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SPECTRUM - command syntax

## Invocation

Primary input is assumed to be from"sysinput".

## General Commands

## echo [ off | 0 | 1 | 2 | on ]

Adjust level of i/o reported at terminal.

## debug [ mn | wh | in | ln | op | at | md | ou | ot ]

Provide diagnostic printout for various classes of subroutine:

mn: main program,wh: subroutine WHOLE,in: subroutine INTEG and SFLUX,op: continuous opacities,ln: line opacities,at: atomic data,md: model atmosphere,ou: output,ot: other.## check

Confirm choices for Spectrum parameters

## end, exit, q

No more input!

## Parameter Definition

## nsource <n>

Choice of how the source function is calculated.

Default= 3.

- nsource 1 = planck: Snu = Bnu : Planck function
- nsource 2 = avrett : Snu from Avrett Loeser
- nsource 3 = feautrier : Snu from Feautrier, Fnu/Fcont output (
default)## noptype <n>

Choice of continuous opacity. This variable is set whenever a model atmosphere is read in, so that the default is whatever was used to compute the original model atmosphere. This command allows a user to override that default.

- noptype 0 = QUB : subroutines from ATLAS6
- noptype 1 = KIEL : subs originally from ATLAS6 + Peach tables for C and N
- noptype 2 = OP : b-f cross-sections from Opacity Project
## nhedat<n>

Choice of data for diffuse HeI line Stark broadening tables.

Default= 1

- nhedat 1 : Barnard, Cooper et al. ... (
default)- nhedat 2 : Beachamp et al. ...
## nhestark <n>

choice of theory for low-density HeI line Stark broadening.

Default= 2

- nhestark 0 : old data, sources mixed and incomplete ...
- nhestark 1 : old data, plus Dimitrijevic & Sahal Brechot (1991) for additional lines
- nhestark 2 : Dimitrijevic & Sahal Brechot (1991) for all (
default)## ntheta<n>

Number of angles for which specific intenstities are to be calculated.

Default= 0.## costheta <mu_1> <mu_2> <mu_3> ...<mu_n>

List of cosine angles (cos theta = mu) for which specific intensities are to be computed.

## costmin <mu_min>

The minimum cosine angle at which intensities to be computed in order to avoid singularities.

Default: mu_min = 0.005## Model Atmosphere Input

## read_model <filename>

Read in the model atmosphere from the file aready defined. This command currently reads data from either 25 zone (QUB) or 50 zone (STERNE) models formatted for SPECTRUM (the format is defiened elsewhere. As well as reading in the model, ionisation fractions and other depth-dependent quantities are also computed at this stage. The filename is optional, the

defaultis to read data from a file called "MODEL" which may be specified on the command line, or established using a soft link by a shell script.## read_sterne <filename>

Read in the model atmosphere from the file aready defined. This command reads data a STERNE3 datafile, which may include a stratified composition. The filename is optional, the

defaultis to read data from a file called "MODEL" which may be specified on the command line, or established using a soft link by a shell script.## read_hydro <filename>

Read in a set of scalings and velocities for a hydrodynamic model atmosphere. These scalings are relative to an atmosphere in hydrostatic equilibrium and can thus be applied to a model atmosphere previously read by read_model or read_sterne

## Atomic Data

## read_lines [<filename>]

Read in the linelist from the file given. If not given, the

defaultis to read data from a file called "LINELIST" which may be specified on the command line. The data provided for each line should include atomic number, ionisation stage (neutral = 1), wavelength, log gf, radiative, electron and van der Waal's damping widths, excitation potential of the lower level and (in some cases) a multiplet identification.If a model atmosphere has alredy been read in, this command will filter the lines in the linelist to exclude lines weaker than a limit defined by lines_threshold. This is useful for working with generic linelists which have not been specially prepared by the user.

## line_threshold <value>

A number repersenting a lower limit on the strength of lines to be included in linelist for a spectrum synthesis. The quantity gf.n is computed at a given optical depth (tau=0.1) for the current model atmosphere (if one has been read in) and if greater than <value>, it is retained in the linelist. The

default= 0.01 corresponds roughly to a level where a line would have a minimum equivalent width of about ?? mÅs.## wavmax <w_max>

The maximum wavelength from line centre for which line profiles for metal lines would be computed, if not overridden by some other factor.

Default= 5 Angstrom.## wtol <w_tol>

A parameter used in single line mode with two roles:

a) The maximum difference from the given wavelength at which a line will be identified. Note that the line identified will be thefirstline in the list which satisfies both criteria of element and wavelength.

b) The maximum difference from the wavelength of the identified line for which other componentsof the same multipletwill be included in the calculation, i.e. as a blend.

