Stellar Engines and the Controlled Movement of the Sun

Bădescu, Viorel; Cathcart, Richard B.

doi:10.1007/1-4020-4604-9_12

Cited by 11 publications

(13 citation statements)

References 23 publications

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“…First proposed by Shkadov (1987), this could be in the form of a large mirror placed at some distance from the star, disturbing the radiative symmetry of the radiation field and altering its space velocity. Badescu & Cathcart (2000) noted that this reflection will cause the photospheric temperature to increase and gradually change the star's steady state, but they assumed that the nuclear reaction rate is unchanged. In this scenario, a smooth, mirrored surface reflects back as much light as possible, so we can model it as the specular reflection of some fraction of starlight.…”

Section: Radiative Feedback From Dyson Spheresmentioning

confidence: 99%

Evolutionary and Observational Consequences of Dyson Sphere Feedback

Huston,

Wright

2021

Preprint

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The search for signs of extraterrestrial technology, or technosignatures, includes the search for objects which collect starlight for some technological use, such as those composing a Dyson sphere. These searches typically account for a star's light and some blackbody temperature for the surrounding structure. However, such a structure inevitably returns some light back to the surface of its star, either from direct reflection or thermal re-emission. In this work, we explore how this feedback may affect the structure and evolution of stars, and when such feedback may affect observations. We find that in general this returned light can cause stars to expand and cool. Our MESA models show that this energy is only transported toward a star's core effectively by convection, so low mass stars are strongly affected, while higher mass stars with radiative exteriors are not. Ultimately, the effect only has significant observational consequences for spheres with very high temperatures (much higher than the often assumed ∼300 K) and/or high specular reflectivity. Lastly, we produce color-magnitude diagrams of combined star-Dyson sphere systems for a wide array of possible configurations.

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Section: Radiative Feedback From Dyson Spheresmentioning

confidence: 99%

Evolutionary and Observational Consequences of Dyson Sphere Feedback

Huston,

Wright

2021

Preprint

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“…His approach was general, but many other analyses of the gravitational, radiative, and thermodynamic properties of Dyson spheres invoke specific geometries, purposes, energy generation schemes, or other activities for the Dyson spheres. Some examples are studies of the gravitational dynamics of monolithic rings around stars (McInnes 2003;Rippert 2014, and references therein), the Harrop-Dyson satellite that exploits solar wind particles instead of photons (Harrop & Schulze-Makuch 2010), spheres with an inside surface temperature near 300K (Badescu 1995), much hotter and smaller Dyson spheres that radiate in the optical (Osmanov & Berezhiani 2018), analyses of very cold Dyson spheres (Lacki 2016), and partial shells used for stellar propulsion or energy extraction (Badescu & Cathcart 2000, 2006. Studies have also examined Dyson spheres around white dwarfs (Semiz & Ogur 2015), neutron stars (Osmanov 2016), black holes (Inoue & Yokoo 2011;Opatrný et al 2017), and X-ray binaries (Imara & Di Stefano 2018).…”

Section: Prior Literature: Theorymentioning

confidence: 99%

“…Following Badescu & Cathcart (2000) 10 , we refer to the intrinsic luminosity of the star from all interior processes (e.g. nuclear burning) as L, distinguished from L, the luminosity from its surface, which is somewhat higher than L because some if its emission is being returned by the sphere, and the emergent flux on the surface must increase to maintain energy balance.…”

Section: Relating the Dyson Sphere Properties To Observablesmentioning

confidence: 99%

“…10 In what follows we roughly follow the notation of Badescu & Cathcart (2000), however readers wishing to compare the two treatments should note that we use the subscript s to denote the sphere, while they use the same symbol to denote the star. We also use a to represent the Bond albedo, where they use a to represent the absorptance (which we refer to as e).…”

Section: Relating the Dyson Sphere Properties To Observablesmentioning

confidence: 99%

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Dyson Spheres

Wright

2020

Preprint

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I review the origins and development of the idea of Dyson spheres, their purpose, their engineering, and their detectability. I explicate the ways in which the popular imagining of them as monolithic objects would make them dynamically unstable under gravity and radiation pressure, and mechanically unstable to buckling. I develop a model for the radiative coupling between a star and large amounts of material orbiting it, and connect the observational features of a star plus Dyson sphere system to the gross radiative properties of the sphere itself. I discuss the still-unexplored problem of the effects of radiative feedback on the central star's structure and luminosity. Finally, I discuss the optimal sizes of Dyson spheres under various assumptions about their purpose as sources of low-entropy emission, dissipative work, or computation.

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“…Stellar engines have been explored in several other publications (Badescu & Cathcart 2000Hooper 2018;Caplan 2019;Svoronos 2020) and methods for detecting them during the course of exoplanetary transits were discussed in Forgan (2013).…”

Section: Introductionmentioning

confidence: 99%

Constraints on the abundance of $0.01\,c$ stellar engines in the Milky Way

Lingam,

Loeb

2020

Preprint

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Stellar engines are hypothesized megastructures that extract energy from the host star, typically with the purpose of generating thrust and accelerating the stellar system. We explore the maximum potential speeds that could be realizable by stellar engines, and determine that speeds up to ∼ 0.1 c might perhaps be attainable under optimal conditions. In contrast, natural astrophysical phenomena in the Milky Way are very unlikely to produce such speeds. Hence, astrometric surveys of hypervelocity stars may place constraints on the abundance of high-speed stellar engines in the Milky Way. In particular, Gaia DR-2 suggests that less than one in ∼ 10 7 stars is propelled by stellar engines to speeds 0.01 c.

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Stellar Engines and the Controlled Movement of the Sun

Cited by 11 publications

References 23 publications

Evolutionary and Observational Consequences of Dyson Sphere Feedback

Evolutionary and Observational Consequences of Dyson Sphere Feedback

Dyson Spheres

Constraints on the abundance of $0.01\,c$ stellar engines in the Milky Way

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