Version 15 June 2007 compiled: 11-11-2009 - Hamburger Sternwarte

Abstract
This (very brief) manual is intended to serve as a guideline for users of PHOENIX. The description
is very short and preliminary, however, even a short manual seems to be better than no manual at
all. Warning: This manual is partly outdated, version 14 includes many more features than described
here. I basically have not enough time to update the manual continuously. The earliest versions of
this code were named SNIRIS but beginning with SNIRIS version 3.0α the code has been renamed to
PHOENIX. The main reasons are the large number of changes to the old code, so that PHOENIX has
“risen from the ashes” of SNIRIS. The first part of this manuscript gives a description of the purpose
of the code and the equations and numerical methods used in PHOENIX, whereas the second part
gives details about the input and output files and the control variables used by PHOENIX.
1 Introduction
Version 13 of PHOENIX includes
1. many NLTE species (too many to list, e.g., all CHIANTI or APED data can be included as NLTE
species),
2. molecular NLTE (currently for CO, water and TiO planned),
3. up to 110 chemical elements (all 83 with known solar abundances)
4. updated equations of state with more molecules and dust formation,
5. dust settling,
6. more molecular band and line opacities,
7. exponential density profile,
8. a much improved user interface (by using namelist input),
9. the capability to compute wind models for O stars and novae,
10. parameterized clouds (for very cool objects),
Later versions of this report will contain also information about the internal structure of PHOENIX
(subroutines/functions, calling sequences and code parameters/variables).
1.1 Purpose of PHOENIX
PHOENIX was designed as an extremely general stellar atmosphere code 1 . Its first first application
was the computation of the radiation emergent from a rapidly expanding supernova or nova envelope
during the first weeks and months after explosion. PHOENIX is also used to construct LTE and NLTE
model atmospheres for dwarf and giant stars all across the HRD, brown dwarfs, extrasolar planets
(including irradiation), hot winds from CVs in outburst, AGN disks (with Herbert Störzer), and a lot
of other things.
1.2 Physical assumptions
• spherical symmetry,
• steady state, i.e., ∂/∂t ≡ 0,
• homologous expansion, i.e., v(r) = v0(r/R0) for supernova models or constant mass-loss rate for
nova models,
• expansion velocity v0, typically v0 ≈ 10 4 km s −1 for supernovae and v0 ≈ 10 3 km s −1 for novae,
• power law density, i.e., ρ(r) = ρ0 (r/R0) −nρ , or exponential density profile
ρ(r) = ρ0 exp (ve/v0(r − R0)), or hydrostatic equilibrium,
• energy conservation, especially radiative equilibrium, in the Lagrangian frame,
1 The true purpose of the code is, of course, to be written and modified. Yes, it is self-sufficient!
2