Orbital Evolution of Mass-Transferring Eccentric Binary Systems. Ii. Secular Evolution

Dosopoulou, Fani; Kalogera, V.

doi:10.3847/0004-637x/825/1/71

Cited by 69 publications

(57 citation statements)

References 31 publications

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“…Our results show a good agreement with the secular evolution equations derived by Dosopoulou & Kalogera (2016) for fast isotropic winds, as long as the outflow in our models approximates the spherically symmetric wind case. However, when the ouflow morphology is modified by interaction with the binary, our results deviate from the analytical description.…”

Section: Resultssupporting

confidence: 84%

“…In addition to these proposed eccentricity pumping mechanisms, detailed analytical studies of the orbital evolution of eccentric binary systems have been performed by Sepinsky et al (2007b), Sepinsky et al (2009) Eggleton (2006), and Dosopoulou & Kalogera (2016). For instance, Eggleton (2006) and Dosopoulou & Kalogera (2016) derive the secular evolution of the semi-major axis and the eccentricity of an eccentric binary when interaction occurs via fast isotropic winds. However, several hydrodynamical studies have shown that wind interaction in AGB binaries can be quite different from the isotropic-wind mode (e.g.…”

Section: Introductionmentioning

confidence: 99%

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The eccentric behaviour of windy binary stars

Saladino

Pols

2019

A&A

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Carbon-enhanced metal-poor stars, CH stars, barium stars and extrinsic S stars, among other classes of chemically peculiar stars, are thought to be the products of the interaction of low-and intermediate-mass binaries which occurred when the most evolved star was in the asymptotic giant branch (AGB) phase. Binary evolution models predict that because of the large sizes of AGB stars, if the initial orbital periods of such systems are shorter than a few thousand days, their orbits should have circularised due to tidal effects. However, observations of the progeny of AGB binary stars show that many of these objects have substantial eccentricities, up to e ≈ 0.9. In this work we explore the impact of wind mass transfer on the orbital parameters of AGB binary stars by performing numerical simulations in which the AGB wind is modelled using a hydrodynamical code and the dynamics of the stars is evolved using an N-body code. We find that in most models the effect of wind mass transfer will contribute to the circularisation of the orbit, but on longer timescales than tidal circularisation if e 0.4. We also find that for relatively low initial wind velocities and pseudo-synchronisation of the donor star, a structure resembling wind Roche-lobe overflow is observed as the stars approach periastron. In this case, the interaction between the gas and the star is stronger than when the initial wind velocity is high and the orbit shrinks while the eccentricity decreases. In one of our models wind interaction is found to pump the eccentricity of the orbit on a similar timescale as tidal circularisation. However, since the orbit of this model is shrinking tidal effects will become stronger during the evolution of the system. Although our study is based on a small sample of models, it offers some insight into the orbital evolution of eccentric binary stars interacting via winds. A larger grid of numerical models for different binary parameters is needed to test if a regime exists where hydrodynamical eccentricity pumping can effectively counteract tidal circularisation, and if this can explain the puzzling eccentricities of the descendants of AGB binaries.

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Section: Resultssupporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

The eccentric behaviour of windy binary stars

Saladino

Pols

2019

A&A

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“…Furthermore, equation (39b) states that, as e → 0, ė ∝ e, i.e., e decays exponentially to zero. In contrast, according to the delta function model of Sepinsky et al (2007b) and Dosopoulou & Kalogera (2016b), for low eccentricities ė ∝ √ 1 − e 2 (1 − e) ≈ 1 − e, i.e., ė is nonzero at e = 0, and this can lead to undesirable properties (see Section 3 below for explicit examples). This is a consequence of the assumption of a delta function mass transfer rate at periapsis, whereas periapsis is not defined for circular orbits.…”

