Carbon, nitrogen, and oxygen abundances in Betelgeuse

Abstract. We present the first synthetic Zeeman-split Stokes I and V profiles of OH lines. They explain the puzzling observations reported by Harvey (1985) of two pairs of lines from the infrared (2, 0) band with Stokes V profiles exhibiting opposite polarities. Our new perturbation calculations of the Zeeman effect in diatomic molecules, which allow states of any multiplicity to be treated, resolve the puzzle. They reveal that the unusual behaviour of these lines stems from the fact that the two pairs have effective Landé factors of similar magnitude, but of opposite signs.

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“…Lambert et al 1984). Relatively recently, for the first time OH lines formed in starspots have been detected (O'Neal & Neff 1997).…”

Section: Discussionmentioning

confidence: 98%

Zeeman-split opposite-polarity OH lines in sunspot spectra: Resolution of a puzzle

Berdyugina

Solanki

2001

A&A

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“…We adopt standard solar abundances of hydrogen and helium, and set the abundances of carbon and oxygen to χ C ∼ 2.5 × 10 −4 and χ O ∼ 6.3 × 10 −4 , respectively (Lambert et al 1984). We assume that the initial fraction of molecular to atomic hydrogen, f = n H 2 /n H , in the Betelgeuse outflow is small, f = 0.001 (on a scale where 0 is atomic and 0.5 is fully molecular).…”

Section: Coolingmentioning

confidence: 99%

3D simulations of Betelgeuse’s bow shock

Mohamed

Mackey²,

Langer³

2012

A&A

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Betelgeuse, the bright, cool red supergiant in Orion, is moving supersonically relative to the local interstellar medium. The star emits a powerful stellar wind that collides with this medium, forming a cometary structure, a bow shock, pointing in the direction of motion. We present the first 3D hydrodynamic simulations of the formation and evolution of Betelgeuse's bow shock. The models include realistic low-temperature cooling and cover a range of plausible interstellar medium densities of 0.3-1.9 cm −3 and stellar velocities of 28-73 km s −1 . We show that the flow dynamics and morphology of the bow shock differ substantially because of the growth of Rayleigh-Taylor or Kelvin-Helmholtz instabilities. The former dominate the models with slow stellar velocities resulting in a clumpy bow shock substructure, whereas the latter produce a smoother, more layered substructure in the fast models. If the mass in the bow shock shell is low, as seems to be implied by the AKARI luminosities (∼3 × 10 −3 M ), then Betelgeuse's bow shock is very young and is unlikely to have reached a steady state. The circular nature of the bow shock shell is consistent with this conclusion. Thus, our results suggest that Betelgeuse only entered the red supergiant phase recently.

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“…The outer envelope of the O-rich Betelgeuse (O/C = 2.5, Lambert et al 1984) has been the subject of extensive studies. VLA observations revealed an extended, cool (∼1000-3000 K) and irregularly shaped gaseous atmosphere of several stellar radii which coexists with the chromospheric gas (Lim et al 1998).…”

Section: The Asymmetric Gaseous Envelopementioning

confidence: 99%

Imaging the spotty surface of Betelgeuse in theHband

Haubois¹,

Perrin²,

Lacour³

et al. 2009

A&A

161

171

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Aims. This paper reports on H-band interferometric observations of Betelgeuse made at the three-telescope interferometer IOTA. We image Betelgeuse and its asymmetries to understand the spatial variation of the photosphere, including its diameter, limb darkening, effective temperature, surrounding brightness, and bright (or dark) star spots. Methods. We used different theoretical simulations of the photosphere and dusty environment to model the visibility data. We made images with parametric modeling and two image reconstruction algorithms: MIRA and WISARD. Results. We measure an average limb-darkened diameter of 44.28 ± 0.15 mas with linear and quadratic models and a Rosseland diameter of 45.03 ± 0.12 mas with a MARCS model. These measurements lead us to derive an updated effective temperature of 3600 ± 66 K. We detect a fully-resolved environment to which the silicate dust shell is likely to contribute. By using two imaging reconstruction algorithms, we unveiled two bright spots on the surface of Betelgeuse. One spot has a diameter of about 11 mas and accounts for about 8.5% of the total flux. The second one is unresolved (diameter < 9 mas) with 4.5% of the total flux. Conclusions. Resolved images of Betelgeuse in the H band are asymmetric at the level of a few percent. The MOLsphere is not detected in this wavelength range. The amount of measured limb-darkening is in good agreement with model predictions. The two spots imaged at the surface of the star are potential signatures of convective cells.

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Carbon, nitrogen, and oxygen abundances in Betelgeuse

Cited by 143 publications

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Zeeman-split opposite-polarity OH lines in sunspot spectra: Resolution of a puzzle

Zeeman-split opposite-polarity OH lines in sunspot spectra: Resolution of a puzzle

3D simulations of Betelgeuse’s bow shock

Imaging the spotty surface of Betelgeuse in theHband

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