The Star Mass Project--Results Table

All spectral types are luminosity class V (main sequence).

Spectrum	Mass	p.e.	N
O3	38.3914	19.5543	6
O3.5	53.0000	7.0000	1
O5	26.4422	9.3993	3
O5.5	30.4009	7.8875	5
O6	25.3664	8.1847	5
O6.5	25.7258	4.5078	2
O7	25.7616	5.4680	11
O7.5	14.4344	1.0844	6
O8	19.2685	0.8892	5
O9	17.1743	2.5155	4
O9.5	16.6383	0.5946	9
O9.8	17.7258	0.0023	2
B0	14.0823	0.5524	11
B0.2	13.7300	0.0500	1
B0.5	12.5881	0.3316	11
B1	9.7502	0.2705	23
B1.5	12.2462	0.1199	4
B2	8.2763	0.3154	20
B2.5	6.0082	0.0296	6
B3	5.3176	0.0474	5
B4	5.1296	0.0301	6
B4.5	4.0900	0.0500	1
B5	4.9427	0.6159	17
B6	4.2264	0.0414	3
B6.5	3.3600	0.1400	1
B7	4.0695	0.0215	6
B8	3.0116	0.0399	14
B8.5	2.5770	0.0980	1
B9	2.4988	0.0255	19
B9.5	2.3549	0.0098	19
A0	2.1265	0.0090	16
A1	2.2553	0.0062	13
A1.5	2.0170	0.0840	1
A2	2.1263	0.0089	23
A3	1.9935	0.0056	14
A4	1.9445	0.0023	11
A5	1.8489	0.0064	14
A6	1.7068	0.0040	13
A7	1.5717	0.0015	19
A8	1.6394	0.0017	13
A9	1.6751	0.1727	7
F0	1.5289	0.0019	31
F1	1.5879	0.0013	9
F2	1.4332	0.0024	23
F3	1.4177	0.0005	17
F4	1.3631	0.0020	9
F5	1.2996	0.0008	53
F5.5	1.0895	0.0004	2
F6	1.3348	0.0003	30
F7	1.3663	0.0013	18
F8	1.1674	0.0009	32
F8.5	1.1100	0.0500	1
F9	1.1283	0.0002	20
F9.5	1.0561	0.0009	4
G0	1.0938	0.0001	20
G1	1.0731	0.0008	14
G1.5	0.7910	0.0030	1
G2	1.0000	0.0000	14
G2.5	1.0629	0.0006	2
G3	1.0392	0.0002	13
G4	1.0928	0.0005	4
G4.5	0.9900	0.1900	1
G5	0.9909	0.0009	12
G6	0.9984	0.0018	6
G6.5	0.9600	0.1500	1
G7	0.9138	0.0001	4
G8	0.9639	0.0002	12
G9	0.9055	0.0032	6
K0	0.8449	0.0004	15
K1	0.8765	0.0006	6
K2	0.8242	0.0004	14
K3	0.8014	0.0008	13
K4	0.7542	0.0003	10
K4.5	0.6210	0.0580	1
K5	0.7220	0.0013	11
K6	0.6644	0.0002	11
K7	0.6923	0.0009	13
K7.5	0.5200	0.1300	1
K8	0.5828	0.0002	3
K9	0.6620	0.0050	1
M0	0.5455	0.0006	6
M0.5	0.5677	0.0017	3
M1	0.5606	0.0002	15
M1.5	0.5369	0.0001	3
M2	0.4779	0.0002	8
M2.5	0.5016	0.0004	9
M3	0.2702	0.0003	24
M3.5	0.3502	0.0002	17
M4	0.3011	0.0002	17
M4.3	0.1940	0.0003	1
M4.3	0.2098	0.0014	1
M4.5	0.2168	0.0002	14
M5	0.1616	0.0002	28
M5.5	0.1935	0.0002	7
M6	0.1491	0.0001	11
M7	0.0927	0.0000	5
M7.5	0.0950	0.0040	1
M8	0.0847	0.0000	14
M8.5	0.0831	0.0001	4
M9	0.0856	0.0001	3
M9.5	0.0838	0.0000	2
L0	0.0794	0.0000	4
L1	0.0760	0.0140	1
L1.5	0.0750	0.0000	2

Masses are graphed against spectral class index below:

Note how uneven this is. This is not a smooth progression, but it probably is in nature.

For a while I was showing a separate graph of the above data with a second-degree Loess smooth added. However, as more and more points accumulate, the smoothed line deviates more and more from the actual data points. I'm going to have to give up the hopes I had pinned on the loess smooth for eventually compiling my table. It has the desirable property of providing a monotic decrease in mass as spectral type goes from early to late, but it just isn't close enough to the data. A moving average doesn't work badly, but it isn't monotonic, so that's out as well.

I was also graphing mean relative absolute deviation for all groups with the same number of cases--the deviations being measured from the Loess smooth. That goes out the window too. But here's a graph of the mean probable error versus number of cases:

As of 04/17/2022, all spectral types with 30 or more mass figures available are:

• F0Vwith 31. Average mass: 1.53 M_☉.
• F5Vwith 53. Average mass: 1.30 M_☉.
• F6Vwith 30. Average mass: 1.33 M_☉.
• F8Vwith 32. Average mass: 1.17 M_☉.

The average for the whole database, so far, is 9.9 star masses found per spectral type. Note how, as of this date, all the best values are of spectral class F. This apparently hits the sweet spot between the rarity of type O at the early end of the sequence and the dimness of types M and L at the late end. Note, though, how an F5V star appears to be less massive than an F6 star. This is undoubtedly an artifact of sampling error, showing that this project still has a long way to go.

(Figures in red are updated with each acquisition of new data and subsequent reanalysis.)