a detailed study with both a full pulsation analysis and dedicated spectroscopy
| reference | Reed et al. 2014, MNRAS 440, 3809 |
| title | Analysis of the rich frequency spectrum of KIC 10670103 revealing the most slowly rotating subdwarf B star |
| Kepler data used | 2.75 yr short cadence; 1.4 million points, 93.8% duty cycle, 5-sigma limit 0.1 ppt |
| pulsations | 278 periodicities, the richest sdBV known at the time; 163 (59%) identified as l <= 2; spin period 88 +- 8 d |
| spectra behind it | nine WHT/ISIS R600B spectra, grating R600B, 1 arcsec slit; no significant radial-velocity variation |
| atmospheric parameters | Teff 21485 +- 540 K, log g 5.14 +- 0.05, log N(He)/N(H) -2.60 +- 0.04 |
| earlier values | Ostensen et al. (2010b) had 20900 +- 300 K, log g 5.11 +- 0.04 from NOT spectroscopy |
| the spectrum behind it | Reed et al. used nine WHT/ISIS R600B spectra plus KPNO and NOT; the WHT, NOT and KPNO means are all here. |
| note | The published values were a weighted combination across observatories with systematics folded into the errors. |
Paper: Reed14.pdf, in /home/roy/sync/old/sddoc.
| observation | telescope | date | n | S/N | FWHM [Å] | Teff [K] | log g | log n(He)/n(H) | residual | χ² |
|---|---|---|---|---|---|---|---|---|---|---|
| KPNO | kp4m / test | 2010-08-13 | 11 | 116.3 | 1.66 | 22096 ± 255 | 5.068 ± 0.031 | -2.60 ± 0.05 | 2.22% | 2.22 |
| KPNO-c | kp4m / test | 2010-08-13 | 11 | 111.6 | 1.67 | 21579 ± 230 | 5.192 ± 0.029 | -2.56 ± 0.04 | 1.90% | 1.37 |
| NOT | NOT / ALFOSC_FASU | 2011-07-22 | 10 | 120.3 | 2.76 | 21843 ± 165 | 5.208 ± 0.021 | -2.59 ± 0.05 | 1.72% | 2.00 |
| NOT-c | NOT / ALFOSC_FASU | 2011-07-22 | 10 | 119.6 | 2.75 | 21356 ± 162 | 5.247 ± 0.021 | -2.57 ± 0.05 | 1.66% | 1.76 |
| WHT ★ | WHT / ISIS blue arm | 2010-07-28 | 9 | 207.7 | 1.81 | 22236 ± 75 | 5.220 ± 0.010 | -2.57 ± 0.03 | 1.07% | 1.98 |
| WHT-c | WHT / ISIS blue arm | 2010-07-28 | 9 | 208.5 | 1.81 | 22090 ± 73 | 5.244 ± 0.009 | -2.56 ± 0.03 | 1.06% | 1.99 |
★ marks the observation adopted for the sample table — the one with the smallest residual, which is what says how well the model reproduces the spectrum. Signal-to-noise does not.
The line fit gives a temperature and a gravity but says nothing about size. Held at those parameters, the broadband spectral energy distribution has one free scale — the angular diameter — and the Gaia parallax turns that into a radius. Then M = gR²/G, which is linear in g: a tenth of a dex in gravity is 26 per cent in mass, so this is where the gravity scale bites hardest.
| distance [pc] | 2484 |
| parallax error [%] | 10.0 (per cent; the mass error is twice this) |
| E(44−55) [mag] | 0.056 (0.042–0.068) |
| … the dust map | 0.0818 (SFD×disk(f=0.99)) |
| log Θ [rad] | -11.362 +0.007 −0.008 |
| R [R☉] | 0.239 +0.027 −0.022 |
| M [M☉] | 0.347 +0.094 −0.071 |
| L [L☉] | 12.6 +3.0 −2.3 |
Bamberg v25 ATLAS12 through the real filter curves, reddened by Fitzpatrick (1999) — its A(5500)/E(B−V) is 3.03, so this E(B−V) and the E(44−55) of Heber's group are the same number to under one per cent. Prescribed at 22236 K and log g 5.220 from WHT, with 27 of the fitted bands and reduced χ² 0.14. The gravity error carried into the mass is 0.050 dex — the scatter between telescopes, not the formal error, because the formal one would claim a two per cent mass.
Bands left out: Johnson:B, GALEX:NUV, GALEX:FUV, 2MASS:H, 2MASS:J, 2MASS:Ks, WISE:W2, GAIA/GAIA3:G, GAIA/GAIA3:Gbp, GAIA/GAIA3:Grp, SDSS:u, SDSS:g, SDSS:r, SDSS:i, SDSS:z, SDSS:u/SDSS:u', SDSS:g/SDSS:g', SDSS:r/SDSS:r', SDSS:i/SDSS:i', SDSS:z/SDSS:z', Johnson:U, Johnson:V, Cousins:U.
| reference | U. Heber, September 2026: KIC10670103_photometry_results1.pdf and KIC10670103N_photometry_results1.pdf -- he fitted this star twice |
| his fit | with Ostensen et al. (2014), 21500 +- 700 K / 5.14 +- 0.08: E(44-55) 0.063, log Theta -11.345, R 0.243 +0.029 -0.024, M 0.29 +0.10 -0.07, L 11.0, reduced chi2 0.77 |
| and again | with the newer 22300 +- 700 K / 5.24 +- 0.08 (his "ADSRoy"): E(44-55) 0.071, log Theta -11.354, R 0.239 +0.028 -0.023, M 0.35 +0.12 -0.09, L 12.4, reduced chi2 0.84 |
| reproduced here | Reproduced here on the same prescriptions: 0.072 / -11.344 / 0.250 / 0.315 and 0.084 / -11.350 / 0.246 / 0.385. Log Theta lands within 0.001 and 0.004 dex, the radius within 3 per cent. |
| how they compare | That pair IS the experiment this project keeps running into. The only thing Uli changed between his two fits was the prescribed gravity, 5.14 to 5.24, and the mass moved 0.29 to 0.35. Nothing about the star changed; the grid the gravity came from did. |
| note | The 2MASS H and Ks and the WISE fluxes are dropped: at V = 16.4 they are past the surveys' depth, and Ks comes back 108 per cent above the model carrying a 2 per cent error bar. With them in, reduced chi2 is 11 and the radius is 4 per cent too big. The ten optical bands alone fit to |chi| < 1 throughout. |