# Glossary

```{glossary}
Stellar types
    | Acronym | Stellar phase                         |
    |-------|-------------------------------------------------|
    | MS    | Main Sequence                                   |
    | HG    | Hertzsprung Gap                                 |
    | RGB   | Red Giant Branch                                |
    | cHeB  | Core Helium Burning                             |
    | AGB   | Asymptotic Giant Branch                         |
    | TPAGB | Thermally Pulsing Asymptotic Giant Branch       |
    | He-MS | Helium Main Sequence (naked helium stars only)      |
    | He-HG | Helium Hertzsprung Gap (naked helium stars only)    |
    | He-GB | Helium Giant Branch (naked helium stars only)       |

SSE-style file
    ::: {Important}
    These files can only be created in the standalone mode of METISSE.
    :::

    METISSE can produce two types of output files, one of them are SSE-style files. 
    SSE-style output files are text files ending with .dat and are controlled by the `write_output_to_file` function in SSE_input_controls. These files have a file structure similar to the popular [SSE](https://astronomy.swin.edu.au/~jhurley/bsedload.html) code. They contain the below listed stellar parameters up to the maximum age. Time and age at hydrogen ZAMS are assumed to be zero at the beginning of the code. 

    | Column Header | Description |
    |-----------------|-----------------|
    | time | Physical time [Myr] |
    | age | Age of star [Myr] |
    | mass | Current mass of the star [M<sub>$_\odot$</sub>] |
    | core_mass | Mass of dominant core [M<sub>$_\odot$</sub>] |
    | He_core | Mass of helium core [M<sub>$_\odot$</sub>] |
    | CO_core | Mass of carbon-oxygen core [M<sub>$_\odot$</sub>] |
    | log_L | Log of surface luminosity [L<sub>$_\odot$</sub>] |
    | log_Teff | Log of effective temperature [K] |
    | log_radius | Log of radius [R<sub>$_\odot$</sub>] |
    | phase | SSE stellar type/phase |

MIST-style file


    MIST-style files, which end with .eep, are produced for debugging purposes. The file structure follows the same format used in the files from the [MIST](https://waps.cfa.harvard.edu/MIST/model_grids.html) project. METISSE can write a mass-interpolated track to an output file with the same columns as input files, including a stellar phase column. This output file only contains data from ZAMS to the end of the nuclear-burning phases and does not include information about the remnant phase. It is controlled by the `write_eep_file` function in METISSE_input_controls.



Metallicity File

    This file ends with `_metallicity.in`and contains information about the input tracks for a specific metallicity, including the path to the folder containing the EEP tracks, the metallicity value, and other relevant information and metadata. For more details see [](using_custom_input_tracks.md#metallicity-controls).


Format files


    The format file contains information on how to read files, such as header location, important EEPs, and certain column names. The path to a format file is provided through the metallicity file. For more details see [](using_custom_input_tracks.md#format-controls).


Fortran namelists

    Namelists offer a convenient method for inputting data into Fortran programs. Each entry within a namelist follows this structure:

    ```
    name = value ! comment
    ```

    Values are provided using typical Fortran syntax. `SSE_input_controls`, `METISSE_input_controls`, `metallicity_controls` and `format_controls` are Fortran namelists, so comments (anything after the exclamation mark symbol!) and whitespaces can be used freely. Characters are also case-insensitive. It is important to ensure that there is a blank line at the end of the file following the `/` symbol.

    :::{Note}

    Never modify any file directly inside the `defaults` folder.

    :::

Stellar tracks and stellar models

    A stellar model represents the physical parameters of a star at a specific point in time. By calculating a series of stellar models from the star's formation to the end of its nuclear-burning phase, we can determine the evolutionary history of the star, also known as its stellar track. In this documentation, we use "stellar track" to refer to a time sequence of stellar models. In contrast "set of stellar models" or "set of stellar tracks" refers to the evolutionary tracks of stars with different initial masses but the same metallicity.


```
