Eccentricity and spin-orbit misalignment in short-period stellar binaries as a signpost of hidden tertiary companions

Anderson, Kassandra R.; Lai, Dong; Storch, Natalia I.

doi:10.1093/mnras/stx293

Cited by 82 publications

(76 citation statements)

References 48 publications

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“…Measurements of the Rossiter-McLaughlin effect, which probe the projected obliquity of the orbit, will serve to help better understand the strength of tidal realignment, and confront theoretical expectations (e.g. Anderson et al 2017).…”

Section: A Discussion On Tidal Evolutionmentioning

confidence: 99%

The EBLM Project

Triaud

Martin

Ségransan

et al. 2017

A&A

125

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We present 2271 radial velocity measurements taken on 118 single-line binary stars, taken over eight years with the CORALIE spectrograph. The binaries consist of F/G/K primaries and M dwarf secondaries. They were initially discovered photometrically by the WASP planet survey, as their shallow eclipses mimic a hot Jupiter transit. The observations we present permit a precise characterisation of the binary orbital elements and mass function. With modelling of the primary star, this mass function is converted to a mass of the secondary star. In the future, this spectroscopic work will be combined with precise photometric eclipses to draw an empirical mass/radius relation for the bottom of the mass sequence. This has applications in both stellar astrophysics and the growing number of exoplanet surveys around M dwarfs. In particular, we have discovered 34 systems with a secondary mass below 0.2 M , and so we will ultimately double the number of known very low-mass stars with well-characterised masses and radii. The quality of our data combined with the amplitude of the Doppler variations mean that we are able to detect eccentricities as small as 0.001 and orbital periods to sub-second precision. Our sample can revisit some earlier work on the tidal evolution of close binaries, extending it to low mass ratios. We find some exceptional binary systems that are eccentric at orbital periods below three days, while our longest circular orbit has a period of 10.4 days. Amongst our systems, we note one remarkable architecture in J1146-42 that boasts three stars within one astronomical unit. By collating the EBLM binaries with published WASP planets and brown dwarfs, we derive a mass spectrum with twice the resolution of previous work. We compare the WASP/EBLM sample of tightly bound orbits with work in the literature on more distant companions up to 10 AU. We note that the brown dwarf desert appears wider, as it carves into the planetary domain for our short-period orbits. This would mean that a significantly reduced abundance of planets begins at ∼3 M Jup , well before the deuterium-burning limit. This may shed light on the formation and migration history of massive gas giants.

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Section: A Discussion On Tidal Evolutionmentioning

confidence: 99%

The EBLM Project

Triaud

Martin

Ségransan

et al. 2017

A&A

125

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“…In hierarchical triples, Lidov-Kozai (LK) oscillations (Lidov 1962;Kozai 1962; see Naoz 2016 for a review) can drive high eccentricities in the inner orbit on potentially long timescales. High eccentricities can couple with strong tidal evolution, producing short-period binaries (e.g., Mazeh & Shaham 1979;Eggleton & Kiseleva-Eggleton 2001;Eggleton & Kisseleva-Eggleton 2006;Fabrycky & Tremaine 2007;Hamers et al 2013;Naoz & Fabrycky 2014;Toonen et al 2016;Anderson et al 2017;Bataille et al 2018;Rose et al 2019), although it has recently been cast into doubt whether this effect is responsible for producing an enhanced population of short-period binaries (Moe & Kratter 2018;Tokovinin 2019b;Tokovinin & Moe 2020). In addition, LK cycles in triples * E-mail: hamers@mpa-garching.mpg.de can couple with stellar evolution, giving rise to strong interactions during or after the main-sequence (MS; e.g., Hamers et al 2013;Toonen et al 2016;Stephan et al 2016;Antonini et al 2017;Toonen et al 2018;Hamers & Thompson 2019).…”

