The Grand Challenges of Exoplanets

Howell, Steve B.

doi:10.3389/fspas.2020.00010

Cited by 15 publications

(11 citation statements)

References 16 publications

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“…It has been shown that there is an observational bias against detecting Earth-sized, transiting planets due to "third light" contamination of the light curves, which is caused by stellar companions (Lester et al 2021). This third light contamination can lead to additional obstacles in planet characterization including underestimated planet radii (Ciardi et al 2015), skewed planet radius distributions and occurrence rates (Hirsch et al 2017;Bouma et al 2018;Teske et al 2018), incorrect characterization of both stars' properties (Furlan & Howell 2020), and improper mean density and atmospheric values (Howell 2020). Additionally, close-in stellar companions (typically <50-100 au) have dynamical influences on planetary formation processes and the planets in their systems, including the perturbation and truncation of protoplanetary disks (Jang-Condell 2015), the gravitational excitement of planetesimals causing collisional destruction (Rafikov & Silsbee 2015a, 2015b, and the scattering or ejection of planets that have formed (Haghighipour & Raymond 2007).…”

Section: Introductionmentioning

confidence: 99%

A Dearth of Close-in Stellar Companions to M-dwarf TESS Objects of Interest

Clark¹,

Belle²,

Ciardi³

et al. 2022

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TESS has proven to be a powerful resource for finding planets, including those that orbit the most prevalent stars in our galaxy: M dwarfs. Identification of stellar companions (both bound and unbound) has become a standard component of the transiting planet confirmation process in order to assess the level of light-curve dilution and the possibility of the target being a false positive. Studies of stellar companions have also enabled investigations into stellar multiplicity in planet-hosting systems, which has wide-ranging implications for both exoplanet detection and characterization, as well as for the formation and evolution of planetary systems. Speckle and AO imaging are some of the most efficient and effective tools for revealing close-in stellar companions; we therefore present observations of 58 M-dwarf TOIs obtained using a suite of speckle imagers at the 3.5 m WIYN telescope, the 4.3 m Lowell Discovery Telescope, and the 8.1 m Gemini North and South telescopes. These observations, as well as near-infrared adaptive optics images obtained for a subset (14) of these TOIs, revealed only two close-in stellar companions. Upon surveying the literature, and cross-matching our sample with Gaia, SUPERWIDE, and the catalog from El-Badry et al., we reveal an additional 15 widely separated common proper motion companions. We also evaluate the potential for undetected close-in companions. Taking into consideration the sensitivity of the observations, our findings suggest that the orbital period distribution of stellar companions to planet-hosting M dwarfs is shifted to longer periods compared to the expected distribution for field M dwarfs.

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Section: Introductionmentioning

confidence: 99%

A Dearth of Close-in Stellar Companions to M-dwarf TESS Objects of Interest

Clark¹,

Belle²,

Ciardi³

et al. 2022

Self Cite

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show abstract

“…"Third-light" contamination within the aperture reduces the transit depth, causing the analysis to yield an exoplanet of a smaller radius than it really is (Ciardi et al 2015). Other effects as well come into play, which can produce incorrect characterization of both the host star's properties (Furlan & Howell 2020) and, with the incorrect planet radius, a skewed planet radius distribution and occurrence rates (Bouma et al 2018;Teske et al 2018), as well as improper mean density and atmospheric values (Howell 2020).…”

Section: Introductionmentioning

confidence: 99%

Speckle Observations of TESS Exoplanet Host Stars: Understanding the Binary Exoplanet Host Star Orbital Period Distribution

Howell

Matson

Ciardi

et al. 2021

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We present high-resolution speckle interferometric imaging observations of TESS exoplanet host stars using the NN-EXPLORE Exoplanet and Stellar Speckle Imager instrument at the 3.5 m WIYN telescope. Eight TESS objects of interest that were originally discovered by Kepler were previously observed using the Differential Speckle Survey Instrument. Speckle observations of 186 TESS stars were carried out, and 45 (24%) likely bound companions were detected. This is approximately the number of companions we would expect to observe given the established 46% binarity rate in exoplanet host stars. For the detected binaries, the distribution of stellar mass ratio is consistent with that of the standard Raghavan distribution and may show a decrease in high-q systems as the binary separation increases. The distribution of binary orbital periods, however, is not consistent with the standard Ragahavan model, and our observations support the premise that exoplanet-hosting stars with binary companions have, in general, wider orbital separations than field binaries. We find that exoplanet-hosting binary star systems show a distribution peaking near 100 au, higher than the 40-50 au peak that is observed for field binaries. This fact led to earlier suggestions that planet formation is suppressed in close binaries.

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“…"Third light" contamination within the aperture reduces the transit depth, causing the analysis to yield an exoplanet of a smaller radius than it really is (Ciardi et al 2015). Other effects as well come into play which can produce incorrect characterization of both the host star's properties (Furlan & Howell 2020) and, with the incorrect planet radius, a skewed planet radius distribution and occurrence rates (Teske et al 2018;Bouma et al 2018) as well as improper mean density and atmospheric values (Howell 2020).…”

Section: Introductionmentioning

confidence: 99%

Speckle Observations of TESS Exoplanet Host Stars: Understanding the Binary Exoplanet Host Star Orbital Period Distribution

Howell,

Matson,

Ciardi

et al. 2021

Preprint

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We present high-resolution speckle interferometric imaging observations of TESS exoplanet host stars using the NN-EXPLORE NESSI instrument the at the 3.5-m WIYN telescope. Eight TOIs, that were originally discovered by Kepler, were previously observed using the Differential Speckle Survey Instrument (DSSI). Speckle observations of 186 TESS stars were carried out and 45 (24%) likely bound companions were detected. This is approximately the number of companions we would expect to observe given the established 46% binarity rate in exoplanet host stars. For the detected binaries, the distribution of stellar mass ratio is consistent with that of the standard Raghavan distribution and may show a decrease in high-q systems as the binary separation increases. The distribution of binary orbital periods, however, is not consistent with the standard Ragahavan model and our observations support the premise that exoplanet-hosting stars with binary companions have, in general, wider orbital separations than field binaries. We find that exoplanet-hosting binary star systems show a distribution peaking near 100 au, higher than the 40-50 au peak that is observed for field binaries. This fact led to earlier suggestions that planet formation is suppressed in close binaries.

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The Grand Challenges of Exoplanets

Cited by 15 publications

References 16 publications

A Dearth of Close-in Stellar Companions to M-dwarf TESS Objects of Interest

A Dearth of Close-in Stellar Companions to M-dwarf TESS Objects of Interest

Speckle Observations of TESS Exoplanet Host Stars: Understanding the Binary Exoplanet Host Star Orbital Period Distribution

Speckle Observations of TESS Exoplanet Host Stars: Understanding the Binary Exoplanet Host Star Orbital Period Distribution

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