DIRT User Input Help

Overview

When you start DIRT, you are presented with a small window from which you select the parameters of the models you wish to investigate. When you press Go!, all the models that match your inputs will be fetched from the database and scaled to the chosen distance. Currently, only Spherical Envelope models are available (so you can't set Surface Density Law or Temperature Law).
The model files are large, so it takes about 0.5 - 1 seconds to load each model. If your parameters match more than about 50 models, expect to wait close to a minute before the display appears.
Model Parameter Selection

Selecting Model Parameters

Select the model input parameters for which you wish to institute a database search. The available parameters are:

Model Type - circumstellar Disk or circumstellar spherical Envelope. Currently the database contains only Envelopes.

Grain Model - the model of dust grains composition and size distribution. Currently available Grain Models are:

MRN - from Mathis, Rumpl, & Nordsieck 1977, ApJ, 217, 425, using graphite and silicate grains distributed in size, a, as

n(a) ~ a^-3.5

with optical constants from Draine & Lee 1984, ApJ, 285, 89 and Draine & Lee 1987, ApJ, 318, 485 . This is pretty much the 'standard' dust model. Consult the Dust Grain Opacities page for further details.
Luminosity - the luminosity in solar units of the embedded star
Effective Temperature - The effective temperature in Kelvin of the embedded protostar
Outer Radius - The outer radius of the envelope or disk in cm. Models with inner radii varying from 1.0E13 cm up to a factor of 10 smaller than the selected outer radius will be returned.
Density Law - (Envelope models only). The power law exponent for the density structure of the envelope, that is, p where

(r) = (r_i) r ^-p

and (r_i) is the density at the inner radius.
Surface Density Law - (Disk models only). The power law exponent p for the disk surface density where

(r) = (r_i) r ^-p

and (r_i) is the central surface density (or the innermost surface density if the disk has a hole in the center).
Temperature Law - (Disk models only). The power law exponent q for the disk temperature where

T(r) = T(r_i) r ^-q

and T(r_i) is the central temperature.
Distance - the distance in parsecs to the source. Model fluxes and luminosities are scaled appropriately for your chosen distance.

When ready, click Go!

What The Messages Mean

After you click Go, the yellow information line tells you what is happening while you wait for your models to load. Here is the list of messages and what they mean:

Looking up models - the database is being queried as to the number and names of the models which match your inputs. The models are copied to a disk staging area.

Fetching N models from the database - The matched models (N of them) are now being sucked into the DIRT applet.

Loading models into plotter - the models are being transferred into the display (aka the Plot Controller).
Pre-filtering display by Inner Radius - too many models makes for a confusing plot (too many points to see what is going on) and also slows down the interactive part of the display. So, if necessary, DIRT will pre-filter the display to select only one or two inner radii. The entire range of inner radii is still available to you. Simply unfilter the range you want back into the display (using the Filter button on the Plot Controller).
Initializing plotter layout - DIRT is constructing the Plot Controller window
Cleaning up - when you quit DIRT or close the Plot Controller, the temporary files in the staging area are removed.

DIRT won't allow more than one Plot Controller at a time. Once the Plot Controller is up, the Go button will be disabled. It will be reenabled after you close the Plot Controller and the staging area is clean.

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