THE WEBCESAM PROJECT

Experimental version

WEBCESAM is a Web based interface to the evolutionary code CESAM, it manages all the computation steps after an user request. It has been written by D. Cordier in PERL langage. WEBCESAM is not a simple applet, the whole set of softwares represents more than 3,000 lines of PERL language, around 35,000 of FORTRAN code lines and more than 200 MB of tabulated data. WEBCESAM is currently running under a GNU/Linux system and it is reachable from the Web through an Apache server.

The main goal is to provide a tool to the astrophysists community, making easier and faster the computations of 1D evolutionary stellar models. It also could be useful for educational purpose, for instance in the frame of Digital Campus Projects like this. WEBCESAM chooses numerical setup parameters in a database built with informations derived from several published works like Cordier et al. (2002) or Lebreton et al.(2001).

One of the interesting features of WEBCESAM is to provide -as further data- magnitudes and colors along the tracks. This is done thanks to the BaSeL Stellar Atmosphere Library.

In this experimental version of WEBCESAM the outputs are a "model-name.HR2" file (extended version of "model-name.HR" file from CESAM genuine version) and three files with magnitudes in UBVRI, Geneva and Strömgren photometric systems. After computation completion a web page (with some figures) is generated and an e-mail is sent to the user. One can see various samples of outputs pages here.

For any question and/or suggestion, please contact: D. Cordier

IDENTIFICATION

User Id:  Password: 
(WEBCESAM resquests are submitted to authorisation, if your are not and authorized user: please contact D. Cordier) ) Id of your computation: 
(Choose a characters string with only letter, numbers, dashed, dot and underscore; e.g. star_evol_01) )
PHYSICAL PARAMETERS
Mass : 
(In this version the available range is 0.8 - 12.5 Msun)

Parammeters linked to mixing

Mixing length : 
(1.6 is a very common value)

Overshooting : 
(This value remains a subject of debate, but the majority of authors seems to agree with a mild value around 0.2 Hp)

INITIAL CHEMICAL COMPOSITION

Initial helium mass fraction (Yo) : 
(The cosmological helium value should be around 0.24 (for instance see Izotov et al. 1997) and the helium content is generally scaled on the solar one following a standard helium-metallicity relation: $Y=Y_{\mathrm{P}}+Z (\Delta Y/\Delta Z)$. The calibration of a solar model in luminosity yields $\Delta Y/\Delta Z = 2$ (e.g. Lebreton et al. 1999) from the calibration of the solar model radius)

Initial mass fraction of heavy elements ("metallicity", Zo):  
PHOTOMETRIC SYSTEMS

After calculation completion, theoretical data (effective temperature, surface gravity and luminosity) are converted in observational ones (magnitudes and colors) thanks to BaSel Library. Three photometric systems are used: Johnson UBVRI, Stromgren and Geneva.
PHYSICAL ASSUMPTIONS

In this experimental version, various theoretical assumptions have been made:
SUBMISSION
Press the right button for reset or submit your request.


OTHER RELATED PROJECTS
© 2002, 2003, 2004, 2007 D. Cordier