TABLE 8.
THE ABSOLUTELY FAINTEST STARS.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 |
| Name | Position | Distance | Motion | Magnitude | Spectrum | ||||||||
| (αδ) | Square | l | b | π | r | μ | W | m | M | Sp | m′ | ||
| sir. | sir./st. | m′ | |||||||||||
| 1 | Proxima Centauri | (142262) | GD10 | 281° | - 2° | 0″.780 | 0.26 | 3″.85 | .. | 11m.0 | +13m.9 | .. | 13.5 |
| 2 | van Maanens star | (004304) | GE8 | 92 | -58 | 0.246 | 0.84 | 3.01 | .. | 12.3 | +12.7 | F0 | 12.95 |
| 3 | Barnards star | (175204) | GC12 | 358 | +12 | 0.515 | 0.40 | 10.29 | -19 | 9.7 | +11.7 | Mb | 8.9 |
| 4 | 17 Lyræ C | (190332) | GC2 | 31 | +10 | 0.128 | 1.60 | 1.75 | .. | 11.3 | +10.3 | .. | 12.5 |
| 5 | C. Z. 5h.243 | (050744) | GE7 | 218 | -35 | 0.319 | 0.65 | 8.75 | +51 | 9.2 | +10.1 | K2 | 10.68 |
| 6 | Gron. 19 VIII 234 | (161839) | GB1 | 29 | +44 | 0.162 | 1.27 | 0.12 | .. | 10.3 | + 9.8 | .. | .. |
| 7 | Oe. A. 17415 | (173768) | GB8 | 65 | +32 | 0.268 | 0.77 | 1.30 | .. | 9.1 | + 9.7 | K | 10.5 |
| 8 | Gron. 19 VII 20 | (162148) | GB2 | 41 | +43 | 0.133 | 1.55 | 1.22 | .. | 10.5 | + 9.6 | .. | .. |
| 9 | Pos. Med. 2164 | (184159) | GC2 | 56 | +24 | 0.292 | 0.71 | 2.28 | .. | 8.9 | + 9.6 | K | 10.3 |
| 10 | Krüger 60 | (222457) | GC8 | 72 | 0 | 0.256 | 0.81 | 0.94 | .. | 9.2 | + 9.6 | K5 | 10.8 |
| 11 | B. D. +56°532 | (021256) | GD8 | 103 | - 4 | 0.195 | 1.06 | .. | .. | 9.5 | + 9.4 | .. | .. |
| 12 | B. D. +55°581 | (021356) | GD8 | 103 | - 4 | 0.185 | 1.12 | .. | .. | 9.4 | + 9.2 | G5 | 10.2 |
| 13 | Gron. 19 VIII 48 | (160438) | GB1 | 27 | +46 | 0.091 | 2.27 | 0.12 | .. | 11.1 | + 9.3 | .. | .. |
| 14 | Lal. 21185 | (105736) | GB5 | 153 | +66 | 0.403 | 0.51 | 4.77 | -18 | 7.6 | + 9.1 | Mb | 8.9 |
| 15 | Oe. A. 11677 | (111466) | GB3 | 103 | +50 | 0.198 | 1.04 | 3.03 | .. | 9.2 | + 9.1 | Ma | 11.0 |
| 16 | Walkey 653 | (155359) | GB2 | 57 | +45 | 0.175 | 1.18 | .. | .. | 9.5 | + 9.1 | .. | .. |
| 17 | Yerkes parallax star | (021243) | GD8 | 107 | -16 | 0.045 | 4.58 | .. | .. | 12.4 | + 9.1 | .. | .. |
| 18 | B. D. +56°537 | (021256) | GD8 | 103 | - 4 | 0.175 | 1.18 | .. | .. | 9.4 | + 9.0 | .. | .. |
| 19 | Gron. 19 VI 266 | (062084) | GC3 | 97 | +27 | 0.071 | 2.80 | 0.09 | .. | 11.3 | + 9.0 | .. | .. |
| sir. | sir./st. | m′ | |||||||||||
| Mean | .. | .. | .. | 27°.5 | 0″.244 | 0.99 | 2″.96 | 29.3 | 10m.0 | +9m.9 | K1 | 10.9 | |
Regarding the absolute brightness of the stars we may draw some conclusions of interest. We find from [table 7] that the absolute magnitude of the parallax stars varies between -4 and +11, the extreme stars being of type M. The absolutely brightest stars have a rather great distance from us and their absolute magnitude is badly determined. The brightest star in the table is Antares with M = -4.6, which value is based on the parallax 0″.014 found by Adams. So small a parallax value is of little reliability when it is directly computed from annual parallax observations, but is more trustworthy when derived with the spectroscopic method of Adams. It is probable from a discussion of the B-stars, to which we return in a later chapter, that the absolutely brightest stars have a magnitude of the order -5m or -6m. If the parallaxes smaller than 0″.01 were taken into account we should find that Canopus would represent the absolutely brightest star, having M = -8.17, and next to it we should find Rigel, having M = -6.97, but both these values are based on an annual parallax equal to 0″.007, which is too small to allow of an estimation of the real value of the absolute magnitude.
If on the contrary the absolutely faintest stars be considered, the parallax stars give more trustworthy results. Here we have only to do with near stars for which the annual parallax is well determined. In [table 8] I give a list of those parallax stars that have an absolute magnitude greater than 9m.
There are in all 19 such stars. The faintest of all known stars is Innes' star “Proxima Centauri” with M = 13.9. The third star is Barnard's star with M = 11.7, both being, together with α Centauri, also the nearest of all known stars. The mean distance of all the faint stars is 1.0 sir.
There is no reason to believe that the limit of the absolute magnitude of the faint stars is found from these faint parallax stars:—Certainly there are many stars in space with M > 13m and the mean value of M, for all stars in the Galaxy, is probably not far from the absolute value of the faint parallax stars in this table. This problem will be discussed in a later part of these lectures.