Section: Introductionmentioning

confidence: 99%

A census of main-sequence interactions in the Multiple Star Catalogue

Hamers

2020

Monthly Notices of the Royal Astronomical Society

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Statistics of hierarchical systems containing three or more stars are continuously improving. The Multiple Star Catalogue (MSC) is currently the most comprehensive catalogue of multiplestar systems and contains component masses, orbital periods, and additional information. The systems in the MSC are interesting for several reasons, including the long-term dynamical evolution of few-body systems. Although the secular evolution of triples and quadruples has been explored before, a systematic study of the systems in the MSC including also quintuples and sextuples has not been carried out. Here, we explore the main-sequence (MS) evolution of stars from the MSC based on approximately 2 × 10 5 secular dynamical integrations. We estimate statistical probabilities for strong interactions during the MS such as tidal evolution and mass transfer, and the onset of dynamical instability. Depending on the assumed model for the unknown orbital elements, we find that the fraction of noninteracting systems is largest for triples (∼ 0.9), and decreases to ∼ 0.6-0.8 for sextuples. The fraction of strong interactions increases from ∼ 0.1 to ∼ 0.2 from triples to sextuples, and the fraction of dynamically unstable systems increases from ∼ 0.001 to ∼ 0.1-0.2. The larger fractions of strong interactions and dynamical instability in systems with increasing multiplicity can be attributed to increasingly complex secular evolution in these systems. Our results indicate that a significant fraction of high-multiplicity systems interact or become dynamically unstable already during the MS, with an increasing importance as the number of stars increases.

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“…This has been attributed to shrinkage of the binary orbit due to tides enhanced by high eccentricities, which are driven by secular Lidov-Kozai (LK) oscillations (Lidov 1962;Kozai 1962; see Naoz 2016 for a review). This process, known as LK cycles with tidal friction, has been studied in detail by numerous authors (Mazeh & Shaham 1979;Eggleton & Kiseleva-Eggleton 2001;Eggleton & Kisseleva-Eggleton 2006;Fabrycky & Tremaine 2007;Hamers et al 2013;Naoz & Fabrycky 2014;Toonen et al 2016;Anderson et al 2017;Bataille et al 2018), and may be responsible for producing a large fraction of short-period binaries that would otherwise not be expected to form due to the larger sizes of the stars during the pre-MS.…”

Section: Introductionmentioning

confidence: 99%

Shrinking orbits in hierarchical quadruple star systems

Hamers

2018

Monthly Notices of the Royal Astronomical Society

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The distribution of the inner orbital periods of solar-type main-sequence (MS) triple star systems is known to be peaked at a few days, and this has been attributed to tidal evolution combined with eccentricity excitation due to Lidov-Kozai oscillations. Solar-type MS quadruple star systems also show peaks in their inner orbital period distributions at a few days. Here, we investigate the natural question whether tidal evolution combined with secular evolution can explain the observed inner orbital period distributions in quadruple stars. We carry out population synthesis simulations of solar-type MS quadruple star systems in both the 2+2 (two binaries orbiting each other's barycentre) and 3+1 (triple orbited by a fourth star) configurations. We take into account secular gravitational and tidal evolution, and the effects of passing stars. We assume that no short-period systems are formed initially, and truncate the initial orbital period distributions below 10 d accordingly. We find that, due to secular and tidal evolution, the inner orbital period distributions develop tails at short periods. Although qualitatively consistent with the observations, we find that our simulated orbital period distributions only quantitatively agree with the observations for the 3+1 systems. The observed 2+2 systems, on the other hand, show an enhancement of systems around 10 d, which is not reproduced in the simulations. This suggests that the inner orbital periods of 2+2 systems are not predominantly shaped by tidal and secular evolution, but by other processes, most likely occurring during the stellar formation and early evolution.

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Eccentricity and spin-orbit misalignment in short-period stellar binaries as a signpost of hidden tertiary companions

Cited by 82 publications

References 48 publications

The EBLM Project

The EBLM Project

A census of main-sequence interactions in the Multiple Star Catalogue

Shrinking orbits in hierarchical quadruple star systems

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