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Close detached white dwarf + brown dwarf binaries: further evidence for low values of the common envelope efficiency
Solar and Stellar Astrophysics · Submitted 28 Apr 2022
abstract compiled · 2026-09-23 · no language-model review
The authors' main claim We conclude that the vast majority of PCEBs form from common envelope evolution that can be parameterized with a small efficiency and without taking into account additional energy sources.
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The abstract, sentence by sentence
Common envelope evolution is a fundamental ingredient in our understanding of the formation of close binary stars containing compact objects which includes the progenitors of type Ia supernovae, short gamma ray bursts and most stellar gravitational wave sources. To predict the outcome of common envelope evolution we still rely to a large degree on a simplified energy conservation equation. Unfortunately, this equation contains a theoretically rather poorly constrained efficiency parameter ($\alpha_{\mathrm{CE}}$) and, even worse, it is unclear if energy sources in addition to orbital energy (such as recombination energy) contribute to the envelope ejection process. In previous works we reconstructed the evolution of observed populations of post common envelope binaries (PCEBs) consisting of white dwarfs with main sequence star companions and found indications that the efficiency is rather small ($\alpha_{\mathrm{CE}}\simeq0.2-0.3$) and that extra energy sources are only required in very few cases. Here we used the same reconstruction tool to investigate the evolutionary history of a sample of observed PCEBs with brown dwarf companions. In contrast to previous works, we found that the evolution of observationally well characterized PCEBs with brown dwarf companions can be understood assuming a low common envelope efficiency ($\alpha_{\mathrm{CE}}=0.24-0.41$), similar to that required to understand PCEBs with main sequence star companions, and that contributions from recombination energy are not required. We conclude that the vast majority of PCEBs form from common envelope evolution that can be parameterized with a small efficiency and without taking into account additional energy sources.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | Common envelope evolution is a fundamental ingredient in our understanding of the formation of close binary stars containing compact objects which includes the progenitors of type Ia supernovae, short gamma ray bursts and most stellar gravitational wave sources. | background 1.00 | 0.04 | 0.02 | asserted 1.00 |
| s1 | To predict the outcome of common envelope evolution we still rely to a large degree on a simplified energy conservation equation. | background 0.95 | 0.04 | 0.01 | asserted 0.99 |
| s2 | Unfortunately, this equation contains a theoretically rather poorly constrained efficiency parameter ($\alpha_{\mathrm{CE}}$) and, even worse, it is unclear if energy sources in addition to orbital energy (such as recombination energy) contribute to the envelope ejection process. | gap 0.83 | 0.05 | 0.02 | asserted 0.91 |
| s3 | In previous works we reconstructed the evolution of observed populations of post common envelope binaries (PCEBs) consisting of white dwarfs with main sequence star companions and found indications that the efficiency is rather small ($\alpha_{\mathrm{CE}}\simeq0.2-0.3$) and that extra energy sources are only required in very few cases. | background 0.69 | 0.69 | 0.05 | hedged possibility 0.90 |
| s4 | Here we used the same reconstruction tool to investigate the evolutionary history of a sample of observed PCEBs with brown dwarf companions. | contribution 0.84 | 0.91 | 0.02 | asserted 0.97 |
| s5 | In contrast to previous works, we found that the evolution of observationally well characterized PCEBs with brown dwarf companions can be understood assuming a low common envelope efficiency ($\alpha_{\mathrm{CE}}=0.24-0.41$), similar to that required to understand PCEBs with main sequence star companions, and that contributions from recombination energy are not required. | result 1.00 | 0.97 | 0.52 | asserted 0.97 |
| s6 | We conclude that the vast majority of PCEBs form from common envelope evolution that can be parameterized with a small efficiency and without taking into account additional energy sources. | interpretation 0.95 | 0.79 | 0.96 | asserted 1.00 |
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The paper
Original abstract
Common envelope evolution is a fundamental ingredient in our understanding of the formation of close binary stars containing compact objects which includes the progenitors of type Ia supernovae, short gamma ray bursts and most stellar gravitational wave sources. To predict the outcome of common envelope evolution we still rely to a large degree on a simplified energy conservation equation. Unfortunately, this equation contains a theoretically rather poorly constrained efficiency parameter ($\alpha_{\mathrm{CE}}$) and, even worse, it is unclear if energy sources in addition to orbital energy (such as recombination energy) contribute to the envelope ejection process. In previous works we reconstructed the evolution of observed populations of post common envelope binaries (PCEBs) consisting of white dwarfs with main sequence star companions and found indications that the efficiency is rather small ($\alpha_{\mathrm{CE}}\simeq0.2-0.3$) and that extra energy sources are only required in very few cases. Here we used the same reconstruction tool to investigate the evolutionary history of a sample of observed PCEBs with brown dwarf companions. In contrast to previous works, we found that the evolution of observationally well characterized PCEBs with brown dwarf companions can be understood assuming a low common envelope efficiency ($\alpha_{\mathrm{CE}}=0.24-0.41$), similar to that required to understand PCEBs with main sequence star companions, and that contributions from recombination energy are not required. We conclude that the vast majority of PCEBs form from common envelope evolution that can be parameterized with a small efficiency and without taking into account additional energy sources.
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How the literature uses it
1 arXiv paper cite this in 1 sentence
What it cites · 8 sentences without a confident label
Uses the method or tool of 1 paper
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For the reconstruction of the CE phase we used the same method we applied in our previous articles [ref] , i.e. based on a grid of stellar evolution tracks generated with the Single Star Evolution (SSE) code from [ref] for solar metallicity and Roche-geometry [ref] .
The White Dwarf Binary Pathways Survey VI: two close post common envelope binaries with TESS light curves · Reconstruction algorithm · 0.99
Compares with 1 paper
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In summary, if we interpret the estimated ages of the BD companions as lower limits on the age of the system, the formation of the eight PCEBs with detached BD companions that we studied can be reproduced by assuming a small CE efficiency ($α_CE = 0.24 - 0.41$) nearly identical to the one that is required to explain the large sample of PCEBs with low mass stellar companions [ref] and the majority of PCEBs with earlier spectral type secondary stars [ref] .
The White Dwarf Binary Pathways Survey VI: two close post common envelope binaries with TESS light curves · Non-eclipsing systems · 0.88
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