TABLE V
Frequency Distribution of Types
| Type | Number | Percentage | Mean Mag. |
|---|---|---|---|
| Elliptical Nebulae | |||
| E0 | 17 | 18 | 11.40 |
| 1 | 13 | 14 | 11.43 |
| 2 | 14 | 15 | 11.52 |
| 3 | 10 | 11 | 11.99 |
| 4 | 13 | 14 | 11.95 |
| 5 | 6 | 6 | 10.97 |
| 6 | 7 | 8 | 10.93 |
| 7 | 5 | 5 | 11.02 |
| Pec | 8 | 9 | 11.55 |
| Total | 93 | 23* | 11.53 |
| Normal Spirals | |||
| Sa | 49 | 21 | 11.69 |
| b | 70 | 29 | 11.55 |
| c | 115 | 49 | 11.75 |
| Pec | 3 | 1 | 12.80 |
| Total | 237 | 59* | 11.68 |
| Barred Spirals | |||
| SBa | 26 | 44 | 11.66 |
| b | 16 | 27 | 11.48 |
| c | 15 | 26 | 11.87 |
| Pec | 2 | 3 | 11.70 |
| Total | 59 | 15* | 11.66 |
| Irregular Nebulae | |||
| 11 | 3* | 11.34 | |
| Totals | |||
| All types | 400 | 100 | 11.63 |
* Percentages of 400, the total number of nebulae investigated. The percentages of the subtypes refer to the number of nebulae in the particular type.
TABLE VI
Frequency Distribution of Magnitudes
| Magnitude Interval | Numbers of Nebulae | ||
|---|---|---|---|
| E | S | All | |
| 8.1– 8.5 | 0 | 2 | 2 |
| 8.6– 9.0 | 2 | 4 | 7 |
| 9.1– 9.5 | 4 | 6 | 11 |
| 9.6–10.0 | 7 | 7 | 19 |
| 10.1–10.5 | 7 | 13 | 20 |
| 10.6–11.0 | 8 | 14 | 32 |
| 11.1–11.5 | 9 | 24 | 49 |
| 11.6–12.0 | 21 | 57 | 88 |
| 12.1–12.5 | 20 | 52 | 86 |
| 12.6–13.0 | 10 | 33 | 51 |
The corrected values of log d were then plotted against the observed magnitudes. This amounts to shifting the approximately parallel correlation curves for the separate types along the axis of log d until they coincide. Since the mean magnitudes of the various types are nearly constant, the relative shifts will very nearly equal the differences in the mean observed log d, and hence the effect of errors in the first approximation to the values of K will be negligible.
Fig. 1.—Frequency distribution of apparent magnitudes among nebulae in Holetschek’s list.
Fig. 2.—Relation between luminosity and diameter among nebulae at the beginning of the sequence of types—E0 and E1 nebulae.