Evidence for radio emission from the giant binary lam and and a search for emission from other stars.

Bath, G. T.; Wallerstein, George

doi:10.1086/130022

Cited by 10 publications

(5 citation statements)

References 8 publications

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“…A compilation of the observed radio emission for λ And is shown in Table 3. As can be seen, radio observations of λ And were mainly published a few decades ago (Bath & Wallerstein 1976;Bowers & Kundu 1981;Lang et al 1985).…”

Section: Radio Observationsmentioning

confidence: 99%

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λ And: a post-main-sequence wind from a solar-mass star

Fionnagáin

Vidotto

Petit

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We investigate the wind of λ And, a solar-mass star that has evolved off the main sequence becoming a sub-giant. We present spectropolarimetric observations and use them to reconstruct the surface magnetic field of λ And. Although much older than our Sun, this star exhibits a stronger (reaching up to 83 G) large-scale magnetic field, which is dominated by the poloidal component. To investigate the wind of λ And, we use the derived magnetic map to simulate two stellar wind scenarios, namely a “polytropic wind” (thermally-driven) and an “Alfven-wave driven wind” with turbulent dissipation. From our 3D magnetohydrodynamics simulations, we calculate the wind thermal emission and compare it to previously published radio observations and more recent VLA observations, which we present here. These observations show a basal sub-mJy quiescent flux level at ∼5 GHz and, at epochs, a much larger flux density (>37 mJy), likely due to radio flares. By comparing our model results with the radio observations of λ And, we can constrain its mass-loss rate $\dot{M}$. There are two possible conclusions. 1) Assuming the quiescent radio emission originates from the stellar wind, we conclude that λ And has $\dot{M} \simeq 3 \times 10^{-9}$ M⊙ yr −1, which agrees with the evolving mass-loss rate trend for evolved solar-mass stars. 2) Alternatively, if the quiescent emission does not originate from the wind, our models can only place an upper limit on mass-loss rates, indicating that $\dot{M} \lesssim 3 \times 10^{-9}$ M⊙ yr −1.

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Section: Radio Observationsmentioning

confidence: 99%

“…One of the goals of our work is to use radio observations of λ And to constrain our wind models. Radio observations of λ And were mainly published a few decades ago (Bath & Wallerstein 1976;Bowers & Kundu 1981;Lang et al 1985).…”

mentioning

confidence: 99%

λ And: a post-main-sequence wind from a solar-mass star

Fionnagáin

Vidotto

Petit

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…A compilation of the observed radio emission for 𝜆 And is shown in Table 3. As can be seen, radio observations of 𝜆 And were mainly published a few decades ago (Bath & Wallerstein 1976;Bowers & Kundu 1981;Lang et al 1985).…”

Section: Radio Observationsmentioning

confidence: 99%

“…One of the goals of our work is to use radio observations of 𝜆 And to constrain our wind models. Radio observations of 𝜆 And were mainly published a few decades ago (Bath & Wallerstein 1976;Bowers & Kundu 1981;Lang et al 1985). Here, we present more recent Karl G. Jansky Very Large Array (VLA) archival data for 𝜆 And.…”

Section: Introductionmentioning

confidence: 99%

“…Being a solar-mass star, 𝜆 And can help us contextualise the future evolution of the wind of our Sun. 𝜆 And is a well studied star with X-ray (Audard et al 2003;Drake et al 2011), EUV (Baliunas et al 1984;Dupree et al 1996;Sanz-Forcada et al 2003), optical (Frasca et al 2008), interferometric imaging (Parks et al 2015), and radio observations (Bath & Wallerstein 1976;Bowers & Kundu 1981;Lang et al 1985, see also Section 5.1 for more recent VLA observations). This wealth of information makes 𝜆 And a great candidate for our study, as we will use some of these observational results to better constrain the results of our wind simulations.…”

Section: Introductionmentioning

confidence: 99%

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Lambda And: A post-main sequence wind from a solar-mass star

Fionnagain,

Vidotto,

Petit

et al. 2020

Preprint

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We investigate the wind of 𝜆 And, a solar-mass star that has evolved off the main sequence becoming a sub-giant. We present spectropolarimetric observations and use them to reconstruct the surface magnetic field of 𝜆 And. Although much older than our Sun, this star exhibits a stronger (reaching up to 83 G) large-scale magnetic field, which is dominated by the poloidal component. To investigate the wind of 𝜆 And, we use the derived magnetic map to simulate two stellar wind scenarios, namely a "polytropic wind" (thermally-driven) and an "Alfven-wave driven wind" with turbulent dissipation. From our 3D magnetohydrodynamics simulations, we calculate the wind thermal emission and compare it to previously published radio observations and more recent VLA observations, which we present here. These observations show a basal sub-mJy quiescent flux level at ∼5 GHz and, at epochs, a much larger flux density (> 37 mJy), likely due to radio flares. By comparing our model results with the radio observations of 𝜆 And, we can constrain its mass-loss rate 𝑀. There are two possible conclusions. 1) Assuming the quiescent radio emission originates from the stellar wind, we conclude that 𝜆 And has 𝑀 3 × 10 −9 M yr −1 , which agrees with the evolving mass-loss rate trend for evolved solar-mass stars. 2) Alternatively, if the quiescent emission does not originate from the wind, our models can only place an upper limit on mass-loss rates, indicating that 𝑀 3 × 10 −9 M yr −1 .

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The HR Diagram for Normal Radio Stars

Gibson

1985

Radio Stars

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Evidence for radio emission from the giant binary lam and and a search for emission from other stars.

Cited by 10 publications

References 8 publications

λ And: a post-main-sequence wind from a solar-mass star

λ And: a post-main-sequence wind from a solar-mass star

Lambda And: A post-main sequence wind from a solar-mass star

The HR Diagram for Normal Radio Stars

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