a detailed study with both a full pulsation analysis and dedicated spectroscopy
The published spectrum is not on disk here. Silvotti et al. fitted WHT and NOT with LTE models and Bok and MMT with NLTE models. Three of the four are now here: the two WHT spectra, and a mean of 20 NOT/ALFOSC spectra that arrived in J. Telting's January 2012 batch in September 2026 and is almost certainly the NOT spectrum the paper fitted. The Bok and MMT spectra, which carry the NLTE half of the published 27500/5.35/-2.95, have still not been found on disk -- ask R. Silvotti.
| reference | Silvotti et al. 2014, A&A 570, A130; Uzundag et al. 2017, MNRAS 472, 700 |
| title | Kepler detection of a new extreme planetary system orbiting the subdwarf-B pulsator KIC 10001893 |
| Kepler data used | the primary mission |
| pulsations | Tens of g-mode frequencies, plus three weak peaks at very low frequency read as the orbital modulation of three Earth-size bodies at P = 5.273, 7.807 and 19.48 h, close to 3:2 and 5:2 resonances |
| spectra behind it | WHT and NOT fitted with LTE models (Heber et al. 2000); Bok and MMT fitted with NLTE models |
| atmospheric parameters | best estimate Teff 27500 +- 500 K, log g 5.35 +- 0.05, log N(He)/N(H) -2.95 +- 0.04 |
| earlier values | The target list previously carried 26700 +- 300 / 5.30 / -2.09, the earlier value this paper cites; superseded by its own best estimate above |
| the spectrum behind it | Silvotti et al. fitted WHT and NOT with LTE models and Bok and MMT with NLTE models. Three of the four are now here: the two WHT spectra, and a mean of 20 NOT/ALFOSC spectra that arrived in J. Telting's January 2012 batch in September 2026 and is almost certainly the NOT spectrum the paper fitted. The Bok and MMT spectra, which carry the NLTE half of the published 27500/5.35/-2.95, have still not been found on disk -- ask R. Silvotti. |
| note | The 26700 +- 300 / 5.30 / -2.09 quoted in the target list is the EARLIER value the paper cites, not its own best estimate. Uzundag et al. (2017) is a later study; no copy here. |
Paper: Silvotti14.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 |
|---|---|---|---|---|---|---|---|---|---|---|
| NOT | NOT / ALFOSC_FASU | 2011-06-08 | 20 | 249.2 | 2.19 | 26830 ± 74 | 5.455 ± 0.013 | -2.92 ± 0.04 | 1.15% | 2.44 |
| WHT ★ | WHT / ISIS blue arm | 2010-07-27 | 2 | 136.6 | 1.74 | 27228 ± 87 | 5.514 ± 0.015 | -2.98 ± 0.06 | 1.07% | 1.80 |
| WHT1 | WHT / ISIS blue arm | 2010-07-27 | 1 | 93.5 | 1.63 | 27289 ± 113 | 5.501 ± 0.020 | -2.94 ± 0.12 | 1.46% | 1.64 |
| WHT2 | WHT / ISIS blue arm | 2010-07-28 | 1 | 73.0 | 1.68 | 27682 ± 161 | 5.486 ± 0.030 | -2.96 ± 0.12 | 1.65% | 1.20 |
★ 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] | 1795 |
| parallax error [%] | 6.7 (per cent; the mass error is twice this) |
| E(44−55) [mag] | 0.034 (0.022–0.048) |
| … the dust map | 0.0530 (SFD×disk(f=0.98)) |
| log Θ [rad] | -11.326 +0.008 −0.007 |
| R [R☉] | 0.188 +0.014 −0.012 |
| M [M☉] | 0.422 +0.084 −0.069 |
| L [L☉] | 17.5 +2.7 −2.2 |
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 27228 K and log g 5.514 from WHT, with 32 of the fitted bands and reduced χ² 0.65. 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:W3, WISE:W4, 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.
means/ holds the two mean spectra of this star from toroy.tgz -- a bundle
of 19 means of 9 Kepler-field stars reduced by J. Telting in January 2012
and sent in September 2026. The whole batch sits on one 3517-5073 A,
0.765 A/px scale, so the telescopes can be compared pixel for pixel.
NOT/ mean of 20 NOT/ALFOSC grism #16 spectra, 2011-06-08, S/N 249. This
is the first NOT spectrum of Otho to be held here, and it is very
likely the NOT spectrum Silvotti et al. (2014) fitted -- they name
WHT and NOT among their four, and this is the only NOT mean of the
star there is.
WHT/ mean of 2 WHT/ISIS R600B spectra, 2010-07-27/28 -- the same two held
singly as WHT1 and WHT2. Its fit has the smallest residual of the
four, 1.07%, so it is the one the sample table quotes.
wht1/ and wht2/ are the original fitprof22 working directories for the two
WHT spectra of KIC 10001893, kept as they were run, with the 2013 line list
they link to. Neither holds an sp.spek, so fitk1 does not read them. The
live directories are NOT/, WHT/, WHT1/ and WHT2/; WHT1 and WHT2 are
extracted from the same K10001893_[12].fits -- IRAF multispec files, so
only band 1 is the spectrum -- and all are linked to the master.