Section: Assumptions Of the Ejection/accretion Radiimentioning

confidence: 99%

“…Nevertheless, the problem of mass loss/mass transfer has been studied for over half a century (e.g., Huang 1956;Hadjidemetriou 1963;Kruszewski 1964;Piotrowski 1964;Matese & Whitmire 1983, 1984, and has received more recent attention in numerical studies (e.g., Regös et al 2005;Church et al 2009;Sepinsky et al 2010;Lajoie & Sills 2011a,b;van der Helm et al 2016;Bobrick et al 2017), as well as in (semi)analytical work (Sepinsky et al 2007b(Sepinsky et al , 2009(Sepinsky et al , 2010Veras et al 2011;Veras & Tout 2012;Veras et al 2013Veras et al , 2014Dosopoulou & Kalogera 2016a,b). Sepinsky et al (2007b) and Dosopoulou & Kalogera (2016b) in particular derived equations for the secular (i.e., orbit-averaged) changes of the orbital elements due to mass transfer in eccentric binaries. For the case of Roche Lobe overflow (RLOF), they assumed that the mass transfer rate is a delta function centered at periapsis, i.e., the donor star transfers its mass in a burst at its closest approach to its companion.…”

Section: Introductionmentioning

confidence: 99%

An Analytic Model for Mass Transfer in Binaries with Arbitrary Eccentricity, with Applications to Triple-star Systems

Hamers

Dosopoulou

2019

ApJ

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Most studies of mass transfer in binary systems assume circular orbits at the onset of Roche lobe overflow. However, there are theoretical and observational indications that mass transfer could occur in eccentric orbits. In particular, eccentricity could be produced via sudden mass loss and velocity kicks during supernova explosions, or Lidov-Kozai (LK) oscillations in hierarchical triple systems, or, more generally, secular evolution in multiple-star systems. However, current analytic models of eccentric mass transfer are faced with the problem that they are only well defined in the limit of very high eccentricities, and break down for less eccentric and circular orbits. This provides a major obstacle to implementing such models in binary and higher-order population synthesis codes, which are useful tools for studying the long-term evolution of a large number of systems. Here, we present a new analytic model to describe the secular orbital evolution of binaries undergoing conservative mass transfer. The main improvement of our model is that the mass transfer rate is a smoothly varying function of orbital phase, rather than a delta function centered at periapsis. Consequently, our model is in principle valid for any eccentricity, thereby overcoming the main limitation of previous works. We implement our model in an easy-to-use and publicly available code that can be used as a basis for implementations of our model into population synthesis codes. We investigate the implications of our model in a number of applications with circular and eccentric binaries, and triples undergoing LK oscillations.

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“…These mass transfer rates are not unreasonable to assume and we thus proceed with this proof-ofconcept calculation. We note that alternative models exist (Hamers & Dosopoulou 2019;Dosopoulou & Kalogera 2016;Sepinsky et al 2007) that incorporate orbital evolution, and will be included in future work.…”

Section: Mass Transfermentioning

confidence: 99%

Interacting young M-dwarfs in triple system – Par 1802 binary system case study

Cheng

Vinson

Naoz

2019

Monthly Notices of the Royal Astronomical Society

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The binary star Par 1802 in the Orion Nebula presents an interesting puzzle in the field of stellar dynamics and evolution. Binary systems such as Par 1802 are thought to form from the same natal material and thus the stellar members are expected to have very similar physical attributes. However, Par 1802's stars have significantly different temperatures despite their identical (within 3%) masses of about 0.39 solar mass. The leading proof-of-concept idea is that a third companion gravitationally induced the two stars to orbit closer than their Roche-limit, which facilitated heating through tidal effects. Here we expand on this idea and study the three-body dynamical evolution of such a system, including tidal and pre-main-sequence evolution. We also include tidal heating and mass transfer at the onset of Roche-limit Crossing. We show, as a proof-of-concept, that mass transfer combined with tidal heating can naturally explain the observed temperature discrepancy. We also predict the orbital configuration of the possible tertiary companion. Finally we suggest that the dynamical evolution of such a system has pervasive consequences. We expect an abundance of systems to undergo mass transfer during their pre-main-sequence time, which can cause temperature differences.

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Orbital Evolution of Mass-Transferring Eccentric Binary Systems. Ii. Secular Evolution

Cited by 69 publications

References 31 publications

The eccentric behaviour of windy binary stars

The eccentric behaviour of windy binary stars

An Analytic Model for Mass Transfer in Binaries with Arbitrary Eccentricity, with Applications to Triple-star Systems

Interacting young M-dwarfs in triple system – Par 1802 binary system case study

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