Research in astronomy

• Morphology of early-type galaxies in different environments
• Young starbursts in barred spiral galaxies
• Structure and dynamics of globular clusters
• Astronomical imaging in true colors
• Search for millisecond pulsars for fundamental research and astrometry
• Bibliometric analyses

Morphology of early-type galaxies in different environments

In the frame of a long-term project on the effects of the environment on the morphology of elliptical galaxies by the analysis of CCD images of large samples, I study the morphological segregation of ellipticals and lenticulars in clusters of galaxies. I also pursue a dynamical and morphological study of pairs of elliptical galaxies.

The most remarkable result in this domain is the discovery that old clusters like Perseus and Coma are not in stable equilibrium. This questions numerous results relying on this assumption.

Collaborators : Patrick Poulain (Observatoire Midi-Pyrénées), Stefano Andreon (Osservatorio di Capodimonte, Italie), Raymond Michard (Observatoire de Nice).

S. Andreon, R. Pello, E. Davoust, R. Dominguez, P. Poulain
Extensive near-infrared (H-band) photometry in Coma
Astronomy & Astrophysics, Supplement Series, 141, 113-122, 2000. (Abstract, Preprint).

S. Andreon, E. Davoust, P. Poulain.
Morphological classification and structural parameters of galaxies in the Coma and Perseus clusters.
Astronomy & Astrophysics, Supplement series, , 126, 67-72, 1997.
(Abstract, Preprint).

S. Andreon, E. Davoust, T. Heim.
The morphological segregation of galaxies in clusters. III. The distant cluster Cl0939+4713 (Abell 851).
Astronomy & Astrophysics, 323, 337-348, 1997. (Abstract, Preprint).

S. Andreon, E. Davoust.
Structural classification of galaxies in clusters.
Astronomy & Astrophysics, 319, 747-756, 1997. (Abstract). (Preprint).

S. Andreon, E. Davoust, R. Michard, J.-L. Nieto, P. Poulain.
Morphological classification and structural parameters for early-type galaxies in the Coma cluster.
Astronomy & Astrophysics, Supplement Series, 116 , 429-445, 1996. (Abstract, Reprint).

E. Davoust, S. Considère.
Kinematical observations of pairs of galaxies.
Astronomy & Astrophysics, Supplement Series, 110 , 19-26, 1995. (Abstract).

E. Davoust.
The morphology of elliptical galaxies in different environments.
Astrophysical letters & communications, 31, 183 -- 186, 1995.

J.-L. Nieto, P. Poulain, E. Davoust.
The nature of elongated ellipticals.
Astronomy & Astrophysics, 283, 1-11, 1994.

P. Poulain, J.-L. Nieto, E. Davoust.
Isophotal shapes of early-type galaxies. II. The Perseus Cluster.
Astronomy & Astrophysics, Supplement Series, 95, 129-193, 1992.

J.-L. Nieto, P. Poulain, E. Davoust, P. Rosenblatt.
Isophotal shapes of early-type galaxies. I. Elongated ellipticals.
Astronomy & Astrophysics, Supplement Series, 88, 559-613, 1991.

J.-L. Nieto, R. Bender, E. Davoust, P. Prugniel.
The low-mass extension of the fundamental plane of elliptical galaxies,
Astronomy & Astrophysics, 230, L17-L20, 1990.

P. Prugniel, E. Davoust, J.-L. Nieto.
Hierarchical pairs and the evolution of elliptical galaxies.
Astronomy & Astrophysics, 222, 5-26, 1989.

Young starbursts in barred spiral galaxies

I am pursuing research on several categories of starburst galaxies, mainly Markarian barred IRAS galaxies, but also unbarred, circumnuclear-ring and elliptical galaxies, using multifrequency data : CCD images (Observatoire du Pic du Midi), high and low resolution long-slit spectroscopy (Observatoire de Haute-Provence), the neutral hydrogen line (Observatoire de Nançay) and molecular lines (IRAM). We essentially look for the effects of starbursts on the morphology and dynamics of the galaxies.

The most important result to date is the discovery of several Wolf-Rayet galaxies, which are extremely rare (only 40 galaxies of this type are known). These galaxies are of major importance for constraining starbursts in galaxies, as well as the models of stellar evolution.

Collaborators : Thierry Contini (Wise Observatory, Tel Aviv University, Israel), Suzanne Considère (Observatoire de Besançon), Hervé Wozniak (Observatoire de Marseille), Roger Coziol (LNA/CNPq, Itajuba, Brazil), Ming Zhu (University of Toronto).

S. Considère, T. Contini, E. Davoust, R. Coziol
Starbursts in barred spiral galaxies. IV. On young bars and the formation of abundance gradients.
Astronomy & Astrophysics, 356, 89-101, 2000. (Abstract, Preprint).

R. Coziol, S. Considère, E. Davoust, T. Contini
The formation of bars and disks in Markarian starburst galaxies.
Astronomy & Astrophysics, 356, 102-107, 2000. (Abstract, Preprint).

Ming Zhu, E.R. Seaquist, Emmanuel Davoust, David T. Frayer and Howard A. Bushouse
Molecular gas in strongly interacting galaxies. I. CO(1 - 0) observations
Astronomical Journal, 118, 145-161, 1999.
(Abstract)

R. Coziol, R. E. Carlos Reyes, S. Considère, E. Davoust, T. Contini.
The abundance of nitrogen in starburst nucleus galaxies.
Astronomy & Astrophysics, 345, 733-746, 1999. (Abstract, Preprint).

Sandra Chapelon, Thierry Contini and Emmanuel Davoust
Starbursts in barred spiral galaxies. V. Morphological analysis of bars
Astronomy & Astrophysics, 345, 81-92, 1999. (Abstract, Preprint).

Roger Coziol, Carlos A. O. Torres, Germano R. Quast, Thierry Contini and Emmanuel Davoust
The Pico Dos Dias survey starburst galaxies
Astrophysical Journal, Supplement Series, 119, 239-253, 1998. (Abstract, Preprint).

T. Contini, S. Considère, E. Davoust.
Starbursts in barred spiral galaxies. III. Definition of a homogeneous sample of Starburst Nucleus Galaxies.
Astronomy & Astrophysics, Supplement Series, 130, 285-298, 1998. (Abstract, Preprint).

H. Wozniak, T. Contini, S. Considère, E. Davoust,
Outflow of molecular gas in the nuclei of barred starburst galaxies.
In``The Far Infrared and Submillimetre Universe'', M. Rowan-Robinson, S. Volonte, B. Kaldreich-Schürmann (eds.), ESA Symposium, in press.

T. Contini, H. Wozniak, S. Considère, E. Davoust.
Starbursts in barred spiral galaxies. II. The interstellar matter of three Wolf-Rayet galaxies.
Astronomy & Astrophysics, 324, 41-50, 1997. (Abstract, Preprint).

R. Coziol, T. Contini, E. Davoust, S. Considère.
The Chemical Evolution of Starburst Nucleus Galaxies.
Astrophysical Journal, Letters, , 481, L67-70, 1997.
(Abstract, Preprint).

T. Contini, H. Wozniak, S. Considère, E. Davoust.
A correlation between CO linewidth and starburst age in barred spiral galaxies.
Astronomy & Astrophysics, letters, 318, L51-L54, 1997.
IRAM Preprint 428, (Abstract, Reprint).

T. Contini, E. Davoust, S. Considère.
Starbursts in barred spiral galaxies. I. Mrk 712, a new Wolf-Rayet galaxy.
Astronomy & Astrophysics, 303, 440-448, 1995. (Abstract, Reprint).

T. Contini, E. Davoust, S. Considère.
Detection of circum-nuclear rings in barred spiral galaxies.
Astrophysical letters & communications, 31, 223 -- 225, 1995.

S. Considère, E. Davoust.
Counter-rotation in the interacting starburst galaxies UGC 9922.
Astronomy & Astrophysics, 252, 56-62, 1991.

Structure and dynamics of globular clusters

The morphological study of globular clusters can provide information on their dynamical evolution. I am presently measuring the flattening of the globular clusters of our Galaxy and I am looking for color and distance effects on this flattening. I am also interested in the Fundamental Plane of globular clusters.

I continue the morphological analysis and the measure of the radial velocity and velocity dispersion of globular clusters in the nearby external galaxies M31 and NGC 147.

Collaborators : Philippe Prugniel (Observatoire de Lyon), Vladimir Golev (Observatoire de l'Université de Sofia, Bulgarie), Terry Bridges (Institute for Astronomy, Cambridge).

E. Davoust, Ph. Prugniel.
On the flattening of globular clusters.
Astronomy & Astrophysics, 230, 67-72, 1990.

Astronomical imaging in true colors

I have developed software for producing trichromatic images of galaxies and nebulae. This software has been applied to the best CCD images obtained during my numerous runs at Pic du Midi. I am currently improving this software by implementing better algorithms for optomizing the palette and by rendering it more versatile and more user friendly.

Collaborators : Sébastien Morel (Observatoire Midi-Pyrénées), Youssef Belgued (ENSEEIHT, Toulouse).

S. Morel, E. Davoust.
Software for producing trichromatic images in astronomy.
Experimental Astronomy, 6, 223-234, 1995. (Abstract, Reprint).

Search for millisecond pulsars for fundamental research and astrometry

I contribute to the development of software for improving the detection of millisecond pulsars of short period. The goal is to increase the signal-to-noise ratio by windowing the signal from the pulsar and eliminating the signal received between pulses. The observing campaigns are done at the large radiotelescope of Observatoire de Nançay. We must also optimize the detection probability by selecting the regions of the sky where millisecond pulsars are most likely to be found.

Collaborators : Bénédicte Rougeaux (Observatoire Midi-Pyrénées), Thierry Fayard (CNES), Gérard Petit (Bureau International des Poids et Mesures).

B. Rougeaux, G. Petit , T. Fayard, E. Davoust
Experimental set-up for detecting very fast and dispersed millisecond pulsars
Experimental Astronomy 10, 473-485, 2000.