2019A&A...624A..10G


Query : 2019A&A...624A..10G

2019A&A...624A..10G - Astronomy and Astrophysics, volume 624A, 10-10 (2019/4-1)

Accurate effective temperature from Hα profiles.

GIRIBALDI R.E., UBALDO-MELO M.L., PORTO DE MELLO G.F., PASQUINI L., LUDWIG H.-G., ULMER-MOLL S. and LORENZO-OLIVEIRA D.

Abstract (from CDS):


Context. The determination of stellar effective temperature (Teff) in F, G, and K stars using Hα profile fitting is a quite remarkable and powerful tool because it does not depend on reddening and is only slightly sensitive to other atmospheric parameters. Nevertheless, this technique is not frequently used because of the complex procedure needed to recover the profile of broad lines in echelle spectra. As a consequence, tests performed on different models have sometimes provided ambiguous results.
Aims. The main aim of this work is to test the ability of the Hα profile fitting technique to derive Teff. We also aim to improve the applicability of this technique to echelle spectra and to test how well 1D + LTE models perform on a variety of F-K stars. We also apply the technique to HARPS spectra and test the reliability and the stability of the HARPS response over several years using the Sun.
Methods. We have developed a normalization method for recovering undistorted Hα profiles and we have first applied it to spectra acquired with the single-order Coude instrument (resolution R=45000) at do Pico dos Dias Observatory to avoid the problem of blaze correction. The continuum location around Hα is optimised using an iterative procedure, where the identification of minute telluric features is performed. A set of spectra was acquired with the MUSICOS echelle spectrograph (R=40000) to independently validate the normalization method. The accuracy of the method and of the 1D + LTE model is determined using Coude/HARPS/MUSICOS spectra of the Sun and Coude-only spectra of a sample of ten Gaia Benchmark Stars with Teff determined from interferometric measurements. HARPS, Coude, and MUSICOS spectra are used to determine Teff of 43 sample stars.
Results. We find that a proper choice of spectral windows of fits plus the identification of telluric features allow for a very careful normalization of the spectra and produce reliable Hα profiles. We also find that the most used solar atlases cannot be used as templates for Hα temperature diagnostics without renormalization. The comparison with the Sun shows that Hα profiles from 1D + LTE models underestimate the solar Teff by 28K. We find the same agreement between Hα and interferometry and between Hα and Infrared Flux Method: a shallow dependency on metallicity according to the relation Teff =Teff-159[Fe/H]+28K within the metallicity range -0.70 to +0.40dex. The comparison with the Infrared Flux Method shows a scatter of 59K dominated by photometric errors (52K). In order to investigate the origin of this dependency, we analyzed spectra from 3D models and found that they produce hotter temperatures, and that their use largely improves the agreement with the interferometric and Infrared Flux Method measurements. Finally, we find HARPS spectra to be fully suitable for Hα profile temperature diagnostics; they are perfectly compatible with the Coude spectra, and lead to the same Teff for the Sun as that found when analysing HARPS spectra over a timespan of more than 7yr.

Abstract Copyright: © ESO 2019

Journal keyword(s): line: profiles - techniques: spectroscopic - stars: atmospheres - stars: fundamental parameters - stars: late-type - stars: solar-type

