### Wind from the Sun or other stars

#### (supervisor: Xing Li)

Nature of project: **theory**, data analysis

Available to
students on full-time physics degree schemes only.

#### Project description and methodology

The idea of the Sun-like star producing a fully ionized wind was fully established in the 1950s. The theory that led to supersonic solar wind solutions can be realised using MHD mass and momentum conservation equations, plus some basic assumptions and simplifications. This project aims to revisit the development of the solar wind theory. Using time independent mass and momentum conservation equations, the project will show the conditions under which the solar wind is possible. The solutions will then be compared to satellite observation data.

*A successful project will develop beyond the above in one/some of the following directions:*

Students have a choice to further develop their numerical simulation skills from two options:

1, write their own code to numerically solve time independent mass and momentum conservation equations of the solar wind.

2, use a fortran code provided by the supervisor to find numerical solar wind solutions. The code solves time dependent solar wind equations.

When considering where to take your project, please bear in mind the time available. It is preferable to do fewer things well than to try many and not get conclusive results on any of them. However, sometimes it is useful to have a couple of strands of investigation in parallel to work on in case delays occur.

*Additional scope or challenge if taken as a Year-4 project:* 4th year student can discuss the stellar wind from other stars.

Please speak to **Xing Li** if you consider doing this project.

*Initial literature for students:*

- Parker, E., Astrophysical Journal, 128, 664, 1958
- Priest, E., Magnetohydrodynamics of the Sun, Chapter 13, Cambridge University Press, 2014
- Leer, E., and Holzer, T.E., Journal of Geophysical Research, 85, 4681, 1980.
- Li, X., et al., Journal of Geophysical Research, 104, 2521, 1999

#### Novelty, degree of difficulty and amount of assistance required

Not difficult. Supervisor will provide help in modelling

#### Project milestones and deliverables (including timescale)

milestone | to be completed by |

Have good understanding of MHD theory after finishing PH39710 | Christmas |

Have the basic theoretical development of the solar wind | end of February |

Have a reatively complete theoretical development of the solar wind, if possible do numerical simulation (but not mandatory) | mid-March |

Achieve some 1-D solar wind solutions from any method (theory, time-independent modelling, or time dependent modelling) | Easter |