I've just updated both the MESA SDK and the Mad SDK. Both now use the latest (July 24 2013) trunk version of gcc/gfortran, which includes support for Fortran 2003 finalization (nice!) and a fix to a rather nasty memory leak which was plaguing the MESA-GYRE interface. Also, I've hacked the ODEPACK library bundled with the Mad SDK so that it behaves nicely when used with OpenMP.
As I mentioned the a post below, last month I released the first public version of GYRE, the new oscillation code suite I've been developing with Seth Teitler. From the blurb in the abstract of the paper discussing GYRE:
We present a new oscillation code, GYRE, which solves the stellar pulsation equations (both adiabatic and non-adiabatic) using a novel Magnus Multiple Shooting numerical scheme devised to overcome certain weaknesses of the usual relaxation and shooting schemes appearing in the literature. The code is accurate (up to 6th order in the number of grid points), robust, efficiently makes use of multiple processor cores and/or nodes, and is freely available in source form for use and distribution. We verify the code against analytic solutions and results from other oscillation codes, in all cases finding good agreement. Then, we use the code to explore how the asteroseismic observables of a 1.5 M☉ star change as it evolves through the red-giant bump.
So, there you have it. Work is now underway to develop GYRE further on a number of fronts, including refinement of the entropy calculation in the non-adiabatic code; inclusion of the Coriolis force due to rotation; and integration into MESA's asteroseismic module. Full source code, documentation and related resources can be found here.
It's been rather quiet around here, so I thought I should sweep away the tumbleweed and add some new content. On the papers front, I've cranked out a couple first-author efforts. The first (see offprint here) discusses the light curve of the magntospheric archetype σ Ori E, as measured by the MOST microsatellite. Surprisingly, apart from the well known twice-per-rotation cycle eclipse-like dimmings, arising when magnetospheric plasma transits across the stellar disk, the lightcurve is lacking any signature of 'centrifugal breakout' episodes. This directly challenges the prevailing narrative for mass loss from massive-star magnetospheres.
The second paper (submitted; I'll post a preprint when accepted) reports on work over the past three years with my postdoc Seth Teitler, to develop a new stellar oscillation code. Why so long? Along the way we had to devise a new 'Magnus Multiple Shooting' scheme for solving linear two-point boundary value problems. Luckily, this effort appears to have paid off, and the new oscillation code — 'GYRE' — is robust, very accurate, and makes efficient use of multiple cores and/or cluster nodes. We released GYRE last month (more on that in a later post), and there appears to be a fair bit of interest in the asteroseismic community.
In addition to writing these two papers I've helped out on a number of others, including the write-up of the 'IPOD' diagram (I forget what the acronym means!) devised by Veronique Petit and Stan Owocki (see offprint here); and the second MESA instrument paper (see offprint here). The MESA paper documents the many improvements and optimizations which have taken place since the first instrument paper, and includes a discussion of my modest contribution — the MESA SDK.
I've recently returned from the inaugural MESA Summer School, where I presented a couple of lectures and labs on the pulsation and asteroseismology capabilities within the MESA stellar evolution code. The presentation materials (slides, PDFs, etc.) are hosted on a newly-created 'Talks' section on mad star; when I get around to it, I plan to upload the media from other talks I've given.
It seems EZ-Web broke recently, due to my messing around with libraries on the server machine as part of the ongoing MESA SDK development. I've fixed this now, and hopefully avoided any future incidents by making stand-alone copies of the libraries. (I tried using the excellent statifier tool, which converts dynamic ELF executables into static ones; but it segfaults on the server. Bah!)