C. Alard

The DENIS Point Source Catalogue towards the Magellanic Clouds

We have compiled the near infrared Point Source Catalogue (PSC) towards the Magellanic Clouds (MCs) extracted from the data obtained with the Deep Near Infrared Survey of the Southern Sky - DENIS (Epchtein et al. 1997). The catalogue covers an area of of 19.87* 16 square degrees centered on (RA, DEC)=(5h27m20s, -69o0000) for the Large Magellanic Cloud (LMC) and 14.7* 10 square degrees centered on (RA, DEC)=(h02m40s, -73o0000 for the Small Magellanic Cloud (SMC) at the epoch J2000. It contains about 1300000 sources towards the LMC and 300000 sources towards the SMC each detected in at least 2 of the 3 photometric bands involved in the survey (I, J, Ks). 70% of the detected sources are true members of the Magellanic Clouds, respectively and consist mainly of red giants, asymptotic giant branch stars and super-giants. The observations have all been made with the same instrument and the data have been calibrated and reduced uniformly. The catalogue provides a homogeneous set of photometric data.

Combined Analysis of the Binary Lens Caustic-crossing Event MACHO 98-SMC-1

We fit the data for the binary lens microlensing event MACHO 98-SMC-1 from five different microlensing collaborations and find two distinct solutions characterized by binary separation d and mass ratio q: (d,q) = (0.54,0.50) and (d,q) = (3.65,0.36), where d is in units of the Einstein radius. However, the relative proper motion of the lens is very similar in the two solutions, 1.30 km s-1 kpc-1 and 1.48 km s-1 kpc-1, thus confirming that the lens is in the Small Magellanic Cloud. The close binary can be either rotating or approximately static but the wide binary must be rotating at close to its maximum allowed rate to be consistent with all the data. We measure limb-darkening coefficients for five bands ranging from I to V. As expected, these progressively decrease with rising wavelength. This is the first measurement of limb darkening for a metal-poor A star.