Default= min(1,<w_tol)> Å or min(0.1,<w_tol)> Å if calc_prof or calc_abund is used with negative <z>## Abundances

## abund <z> <n_z>

Define the abundance of chemical element with atomic number <z>. Use logarithmic form normalized s.t Sum.log.mu.n = 12.15. Conventionally, solar H abundance = 12.00

1. Default for all elements -- solar abundance.

2. All elements scaled to iron unless specified explicitly.## abfrac <z> <n_z>

Define the fractional abundance (by number) of chemical element with atomic number <z>: n_z/n_total. (NB:

NOTn_z/n_H)## ablog <z> <n_z>

Define the abundance of chemical element with atomic number <z>. Use logarithm of the fractional abundance by number (see abfrac)

The following are equivalent for a hydrogen-rich atmosphere (H=12.00):

- abund 6 10.0
- abfrac 6 0.01
- ablog 6 -2.0
## abmodel

Take abundances of elements used in synthesis directly from the model atmosphere. This is NOT the default option. Can be overridden selectively by subsequent use of

abund## Velocities, etc

## vturb <v_t>

The microturbulent velocity, in km/s, to be used in a spectral synthesis calculation.

Default= 0 km/s.## nvturb <n_vt>

The number of microturbulences to be entered in a depth-dependent microturbulence calculation

## vtrb_tau

The microturbulent velocity, in km/s, as a function of optical depth (tau), entered as <n_vt> pairs of values ( <tau_i>, <vturb_i> ), i = 1,<n_vt>. This function is mapped onto the model optical depth scale with a 2nd order polynomial interpolation.

## vrad <v_r>

The radial velocity, in km/s, to be used in a spectral synthesis calculation.

Default= 0 km/s.## nvrad <n_vr>

The number of radial velcoities to be entered in a depth-dependent radial velocity calculation

## vrad_tau

The radial velocity, in km/s, as a function of optical depth (tau), entered as <n_vr> pairs of values ( <tau_i>, <vrad_i> ), i = 1,<n_vt>. This function is mapped onto the model optical depth scale with a 2nd order polynomial interpolation.

## tau_exp <n>

Expand the optical depth scale by a factor <n> by interpolating additional depth points intermediated between existing points.

## tauscale <n_tau>

Rescale the optical depth scale onto a new scale with <n_tau> depth points. The <tau> values to be used msut be entered immediately after this command.

## taulogsc <n_tau>

Rescale the optical depth scale onto a new scale with <n_tau> depth points. This is the same as "tauscale" except that the <tau> values are to be given as log_10. The <log tau> values to be used must be entered immediately after this command.

## Radiative Transfer Calculations

## calc_prof <z> <wl> <ab> <v_t>

Compute the line profile and equivalent width for a single absorption line, or for a blend, if lines from the same multiplet lie within a factor <wtol> of the line given. The arguments are:

- <z> Atomic number for the ion giving rise to the absorption line
- <wl> Wavelength of the absoption line, accurate to <wtol>
- <ab> The abundance of element <z>. Use logarithmic form normalized s.t Sum.log.mu.n = 12.15. Conventionally, solar H abundance = 12.00.
- <v_t> The microturbulent velocity to use for this line, in km/s.
The line profiles is normalized to the continuum at line centre. The wavelength scale is (currently) centred at 0Å at line centre, but given in Angstrom.

Note that the program searches the linelist for the first line of the given atomic number within <wtol< of the given <wl>. Default <wtol<=1Å, or 0.1Å if <z><0## calc_abund <z> <wl> <ew> <v_t>

Compute the line profile for a single absorption line, or for a blend, if lines from the same multiplet lie within a factor <wtol> of the line given. The profile is computed for a given equivalent width; the elemental abundance required to reproduce this equivalent width is computed by Newton's method. The arguments are:

- <z> Atomic number for the ion giving rise to the absorption line
- <wl> Wavelength of the absoption line, accurate to <wtol>
- <ew> The equivalent width of the absoption line in milliAngstrom.
- <v_t> The microturbulent velocity to use for this line, in km/s.
The line profiles is normalized to the continuum at line centre. The wavelength scale is (currently) centred at 0Å at line centre, but given in Angstrom.

Note that the program searches the linelist for the first line of the given atomic number within <wtol< of the given <wl>. Default <wtol<=1Å, or 0.1Å if <z><0## calc_synth <w_min> <w_max>

Calculate the emergent spectrum form the specified model in the wavelength range <w_min> to <w_max>. The program provides the emergent normalized fluxes, the total emergent flux, and the total emergent "continuum" flux. If <n_theta> > 0, then specific intensities (total and normalized) are also computed.

## calc_lines <w_min> <w_max>

Calculate equivalent widths for all the lines given in the input linelist using the specified model, abundances and wavelength range <w_min> to <w_max>. The program provides a simple list containing Z, WL, TEFF, LG_G, LG_AHE, LG_GF, MULT, VT, LOG_AB and EW for each line. This option is particularly designed for use with id_lines

Examples

SPECTRUM is maintained by:

Simon Jeffery (csj@arm.ac.uk)

Last modified: Mar 02, 2007