On the magnetic structure and wind parameter profiles of Alfvén wave driven winds in late-type supergiant stars

Falceta‐Gonçalves, D.; Vidotto, A. A.; Jatenco‐Pereira, V.

doi:10.1111/j.1365-2966.2006.10190.x

Cited by 25 publications

(20 citation statements)

References 28 publications

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“…On the contrary, exploration of our model suggests that the shell temperatures must be > ∼ 6000 K in order to produce the observed line profiles, though we cannot determine this accurately using only the physics we have incorporated into the model. This latter figure would be in better agreement with other predictions, such as those of Falceta-Gonçalves et al (2006). We assume a shell temperature of 8500 K (following Dupree et al 1984).…”

Section: Shell Temperatures and Chromospheressupporting

confidence: 80%

Dust, pulsation, chromospheres and their rôle in driving mass loss from red giants in Galactic globular clusters

McDonald¹,

Loon²

2007

A&A

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Context. Mass loss from red giants in old globular clusters affects the horizontal branch (HB) morphology and post-HB stellar evolution including the production of ultraviolet-bright stars, dredge up of nucleosynthesis products and replenishment of the intracluster medium. Study of mass loss in globular clusters also allows one to investigate the metallicity dependence of the mass loss from cool, low-mass stars down to very low metallicities. Aims. We present an analysis of new VLT/UVES spectra of 47 red giants in the Galactic globular clusters 47 Tuc (NGC 104), NGC 362, ω Cen (NGC 5139), NGC 6388, M 54 (NGC 6715) and M 15 (NGC 7078). The spectra cover the wavelength region 6100−9900 Å at a resolving power of R = 110 000. Some of these stars are known to exhibit mid-infrared excess emission indicative of circumstellar dust. Our aim is to detect signatures of mass loss, identify the mechanism(s) responsible for such outflows, and measure the mass-loss rates. Methods. We determine for each star its effective temperature, luminosity, radius and escape velocity. We analyse the Hα and nearinfrared calcium triplet lines for evidence of outflows, pulsation and chromospheric activity, and present a simple model for estimating mass-loss rates from the Hα line profile. We compare our results with a variety of other, independent methods. Results. We argue that a chromosphere persists in Galactic globular cluster giants and controls the mass-loss rate to late-K/early-M spectral types, where pulsation becomes strong enough to drive shock waves at luminosities above the RGB tip. This transition may be metallicity-dependent. We find mass-loss rates of ∼10 −7 to 10 −5 M yr −1 , largely independent of metallicity.

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Section: Shell Temperatures and Chromospheressupporting

confidence: 80%

Dust, pulsation, chromospheres and their rôle in driving mass loss from red giants in Galactic globular clusters

McDonald¹,

Loon²

2007

A&A

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“…Self-consistent heating/acceleration mechanism The first approach involves a more rigorous computation of the wave energy and momentum transfer, i.e., the computations are done from "first principles" (e.g., Hollweg 1973;Holzer et al 1983;Hartmann and MacGregor 1980;Jatenco-Pereira and Opher 1989;Vidotto and Jatenco-Pereira 2006;Falceta-Gonçalves et al 2006;Cranmer 2008;Cranmer and Saar 2011;Suzuki et al 2013). In these models, the increase in temperature from the colder photosphere to the hotter corona arises naturally in the solution of the equations as does the wind acceleration.…”

Section: Models Of Stellar Coronal Windsmentioning

confidence: 99%

Stellar Coronal and Wind Models: Impact on Exoplanets

Vidotto

2018

Handbook of Exoplanets

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Surface magnetism is believed to be the main driver of coronal heating and stellar wind acceleration. Coronae are believed to be formed by plasma confined in closed magnetic coronal loops of the stars, with winds mainly originating in open magnetic field line regions. In this Chapter, we review some basic properties of stellar coronae and winds and present some existing models. In the last part of this Chapter, we discuss the effects of coronal winds on exoplanets.

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“…The magnetic field could also contribute to the stellar mass-loss mechanism (Falceta-Gonçalves et al 2006). But crucial information on the magnetic field morphology is still lacking.…”

Section: Evolved Stars and Planetary Nebulaementioning

confidence: 99%

Magnetic Fields with the Atacama Large Millimeter/Submillimeter Array

Vlemmings

2014

Astrophysics and Space Science Library

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The Atacama Large Millimeter/submillimeter Array (ALMA) is one of the largest radio telescopes and is located at 5;000 m altitude in the Atacama desert in Chile. Its unprecedented sensitivity at extremely high angular and spectral resolution in the (sub-)millimetre wavelength regime, allows for countless advances in astrophysics. One of the areas in which ALMA can make unique contributions, is in that of the study of astrophysical magnetic fields. ALMA is expected to map the magnetic field geometry, and in some cases strength, in a large number of star forming regions, around evolved stars and planetary nebulae, and in nearby galaxies. This chapter provides examples of the amount of improvement ALMA offers the study of magnetic fields based on the current state-of-the-art and shortly introduces new tools that will be available to analyse (sub-)millimetre polarimetric observations. The Atacama Large Millimeter/Submillimeter ArrayThe Atacama Large Millimeter/submillimeter Array (ALMA) is a large international (sub-)millimeter-wavelength radio telescope array in the Atacama Desert of northern Chile. It consists of a total of 66 antennas operating in the wavelength range from 0:4 to 4 mm. Because of its unmatched sensitivity at very high spectral and spatial resolution, ALMA provides new insights into many astrophysical topics, from the formation of stars and planets to the evolution of the most distant galaxies. As ALMA is able to observe in full polarization mode, it can also reveal the magnetic field with a sensitivity and resolution that has not previously been possible.ALMA is a partnership between Europe, North America (USA and Canada) and East Asia (Japan and Taiwan) in cooperation with the Republic of Chile. The ALMA project is coordinated by the Joint ALMA Office based in Santiago de Chile. The ALMA observatory is operated from the Operation Support Facility (OSF), which is situated at 2,900 m altitude. The array itself and the correlator are located at the W. Vlemmings ( )

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On the magnetic structure and wind parameter profiles of Alfvén wave driven winds in late-type supergiant stars

Cited by 25 publications

References 28 publications

Dust, pulsation, chromospheres and their rôle in driving mass loss from red giants in Galactic globular clusters

Dust, pulsation, chromospheres and their rôle in driving mass loss from red giants in Galactic globular clusters

Stellar Coronal and Wind Models: Impact on Exoplanets

Magnetic Fields with the Atacama Large Millimeter/Submillimeter Array

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