doubt is cast on their membership to the proposed host clusters or associations. These cases deserve further study.
- ItemGROUPS OF GALAXIES WITHIN 80 MPC .1. GROUPING HIERARCHICAL METHOD AND STATISTICAL PROPERTIES(1992) GOURGOULHON, E; CHAMARAUX, P; FOUQUE, PA hierarchial algorithm, similar to Tully's (1987) one, has been devised and applied to an all-sky sample of 4143 galaxies comprising all the objects with an apparent diameter D25 larger than 100 arcsec and having known recession velocities smaller than 6000 km s-1 (i.e. closer than 80 Mpc, with H0 = 75 km s-1 Mpc-1). This sample is at least 84% complete to these limits of diameter and redshift. The hierarchy is built on the mass density of the aggregates progressively formed by the method, corrected for the loss of faint galaxies with the distance; this correction represents the main improvement upon Tully's treatment. In the method, a group is defined as an entity having an average luminosity density higher than 8 10(9) L(B). Mpc-3, chosen as to ensure that the group is gravitationally bound and does not follow the Hubble expansion. 264 groups of at least three members have been identified in this way, among which 82 have more than five members and are located at distances lower than 40 Mpc. Our sample represents the deepest and richest collection of groups homogeneous over both hemispheres and whose global properties do not present significant biases with the distance; it can thus be used confidently for a variety of statistical studies. A first quick analysis of the sample leads to the following main conclusions: (i) almost all the crossing times are lower than H0(-1), which confirms the bound nature of our groups; (ii) the median virial mass to blue luminosity ratio of the groups is 74 M. L(B).-1, a high value, but lower than those obtained in previous studies; (iii) we confirm clearly the increasing of the M/L ratio with the group size, a result which can be taken as an indication of the presence of dark matter around galaxies to a distance of 500 kpc.
- ItemGROUPS OF GALAXIES WITHIN 80 MPC .2. THE CATALOG OF GROUPS AND GROUP MEMBERS(1992) FOUQUE, P; GOURGOULHON, E; CHAMARAUX, P; PATUREL, GThis paper gives a catalogue of the groups and associations obtained by means of a revised hierarchical algorithm applied to a sample of 4143 galaxies with diameters D25 larger than 100 arcsec and redshifts smaller than 6000 km s-1 (the method and the groups properties are detailed in Paper I). In the present paper, the 264 groups of galaxies obtained in this way (and which contain at least 3 sample galaxies) are listed, with the loose associations surrounding them and the individual members of each aggregate as well; moreover, the location of every entity among 13 regions corresponding roughly to superclusters, is specified. Finally, 1729 galaxies belong to the groups, and 466 to the associations, i.e. the total fraction of galaxies within the various aggregates amounts to 53%.
- ItemIDENTIFICATION OF 106 NEW INFRARED CARBON STARS IN THE IRAS POINT-SOURCE CATALOG - NEAR-INFRARED PHOTOMETRY AND THEIR SPACE DISTRIBUTION IN THE GALAXY(1993) GUGLIELMO, F; EPCHTEIN, N; LEBERTRE, T; FOUQUE, P; HRON, J; KERSCHBAUM, F; LEPINE, JRDThis paper reports on JHKLM observations of 1332 IRAS evolved stars with thick dust and gas envelopes, selected according to their colour properties. These observations were primarily aimed at identifying, with an original method, new distant carbon stars suspected to experience high mass loss (Infrared Carbon Stars or IRCS). Combining the measured K - L colour with the IRAS [12 - 25] colour, we recognized more than 100 new candidates. Several new results on the space distribution of IRCS are drawn out. Their surface number density is estimated to be approximately 12 per kpc2 and is shown to be constant in the galactocentric distance range 5-11 kpc with a scale height of 190 pc. No star is found to belong to the bulge population and their number density might present a cut off at about 4 kpc from the Sun toward the galactic center direction. IRCS represent approximately 25 % of the total number of carbon stars. As they lose mass at a rate in the range of 10(-6) - 10(-5) M./year which is 10 to 100 times larger than the average rate of ''optical'' carbon stars, IRCS are the major contributors to the enrichment of the interstellar medium in heavy elements processed in carbon stars. We evaluate a rate of restitution by carbon stars of approximately 10(-4) M./year/kpc2. Finally, our large set of near-IR data is used to test the completeness of the 4th edition of the General Catalogue of Variable Stars for IRAS samples.
