Once sufficient heat is obtained by the gas particles, ionization can cause attraction if the particles become oppositely polarized. Ionization of hydrogen by high temperatures, for example, typically results in the loss of the electron. The hydrogen ions are therefore mostly positively charged and will repel each other. Electrostatic attraction is therefore not a correct model.
Compression by a magnetic field remains the only viable option to explain star formation at high temperatures and with particles that tend to repel each other. To obtain a magnetic field, there must be electric current, either electrons moving or positive ions moving. As stated earlier, a hydrogen ion that has been stripped of its electron is positive and will tend to repel other hydrogen ions. An interesting thing occurs when positive ions travel in the same direction. These ions form a magnetic field that pushes them together, despite their inherent repulsion. The forces by the magnetic field can be tremendous with large currents (i.e. Birkeland currents). Magnetic compression is therefore the most likely force causing star formation.
Birkeland current:
Herbig-Haro 212:
Possible Birkeland current paths:
