The close circumstellar environment of Betelgeuse

Kervella, P.; Lagadec, E.; Montargès, M.; Ridgway, Stephen T.; Chiavassa, A.; Haubois, X.; Schmid, Hans Martin; Langlois, M.; Gallenne, A.; Perrin, G.

doi:10.1051/0004-6361/201527134

Cited by 58 publications

(73 citation statements)

References 26 publications

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“…The signature of an unresolved UV-bright asymmetry was also found and was suggested to be associated with the pole of the star (Uitenbroek et al 1998). Kervella et al (2016) imaged inhomogeneous hot Hα emission mostly contained within 3 R with SPHERE on the Very Large Telescope (VLT) while Harper & Brown (2006) showed that the chromospheric gas decouples from co-rotation at about 3 R . Lim et al (1998) used multi-wavelength, spatially resolved Very Large Array (VLA) radio observations to show that the hot chromospheric gas has a small filling factor and that the mean temperature at these radii is relatively cool (T gas 3600 K).…”

Section: Introductionmentioning

confidence: 89%

The inhomogeneous submillimeter atmosphere of Betelgeuse

O’Gorman

Kervella

Harper

et al. 2017

A&A

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The mechanisms responsible for heating the extended atmospheres of early-M spectral-type supergiants are poorly understood. So too is the subsequent role these mechanisms play in driving the large mass-loss rates of these stars. Here we present ALMA long (i.e., ∼16 km) baseline 338 GHz (0.89 mm) continuum observations of the free-free emission in the extended atmosphere of the M2 spectral-type supergiant Betelgeuse. The spatial resolution of 14 mas exquisitely resolves the atmosphere, revealing it to have a mean temperature of 2760 K at ∼1.3 R , which is below both the photospheric effective temperature (T eff = 3690 K) and the temperatures at ∼2 R . This is unambiguous proof for the existence of an inversion of the mean temperature in the atmosphere of a red supergiant. The emission is clearly not spherically symmetric with two notable deviations from a uniform disk detected in both the images and visibilities. The most prominent asymmetry is located in the north-east quadrant of the disk and is spatially resolved showing it to be highly elongated with an axis-ratio of 2.4 and occupying ∼5% of the disk projected area. Its temperature is approximately 1000 K above the measured mean temperature at 1.3 R . The other main asymmetry is located on the disk limb almost due east of the disk center and occupies ∼3% of the disk projected area. Both emission asymmetries are clear evidence for localized heating taking place in the atmosphere of Betelgeuse. We suggest that the detected localized heating is related to magnetic activity generated by large-scale photospheric convection.

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Section: Introductionmentioning

confidence: 89%

The inhomogeneous submillimeter atmosphere of Betelgeuse

O’Gorman

Kervella

Harper

et al. 2017

A&A

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“…Technical descriptions of the instrument are given in, for example, Beuzit et al (2008), Kasper et al (2012), Dohlen et al (2006), Fusco et al (2014), and references therein, and much basic information can be found in the SPHERE user manual and related technical websites 1 of the European Southern Observatory (ESO). A first series of SPHERE science papers demonstrate the performance of various observing modes of this instrument (e.g., Vigan et al 2016;Maire et al 2016;Zurlo et al 2016;Bonnefoy et al 2016;Boccaletti et al 2015;Thalmann et al 2015;Kervella et al 2016;Garufi et al 2016).…”