- ItemNEAR-INFRARED PHOTOMETRY OF A SAMPLE OF IRAS POINT SOURCES(1992) FOUQUE, P; LEBERTRE, T; EPCHTEIN, N; GUGLIELMO, F; KERSCHBAUM, FThis paper presents the J, H, K, L, M photometry of 516 sources pertaining to a sample of 787 sources which has been extracted from the IRAS Point Source Catalogue in order to study the late stages of stellar evolution and the concomitant phenomena of mass loss. Three different classifications of these sources based on broadband photometry and IRAS low resolution spectra are given, and the distributions of the sources in terms of these classifications are presented. A sub-sample of peculiar sources, believed to have recently undergone a helium flash, has been isolated using the K - L, [12-mu-m] - [25-mu-m] colour diagram. Some objects worth further studies are also mentioned.
- ItemOBSERVATIONAL DATA FOR THE KINEMATICS OF THE LOCAL UNIVERSE .1. RADIAL-VELOCITY MEASUREMENTS(1992) BOTTINELLI, L; DURAND, N; FOUQUE, P; GARNIER, R; GOUGUENHEIM, L; PATUREL, G; TEERIKORPI, PThe study of the local velocity field requires the use of a very large sample to describe as accurately as possible some prominent features of the local kinematics. The problem of collecting a large sample is made more difficult because of the Malmquist bias which plagues distance determinations. Our programme aims at determining bias-free distances for a complete sample in order to study the local velocity field. The present paper gives 303 preliminary optical and radio redshifts measured for this program at ESO, OHP and Nancay Observatories.
- ItemOBSERVATIONAL DATA FOR THE KINEMATICS OF THE LOCAL UNIVERSE .2. 2ND SET OF RADIAL-VELOCITY MEASUREMENTS(1993) BOTTINELLI, L; DURAND, N; FOUQUE, P; GARNIER, R; GOUGUENHEIM, L; LOULERGUE, M; PATUREL, G; PETIT, C; TEERIKORPI, PThis paper is the second one in a series dedicated to the study of the kinematics of the local universe. It gives 361 new optical and radio redshifts measured at ESO, OHP and Nancay Observatories.
- ItemON THE DIFFICULTY OF DETERMINING THE COLOR-TERM IN THE CEPHEID PLC RELATION(1993) FOUQUE, P; GIEREN, WPWe present here a new tentative to determine the color-term of the Cepheid period - luminosity - color relation, using a large sample of 100 galactic Cepheids, whose distances are known from the visual surface brightness method (approximately 10% accuracy). The derived coefficient seems lower (between 0 and 1) than both its observed value in the Magellanic Clouds (about 2.1) and the semi-theoretical value of about 3.4. Systematic effects due to metallicity are investigated, and discarded as a possible explanation of the discrepancy. Statistical effects are reviewed, and a formalism useful to other topics is presented. Statistical corrections remove only part of the discrepancy we find. We therefore still recommend not to use the PLC relation to determine extragalactic distances, but to prefer a simple PL relation, as long as the question of the PLC color-term is not clearly resolved.
- ItemTHE MEDIUM REDSHIFT CLUSTERS CL-0017-20 AND CL-0500-24(1994) INFANTE, L; FOUQUE, P; HERTLING, G; WAY, MJ; GIRAUD, E; QUINTANA, HWe present magnitudes and redshifts of galaxies in the cluster of galaxies CL 0017-20 and in the double cluster CL 0500-24. Luminosity functions and velocity distributions have been derived. CL 0017-20 possesses a virial mass of 2.9 x 10(14) M(circle dot) and a V band luminosity of 2.3+/-0.5 x 10(12) L(circle dot) (M/L(V) = 127), much of it in a very compact core of size 113 kpc. Our new velocities and photometry of CL 0500-24 confirm its double nature. Our group algorithm clearly detects two subconcentrations with masses 1.9 and 2.2 x 10(14) M(circle dot). Its total V band luminosity amounts to 2.7+/-0.8 x 10(12) L(circle dot) (M/L(V) of 157). Since the crossing and collapse times in both clusters are smaller than the age of the Universe, they appear bound and virialized. It is surprising that although M/L is small in these clusters, giant arcs have been detected in both.