Measurement at 11 Micron Wavelengths of the Diameters of alpha Orionis and alpha Scorpii: Changes in Effective Temperature of alpha Orionis and Very Recent Dust Emission

Bester, M.; Danchi, W. C.; Hale, D. S.; Townes, C. H.; Degiacomi, C. G.; Mékarnia, D.; Geballe, T. R.

doi:10.1086/177246

Cited by 58 publications

(66 citation statements)

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“…While they report O-rich miras are larger near the edges of the band, a different behavior is observed for C-rich stars; this tentatively confirms the role of O-bearing molecules (e.g., H 2 O). Moving further into the infrared, Weiner et al (2000) (following earlier work by Bester et al, 1996) actually find stars to be larger in true 11.15µm continuum channels (using the ISI interferometer) than at 2.2µm, a somewhat confusing result since the near-IR wavelengths are expected to be significantly contaminated by molecular effects. I am aware of even more results which have not made it to press yet (e.g., adaptive optics at the Subaru Telescope, narrow-band IOTA interferometry), and anticipate rapid progress in this area over the coming years.…”

Section: Stellar Diameters and Effective Temperaturesmentioning

confidence: 88%

Optical interferometry in astronomy

2003

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Abstract. Here I review the current state of the field of optical stellar interferometry, concentrating on ground-based work although a brief report of space interferometry missions is included. We pause both to reflect on decades of immense progress in the field as well as to prepare for a new generation of large interferometers just now being commissioned (most notably, the CHARA, Keck and VLT Interferometers). First, this review summarizes the basic principles behind stellar interferometry needed by the lay-physicist and general astronomer to understand the scientific potential as well as technical challenges of interferometry. Next, the basic design principles of practical interferometers are discussed, using the experience of past and existing facilities to illustrate important points. Here there is significant discussion of current trends in the field, including the new facilities under construction and advanced technologies being debuted. This decade has seen the influence of stellar interferometry extend beyond classical regimes of stellar diameters and binary orbits to new areas such as mapping the accretion disks around young stars, novel calibration of the Cepheid Period-Luminosity relation, and imaging of stellar surfaces. The third section is devoted to the major scientific results from interferometry, grouped into natural categories reflecting these current developments. Lastly, I consider the future of interferometry, highlighting the kinds of new science promised by the interferometers coming on-line in the next few years. I also discuss the longer-term future of optical interferometry, including the prospects for space interferometry and the possibilities of large-scale ground-based projects. Critical technological developments are still needed to make these projects attractive and affordable. †

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Section: Stellar Diameters and Effective Temperaturesmentioning

confidence: 88%

Optical interferometry in astronomy

2003

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“…A careful scrutiny of the object from the photospheric scale up to the distance in its circumstellar envelope (CSE) where dust can condense is the path to understanding this prototypical and enigmatic star. It is also known from interferometric observations in the thermal infrared domain by Bester et al (1996) that Betelgeuse experiences episodic mass loss. Our new NACO observations aim at probing the close environment of Betelgeuse to etablish a link between the photosphere and mass loss.…”

Section: Introductionmentioning

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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“…and episodi-R * ) cally (dust shell inner radii e.g., Dyck et al 1984 ; ?1R * ; Danchi et al 1994 ;Bester et al 1996). However, recent studies have also shown that the dust shells around certain stars can change signiÐcantly in the span of a few years (e.g., Bester et al 1996 ;Lopez et al 1997 ;Hani † & Buscher 1998), challenging our understanding of the physics responsible for the dust production and the mass loss in general.…”

Section: Introductionmentioning

confidence: 99%

Mid‐Infrared Interferometry on Spectral Lines. II. Continuum (Dust) Emission around IRC +10216 and VY Canis Majoris

Monnier

Danchi

Hale

et al. 2000

ApJ

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The University of California Berkeley Infrared Spatial Interferometer has measured the mid-infrared visibilities of the carbon star IRC ]10216 and the red supergiant VY CMa. The dust shells around these sources have been previously shown to be time variable, and these new data are used to probe the evolution of the dust shells on a decade timescale, complementing contemporaneous studies at other wavelengths. Self-consistent, spherically symmetric models at maximum and minimum light both show the inner radius of the IRC ]10216 dust shell to be much larger (150 mas) than expected from the dust-condensation temperature, implying that dust production has slowed or stopped in recent years. Apparently, dust does not form every pulsational cycle (638 days), and these mid-infrared results are consistent with recent near-infrared imaging, which indicates little or no new dust production in the last 3 yr. Spherically symmetric models failed to Ðt recent VY CMa data, implying that emission from the inner dust shell is highly asymmetric and/or time variable.

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Measurement at 11 Micron Wavelengths of the Diameters of alpha Orionis and alpha Scorpii: Changes in Effective Temperature of alpha Orionis and Very Recent Dust Emission

Cited by 58 publications

References 0 publications

Optical interferometry in astronomy

Optical interferometry in astronomy

The close circumstellar environment of Betelgeuse

Mid‐Infrared Interferometry on Spectral Lines. II. Continuum (Dust) Emission around IRC +10216 and VY Canis Majoris

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