2007A&A...468..205L


C.D.S. - SIMBAD4 rel 1.7 - 2021.05.18CEST04:37:18

2007A&A...468..205L - Astronomy and Astrophysics, volume 468, 205-220 (2007/6-2)

Near-IR spectra of red supergiants and giants. I. Models with solar and with mixing-induced surface abundance ratios.

LANCON A., HAUSCHILDT P.H., LADJAL D. and MOUHCINE M.

Abstract (from CDS):

It remains difficult to interpret the near-IR emission of young stellar populations. One main reason is our incomplete understanding of the spectra of luminous red stars. This work provides a grid of theoretical spectra of red giant and supergiant stars, that extends through optical and near-IR wavelengths. For the first time, models are also provided with modified surface abundances of C, N and O, as a step towards accounting for the changes that occur due to convective dredge-up in red supergiants or may occur at earlier evolutionary stages in the case of rotation. The aims are (i) to assess how well current models reproduce observed spectra, in particular in the near-IR; (ii) to quantify the effects of the abundance changes on the spectra; and (iii) to determine how these changes affect estimates of fundamental stellar parameters. Spectra are computed with the model atmosphere code PHOENIX and compared with a homogeneous set of observations. Although the empirical spectra have a resolution of only λ/Δλ∼1000, we emphasize that models must be calculated at high spectral resolution in order to reproduce the shapes of line blends and molecular bands. Giant star spectra of class III can be fitted extremely well at solar metallicity down to ∼3400K, where difficulties appear in the modelling of near-IR H2O and TiO absorption bands. Luminous giants of class II can be fitted well too, with modified surface abundances preferred in a minority of cases, possibly indicating mixing in excess of standard first dredge-up. Supergiant stars show a larger variety of near-IR spectra, and good fits are currently obtained for about one third of the observations only. Modified surface abundances help reproducing strong CN bands, but do not suffice to resolve the difficulties. The effect of the abundance changes on the estimated Teff depends on the wavelength range of observation and can amount several 100K. While theoretical spectra for giant stars are becoming very satisfactory, red supergiants require further work. The model grid must be extended, in particular to larger micro-turbulent velocities. Some observed spectra may call for models with even lower gravities than explored here (and therefore probably stellar winds), and/or with more extreme abundances than predicted by standard non-rotating evolution models. Non-static atmospheres models should also be envisaged.

Abstract Copyright:

Journal keyword(s): stars: fundamental parameters - stars: abundances - infrared: stars - stars: atmospheres

VizieR on-line data: <Available at CDS (J/A+A/468/205): table1.dat m15rsg/* m15solar/* m1solar/*>

CDS comments: In Figure 12 : BD-29 2374 is a misprint for BD +29 2374.

Simbad objects: 30

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Number of rows : 30

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 C 0132+610 OpC 01 35 38 +61 16.5   8.35 8.1     ~ 93 0
2 * alf Ori s*r 05 55 10.30536 +07 24 25.4304 4.38 2.27 0.42 -1.17 -2.45 M1-M2Ia-Iab 1519 0
3 V* AB Pyx s*r 08 30 29.7960111387 -36 43 16.791976842   8.665 6.783     M3-Iab-Ib 30 0
4 M 82 IG 09 55 52.430 +69 40 46.93 9.61 9.30 8.41     ~ 5453 6
5 V* EV Car s*r 10 20 21.6003517303 -60 27 15.752647582   10.00 9.20     M4.5Ia 67 0
6 V* CL Car s*r 10 53 59.8805034264 -61 05 31.306416347   10.30 8.600     M5Iab 42 0
7 * 56 Leo LP? 10 56 01.4689991 +06 11 07.327524 8.45 7.24 5.78 3.53 1.44 M5.5III: 162 0
8 * 75 Leo PM* 11 17 17.4004068 +02 00 38.003295 8.54 6.70 5.18 3.91 2.97 M0III 106 0
9 HD 98817 s*r 11 21 38.9672659667 -60 59 28.223851860 12.41 10.44 8.30     M1Iab-Ib 40 0
10 * e Leo * 11 30 18.8919616628 -03 00 12.571219475 8.14 6.31 4.77     K3+IIIFe-0.5 127 0
11 HD 114401 * 13 09 57.0242854310 +28 48 16.610828682   9.77 8.59 8.1   K2III 27 0
12 V* ET Vir LP* 14 10 50.4870574246 -16 18 07.310535267 8.76 6.63 4.91     M2IIIa 95 0
13 * 2 Ser ** 15 01 48.9290090089 -00 08 24.695445161 8.79 7.23 5.71     M0.5IIb 64 0
14 HD 142676 V* 15 59 50.0296179068 -64 51 14.938961541   8.60 6.85     M0/1II 14 0
15 HD 145480 * 16 11 41.3931381059 -13 58 05.778917528   10.79 9.21     M5III 3 0
16 * 39 Nor LP? 16 13 16.9696543422 -53 40 16.223419053   7.863 5.944     M0III 28 0
17 * 24 Sco * 16 41 34.3840737202 -17 44 31.804671164   5.994 4.923     G7.5II-IIICN1Ba0.5 89 0
18 HD 153961 * 17 03 18.6854384351 -20 08 26.331576311   9.86 8.16     M3II 9 0
19 HD 155603 sg* 17 14 27.6552731387 -39 45 59.943671782 11.17 8.69 6.44 4.60 3.36 K0_0-Ia 63 0
20 V* V774 Sgr s*r 17 54 26.1321650900 -23 14 09.660274353   12.16 9.606     M4I 40 0
21 IRC -20427 s*r 18 05 35.4932917859 -21 13 42.219485368     12 10.46   M3/4I 33 0
22 V* AX Sgr s*r 18 08 26.5116566609 -18 33 07.939243877   11.34 9.20     K0Ia 78 0
23 HD 168815 * 18 22 13.8875390782 -15 05 17.835714652   9.73 7.83     K5+II 28 0
24 HD 170234 * 18 28 53.5147002616 -12 57 36.588556598   10.02 8.20     G5Iab 7 0
25 * 23 Sgr * 18 30 29.1600397796 -23 15 02.320131352   8.44 6.97     G8Ib/II 16 0
26 HD 182296 * 19 23 38.7254589157 +08 39 36.004989137   8.34 7.06     G3Ib 40 0
27 V* V340 Sge LP? 19 39 25.3354745662 +16 34 16.036192017   8.330 6.344     K4Ib 80 0
28 HD 187238 * 19 48 11.8385353558 +22 45 46.343064783 11.27 9.23 7.19 5.60 4.59 K2Iab-Ib 48 0
29 * c Cap * 21 45 00.2545490920 -09 04 56.747788074   6.189 5.079     G7.5II-IIICN0.5 52 0
30 V* LS Aqr LP* 23 10 25.3934642630 -13 18 35.343074700   9.92 8.42     G6/8Ib 35 0

    Equat.    Gal    SGal    Ecl

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2021.05.18-04:37:18

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