Robo-AO Kepler Survey. IV. The Effect of Nearby Stars on 3857 Planetary Candidate Systems

Ziegler, Carl; Law, Nicholas M.; Baranec, Christoph; Riddle, Reed; Duev, Dmitry A.; Howard, Ward S.; Jensen-Clem, Rebecca; Kulkarni, S. R.; Morton, Tim; Salama, M.S.

doi:10.3847/1538-3881/aab042

Cited by 54 publications

(51 citation statements)

References 77 publications

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“…Slawson et al (2011) identify KOI-959 to be an eclipsing binary, which makes this planet candidate an astrophysical false positive. Additionally, Furlan et al (2017) and Ziegler et al (2018) find a nearby companion to KOI-959 at a separation of ∼0. ′′ 77 using adap- tive optics imaging.…”

Section: Mid-type M Dwarf Planetsmentioning

confidence: 97%

Kepler Planet Occurrence Rates for Mid-type M Dwarfs as a Function of Spectral Type

et al. 2019

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Previous studies of planet occurrence rates largely relied on photometric stellar characterizations. In this paper, we present planet occurrence rates for mid-type M dwarfs using spectroscopy, parallaxes, and photometry to determine stellar characteristics. Our spectroscopic observations have allowed us to constrain spectral type, temperatures, and in some cases metallicities for 337 out of 561 probable mid-type M dwarfs in the primary Kepler field. We use a random forest classifier to assign a spectral type to the remaining 224 stars. Combining our data with Gaia parallaxes, we compute precise (∼3%) stellar radii and masses, which we use to update planet parameters and planet occurrence rates for Kepler mid-type M dwarfs. Within the Kepler field, there are seven M3 V to M5 V stars which host 13 confirmed planets between 0.5 and 2.5 Earth radii and at orbital periods between 0.5 and 10 days. For this population, we compute a planet occurrence rate of 1.19 +0.70 −0.49 planets per star. For M3 V, M4 V, and M5 V, we compute planet occurrence rates of 0.86 +1.32 −0.68 , 1.36 +2.30 −1.02 , and 3.07 +5.49 −2.49 planets per star, respectively. 2. TARGET SELECTION, OBSERVATIONS, AND DATA REDUCTION Using revised KIC temperature estimates, DC13 identified 202 stars with T eff 3, 300 K. Muirhead et al. (2015) identified 509 probable mid-type M dwarfs from KIC photometry using the following color selection criteria: r − J > 3.2 to identify red objects, and J − K < 0.0555×(r−J)+0.7622 to remove giant stars. The union between these samples produces 561 probable mid-type M dwarfs which we targeted in this study. In total, we observed 337 of the 561 targets (60%), obtaining optical spectra of 327 stars and near-infrared spectra of 82 stars. We have both optical and infrared spectra for 72 targets. Magnitude distributions of our targets in rband and K s -band are shown in Figure 1, including the distributions of targets we observed.

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Section: Mid-type M Dwarf Planetsmentioning

confidence: 97%

Kepler Planet Occurrence Rates for Mid-type M Dwarfs as a Function of Spectral Type

et al. 2019

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“…We counted stars within 2598 full-frame images, not including the target star or any stars within 4″ of the target star, to determine the observed stellar density with Robo-AO as a function of Galactic coordinates. The typical depth of Robo-AO images, based on the image performance metrics described in Ziegler et al (2018), is 4-7 mag fainter than the KOI, equivalent to a » V 20 star. The simulations described in Section 3.2 suggest that the vast majority of stars outside 4″ are unbound to the target star.…”

Section: Galactic Latitude and Stellar Densitymentioning

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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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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“…The discovery of thousands of exoplanets presents a variety of exotic configurations of their orbits around the host star. Horch et al (2014); Deacon et al (2016); Matson et al (2018); Ziegler et al (2018) estimated that roughly 50% of these planets might be hosted by binary systems. Planet formation in a binary system is particularly worth investigating in order to explain high inclination, eccentric close-in planets that have been observed.…”

Section: Introductionmentioning

confidence: 99%

Multiplanet disc interactions in binary systems

Franchini

Martin

Lubow

2019

Monthly Notices of the Royal Astronomical Society

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We investigate the evolution of a multi-planet-disc system orbiting one component of a binary star system. The planet-disc system is initially coplanar but misaligned to the binary orbital plane. The planets are assumed to be giants that open gaps in the disc. We first study the role of the disc in shaping the mutual evolution of the two planets using a secular model for low initial tilt. In general we find that the planets and the disc do not remain coplanar, in agreement with Lubow & Martin (2016) for the single planet case. Instead, the planets and the disc undergo tilt oscillations. A high mass disc between the two planets causes the planets and the disc to nodally precess at the same average rate but they are generally misaligned. The amplitude of the tilt oscillations between the planets is larger while the disc is present. We then consider higher initial tilts using hydrodynamical simulations and explore the possibility of the formation of eccentric Kozai-Lidov (KL) planets. We find that the inner planet's orbit undergoes eccentricity growth for a large range of disc masses and initial misalignments. For a low disc mass and large initial misalignment both planets and the disc can undergo KL oscillations. Furthermore, we find that sufficiently massive discs can cause the inner planet to increase its inclination beyond 90 • and therefore to orbit the binary in a retrograde fashion. The results have important implications for the explanation of very eccentric planets and retrograde planets observed in multi-planet systems.

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Robo-AO Kepler Survey. IV. The Effect of Nearby Stars on 3857 Planetary Candidate Systems

Cited by 54 publications

References 77 publications

Kepler Planet Occurrence Rates for Mid-type M Dwarfs as a Function of Spectral Type

Kepler Planet Occurrence Rates for Mid-type M Dwarfs as a Function of Spectral Type

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

Multiplanet disc interactions in binary systems

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