Debris Disk Simulator

The head of the file may start with an arbitrary number of comment lines (e.g. describing the dust data etc.). These comment lines have to have a "#" character at the beginning.

2.3 0.34
...

wavelength [micron]

Flux [W m^-1 sr^-1]

Disk Size

Inner Radius

sublimation radius = f ( grain radius, grain chemical composition )

no dust grains exist within the sublimation radius, even if a fixed inner radius was defined or an external density distribution was uploaded

Disk Density Distribution

Analytical Description

if other (reasonable) analytically described density distributions should be made available, send them to wolf@astrophysik.uni-kiel.de

Density Distribution Upload

The DDS is equipped with the capability to compute spectral energy distributions of optically thin dust configurations of arbitrary structure: (clumpy) circumstellar shells, debris disks (e.g., with/without gaps), three-dimensional structures. The illuminating and heating source (star) may be arbitrarily placed in respect to this configuration. All that needs to be done is to provide the mean number density of grains as a function of the radial distance from the star (see here for an explanation).

The structure of the input file is given below. The density is interpolated linearly between the radial points provided.

# Remarks
#

The head of the file may start with an arbitrary number of comment lines (e.g. describing the dust data etc.). These comment lines have to have a "#" character at the beginning.

Number of radial positions

0.3 7.33
.....

Radial distance from the star [AU]

Relative Dust number density [arbitrary unit, e.g., m^-3]

Note:

[1]	The inner and outer radius considered by the DDS are those defined in the density upload file, not the one defined on the input webpage.
[2]	The mass of the disk has to be defined on the input webpage, since the uploaded density distribution describes the relative radial density profile only.
[3]	Only dust outside the dust sublimation radius is considered (also for the mass normalization).

Hint: See here if you plan to upload density distribution resulting from n-particle simulations.

Dust Mass

takes into account only the grains outside the sublimation radius/radii

Dust Grain Size Distribution

32 grain radii logarithmically distributed within the user-defined grain size range are considered (see Wolf 2003 )

Chemical Dust Grain Composition

Silicates, Oxides / Sulfides, Carbon

data from the Jena Database of Optical Constants and B. Draine (and co-authors)

Optical Dust Data Upload

In addition to the provided chemical dust components, data files describing the optical and physical properties of dust grains may be uploaded. These files have to have the following structure:

# Remarks, remarks, ...
#

The head of the file may start with an arbitrary number of comment lines (e.g. describing the dust data etc.). These comment lines have to have a "#" character at the beginning.

Mg(2)SiO(4)_[Astrosil]

Name of the chemical composition (no blanks! - use "-" or "_" instead).
The Name must start with the the chemical description and maybe followed by a brief description (a few characters only!)

2.50

Specific dust grain density in units of [g/cm^3]

1250.0

Sublimation temperature of the dust grains in units of [K]

Number of Wavelengths in the file. The minimum wavelength range covered is 0.2 - 500 micron.

1.25 1.23 2.02
.....

wavelength [micron]

n = Real( complex refractive index )

k = Im( complex refractive index)

See the dust data file for Mg SiO(3) [2.71 g/ccm] as an example.

Further Internet resources:	Jena Database of Optical Constants
	Dust data obtained by B. Draine et al.

Relative Abundances

The relative abundances of chemically different dust grains can be defined either in respect of their mass ratio in the circumstellar environment or their relative number density. See this figure for illustration.

Example: Shell with two chemical components:

(a) Mg(0.4) Fe(0.6) SiO(3) [3.2 g/ccm]
(b) 600°C configuration of Carbon [1.67 g/ccm]

Let's assume a relative mass ratio of (a):(b)=85%:15% in the shell. According to the (different) specific dust grain densities, the corresponding dust number density ratio amounts to approx. (a):(b)=75%:25%.

Remark: Due to different sublimation temperatures of different chemical components and different optical properties (and therefore different radial temperature distributions of chemically different dust grains and grains with different size, the inner region of the shell depends on the grain size and chemistry ("Sublimation radius"). For this reason the relative abundances may not be valid at the inner most regions of the dust shell/disk and the total mass and number density ratio may (very) slighty differ from the defined values.

Simulation specifications

Observed SED

Observed flux values may be uploaded and overplotted to the simulated SED. The file containing these values has to have the structure shown below. Here, the quantities delta1 and delta2 mark the error interval: Flux = [observed flux - delta1, observed flux + delta 2].

# remarks...
# ...

The head of the file may start with an arbitrary number of comment lines (e.g. describing the dust data etc.). These comment lines have to have a "#" character at the beginning.

### nlambda 200

number of wavelengths given in the last line of the header

4 more comment lines

2.3 0.34 0.05 0.06
...

wavelength [micron]

Observed Flux [mJy]

delta1 [mJy]

delta2 [mJy]

Input file size limits

Density distribution	250 kByte
Dust data files	250 kByte
Stellar SED	250 kByte
Observed SED	250 kByte

Model / Simulation restrictions + Internal Parameter settings (user relevant parameters only)

1. Model restrictions

2. Further (possible) restrictions

min./max. wavelengths for the stellar emission

Dust heating: Wavelength interval of Stellar emission

1. Star = Blackbody

The wavelength interval for stellar emission is given by Wien's law: l_w T_eff = const.
Below the wavelength l_w 25% of the stellar energy is emitted, 75% above.

The total fraction of the energy to be neglected in the radiative transfer process is internally set to >> see parameter file . According to the effective temperature T_eff of the star, the lower wavelength interval is chosen such that 1/4 of the neglected energy will be below this wavelength.The remaining 3/4 of the neglected energy would be emitted at wavelengths beyond the upper limit of the wavelength interval.

2. Arbitrary stellar SED (uploaded or internal)

The wavelength interval for stellar emission is given by the wavelength interval of the uploaded/internal SED.

Sebastian Wolf