VizieR on-line data: <Available at CDS (J/A+A/624/A10): list.dat sp/* spc/*>

Simbad objects: 44

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Number of rows : 44
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 * zet Tuc PM* 00 20 04.2586334956 -64 52 29.257190108 4.82 4.80 4.23 3.73 3.40 F9.5V 362 0
2 * bet Hyi PM* 00 25 45.07036 -77 15 15.2860 3.52 3.41 2.79 2.28 1.94 G0V 576 0
3 HD 3823 PM* 00 40 25.6698671445 -59 27 16.566549816   6.44 5.90     G0VFe-0.9CH-0.4 160 0
4 * tau Cet PM* 01 44 04.0831371922 -15 56 14.927607677 4.43 4.22 3.50 2.88 2.41 G8V 1171 1
5 * eps For PM* 03 01 37.6288785045 -28 05 29.373792325   6.68 5.85     G9:V 176 0
6 * alf For ** 03 12 04.5273570 -28 59 15.433684 4.41 4.36 3.85 3.39 3.08 F6V+G7V 256 0
7 * kap01 Cet BY* 03 19 21.6963205 +03 22 12.715139 5.71 5.52 4.85 4.27 3.91 G5V 848 0
8 * 10 Tau PM* 03 36 52.3837044168 +00 24 05.992097829 5.23 5.15 4.30 4.09 3.77 F9IV-V 541 0
9 * del Eri * 03 43 14.9005379551 -09 45 48.210955899 5.13 4.46 3.54 2.82 2.32 K0+IV 573 0
10 * omi02 Eri Er* 04 15 16.3196189945 -07 39 10.330779018 5.69 5.25 4.43 3.74 3.29 K0V 774 0
11 * alf CMi SB* 07 39 18.11950 +05 13 29.9552 0.82 0.79 0.37 -0.05 -0.28 F5IV-V+DQZ 1820 0
12 * 20 Crt PM* 11 34 29.4864443348 -32 49 52.822793411   6.79 5.98 7.17   K0V 209 0
13 * bet Vir PM* 11 50 41.7185158616 +01 45 53.001539131 4.26 4.15 3.60 3.13 2.85 F9V 892 0
14 HD 114174 ** 13 08 51.0229724195 +05 12 26.065953963   7.47   6.3   G3IV+D 159 0
15 * e Vir PM* 13 16 46.5148594512 +09 25 26.960139646   5.81   4.8   G0V 529 1
16 * 61 Vir PM* 13 18 24.3139864471 -18 18 40.297748582 5.710 5.440 4.740     G6.5V 631 1
17 * eta Boo SB* 13 54 41.07892 +18 23 51.7946 3.440 3.250 2.680 2.24 1.95 G0IV 681 1
18 HD 126053 PM* 14 23 15.2847745835 +01 14 29.641269692 6.98 6.90 6.27 5.71 5.39 G1.5V 384 0
19 * alf Cen A SB* 14 39 36.49400 -60 50 02.3737 0.96 0.72 0.01     G2V 1203 0
20 * psi Ser PM* 15 44 01.8185683752 +02 30 54.600593940       5.4   G2.5V 203 0
21 * chi Her PM* 15 52 40.5410491705 +42 27 05.462878877 5.19 5.19 4.62 4.14 3.82 F8VFe-2Hdel-1 490 0
22 HD 144585 PM* 16 07 03.3696573456 -14 04 16.671141984 7.22 6.98 6.32     G2V 174 0
23 * 18 Sco PM* 16 15 37.2702755653 -08 22 09.982125430   6.15 5.50     G2Va 542 0
24 HD 147513 PM* 16 24 01.2911377368 -39 11 34.729913940 6.17 6.02 5.376     G5V 326 1
25 * zet TrA SB* 16 28 28.1422653048 -70 05 03.824909916   5.446 4.899     F9V 191 0
26 * 12 Oph BY* 16 36 21.4496896968 -02 19 28.513024233 7.00 6.55 5.77 5.13 4.74 K1V 464 0
27 HD 150177 PM* 16 39 39.1296604152 -09 33 16.512558300   6.794 6.332     F6V 147 0
28 V* V2213 Oph BY* 17 05 16.8186610814 +00 42 09.221511649   6.59   5.6   F8.5IV-V 328 0
29 * mu. Ara PM* 17 44 08.7031414872 -51 50 02.591603160   5.85 5.15     G3IV-V 497 2
30 * 70 Oph ** 18 05 27.28518 +02 30 00.3558 5.40 4.89 4.03 3.38 2.92 K0-V 629 0
31 * iot Pav PM* 18 10 26.1537006792 -62 00 07.992182016   6.07 5.49     G0V 104 0
32 HD 172051 ** 18 38 53.4010594968 -21 03 06.750986472   6.518 5.860     G6V 187 1
33 HD 179949 BY* 19 15 33.2300695008 -24 10 45.671448072   6.772 6.237     F8V 377 1
34 * b Aql PM* 19 24 58.1999714302 +11 56 39.888480530 6.35 5.93   4.7   G7IVHdel1 469 0
35 HD 184985 PM* 19 37 34.4135659464 -14 18 06.478148448   5.938 5.451     F7V 95 0
36 * 15 Sge PM* 20 04 06.2207683221 +17 04 12.676556401   6.390 5.788 5.4   G0V 360 0
37 * del Pav PM* 20 08 43.6088716052 -66 10 55.442769229 4.78 4.32 3.56 2.95 2.61 G8IV 371 0
38 * phi02 Pav PM* 20 40 02.6374808954 -60 32 56.018592211   5.63 5.121     G0VFe-0.8CH-0.5 168 1
39 * gam Pav PM* 21 26 26.6049826473 -65 21 58.313057521 4.57 4.70 4.22 3.75 3.45 F9VFe-1.4CH-0.7 394 0
40 V* HN Peg BY* 21 44 31.3299461136 +14 46 18.983292600       6.16   G0V+ 478 0
41 * ksi Peg PM* 22 46 41.5798542334 +12 10 22.388860108 4.66 4.69 4.20 3.73 3.42 F6V 373 0
42 * sig Peg PM* 22 52 24.0744611045 +09 50 08.394417666   5.64   4.9   F6V 271 0
43 * 51 Peg PM* 22 57 27.9804852576 +20 46 07.797040104 6.39 6.16 5.46 4.97 4.61 G2IV 1115 1
44 * iot Psc PM* 23 39 57.0413764 +05 37 34.647529 4.640 4.620 4.120 3.68 3.37 F7V 599 0

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2022.05.26-09:10:32

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