Data, downloads
I will continuously expand this section. If you think I may have data that you want and can't find either here or in the papers then please contact me!


7Msun, Z=0.02 AGB sequence
A 2Msun, Z=0.02 pre-main sequence structure file
Where are the NH stars?
ARAA article - The evolution of AGB stars
AGB pictures, figures for talks, teaching etc
Low mass stellar evolution tracks for metallicity Z=0.02

7Msun, Z=0.02 AGB sequence

This is a standard evolution with overshooting with all output that I produce, including with USEEPP output that gives full resolution structure and abundance profiles at all time steps. The USEEPP files have a tiny bug in them, in that H abundance is not properly written, and some header information is not according to the latest standard. But anyways, .... This sequence can be used for code comparison. (Let me know if you need assistance in reading and interpreting these files. The h5 files are pretty much self-explaining). Check out the abundance evolution for the E-AGB phase and the first few thermal pulses.

A 2Msun, Z=0.02 pre-main sequence structure file

This ASCII file with enclosed fortran file to read it can be used to start your stellar evolution sequence. (for Bill Paxton as part of my effort to help the mesa project). The tar file can be downloaded HERE. Here is an internal abundance profile aproximately 80% through the main-sequence evolution.

Where are the NH stars?

UPDATE (19AUG2008): This problem seems to be solved. Onno Pols has explained to me that a proper accounting of the binary selection effects in assuming a standard IMF for the secondary results exactly in the low-mass bias that we found when searching for NEMP stars. More information should be available in Onno's Sanya (IAU Symp 252) proceedings paper: Modelling the evolution and nucleosynthesis of carbon-enhanced metal-poor stars.

In A Search for Nitrogen-enhanced Metal-poor Stars (Johnson etal. 2007) we find that there are apparently less N-rich extremely metal-poor stars compared to predictions in the scenario in which CEMP stars are polluted in binaries by low-mass AGB stars. Fig.1 in our paper shows predictions from low-metallicity (Z=0.0001, [Fe/H]=-2.3) AGB stellar evolution calculations for 2-6Msun, covering both low-mass C-rich cases (2 and 3Msun) and higher-mass (4-6Msun) hot-bottom burning, and therefore N-rich cases. The data from that plot were first published in Evolution and Yields of Extremely Metal-poor Intermediate-Mass Stars (Herwig 2004). Complete electronic tables are available along with this paper from ApJS. However, ... I have assembled the data to plot this diagram (Fig.1 from Johnson etal), together with a sample gnuplot file, in a tar ball for download here. I have not degraded the data files, so they are still quite large. The whole tar file is 21M. It takes a few seconds to bring up the gnuplot file, even on a modern computer. Have fun ... and let me know what you find, there are some things we know should be different in real stars but can't quantify (yet).

ARAA article - The evolution of AGB stars

In Herwig 2005, ARAA 43, 435, Figs 4 and 5 I show the internal structure and the internal chemical composition of an AGB star of 2Msun, and metal content Z=0.01. Below are links to the data in ASCII data table format. Fig. 1 shows Hertzsprun-Russel diagram of a calculated Z=0.02 star with initially 2Msun. The data to plot the red track (without VLTP) in that data, including gnuplot files, can be found in this gzipped tar archive. You can plot L vs Teff or log g vs Teff or the radius.

AGB pictures, figures for talks, teaching etc

Low mass stellar evolution tracks for metallicity Z=0.02

Radius, core- and envelope-mass evolution, as well as Teff, L and some surface abundances for a Z=0.02, M_ZAMS=1.5Msun track. There is still almost 0.62Msun envelope mass on the core at the end of this calculation, and the core mass is 0.61Msun. Depending on mass loss this track would experience a certain number of additional thermal pulses. The model star has experienced 17 thermal pulses, the last six of them with third dredge-up. During the fourth TP with dredge-up the model star becomes C-rich, and of course remains like that until the end of the calculation.
This particular calculation is unpublished. The code version used corresponds roughly what has been used by Herwig 2004, ApJ 605, 425. For the AGB phase (files *.3) overshooting with f=0.016 and Bloecker mass loss with a scaling factor eta=0.1 has been used.
Files can be found in this tar ball.

Here are two more tracks for 1Msun and 2Msun. There is a README file in the tar ball that explains the columns.


Falk Herwig, Last update: Thu Jun 18 17:25:11 PDT 2009 , WWW home