no detailed study of the Kepler data; the survey papers mention it, but a survey is not a study
No detailed study. An sdO+dM; 24 INT exposures exist and no mean was ever built.
| survey archive | A BOSS spectrum exists and is here as BOSS/, fitted in the BOSS sample: 48973 +- 1205 / 5.746 +- 0.073 at reduced chi-square 0.98 -- the best-fitting spectrum of this star, and 2200 K hotter than the INT mean. |
| observation | telescope | date | n | S/N | FWHM [Å] | Teff [K] | log g | log n(He)/n(H) | residual | χ² |
|---|---|---|---|---|---|---|---|---|---|---|
| BOSS | BOSS | 1 | 67.7 | 2.00 | 48973 ± 1205 | 5.746 ± 0.073 | -2.40 ± 0.29 | 2.30% | 0.98 | |
| INT ★ | INT / IDS | 2010-06-29 | 10 | 177.0 | 4.32 | 46748 ± 405 | 5.611 ± 0.023 | -2.20 ± 0.05 | 0.95% | 1.85 |
| NOT | NOT / ALFOSC_FASU | 2008-09-21 | 1 | 86.9 | 6.50 | 43812 ± 638 | 5.491 ± 0.064 | -2.19 ± 0.11 | 4.03% | 12.65 |
★ 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] | 2413 |
| parallax error [%] | 9.0 (per cent; the mass error is twice this) |
| E(44−55) [mag] | 0.064 (= E(44-55); R(55) = 3.03; HELD at this value for the two-component fit, not fitted) |
| … the dust map | 0.0568 (SFD×disk(f=1.00)) |
| log Θ [rad] | — |
| R [R☉] | 0.174 +0.017 −0.014 |
| M [M☉] | 0.451 +0.111 −0.085 |
| L [L☉] | 130.4 +27.1 −20.8 |
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 46748 K and log g 5.611 from INT, with 31 of the fitted bands and reduced χ² 1.50. 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, WISE:W1, WISE:W2.
A cool companion and extra reddening both redden the model, so the reddening is HELD rather than fitted -- at the one-star value where that agreed with the dust map, and at the map's value where it did not, since there the disagreement IS the companion.
| companion Teff [K] | 4000 |
| … log g (held) | 4.50 |
| R1 [R☉] | 0.1741 |
| R2 [R☉] | 0.7520 |
| main-sequence R at that T [R☉] | 0.550 |
| R2 over that | 1.37 |
| Δχ² over one star | 103.3 |
| reduced χ² | 1.50 |
| excess over one star | 11.1 sigma on WISE:W1 |
| bands put back for it | WISE:W1, WISE:W2 |
| reddening | 0.064 (held) |
| verdict | kept |
The radius and mass above come from this fit, not from the one-star one. With the companion's red flux unaccounted for, a single star buys the excess as reddening and inflates the scale — here it wanted E(44−55) 0.064 against a sightline carrying 0.0568, and returned a mass no subdwarf has.
not/ is a copy of the 2008 fitprof22 working directory from data/spek/kepler/KepVI/J18431+4259; int/ holds the ten INT/IDS exposures of 2010-06-29 from data/spek/kepler/J18431+4259/fits. Neither is read by fitk1. NOT/ is taken from not/J18431+4259.spek, not from the FITS beside it: that frame carries CTYPE1 = 'X' with CRVAL1 = CDELT1 = 1, which is pixel number and not a wavelength scale. It fits badly (reduced chi-square 12.7) and should not be used -- at 6.5 A resolution the per-line centring runs to +-28 A. The 2008 fit had exactly the same shifts and quoted 42870 K anyway. INT/ is a straight mean of the ten exposures, trimmed to 3200-6400 A, and is much better (chi-square 1.9). It is NOT shifted to rest: the exposure to exposure velocities scatter 14 km/s rms over 3.8 h with no smooth trend, consistent with noise at this S/N, so shifting would add noise. A proper rest-frame co-add needs an orbit this star does not yet have.