Section: The Sphere/zimpol Instrumentmentioning

confidence: 99%

SPHERE/ZIMPOL observations of the symbiotic system R Aquarii

Schmid

Bazzon

Milli

et al. 2017

A&A

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Context. R Aqr is a symbiotic binary system consisting of a mira variable, a hot companion with a spectacular jet outflow, and an extended emission line nebula. Because of its proximity to the Sun, this object has been studied in much detail with many types of high resolution imaging and interferometric techniques. We have used R Aqr as test target for the visual camera subsystem ZIMPOL, which is part of the new extreme adaptive optics (AO) instrument SPHERE at the Very Large Telescope (VLT). Aims. We describe SPHERE/ZIMPOL test observations of the R Aqr system taken in Hα and other filters in order to demonstrate the exceptional performance of this high resolution instrument. We compare our observations with data from the Hubble Space Telescope (HST) and illustrate the complementarity of the two instruments. We use our data for a detailed characterization of the inner jet region of R Aqr. Methods. We analyze the high resolution ≈25 mas images from SPHERE/ZIMPOL and determine from the Hα emission the position, size, geometric structure, and line fluxes of the jet source and the clouds in the innermost region <2 (<400 AU) of R Aqr. The data are compared to simultaneous HST line filter observations. The Hα fluxes and the measured sizes of the clouds yield Hα emissivities for many clouds from which one can derive the mean density, mass, recombination time scale, and other cloud parameters. for the "outer" clouds around 300 AU, N e ≈ 3 × 10 6 cm −3 for the "inner" clouds around 50 AU, and even higher for the central jet source. The high N e of the clouds implies short recombination or variability timescales of a year or shorter. Conclusions. Hα high resolution data provide a lot of diagnostic information for the ionized jet gas in R Aqr. Future Hα observations will provide the orientation of the orbital plane of the binary and allow detailed hydrodynamical investigations of this jet outflow and its interaction with the wind of the red giant companion.

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“…Moreover, as we show in Section 3, CSM interaction persists at late times, implying the presence of a highly extended tenuous CSM envelope. RSG winds have long been known to contain dust (Zuckerman 1980), and high-resolution imaging and polarimetric observations of the RSGs Betelgeuse and Antares have shown that such dust can be clumpy (Kervella et al 2011(Kervella et al , 2016Ohnaka 2014); this material could provide an asymmetric scattering medium and, if viewed at a suitable orientation, a major source of polarization. Depending upon the composition and size of dust grains and their distance from the SN, circumstellar dust can potentially survive if the UV pulse of SN shock breakout fades faster than the sublimation timescale at a given radius.…”

Section: Spectropolarimetric Modelingmentioning

confidence: 99%

Asphericity, Interaction, and Dust in the Type Ii-P/Ii-L Supernova 2013ej in Messier 74

Mauerhan

Dyk

Johansson

et al. 2017

ApJ

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SN 2013ej is a well-studied core-collapse supernova (SN) that stemmed from a directly identified red supergiant (RSG) progenitor in galaxy M74. The source exhibits signs of substantial geometric asphericity, X-rays from persistent interaction with circumstellar material (CSM), thermal emission from warm dust, and a light curve that appears intermediate between supernovae of Types II-P and II-L. The proximity of this source motivates a close inspection of these physical characteristics and their potential interconnection. We present multiepoch spectropolarimetry of SN 2013ej during the first 107 days and deep optical spectroscopy and ultraviolet through infrared photometry past ∼800 days. SN 2013ej exhibits the strongest and most persistent continuum and line polarization ever observed for a SN of its class during the recombination phase. Modeling indicates that the data are consistent with an oblate ellipsoidal photosphere, viewed nearly edge-on and probably augmented by optical scattering from circumstellar dust. We suggest that interaction with an equatorial distribution of CSM, perhaps the result of binary evolution, is responsible for generating the photospheric asphericity. Relatedly, our late-time optical imaging and spectroscopy show that asymmetric CSM interaction is ongoing, and the morphology of broad Hα emission from shock-excited ejecta provides additional evidence that the geometry of the interaction region is ellipsoidal. Alternatively, a prolate ellipsoidal geometry from an intrinsically bipolar explosion is also a plausible interpretation of the data but would probably require a ballistic jet of radioactive material capable of penetrating the hydrogen envelope early in the recombination phase. Finally, our latest space-based optical imaging confirms that the late interaction-powered light curve dropped below the stellar progenitor level, confirming the RSG star's association with the explosion.

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The close circumstellar environment of Betelgeuse

Cited by 58 publications

References 26 publications

The inhomogeneous submillimeter atmosphere of Betelgeuse

The inhomogeneous submillimeter atmosphere of Betelgeuse

SPHERE/ZIMPOL observations of the symbiotic system R Aquarii

Asphericity, Interaction, and Dust in the Type Ii-P/Ii-L Supernova 2013ej in Messier 74

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