2009A&A...503..183O


Query : 2009A&A...503..183O

2009A&A...503..183O - Astronomy and Astrophysics, volume 503, 183-195 (2009/8-3)

Spatially resolving the inhomogeneous structure of the dynamical atmosphere of Betelgeuse with VLTI/AMBER.

OHNAKA K., HOFMANN K.-H., BENISTY M., CHELLI A., DRIEBE T., MILLOUR F., PETROV R., SCHERTL D., STEE P., VAKILI F. and WEIGELT G.

Abstract (from CDS):

We present spatially resolved, high-spectral resolution K-band observations of the red supergiant Betelgeuse ({alpha} Ori) using AMBER at the Very Large Telescope Interferometer (VLTI). Our aim is to probe inhomogeneous structures in the dynamical atmosphere of Betelgeuse. Betelgeuse was observed in the wavelength range between 2.28 and 2.31µm with VLTI/AMBER using baselines of 16, 32, and 48m. The spectral resolutions of 4800-12000 allow us to study inhomogeneities seen in the individual CO first overtone lines. Spectrally dispersed interferograms have been successfully obtained in the second, third, and fifth lobes, which represents the highest spatial resolution (9mas) achieved for Betelgeuse. This corresponds to five resolution elements over its stellar disk. The AMBER visibilities and closure phases in the K-band continuum can be reasonably fitted by a uniform disk with a diameter of 43.19±0.03mas or a limb-darkening disk with 43.56±0.06mas and a limb-darkening parameter of (1.2±0.07)x10–1. These AMBER data and the previous K-band interferometric data taken at various epochs suggest that Betelgeuse seen in the K-band continuum shows much smaller deviations from the above uniform disk or limb-darkened disk than predicted by recent 3-D convection simulations for red supergiants. On the other hand, our AMBER data in the CO lines reveal salient inhomogeneous structures. The visibilities and phases (closure phases, as well as differential phases representing asymmetry in lines with respect to the continuum) measured within the CO lines show that the blue and red wings originate in spatially distinct regions over the stellar disk, indicating an inhomogeneous velocity field that makes the star appear different in the blue and red wings. Our AMBER data in the CO lines can be roughly explained by a simple model, in which a patch of CO gas is moving outward or inward with velocities of 10-15km/s, while the CO gas in the remaining region in the atmosphere is moving in the opposite direction at the same velocities. Also, the AMBER data are consistent with the presence of warm molecular layers (so-called MOLsphere) extending to ∼1.4-1.5R* with a CO column density of ∼1x1020cm–2. Our AMBER observations of Betelgeuse are the first spatially resolved study of the so-called macroturbulence in a stellar atmosphere (photosphere and possibly MOLsphere as well) other than the Sun. The spatially resolved CO gas motion is likely to be related to convective motion in the upper atmosphere or intermittent mass ejections in clumps or arcs.

Abstract Copyright:

Journal keyword(s): infrared: stars - techniques: interferometric - stars: supergiants - stars: late-type - stars: atmospheres - stars: individual: Betelgeuse

Simbad objects: 27

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Number of rows : 27
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 * iot Cet * 00 19 25.6741634 -08 49 26.111055 5.94 4.77 3.55 2.70 2.11 K1+IIICN0.5 174 0
2 * bet Cet PM* 00 43 35.37090 -17 59 11.7827 3.90 3.02 2.01 1.29 0.78 G9.5IIICH-1 509 0
3 * chi Phe PM* 02 01 42.3763488264 -44 42 48.626334576 8.45 6.63 5.14 3.92 3.03 K5IV 59 0
4 * pi. Eri LP? 03 46 08.5352200200 -12 06 05.718535236 8.05 6.04 4.42 3.08 2.03 M1III 56 0
5 * eps Lep PM* 05 05 27.6653698 -22 22 15.723893 6.41 4.64 3.18 2.08 1.27 K4III 150 0
6 * bet Ori s*b 05 14 32.27210 -08 12 05.8981 -0.56 0.10 0.13 0.13 0.15 B8Iae 745 0
7 * 31 Ori V* 05 29 43.9820095248 -01 05 32.058334392   6.28 4.71     K4III 89 0
8 * 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 1579 0
9 * alf CMa SB* 06 45 08.91728 -16 42 58.0171 -1.51 -1.46 -1.46 -1.46 -1.43 A0mA1Va 1479 0
10 * tau Pup SB* 06 49 56.1684595 -50 36 52.443676   4.13 2.93     K1III 101 0
11 * tet CMa PM* 06 54 11.3988612864 -12 02 19.061163780 7.20 5.51 4.08 2.95 2.17 K3/4III 213 0
12 * del CMa s*y 07 08 23.4840514 -26 23 35.518484 3.06 2.52 1.84 1.33 1.00 F8Ia 331 0
13 V* VY CMa s*r 07 22 58.32877 -25 46 03.2355 12.01 10.19 7.95     M5Iae 1059 0
14 * alf CMi SB* 07 39 18.11950 +05 13 29.9552 0.82 0.79 0.37 -0.05 -0.28 F5IV-V+DQZ 1828 0
15 * 1 Pup V* 07 43 32.3866853568 -28 24 39.188693988 8.16 6.22 4.59 3.29 2.32 K5III 101 0
16 * bet Cnc PM* 08 16 30.9210081 +09 11 07.957924 6.750 5.000 3.520 2.42 1.62 K4IIIBa0.5: 357 0
17 * zet Hya PM* 08 55 23.6261352 +05 56 44.035380 4.92 4.10 3.10 2.39 1.90 G8.5III 234 0
18 * alf Hya * 09 27 35.24270 -08 39 30.9583 5.14 3.42 1.97 0.93 0.16 K3IIIa 419 0
19 * N Vel V* 09 31 13.3189137 -57 02 03.757780   4.691 3.139     K5III 93 0
20 * iot Hya PM* 09 39 51.3614457 -01 08 34.113491 6.68 5.23 3.91 2.92 2.25 K2.5III 171 0
21 IRC +10216 C* 09 47 57.40632 +13 16 43.5648           C9,5e 2256 0
22 V* RW LMi C* 10 16 02.2777043904 +30 34 19.045098516       15.27   C4,3e 386 0
23 * q Car LP* 10 17 04.9753050 -61 19 56.288301   4.899 3.350     K2.5II 135 0
24 * gam01 Leo PM* 10 19 58.354462 +19 50 29.35920 4.13 3.13 1.98 1.13 0.51 K1-IIIFe-1 278 1
25 * mu. Hya PM* 10 26 05.42630 -16 50 10.6429 7.11 5.29 3.81 2.70 1.87 K4III 121 0
26 * mu. Cep s*r 21 43 30.4610574 +58 46 48.160181 8.85 6.43 4.08 1.98 0.22 M2-Ia 650 1
27 * eps Peg LP* 21 44 11.1561394 +09 52 30.031152 5.61 3.91 2.39 1.34 0.58 K2Ib-II 439 0

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2022.10.07-14:47:44

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