published, but the study is early or one-sided: only part of the Kepler data, or no spectroscopy of its own
| reference | Pablo et al. 2011, ApJ 740, L47; Baran & Winans 2012, AcA 62, 343 |
| title | (no copy in the local library) |
| atmospheric parameters | Reed et al. (2012, MNRAS 427, 1245) list B4 for comparison: Kp 17.924, Teff 24786 +- 665 K, log g 5.30 +- 0.09, log N(He)/N(H) -2.86 +- 0.20 |
| the spectrum behind it | Reed et al. obtained ALFOSC spectra at the NOT in 2012 May; the B4 extraction from that run is here. |
| as a reference object | no At Kp ~18 in a crowded cluster field these are the faintest stars in the project; the spectra reach S/N 27-55 and are not good reference objects for spectroscopy. They are here for completeness. |
| note | One of three NGC 6791 cluster members here, and the faintest part of the sample. |
No copy of the paper is in /home/roy/sync/old/sddoc, so only the reference is given above — nothing here is quoted from it.
| observation | telescope | date | n | S/N | FWHM [Å] | Teff [K] | log g | log n(He)/n(H) | residual | χ² |
|---|---|---|---|---|---|---|---|---|---|---|
| NOT ★ | NOT / ALFOSC_FASU | 2012-05-17 | 1 | 30.4 | 4.50 | 25039 ± 582 | 5.478 ± 0.087 | -2.74 ± 0.24 | 4.35% | 1.12 |
★ 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 +-27%. The numbers below are what the photometry gives; these are the reasons it may not be giving much.
| distance [pc] | 3368 |
| parallax error [%] | 26.6 (per cent; the mass error is twice this) |
| E(44−55) [mag] | 0.086 (0.070–0.104) |
| … the dust map | 0.1310 (SFD×disk(f=0.99)) |
| log Θ [rad] | -11.693 +0.010 −0.010 |
| R [R☉] | 0.151 +0.055 −0.032 |
| M [M☉] | 0.252 +0.219 −0.098 |
| L [L☉] | 8.1 +6.9 −3.1 |
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 25039 K and log g 5.478 from NOT, with 10 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.
The lower-case directories (b3/, b3-1/, b3-2/, b4/, b5/) are copies of the 2012 fitprof22 working directories from data/spek/NGC6791, kept as they were run, each with the line list of its own era. None holds an sp.spek, so fitk1 does not read them. The live directories are NOT/ (and NOT-1/, NOT-2/ for Fredegar), extracted from the same FITS and linked to the master. All five spectra are NOT/ALFOSC Grism #16 through a 1.0in slit, so they share one resolution: 4.50 A, the value the 2012 fits used. Ca II K cannot supply it here -- at S/N 25-55 the line is only 6-16% deep and its measured width scatters from 1.9 to 4.1 A between spectra of the same field. Two stars share each slit: b3b6 (Fredegar and B6) and b4b5 (Adamanta and Adelard). The header RA/DEC is the slit centre, not the star, and B6 is not one of the nineteen -- its spectra stay in data/spek/NGC6791.