The frequency distribution of magnitudes for all types together and for
the elliptical nebulae and the spirals separately is shown in Table VI
and Figure 1. With the exception of the two outstanding spirals, M 31
and M 33, the apparent luminosities are about uniformly distributed
among the different types. The relative numbers of the elliptical
nebulae as compared with the spirals decrease somewhat with decreasing
luminosity, but this is very probably an effect of selection.
The elliptical nebulae are more compact than the spirals and become
more stellar with decreasing luminosity. For this reason some of the
fainter nebulae are missed when small-scale instruments are used,
although the same luminosity spread over a larger area would still be
easily detected. The effect is very pronounced on photographic plates.
It accounts also for the slightly brighter mean magnitude of the
elliptical nebulae as compared with the spirals in Table V.
TABLE I
Elliptical Nebulae
==========+===========+========
N.G.C. | m_{T} | log d
----------+-----------+--------
E0 (17)
----------+-----------+--------
404 | 11.1 | +0.11
474 | 12.6 | – .40
1407 | 10.9 | .15
3348 | 11.8 | – .15
3379* | 9.4 | + .30
4283 | 12.2 | – .52
4486* | 9.7 | + .30
4494* | 10.1 | – .15
4552* | 9.9 | + .23
4589 | 11.4 | – .30
4648 | 12.3 | .52
5044 | 11.8 | .30
5216 | 13.3 | .70
5273 | 12.1 | .52
5557 | 12.3 | .40
5812 | 12.0 | – .40
5846 | 10.9 | 0.0
|-----------|---------
Mean | 11.40 | –0.204
----------+-----------+---------
E1 (13)
----------+-----------+---------
467 | 13.0 | –0.70
596 | 11.8 | .22
1400 | 11.1 | .22
2880 | 12.0 | .52
3226 | 12.0 | .10
3962 | 11.8 | – .30
4278* | 10.8 | .0
4374* | 9.9 | + .08
4472 | 8.8 | + .30
4478 | 11.5 | – .10
4636 | 10.9 | + .08
5813 | 12.6 | – .30
7626 | 12.3 | –0.30
----------+-----------+---------
Mean | 11.43 | –0.177
----------+-----------+---------
E2 (14)
----------+-----------+---------
221* | 8.8 | +0.42
1453 | 11.9 | – .10
2672 | 12.8 | – .40
3193 | 12.1 | 0.0
3599 | 12.0 | –0.30
3608 | 11.6 | .22
3640 | 11.1 | – .05
4261 | 11.1 | + .20
4291 | 12.3 | – .52
4377 | 11.9 | – .05
4406* | 10.0 | + .30
4476 | 12.8 | – .30
4649* | 9.5 | + .30
5127 | 13.3 | –0.52
----------+-----------+---------
Mean | 11.52 | –0.088
----------+-----------+---------
E3 (10)
----------+-----------+---------
1052 | 11.8 | –0.15
1600 | 12.7 | + .17
3222 | 13.3 | – .15
4319 | 12.8 | – .52
4365 | 11.4 | + .04
4386 | 12.3 | – .52
5322* | 9.6 | + .15
5982 | 11.4 | .0
7562 | 12.8 | – .22
7619 | 11.8 | – .15
----------+-----------+---------
Mean | 11.99 | –0.133
----------+-----------+---------
E4 (13)
----------+-----------+---------
584 | 10.9 | +0.30
1700 | 12.5 | – .10
2974 | 11.8 | .15
3605 | 12.5 | – .52
3610 | 11.8 | + .15
3894 | 12.8 | – .05
4125* | 10.3 | + .30
4378 | 12.1 | – .15
4382* | 10.0 | + .48
4551 | 12.8 | + .04
