The Nonspherical Shape of Betelgeuse in the Mid-Infrared

Tatebe, K.; Chandler, A. A.; Wishnow, Edward H.; Hale, David; Townes, C. H.

doi:10.1086/524108

Cited by 27 publications

(29 citation statements)

References 20 publications

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“…But this result disagrees with later findings by Skinner et al (1997), who claim an inner radius of not more than 0.5 arcsec. This environment of dust is also reported by Tatebe et al (2007) as the origin of a visibility drop at short baselines of more than 40% in new ISI measurements. Lambert & Snell (1975) interpreted Betelgeuse spectra and found that the infrared excess could be explained by a chromospheric emission.…”

Section: A Dusty Environmentsupporting

confidence: 78%

“…Confirming previous results, Young et al (2000) observed spots in the visible but show a fully centro-symmetric picture of Betelgeuse in the near infrared (at 1.29 μm). Lately Tatebe et al (2007) also report the observation of an asymmetry at 11.15 μm located on the southern edge of the disk of Betelgeuse. In order to deepen our knowledge on RSGs, it is critical to observe spots at high angular resolution.…”

Section: The Spots Observed On the Surface Of Betelgeusementioning

confidence: 97%

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Imaging the spotty surface of Betelgeuse in theHband

Haubois¹,

Perrin²,

Lacour³

et al. 2009

A&A

160

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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Section: A Dusty Environmentsupporting

confidence: 78%

Section: The Spots Observed On the Surface Of Betelgeusementioning

confidence: 97%

Imaging the spotty surface of Betelgeuse in theHband

Haubois¹,

Perrin²,

Lacour³

et al. 2009

A&A

160

171

View full text Add to dashboard Cite

show abstract

“…A large spot was detected by Uitenbroek et al (1998) with HST. The non-spherical shape of Betelgeuse was also detected by Tatebe et al (2007) in the mid-infrared. A&A 515, A12 (2010) Haubois et al (2009) published a reconstructed image of Betelgeuse in the H band with two spots using the same data as presented in this work.…”

Section: Introductionmentioning

confidence: 78%

Radiative hydrodynamics simulations of red supergiant stars

Chiavassa

Haubois

Young

et al. 2010

A&A

125

130

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Context. The red supergiant (RSG) Betelgeuse is an irregular variable star. Convection may play an important role in understanding this variability. Interferometric observations can be interpreted using sophisticated simulations of stellar convection. Aims. We compare the visibility curves and closure phases obtained from our 3D simulation of RSG convection with CO5BOLD to various interferometric observations of Betelgeuse from the optical to the H band to characterize and measure the convection pattern on this star. Methods. We use a 3D radiative-hydrodynamics (RHD) simulation to compute intensity maps in different filters and thus derive interferometric observables using the post-processing radiative transfer code OPTIM3D. The synthetic visibility curves and closure phases are compared to observations. Results. We provide a robust detection of the granulation pattern on the surface of Betelgeuse in both the optical and the H band based on excellent fits to the observed visibility points and closure phases. We determine that the Betelgeuse surface in the H band is covered by small to medium scale (5−15 mas) convection-related surface structures and a large (≈30 mas) convective cell. In this spectral region, H 2 O molecules are the main absorbers and contribute to both the small structures and the position of the first null of the visibility curve (i.e., the apparent stellar radius).

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“…At thermal infrared wavelengths (λ = 11.15 μm), Tatebe et al (2007) identified an asymmetry on the disk of Betelgeuse from three-telescope interferometric observations with the ISI instrument obtained in November and December 2006. They interpreted this asymmetry as the signature of a hot spot located on the southern limb of the star at a PA of 170−180 • .…”

Section: Previous High Angular Resolution Observationsmentioning

confidence: 99%

The close circumstellar environment of Betelgeuse

Kervella¹,

Verhoelst

Ridgway

et al. 2009

A&A

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Context. Betelgeuse is one the largest stars in the sky in terms of angular diameter. Structures on the stellar photosphere have been detected in the visible and near-infrared as well as a compact molecular environment called the MOLsphere. Mid-infrared observations have revealed the nature of some of the molecules in the MOLsphere, some being the precursor of dust. Aims. Betelgeuse is an excellent candidate to understand the process of mass loss in red supergiants. Using diffraction-limited adaptive optics (AO) in the near-infrared, we probe the photosphere and close environment of Betelgeuse to study the wavelength dependence of its extension, and to search for asymmetries. Methods. We obtained AO images with the VLT/NACO instrument, taking advantage of the "cube" mode of the CONICA camera to record separately a large number of short-exposure frames. This allowed us to adopt a "lucky imaging" approach for the data reduction, and obtain diffraction-limited images over the spectral range 1.04−2.17 μm in 10 narrow-band filters. Results. In all filters, the photosphere of Betelgeuse appears partly resolved. We identify an asymmetric envelope around the star, with in particular a relatively bright "plume" extending in the southwestern quadrant up to a radius of approximately six times the photosphere. The CN molecule provides an excellent match to the 1.09 μm bandhead in absorption in front of the stellar photosphere, but the emission spectrum of the plume is more difficult to interpret. Conclusions. Our AO images show that the envelope surrounding Betelgeuse has a complex and irregular structure. We propose that the southwestern plume is linked either to the presence of a convective hot spot on the photosphere, or to the rotation of the star.

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The Nonspherical Shape of Betelgeuse in the Mid-Infrared

Cited by 27 publications

References 20 publications

Imaging the spotty surface of Betelgeuse in theHband

Imaging the spotty surface of Betelgeuse in theHband

Radiative hydrodynamics simulations of red supergiant stars

The close circumstellar environment of Betelgeuse

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