2022A&A...658A.185C


Query : 2022A&A...658A.185C

2022A&A...658A.185C - Astronomy and Astrophysics, volume 658A, 185-185 (2022/2-1)

The extended atmosphere and circumstellar environment of the cool evolved star VX Sagittarii as seen by MATISSE.

CHIAVASSA A., KRAVCHENKO K., MONTARGES M., MILLOUR F., MATTER A., FREYTAG B., WITTKOWSKI M., HOCDE V., CRUZALEBES P., ALLOUCHE F., LOPEZ B., LAGARDE S., PETROV R.G., MEILLAND A., ROBBE-DUBOIS S., HOFMANN K.-H., WEIGELT G., BERIO P., BENDJOYA P., BETTONVIL F., DOMICIANO DE SOUZA A., HEININGER M., HENNING T., ISBELL J.W., JAFFE W., LABADIE L., LEHMITZ M., MEISENHEIMER K., SOULAIN A., VARGA J., AUGEREAU J.-C., VAN BOEKEL R., BURTSCHER L., DANCHI W.C., DOMINIK C., DREVON J., GAMEZ ROSAS V., HOGERHEIJDE M.R., HRON J., KLARMANN L., KOKOULINA E., LAGADEC E., LEFTLEY J., MOSONI L., NARDETTO N., PALADINI C., PANTIN E., SCHERTL D., STEE P., SZABADOS L., WATERS R., WOLF S. and YOFFE G.

Abstract (from CDS):


Context. VX Sgr is a cool, evolved, and luminous red star whose stellar parameters are difficult to determine, which affects its classification.
Aims. We aim to spatially resolve the photospheric extent as well as the circumstellar environment.
Methods. We used interferometric observations obtained with the MATISSE instrument in the L (3-4 µm), M (4.5-5 µm), and N (8-13 µm) bands. We reconstructed monochromatic images using the MIRA software. We used 3D radiation-hydrodynamics simulations carried out with CO5BOLD and a uniform disc model to estimate the apparent diameter and interpret the stellar surface structures. Moreover, we employed the radiative transfer codesOPTIM3D andRADMC3D to compute the spectral energy distribution for the L, M, and N bands, respectively.
Results. MATISSE observations unveil, for the first time, the morphology of VX Sgr across the L, M, and N bands. The reconstructed images show a complex morphology with brighter areas whose characteristics depend on the wavelength probed. We measured the angular diameter as a function of the wavelength and showed that the photospheric extent in the L and M bands depends on the opacity through the atmosphere. In addition to this, we also concluded that the observed photospheric inhomogeneities can be interpreted as convection-related surface structures. The comparison in the N band yielded a qualitative agreement between the N-band spectrum and simple dust radiative transfer simulations. However, it is not possible to firmly conclude on the interpretation of the current data because of the difficulty in constraing the model parameters using the limited accuracy of our absolute flux calibration.
Conclusions. MATISSE observations and the derived reconstructed images unveil the appearance of VX Sgr's stellar surface and circumstellar environment across a very large spectral domain for the first time.

Abstract Copyright: © A. Chiavassa et al. 2022

Journal keyword(s): stars: atmospheres - stars: late-type - stars: individual: VX Sgr - techniques: interferometric - infrared: stars - stars: imaging

Simbad objects: 7

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Number of rows : 7
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 * 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 1594 0
2 * alf Ser PM* 15 44 16.0743159 +06 25 32.263272 5.080 3.800 2.630 1.82 1.25 K2IIIbCN1 510 0
3 * nu. Oph PM* 17 59 01.5919129 -09 46 25.079852 5.20 4.33 3.34 2.64 2.16 G9IIIa 204 1
4 Ass Sgr OB 1 As* 18 06 -22.8           ~ 123 0
5 V* VX Sgr s*r 18 08 04.0442790744 -22 13 26.600899044 11.72 9.41 6.52 3.90 2.11 M8.5Ia 581 0
6 * del Sgr * 18 20 59.6435424 -29 49 41.165919   4.069 2.668     K2.5IIIaCN0.5 171 0
7 * b Sgr * 19 56 56.8316470 -27 10 11.640936   5.980 4.528     K2.5IIb 63 0

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2023.02.08-01:52:45

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