published, but the study is early or one-sided: only part of the Kepler data, or no spectroscopy of its own
| reference | Ostensen et al. 2014, A&A 564, L14 |
| title | Stochastic pulsations in the subdwarf-B star KIC 2991276 |
| Kepler data used | nearly three years |
| pulsations | Two modes at 122 and 132 s plus weaker modes 118-216 s; amplitudes and phases vary on ~1 month timescales, sometimes vanishing -- the first unambiguous stochastic oscillations in a hot subdwarf |
| spectra behind it | one WHT spectrum (2009) and three NOT spectra (2011); the paper's spectroscopy section is four sentences |
| atmospheric parameters | Teff 33900 +- 200 K, log g 5.82 +- 0.04, on the Heber (2000) LTE grid, from the WHT spectrum via Ostensen et al. (2010b) |
| the spectrum behind it | The 2009 WHT spectrum the parameters come from is here, as are the three 2011 NOT spectra. |
| note | A Letter. The Kepler analysis is complete but there is no spectroscopic analysis of its own, and the NOT spectra are explicitly described as low signal-to-noise. Its contamination discussion is photometric only. |
Paper: Ostensen14a.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 | 2011-05-31 | 3 | 39.6 | 2.28 | 34455 ± 564 | 5.763 ± 0.069 | -2.70 ± 0.20 | 3.41% | 1.25 |
| WHT ★ | WHT / ISIS blue arm | 2009-07-15 | 1 | 81.9 | 3.37 | 35053 ± 342 | 5.973 ± 0.039 | -3.42 ± 0.54 | 1.72% | 1.19 |
★ 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.
Treat this fit with care. parallax +-28%. The numbers below are what the photometry gives; these are the reasons it may not be giving much.
| distance [pc] | 4125 |
| parallax error [%] | 28.2 (per cent; the mass error is twice this) |
| E(44−55) [mag] | 0.114 (0.080–0.150) |
| … the dust map | 0.1320 (SFD×disk(f=1.00)) |
| log Θ [rad] | -11.719 +0.022 −0.021 |
| R [R☉] | 0.175 +0.069 −0.039 |
| M [M☉] | 1.052 +1.013 −0.428 |
| L [L☉] | 41.7 +39.6 −16.6 |
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 35053 K and log g 5.973 from WHT, with 16 of the fitted bands and reduced χ² 0.30. 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, 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, WISE:W1 — the last of these was not excluded by rule but clipped, sitting beyond five sigma of a model that fits its neighbours.
The lower-case directories here that hold no sp.spek (not/, wht/, heiko/, std/, uli1/) are the original fitprof22 working directories, kept as they were run so the numbers in their fit.out can still be reproduced. Each carries the line list of its own era, which is why it does not match the master. They are archives, not inputs. fitk1 fits any directory containing sp.spek, so a directory that has one is live and must link to the master -- lower-case name or not. Hamfast was exactly that case: three live directories with a private list, refitted for months against it. If you add a spectrum to a directory here, link its chidel.dat to the master at the same time. mkspek extracts the FITS in data/ into upper-case directories beside these (NOT/, WHT/, KPNO/) and links those to the master.