4742 | 12.3 | .0
5576 | 12.3 | – .15
7454 | 13.3 | 0.0
----------+-----------+---------
Mean | 11.95 | –0.011
----------+-----------+---------
E5 (6)
----------+-----------+---------
720 | 10.9 | + .11
2693 | 12.3 | – .15
3377 | 10.9 | + .17
4473 | 10.3 | .11
4621* | 10.0 | + .30
4660 | 11.4 | 0.0
----------+-----------+---------
Mean | 10.97 | +0.090
----------+-----------+---------
E6 (7)
----------+-----------+---------
821 | 11.8 | 0.0
2768 | 10.7 | + .18
3613 | 11.8 | .25
4179 | 11.8 | .34
4435* | 10.5 | .11
4546* | 10.3 | .18
4697* | 9.6 | +0.48
----------+-----------+---------
Mean | 10.93 | +0.220
----------+-----------+---------
E7 (5)
----------+-----------+---------
3115* | 9.5 | +0.60
4111 | 10.1 | .54
4270 | 12.1 | .0
4570 | 11.1 | .38
5308 | 12.3 | +0.28
----------+-----------+---------
Mean | 11.02 | +0.360
----------+-----------+---------
Peculiar (8)
----------+-----------+---------
185 | 12.3 | +0.48
205* | 9.3 | .90
524† | 11.9 | .41
3607† | 9.9 | .11
3998† | 12.1 | + .23
4459‡ | 11.3 | – .22
5485‡ | 12.3 | .05
5739 | 13.3 | –0.40
----------+-----------+---------
The various types are homogeneously distributed over the sky, their
spectra are similar, and the radial velocities are of the same general
order. These facts, together with the equality of the mean magnitudes
and the uniform frequency distribution of magnitudes, are consistent
with the hypothesis that the distances and absolute luminosities
as well are of the same order for the different types. This is an
assumption of considerable importance, but unfortunately it cannot yet
be subjected to positive and definite tests. None of the individual
similarities necessarily implies the adopted interpretation, but the
totality of them, together with the intimate series relations among
the types, which will be discussed later, suggests it as the most
reasonable working hypothesis, at least until inconsistencies should
appear.
TABLE II
Barred Spirals
==========+===========+=========
N.G.C. | m_{T} | log d
----------+-----------+---------
SBa (26)
----------+-----------+---------
936 | 11.1 | +0.48
1023* | 10.2 | .78
2732 | 12.3 | .11
2781 | 12.3 | .11
2787 | 11.4 | .36
2859 | 11.1 | .28
2950 | 11.6 | .15
3384* | 10.7 | .48
3412* | 11.2 | + .40
3418 | 13.1 | .0
3458 | 12.8 | – .22
3945 | 11.5 | + .20
4026 | 11.1 | .48
4203 | 11.1 | .36
4346 | 12.0 | .20
4371 | 12.0 | .18
4421 | 12.8 | .17
4442 | 10.9 | .50
4477 | 10.9 | .40
4596 | 12.0 | .25
4643 | 11.1 | .26
4754 | 10.9 | .48
5473 | 12.0 | + .08
5574 | 13.0 | – .05
5689 | 12.0 | + .30
5701 | 12.3 | +0.17
+-----------+---------
Mean | 11.66 | +0.267
----------+-----------+---------
SBb (16)
----------+-----------+---------
1022 | 11.8 | +0.04
2650 | 12.8 | .0
3351* | 11.4 | + .48
3400 | 12.5 | – .10
3414 | 11.5 | + .26
3504 | 11.4 | .30
3718 | 11.8 | +0.48
4102 | 12.0 | +0.36
