Observations of CO circumstellar absorption in the 4.6 micron spectrum of Alpha Orionis

Bernat, Andrew; Hall, Donald N. B.; Hinkle, K. H.; Ridgway, S. T.

doi:10.1086/183092

Cited by 61 publications

(45 citation statements)

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“…Two shells (S1 and S2) have been observed in absorption in 12 C 16 O and 13 C 16 O at 4.6 μm by Bernat et al (1979) but their spatial extent was not directly determined. Phoenix 4.6 μm spectra obtained by Harper et al (2009) led to an estimation of the size for S1 and S2.…”

Section: Two Outer Shellsmentioning

confidence: 99%

Imaging the spotty surface of Betelgeuse in theHband

Haubois¹,

Perrin²,

Lacour³

et al. 2009

A&A

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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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Section: Two Outer Shellsmentioning

confidence: 99%

Imaging the spotty surface of Betelgeuse in theHband

Haubois¹,

Perrin²,

Lacour³

et al. 2009

A&A

Self Cite

161

171

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“…(2) Smith et al (2009) and references therein. (3) Bernat et al (1979). (4) Noriega-Crespo et al (1997).…”

Section: Introductionmentioning

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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“…For the solar system this ratio has a value of approximately 90, while for a Orionis it has been determined to be 7 [14-161 from near-IR CN lines, 6 from IR CO lines [17], and between 10 and 20 [18] from UV CO lines. Harper et al (this conference) present evidence for multiple layers of circumstellar material, which may impact these interpretations.…”

Section: Analyzing the Spectrum Of A Orionismentioning

confidence: 99%

Heavy Elements and Cool Stars

Wahlgren

Carpenter²,

Norris³

2009

AIP Conference Proceedings

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Abstract. We report on progress in the analysis of high-resolution near-IR spectra of a Orionis (M2 Iab) and other cool, luminous stars. Using synthetic spectrum techniques, we search for atomic absorption lines in the stellar spectra and evaluate the available line parameter data for use in our abundance analyses. Our study concentrates on the post iron-group elements copper through zirconium as a means of investigating the slow neutron-capture process of nucleosynthesis in massive stars and the mechanisms that transport recently processed material up into the photospheric region. We discuss problems with the atomic data and model atmospheres that need to be addressed before theoretically derived elemental abundances from pre-supernova nucleosynthesis calculations can be tested by comparison with abundances determined from observations of cool, massive stars. Keywords ELEMENTAL ABUNDANCES AND THE WEAK S-PROCESSNucleosynthesis by the slow neutron capture process (s-process) is associated with different stellar sites. The main s-process is active in the interior regions of asymptotic giant-branch stars and contributes to the creation of all elements heavier than zinc up to and including bismuth. A variant of the s-process is the weak s-process, which is attributed to a lower neutron exposure and occurs in massive supergiants during the phases of He-core burning and C-shell burning. Isotopes in the atomic mass range A = 70 to 100 play a role in the weak s-process. Calculations (c.f. [I]) utilizing large nuclear reaction networks show that s-process efficiency increases with stellar mass in the range 15 to 30 solar masses and predict overproduction factors for the s-process nucleosynthesis to be highest for certain isotopes of Ge, Se, Kr, Sr, and Y.The analysis of post iron-group element abundances for massive supergiants has been limited. Studies by [2-61 determined element abundances from optical region spectra for G and K type Ib supergiants. For these low-mass supergiants no abundance patterns were identified that could be interpreted as the dredge-up of recently processed material.The infrared (IR) spectrum (1.1 1 -1.35 pm) of a Orionis (M2 Iab) was investigated by [7] for elements no heavier than zinc, finding most abundances to be metal deficient.We are undertaking the analysis of spectra of cool. luminous stars. Our goals are to identify spectral lines at IR wavelengths for elements heavier than iron and to determine abundances for heavy elements in massive supergiants for comparison with theoretical predictions for abundances produced by the weak s-process. Here. we report on the availability of the atomic data required for this analysis and we present preli~ninary abundance results for the massive supergiant a Orionis.https://ntrs.nasa.gov/search.jsp?R=20080045501 2018-05-12T13:36:26+00:00Z

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Observations of CO circumstellar absorption in the 4.6 micron spectrum of Alpha Orionis

Cited by 61 publications

References 0 publications

Imaging the spotty surface of Betelgeuse in theHband

Imaging the spotty surface of Betelgeuse in theHband

3D simulations of Betelgeuse’s bow shock

Heavy Elements and Cool Stars

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