The Metallicity of Stars with Close Companions

Grether, Daniel; Lineweaver, Charles H.

doi:10.1086/521714

Cited by 35 publications

(51 citation statements)

References 35 publications

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“…Indeed, the median Galactic latitude for KOIs with nearby stars is b=11.2, approximately a degree and a half closer to the Galactic disk compared the median latitude of all KOIs (b med =12.7), while the difference in median Galactic longitude for the two populations is negligible. Apart from a higher number of nearby unbound stars, KOIs with nearby stars may on average be found at lower Galactic latitudes due in part to higher intrinsic binarity rates of thick disk stars compared to thin disk stars (Chiba & Beers 2000;Grether & Lineweaver 2007).…”

Section: Galactic Latitude and Stellar Densitymentioning

confidence: 99%

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Robo-AO Kepler Survey. V. The Effect of Physically Associated Stellar Companions on Planetary Systems

Ziegler

Law

Baranec

et al. 2018

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The Kepler light curves used to detect thousands of planetary candidates are susceptible to dilution due to blending with previously unknown nearby stars. With the automated laser adaptive optics instrument, Robo-AO, we have observed 620 nearby stars around 3857 planetary candidates host stars. Many of the nearby stars, however, are not bound to the KOI. We use galactic stellar models and the observed stellar density to estimate the number and properties of unbound stars. We estimate the spectral type and distance to 145 KOIs with nearby stars using multiband observations from Robo-AO and Keck-AO. Most stars within 1″ of a Kepler planetary candidate are likely bound, in agreement with past studies. We use likely bound stars and the precise stellar parameters from the California Kepler Survey to search for correlations between stellar binarity and planetary properties. No significant difference between the binarity fraction of single and multiple-planet systems is found, and planet hosting stars follow similar binarity trends as field stars, many of which likely host their own non-aligned planets. We find that hot Jupiters are ∼4× more likely than other planets to reside in a binary star system. We correct the radius estimates of the planet candidates in characterized systems and find that for likely bound systems, the estimated planetary radii will increase on average by a factor of 1.77, if either star is equally likely to host the planet. Lastly, we find the planetary radius gap is robust to the impact of dilution.

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Section: Galactic Latitude and Stellar Densitymentioning

confidence: 99%

“…Planetary systems do seem to occur more frequently in metal-rich stars (Fischer & Valenti 2005;Grether & Lineweaver 2007).…”

Section: Stellar Multiplicity and Metallicity Of Koismentioning

confidence: 99%

Robo-AO Kepler Survey. V. The Effect of Physically Associated Stellar Companions on Planetary Systems

Ziegler

Law

Baranec

et al. 2018

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“…On the other hand, stellar companions are more common around metal-poor primaries (Grether & Lineweaver 2007;Raghavan et al 2010), a trend that is more evident for stars with (B−V) > 0.625. Raghavan et al (2010) interpret this (tentative) result by suggesting that lower-metallicity clouds might be more likely to fragment to form binary stars, as is revealed in numerical simulations.…”

Section: Metallicitymentioning

confidence: 99%

The SOPHIE search for northern extrasolar planets

Díaz

Santerne

Sahlmann

et al. 2012

A&A

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Context. The mass domain where massive extrasolar planets and brown dwarfs lie is still poorly understood. Indeed, not even a clear dividing line between massive planets and brown dwarfs has been established yet. This is partly because these objects are very scarce in close orbits around solar-type stars, the so-called brown dwarf desert. Owing to this, it has proven difficult to set up a strong observational base with which to compare models and theories of formation and evolution. Aims. We search to increase the current sample of massive sub-stellar objects with precise orbital parameters, and to constrain the true mass of detected sub-stellar candidates. Methods. The initial identification of sub-stellar candidates was made using precise radial velocity measurements obtained with the SOPHIE spectrograph at the 1.93-m telescope of the Haute-Provence Observatory. Subsequent characterisation of these candidates, with the principal aim of identifying stellar companions in low-inclination orbits, was made by means of different spectroscopic diagnostics such as the measurement of the bisector velocity span and the study of the correlation mask effect. With this objective, we also employed astrometric data from the Hipparcos mission, and a novel method of simulating stellar cross-correlation functions. Results. Seven new objects with minimum masses between ∼10 M Jup and ∼90 M Jup are detected. Out of these, two are identified as low-mass stars in low-inclination orbits, and two others have masses below the theoretical deuterium-burning limit, and are therefore planetary candidates. The remaining three are brown dwarf candidates; the current upper limits for their the masses do not allow us to conclude on their nature. Additionally, we have improved the parameters of an already-known brown dwarf (HD 137510b), confirmed by astrometry.

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“…Latham et al (2002) found in their high proper motion sample, which contains both old and young populations, that there is no significant difference in the binary fraction of the two populations. Grether & Lineweaver (2007) argued stellar companions tend to be more abundant around low-metallicity hosts (see their Figure 15) when they examined the relation between frequency close companions and the metallicity of F, G, and K stars.…”

Section: Horizontal Comparisonmentioning

confidence: 99%

Cool Subdwarf Investigations. Ii. Multiplicity

Jao

Mason

Hartkopf

et al. 2009

The Astronomical Journal

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Cool subdwarfs of types K and M are the fainter counterparts of cool main-sequence dwarfs that dominate the Galactic population. In this paper, we present the results of an optical speckle survey of 62 confirmed cool subdwarf systems within 60 pc. We have resolved two new companions and confirmed two previously known companions with separations 0. 13-3. 29. After including previously known wide companions and all known spectroscopic binaries, we determine the multiplicity rate of cool subdwarfs to be 26% ± 6%, which is somewhat lower than comparable main-sequence stars that have a multiplicity rate of 37% ± 5%. We find that only 3% of the cool subdwarfs surveyed have companions within 10 AU, 3% have companions between 10 and 100 AU, and 14% have companions beyond 100 AU. The other 6% of cool subdwarfs are spectroscopic binaries. This is very different from K/M dwarfs that have most companions (13%) at separations closer than 10 AU. However, because a search for close binaries among a large sample of nearby cool subdwarfs remains elusive, it is not yet settled whether or not the multiplicity rates are significantly different. Nonetheless, several different observational results and theories pointing to a possible dearth of subdwarf multiples are discussed.

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The Metallicity of Stars with Close Companions

Cited by 35 publications

References 35 publications

Robo-AO Kepler Survey. V. The Effect of Physically Associated Stellar Companions on Planetary Systems

Robo-AO Kepler Survey. V. The Effect of Physically Associated Stellar Companions on Planetary Systems

The SOPHIE search for northern extrasolar planets

Cool Subdwarf Investigations. Ii. Multiplicity

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