4245 | 11.1 | .15
4394 | 11.5 | .60
4548 | 11.1 | .60
4699* | 10.0 | .57
4725* | 9.2 | .70
5218 | 12.8 | .25
5566 | 11.1 | .20
7723 | 11.8 | +0.18
+-----------+---------
Mean | 11.48 | +0.317
----------+-----------+---------
SBc (15)
----------+-----------+---------
613 | 10.6 | +0.60
779 | 12.1 | .48
3206 | 13.3 | .45
3344 | 11.4 | .60
3346 | 12.3 | .40
3625 | 13.3 | .0
3686 | 12.0 | .30
3769 | 12.8 | .43
3953 | 11.1 | .74
3992 | 11.5 | .85
4303* | 10.6 | .78
4579* | 9.7 | .45
5383 | 12.6 | .40
5921 | 12.8 | .70
7479 | 12.1 | +0.48
+-----------+---------
Mean | 11.87 | +0.509
----------+-----------+---------
Peculiar (2)
----------+-----------+---------
2782 | 12.3 | +0.26
4314 | 11.1 | +0.34
----------+-----------+---------
TABLE III
Normal Spirals
==========+===========+=========
N.G.C. | m_{T} | log d
----------+-----------+---------
Sa (49)
----------+-----------+---------
488 | 11.8 | +0.48
676 | 13.3 | .30
1332 | 10.9 | .43
2655 | 11.1 | .60
2681 | 10.7 | .48
2775 | 10.9 | .32
2811 | 12.3 | .28
2855 | 12.8 | .11
3169§ | 12.3 | .60
3245 | 11.8 | .30
3301 | 12.4 | .15
3368* | 10.0 | .85
3516 | 12.1 | .20
3619 | 12.3 | .0
3626* | 11.3 | .28
3665 | 12.0 | .0
3682 | 12.1 | .08
3898 | 12.0 | .43
3941 | 10.3 | .30
4036 | 10.9 | .60
4138 | 12.1 | .20
4143 | 11.3 | .11
4150 | 12.0 | .11
4251 | 10.4 | .26
4268 | 12.8 | .0
4274 | 11.1 | +0.54
4281 | 11.5 | +0.18
4429 | 11.5 | .48
4452 | 12.6 | .15
4526 | 11.1 | .70
4550 | 12.1 | .43
4570 | 11.1 | .38
4594 | 9.1 | .85
4665 | 11.8 | + .08
4684 | 12.2 | – .22
4698 | 11.9 | + .43
4710 | 11.8 | .54
4762 | 11.5 | .57
4866 | 12.0 | .50
4958 | 11.4 | .60
5377 | 11.8 | .48
5389 | 12.5 | .25
5422 | 12.1 | + .40
5631 | 12.0 | – .05
5866* | 11.7 | + .48
7013 | 12.8 | .08
7457 | 12.8 | .30
7727 | 11.3 | .43
7814* | 11.4 | +0.48
+-----------+---------
Mean | 11.69 | +0.333
----------+-----------+---------
Sb (70)
----------+-----------+---------
224 | 5.0 | +2.25
672 | 12.8 | 0.54
772 | 11.1 | .70
949 | 13.3 | .0
955 | 12.9 | .40
1068 | 9.1 | .40
1309 | 12.0 | .15
2639 | 12.2 | .0
2715 | 12.5 | .40
2748 | 12.0 | .32
2841* | 9.4 | .78
2985 | 11.4 | 0.48
3031* | 8.3 | +1.20
3182 | 12.9 | –0.22
3190 | 11.9 | + .48
3227 | 12.0 | .48
3277 | 12.6 | .0
3310 | 10.4 | + .18
3380 | 12.1 | – .05
3489* | 11.2 | +0.40
3556 | 11.1 | +0.90
3593 | 11.9 | .60
3623* | 9.9 | .90
3627* | 9.1 | 0.90
3628§ | 11.4 | +1.08
3632 | 13.3 | –0.10
3675 | 11.4 | + .48
3681 | 13.0 | .0
3684 | 13.0 | + .08
3895 | 13.3 | – .05
3900 | 12.1 | + .25
3938 | 12.1 | .65
4020 | 12.3 | .17
4030 | 11.1 | .30
4051* | 11.9 | .60
4085 | 12.5 | .36
4151 | 12.0 | .40
4192 | 10.9 | .90
4216* | 10.8 | 0.85
4244§ | 12.3 | +1.11
4258* | 8.7 | +1.30
4273 | 11.8 | 0.20
4438* | 10.3 | .54
4448 | 11.8 | .48
4450 | 10.6 | + .57
4451 | 12.8 | – .15
4500 | 12.8 | +0.17
4565*§ | 11.0 | 1.17
4736* | 8.4 | 0.70
4750 | 11.8 | .26
