next up previous contents
Next: Measured HI Ly-a Up: Estimates of Line Previous: Assumed Solar Wind

Calculated Line Intensities

The line intensities (in ) calculated for the coronal hole adopting Esser et al. (1986) model are reported in Tables 3 and 4. It is assumed that the coronal hole is spherically symmetric around its center axis, and that the size of the hole is so large, that the contribution from the surrounding quiet region is negligible (e.g., Esser and Withbroe 1989). Subscripts R, C, and e stand for resonantly scattered, collisionally excited, and electron scattered respectively.

TABLE 3. Coronal Hole (all parameters as in Figure 3.1)
Lyman- O VI

TABLE 4. Coronal Hole (n and T as in Figure 3.1, u = const for .)
Lyman- O VI

Note that both Table 3 and 4 were calculated with the assumption that the O VI ions have the same flow speed as the protons. This is presumably not the case at distances (e.g., Bürgi and Geiss 1986; Esser and Leer 1990).

The corresponding intensities calculated for the quiet corona are reported in Table 5.

TABLE 5. Quiet Region (parameters from Figure 3.2)
Lyman- O VI

Figure 3.5 reports the total intensities of the two Oxygen lines simulated by Spadaro and Ventura (1993) for the equatorial coronal hole and the polar coronal hole. The line intensities range from to in the interval of heliocentric distance 1.2 -- 8 .

Concluding this chapter, we would like to stress again that the calculated intensities reported here are meant as order--of--magnitude estimates. Several parameters entering the calculations have never been measured before, e.g., the electron temperature at distances above 1.5 , the Alfvén wave velocity amplitude (if Alfvén waves play a role at all), the magnetic field at the coronal base.



Peter Smith
Fri Jan 17 12:11:15 EST 1997