By Philippe Cardin (Grenoble). About MRI.

13:30, room T2.

I give an overview of the state of our knowledge on the pysics of type Ia supernovae from their progenitors until the thermonuclear explosion. I emphasize the quest for the physical parameters relevant to the luminosity-decline correlation used to probe cosmological parameters. In particular, I show how a systematic study of the Carbon flash allows to determine two independent parameters: the progenitor metallicity and the central density at ignition. I will also suggest how a simple model for the convective Urca process allows to predict the influence of galactic chemical evolution on the luminosity-decline correlation.

Type Ia Supernovae

Journal Club on 01/23/2006 Continued...

Pierre Lesaffre (ENS)

Room T4/5 (3rd floor) at l'ENS (24 rue Lhomond), 13:30

Last time (23/01) I barely had time to present on overview of the physics related to type Ia supernovae. This time I will present my work on the Carbon flash and the convective Urca process (see abstract of the 23/01).

Download the presentation PCMI

Stéphan Fauve (ENS)

Room T2, ENS, 13h30

Presentation of experimental measurements made at Cadarache.

Sulfur depletion in PDRs?

Javier R. Goicoechea (LERMA-ENS)

Room T4/5 (3rd floor) at ENS (24 rue Lhomond), 14:00

Sulfur is an abundant element which remains undepleted in diffuse interstelar gas but it is historically assumed to deplete on grains ( by factors of ~1000) at higher densities. Photodissociation regions (PDRs) are an interesting intermediate medium between translucent and dark clouds where the energetics and dynamics are dominated by an illuminating far-UV raditaion field, and thus they can provide some insights about the sulfur depletion problem. I will present our latest studies on CS and HCS⁺ photochemistry, excitation and radiative transfer in the Horsehead nebula that allow us to infer the sulfur abundance in the PDR.