4800 | 11.8 | .04
4814 | 12.7 | .56
4826 | 9.0 | .90
5055* | 9.6 | .90
5376 | 12.8 | + .17
5379 | 12.9 | –0.05
5394 | 13.3 | +0.17
5633 | 13.0 | – .10
5713 | 12.3 | + .32
5740 | 12.3 | .48
5746 | 10.4 | .87
5750 | 12.8 | .15
5772 | 12.0 | .25
5806 | 12.3 | .30
5985 | 12.0 | .60
6207 | 11.8 | .30
6643 | 11.9 | .48
7331* | 10.4 | .95
7541 | 12.7 | .41
7606 | 12.0 | +0.78
+-----------+---------
Mean | 11.55 | +0.471
----------+-----------+---------
Sc (115)
----------+-----------+---------
157 | 11.4 | +0.40
253 | 9.3 | 1.34
278 | 12.0 | 0.08
470 | 13.1 | 0.20
598 | 7.0 | 1.78
615 | 12.3 | 0.43
628* | 10.6 | .90
908 | 11.9 | .60
1084 | 11.4 | .34
1087 | 12.1 | .36
1637 | 12.6 | .48
2339 | 13.1 | 0.28
2403* | 8.7 | 1.20
2532 | 13.3 | 0.17
2683 | 9.9 | 1.00
2712 | 12.3 | 0.20
2742 | 11.8 | .40
2776 | 12.3 | 0.34
2903* | 9.1 | 1.04
2964 | 11.6 | .40
2976 | 12.0 | .50
3003§ | 13.3 | .78
3021 | 12.3 | .11
3079§ | 12.0 | .90
3147 | 11.4 | .30
3166 | 12.0 | .0
3184 | 12.7 | .78
3198 | 13.0 | .95
3254 | 12.8 | .60
3294 | 12.0 | .48
3389 | 13.1 | +0.30
3395 | 12.6 | +0.11
3396 | 13.3 | – .10
3430 | 12.6 | + .49
3432 | 12.0 | .79
3437 | 12.4 | .28
3445 | 13.1 | .08
3448 | 12.3 | .26
3486 | 11.8 | .58
3488 | 12.8 | .25
3512 | 12.3 | .0
3521* | 10.1 | .65
3549 | 13.3 | .43
3596 | 13.3 | .60
3631 | 11.8 | .66
3642 | 12.0 | .73
3655 | 11.9 | .04
3666 | 11.8 | .54
3672 | 13.0 | .54
3683 | 12.0 | .15
3780 | 13.0 | .40
3810 | 11.3 | .62
3813 | 12.3 | .32
3877 | 11.8 | .64
3887 | 12.3 | .40
3893 | 11.8 | .61
3949 | 11.8 | .34
3982 | 12.1 | .36
4013 | 13.3 | .60
4041 | 11.4 | .30
4062 | 12.6 | .48
4088 | 11.5 | +0.72
4096 | 12.3 | +0.78
4100 | 12.3 | .60
4145 | 12.3 | .70
4157§ | 12.3 | .77
4212 | 12.3 | .30
4220 | 12.1 | 0.40
4236 | 12.8 | 1.04
4254 | 10.4 | 0.65
4321* | 10.5 | .70
4414 | 10.1 | .48
4419 | 11.8 | .36
4460 | 12.1 | .20
4490* | 10.2 | .60
4501* | 10.5 | .70
4504 | 12.1 | 0.48
4517§ | 12.5 | 1.00
4536§ | 12.3 | 0.85
4559 | 10.7 | .90
4569* | 10.9 | .65
4580 | 12.3 | .15
4605 | 9.9 | 0.48
4631* | 9.5 | 1.08
4632 | 13.1 | 0.50
4666 | 12.0 | .60
4713 | 12.3 | .38
4781 | 11.8 | .48
4793 | 12.4 | .20
4808 | 12.6 | +0.34
4995 | 11.8 | +0.36
5005* | 11.1 | .70
5012 | 11.9 | .43
5033* | 11.8 | 0.78
5194* | 7.4 | 1.08
5204 | 12.8 | 0.59
5236 | 10.4 | 1.00
5247 | 13.3 | 0.70
5248 | 11.5 | .50
5290 | 12.5 | .48
5297 | 12.6 | .60
5364 | 13.3 | .60
5395 | 12.8 | 0.30
5457 | 9.9 | 1.34
5474 | 12.0 | 0.60
5585 | 12.3 | .60
5676 | 11.8 | .48
5678 | 11.8 | .41
5832 | 13.1 | 0.56
5907§ | 11.9 | 1.04
6181 | 12.5 | 0.30
6217 | 12.1 | .25
6503 | 9.9 | .70
7448 | 11.8 | + .30
7671 | 13.3 | – .15
+-----------+---------
Mean | 11.75 | +0.537
----------+-----------+---------
Peculiar Spirals (Unclassified)
----------+-----------+---------
972 | 13.3 | +0.17
2537 | 13.3 | .0
4900 | 11.8 | +0.23
----------+-----------+---------