Type Ia supernova rate at a redshift of ~;0.1

Astronomy & Astrophysics manuscript no. rate (DOI: will be inserted by hand later) May 12, 2004 Type Ia supernova rate at a redshift of ∼ 0.1 G. Blanc 1,12,22 , C. Afonso 1,4,8,23 , C. Alard 24 , J.N. Albert 2 , G. Aldering 15,28 , A. Amadon 1 , J. Andersen 6 , R. Ansari 2 , E. Aubourg 1 , C. Balland 13,21 , P. Bareyre 1,4 , J.P. Beaulieu 5 , X. Charlot 1 , A. Conley 15,28 , 1 , T. Dahl´ n 19 , F. Derue 13 , X. Fan 16 , R. Ferlet 5 , G. Folatelli 11 , P. Fouqu´ 9,10 , G. Garavini 11 , C. Coutures e e J.F. Glicenstein 1 , B. Goldman 1,4,8,23 , A. Goobar 11 , A. Gould 1,7 , D. Graff 7 , M. Gros 1 , J. Haissinski 2 , C. Hamadache 1 , D. Hardin 13 , I.M. Hook 25 , J. de Kat 1 , S. Kent 18 , A. Kim 15 , T. Lasserre 1 , L. Le Guillou 1 , E. Lesquoy 1,5 , C. Loup 5 , C. Magneville 1 , J.B. Marquette 5 , E. Maurice 3 , A. Maury 9 , A. Milsztajn 1 , M. Moniez 2 , M. Mouchet 20,22 , H. Newberg 17 , S. Nobili 11 , N. Palanque-Delabrouille 1 , O. Perdereau 2 , L. Pr´ vot 3 , Y.R. Rahal 2 , N. Regnault 2,14,15 , J. Rich 1 , P. Ruiz-Lapuente 27 , M. Spiro 1 , P. Tisserand 1 , e A. Vidal-Madjar 5 , L. Vigroux 1 , N.A. Walton 26 , S. Zylberajch 1 . arXiv:astro-ph/0405211 v1 11 May 2004 DSM/DAPNIA, CEA/Saclay, 91191 Gif-sur-Yvette Cedex, France Laboratoire de l’Acc´ l´ rateur Lin´ aire, IN2P3 CNRS, Universit´ Paris-Sud, 91405 Orsay Cedex, France e e e e Observatoire de Marseille, 2 pl. Le Verrier, 13248 Marseille Cedex 04, France Coll` ge de France, Physique Corpusculaire et Cosmologie, IN2P3 CNRS, 11 pl. M. Berthelot, 75231 Paris e Cedex, France Institut d’Astrophysique de Paris, INSU CNRS, 98 bis Boulevard Arago, 75014 Paris, France Astronomical Observatory, Copenhagen University, Juliane Maries Vej 30, 2100 Copenhagen, Denmark Departments of Astronomy and Physics, Ohio State University, Columbus, OH 43210, U.S.A. Department of Astronomy, New Mexico State University, Las Cruces, NM 88003-8001, U.S.A. European Southern Observatory (ESO), Casilla 19001, Santiago 19, Chile Observatoire Midi-Pyr´ n´ es, 14 avenue Edouard Belin, 31400 Toulouse, France e e Department of Physics, Stockholm University, AlbaNova University Center, S-106 91 Stockholm, Sweden Osservatorio Astronomico di Padova, INAF, vicolo dell’Osservatorio 5 - 35122 Padova, Italy Laboratoire de Physique Nucl´ aire et de Hautes Energies, IN2P3 - CNRS - Universit´ s Paris 6 et Paris 7, 4 e e place Jussieu, 75252 Paris Cedex 05, France Laboratoire Leprince-Ringuet, LLR/Ecole Polytechnique, Route de Saclay, 91128 Palaiseau CEDEX, France Lawrence Berkeley National Lab, 1 Cyclotron Road, Berkeley, CA 94720, U.S.A. Steward Observatory, The University of Arizona, 933 N. Cherry Ave, Tucson, AZ 85721-0065, U.S.A. Rensselaer Polytechnic Institute, 110 Eighth Street, Troy, NY 12180, U.S.A. Fermilab Wilson and Kirk Roads, Batavia, IL 60510-0500, U.S.A. Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21218, U.S.A. LUTH, Observatoire de Paris, 5, Place Jules Janssen, 92195 Meudon Cedex, France Institut d’Astrophysique Spatiale, Bˆ timent 121, Universit´ Paris 11, 91405 Orsay Cedex, France a e Universit´ Paris 7 Denis Diderot, 2, place Jussieu, 75005 Paris, France e NASA/Ames Research Center, Mail Stop 244, Moffet Field, CA 94035, U.S.A. GEPI, Observatoire de Paris, 77 avenue de l’Observatoire, 75014 Paris, France Department of Physics, University of Oxford, Nuclear and Astrophysics laboratory, Keble Road, Oxford OX1 3RH, UK Institute of Astronomy, Madingley Road, Cambridge CB3 0HA, UK Department of Astronomy, University of Barcelona, Barcelona, Spain Visiting astronomer, Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatories, which are operated by the Association of Universities for Research in Astronomy, under contract with the National Science Foundation. Received / Accepted Abstract. We present the type Ia rate measurement based on two EROS supernova search campaigns (in 1999 and 2000). Sixteen supernovae identified as type Ia were discovered. The measurement of the detection efficiency, using a Monte Carlo simulation, provides the type Ia supernova explosion rate at a redshift ∼ 0.13. The result is 0.125 +0.044+0.028 h 2 SNu where 1 SNu = 1 SN / 10 10 L B / century. This value is compatible with the previous EROS measurement (Hardin et al. 2000), done with a much smaller sample, at a similar redshift. Comparison with other values at different redshifts suggests an evolution of the type Ia supernova rate. Key words. (Stars:) supernovae: general – Galaxies: evolution

