2014A&A...566A..88A


C.D.S. - SIMBAD4 rel 1.7 - 2019.08.21CEST06:29:43

2014A&A...566A..88A - Astronomy and Astrophysics, volume 566A, 88-88 (2014/6-1)

VLTI/AMBER observations of cold giant stars: atmospheric structures and fundamental parameters.

ARROYO-TORRES B., MART-VIDA I., MARCAIDE J.M., WITTKOWSKI M., GUIRADO J.C., HAUSCHILDT P.H. and QUIRRENBACH A.

Abstract (from CDS):

The main goal of this research is to determine the angular size and the atmospheric structures of cool giant stars ε Oct, β Peg, NU Pav, ψ Peg, and γ Hya) nd to compare them with hydrostatic stellar model atmospheres, to estimate the fundamental parameters, and to obtain a better understanding of the circumstellar environment. We conducted spectro-interferometric observations of ε Oct, β Peg, NU Pav, ψ Peg in the near-infrared K band (2.13-2.47 µm, and γ Hya (1.9-2.47 µm) ith the VLTI/AMBER instrument at medium spectral resolution (∼1500). To obtain the fundamental parameters, we compared our data with hydrostatic atmosphere models (PHOENIX). We estimated the Rosseland angular diameters of ε Oct, β Peg, NU Pav, ψ Peg, and γ Hya to be 11.66 ± 1.50 mas, 16.87 ± 1.00 mas, 13.03 ± 1.75 mas, 6.31 ± 0.35 mas, and 3.78 ± 0.65 mas, respectively. Together with distances and bolometric fluxes (obtained from the literature), we estimated radii, effective temperatures, and luminosities of our targets. In the β Peg visibility, we observed a molecular layer of CO with a size similar to that modeled with PHOENIX. However, there is an additional slope in absorption starting around 2.3 µm. his slope is possibly due to a shell of H_2 O that is not modeled with PHOENIX (the size of the layer increases to about 5% with respect to the near-continuum level). The visibility of ψ Peg shows a low increase in the CO bands, compatible with the modeling of the PHOENIX model. The visibility data of ε Oct, NU Pav, and γ Hya show no increase in molecular bands. The spectra and visibilities predicted by the PHOENIX atmospheres agree with the spectra and the visibilities observed in our stars (except for β Peg). This indicates that the opacity of the molecular bands is adequately included in the model, and the atmospheres of our targets have an extension similar to the modeled atmospheres. The atmosphere of β Peg s more extended than that predicted by the model. The role of pulsations, if relevant in other cases and unmodeled by PHOENIX, therefore seems negligible for the atmospheric structures of our sample. The targets are located close to the red limits of the evolutionary tracks of the STAREVOL model, corresponding to masses between 1 M and 3 M☉_. he STAREVOL model fits the position of our stars in the Hertzsprung-Russell (HR) diagram better than the Ekstrom model does. STAREVOL includes thermohaline mixing, unlike the Ekstrom model, and complements the latter for intermediate-mass stars. Based on observations made with the VLT Interferometer (VLTI) at Paranal Observatory under programme ID 089.D-0801.Figures 2-4 are available in electronic form at http://www.aanda.org

Abstract Copyright:

Journal keyword(s): stars: AGB and post-AGB - stars: fundamental parameters - stars: atmospheres, stars: individual: eps Oct - Hertzsprung-Russell and C-M diagrams - stars: individual: bet Peg

CDS comments: BS 4432 is HR 4432 in SIMBAD.

Simbad objects: 19

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Number of rows : 19

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2019
#notes
1 * chi Peg PM* 00 14 36.1645107 +20 12 24.120523 8.280 6.380 4.800 3.45 2.32 M2+III 178 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 1435 0
3 V* VY CMa s*r 07 22 58.32877 -25 46 03.2355 12.01 10.19 7.95     M5Iae 978 0
4 * e Leo * 11 30 18.8919616628 -03 00 12.571219475 8.14 6.31 4.77     K3+IIIFe-0.5 121 0
5 * gam Hya SB* 13 18 55.2971856 -23 10 17.451401 4.58 3.92 3.00 2.40 1.93 G8IIIa 159 0
6 * k Hya PM* 14 23 05.7739343948 -27 45 14.460935182 7.59 6.06 4.75 3.78 3.11 K4III 73 0
7 * eta Ara * 16 49 47.1565275 -59 02 28.957499   5.306 3.744     K5III 59 0
8 V* AH Sco s*r 17 11 17.0228220330 -32 19 30.723257250   10.03 8.10     M5Ia-Iab 119 0
9 * eta Pav PM* 17 45 43.9860472 -64 43 25.939391   4.769 3.581     K2II 37 0
10 V* KW Sgr s*r 17 52 00.7276327565 -28 01 20.549258000   11.45 11.00     M4Ia 73 0
11 V* VX Sgr s*r 18 08 04.0431479808 -22 13 26.629744195 11.72 9.41 6.52 3.90 2.11 M8.5Ia 535 0
12 V* UY Sct s*r 18 27 36.5286196699 -12 27 58.893326502   14.20 11.20 9.51 6.93 M4Iae 52 0
13 V* NU Pav LP* 20 01 44.7454026 -59 22 33.217740 7.97 6.66 5.13     M6III 57 0
14 V* RS Cap AB* 21 07 15.4302361628 -16 25 21.486651603   9.56 8.36     M6/7III 63 0
15 * omi Pav V* 21 13 20.5006640815 -70 07 34.503682804   6.613 5.071     M1/2III 31 0
16 * eps Oct LP* 22 20 01.6796965 -80 26 23.094730   6.433 5.177     M5III 54 0
17 * bet Peg LP* 23 03 46.45746 +28 04 58.0336 6.05 4.09 2.42 0.92 -0.40 M2.5II-III 573 0
18 * 55 Peg V* 23 07 00.2589864288 +09 24 34.174103756 8.020 6.080 4.520 3.25 2.23 M1IIIab 128 0
19 * psi Peg ** 23 57 45.5268071 +25 08 29.047968 7.91 6.25 4.66 3.20 1.86 M3III 117 0

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2019.08.21-06:29:43

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