Orion HST

Homework 2018 Thailand

Join the Google discussion group

The Google discussion group is here. There will be announcements posted on the group, and it is a good place to ask questions. When you join you will find a number of options for receiving emails from the group. You should set those to send you any emails, or at a summary for each day, since the announcements are important for the workshop.

Bookmark the class FTP site

The FTP site is here. We will place documents, PDFs of the lectures, and models, in folders below this site.

Introduce yourself

Help prepare the list of participants - due Wednesday May 9

The organizers are creating a handout giving name, institution, a small photo, and research interests of all participants. This will allow us to get to know one another more quickly.

Prepare a 4-minute introductory talk - due Wednesday May 9

We will all give 4-minute introductory presentations on our research interests and background. Please prepare a one-page landscape format (to fit the projector screen) PDF of your talk and send it to the organizers. This will be available on the computer when you give your talk.

We will break up into small teams to work on research projects and this introduction will help identify participants with similar interests.

Astrophysics of Gaseous Nebulae (AGN3)

We will use Osterbrock & Ferland 2006 extensively. Don always called this AGN3 since it is the third version of the book. Bring your copy if you have one. PDFs of some sections are in the docs folder of the FTP site.


Bring a laptop so you can compute models during the workshop

We want to spend our time thinking about the astronomy rather than the computer science. You need to have a working copy of Cloudy to participate. You should be able to create an input deck using an editor, run Cloudy, and make plots of the predictions during the workshop.

It would be best to bring a laptop to do the simulations and plots locally. This is the best way to participate.

The classroom will have wifi so logging into a remote machine is possible.

Download and install Cloudy

We will use the current version of Cloudy. Instructions for downloading and installing Cloudy are here. Vital Fernandez created a nice set of videos on how to build and run Cloudy.

Problems?? Search our Yahoo user group to see if others have solved it, and post a question if you don't find help.

You should make it through at least step 5 of the instructions this site.

When finished you will have an Cloudy executable that can successfully pass its smoke test (run the code with the input having the single command "test").

You should have a script "run" that will read input from "name.in" and produce the "name.out" output file.

Have access to the code's documentation

These are PDF files are located in the docs directory of the Cloudy download, and are also post on the FTP site. You should be able to view the Cloudy Quick Start Guide Hazy1 and Hazy2, the documentation files, on your laptop. Please don't print them.

Typos?? If you notice any please let me know by posting to the Yahoo group.

Read the Cloudy Quick Start Guide

This is a short introduction to all of Cloudy. Read it to get an overview of what we will be discussing.

Run the "orion_hii_open.in" model and plot some results. Due Sunday May 13

Run the model

You will find this model in the subdirectory ../tsuite/auto where .. indicates the top level of your Cloudy download. Several files will be created when you compute the model. The most important is the main output, named "orion_hii_open.out" if you use our recommended "run" script. Look at the last lines in that file. They should say "Cloudy exited OK". If they don't you have problems and should investigate.

Plot the temperature and ionization structure

We will make lots of plots showing predicted quantities during the workshop. You will need to compute models and create plots while in the class. Gnuplot is popular among people who like its command line interface. I use Jeremy Sanders' Veusz program, which is GUI based and very Cloudy friendly. The appendix of the Quick Start Guide explains how we use Veusz.

The file "orion_hii_open.ovr" is the "overview" file that was created when you ran Cloudy. It has lots of information about the physical conditions in the cloud. The first row gives column headers. The remaining rows give properties of the cloud at each depth point. They are tab delimited fields meaning that a tab character separates columns.

Make a plot in which the depth into the cloud is the x-axis and the gas kinetic temperature is the y-axis. The depth in cm is the first column in the overview file. The temperature is the second. Save a copy of the plot in PDF format. Forward the plot as an email to the Google discussion group.

Next plot the hydrogen ionization as a function of depth into the cloud. The depth in cm is the first column, the fraction of hydrogen that is atomic is the seventh column, and the fraction that is ionized is the eighth column. Include both atomic and ionized hydrogen on the same plot.

Plot the emitted spectrum

This is contained in the file orion_hii_open.con. The first column is the wavelength in microns. This is the x-axis and the plot should be a base 10 log and have a range from 0.01 to 1000 microns. Column 7 gives the surface brightness in ergs /cm2 / s and should be the logarithmic y-axis. Make the axis have a minimum at 0.01 erg / cm2 / s.

Plot the H-beta emissivity

The emissivity is an emission line's emission per cubic centimeter. The integral over the emissivity gives the surface brightness or luminosity of the line. The file orion_hii_open.ems gives the emissivity in several lines. Plot the emissivity of the hydrogen H-beta line, listed as "H 1 4861.33A", as a function of depth. We will compare this plot with HST observations of M16.

Post these plots on the Google group by May 13.