Mass-Losing Semiregular Variable Stars in Baade's Windows

By cross-correlating the results of two recent large-scale surveys, the general properties of a well-defined sample of semiregular variable stars have been determined. ISOGAL mid-infrared photometry (7 and 15 ?m) and MACHO V and R light curves are assembled for approximately 300 stars in the Baades windows of low extinction toward the Galactic bulge. These stars are mainly giants of late M spectral type, evolving along the asymptotic giant branch (AGB). They are found to possess a wide and continuous distribution of pulsation periods and to obey an approximate log P-Mbol relation or set of such relations. Approximate mass-loss rates in the range of ~1 ? 10-8 to 5 ? 10-7 M? yr-1 are derived from ISOGAL mid-infrared photometry and models of stellar spectra adjusted for the presence of optically thin circumstellar silicate dust. Mass-loss rates depend on luminosity and pulsation period. Some stars lose mass as rapidly as short-period Mira variables but do not show Mira-like amplitudes. A period of 70 days or longer is a necessary but not sufficient condition for mass loss to occur. For AGB stars in the mass-loss ranges that we observe, the functional dependence of mass-loss rate on temperature and luminosity can be expressed as T?L?, where ? = -8.80 and ? = +1.74, in agreement with recent theoretical predictions. If we include our mass-loss rates with a sample of extreme mass-losing AGB stars in the Large Magellanic Cloud and ignore T as a variable, we get the general result for AGB stars that L2.7, valid for AGB stars with 10-8 < < 10-4 M? yr-1.

New neighbours: II. An M9 dwarf at

we present the discovery of a previously unknown member of the immediate solar neighbourhood, DENIS-P J104814.7 395606.1 (hereafter DENIS 1048 39), identified while mining the DENIS database for new nearby stars. A HIRES echelle spectrum obtained with the 10-m Keck telescope shows that it is an M9 dwarf. DENIS 1048 39 has a very bright apparent magnitude (I = 12.67) for its spectral type and colour (I J = 3.07), and is therefore very nearby. If it is single its distance is only 4.1±0.6 pc, ranking it as between our 12 th and 40 th closest neighbour. It is also the closest star or brown dwarf with a spectral type later than M7V. Its proper motion was determined through comparison of Sky atlas Schmidt plates, scanned by the MAMA microdensitometer, with the DENIS images. At 1.52 yr 1 it primarily attests the closeness of DENIS 1048 39 and hence its dwarf status. These characteristics make it an obvious target for further detailed studies.

{\vec d}\sim

We present an analysis of the light curves of 9.1 million stars observed during three seasons by EROS (Exp erience de Recherche dObjets Sombres), in the Galactic plane away from the bulge. Seven stars exhibit luminosity variations compatible with gravitational microlensing eects due to unseen objects. The corresponding optical depth, averaged over four directions, is = 0:43 0:2 10 6 . While this value is compatible with expectations from simple Galactic models under reasonable assumptions on the target star distances, we nd an excess of events with short timescales toward the direction closest to the Galactic centre. We discuss a possible interpretation involving the contribution of an elongated bar.

4 pc, DENIS-P J104814.7-395606.1

We present the results of a massive variability search based on a photometric survey of a six square degree region along the Galactic plane at (l = 305, b = 0:8 )a nd (l = 330, b = 2:5). This survey was performed in the framework of the EROS II (Exp erience de Recherche dObjets Sombres) microlensing program. The variable stars were found among 1 913 576 stars that were monitored between April and June 1998 in two passbands, with an average of 60 measurements. A new period-search technique is proposed which makes use of a statistical variable that characterizes the overall regularity of the flux versus phase diagram. This method is well suited when the photometric data are unevenly distributed in time, as is our case. 1362 objects whose luminosity varies were selected. Among them we identied 9 Cepheids, 19 RR Lyr, 34 Miras, 176 eclipsing binaries and 266 Semi-Regular stars. Most of them are newly identied objects. The cross-identication with known catalogues has been performed. The mean distance of the RR Lyr is estimated to be4:9 0:3 kpc undergoing an average absorption of3:4 0:2 mag. This distance is in good agreement with that of disc stars that contribute to the microlensing source star population. Our catalogue and light curves are available electronically from the CDS, Strasbourg and from our Web site.

Observation of microlensing toward the galactic spiral arms. EROS II 3 year survey

First results on AGB stars with the ISOGAL mid-infrared survey are presented. We show that M6 and later spectral type giants are detected at 7 and 15 μm up to the distance of the Galactic Centre. Analysis of the observed magnitudes and colours indicates that most of the detected AGB stars in the Galactic Bulge are losing mass. ISOCAM CVF spectra on a field in the Bulge confirm the mass loss and also show a large diversity in the shape of the silicate feature.