A Dynamical Model for Clustered Star Formation in the Galactic Disk

Kamdar, Harshil; Conroy, Charlie; Ting, Yuan-Sen; Bonaca, Ana; Johnson, Benjamin D.; Cargile, Phillip A.

doi:10.3847/1538-4357/ab44be

Cited by 31 publications

(29 citation statements)

References 162 publications

(205 reference statements)

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“…The dependence of planetary system architecture on the local phase space density that we identify in this work suggests that at least some degree of kinematic substructure has a co-natal origin (although it does not preclude the role of galactic perturbations). In support of the hypothesis that stars may retain memory of their formation environment in 6D phase space, simulations that follow star formation and the subsequent orbital evolution of the stars within the host galaxy indicate that formation neighbours persist after the dispersal of the bound cluster 47 . In these simulations, most of the resulting comoving neighbours are younger than 1 Gyr, but beyond that time, a roughly constant number of pairs of such neighbours persist for several Gyr.…”

Section: Methodsmentioning

confidence: 77%

Stellar clustering shapes the architecture of planetary systems

Winter

Kruijssen

Longmore

et al. 2020

Nature

109

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Planet formation is generally described in terms of a system containing the host star and a protoplanetary disk 1 – 3 , of which the internal properties (for example, mass and metallicity) determine the properties of the resulting planetary system 4 . However, (proto)planetary systems are predicted 5 , 6 and observed 7 , 8 to be affected by the spatially clustered stellar formation environment, through either dynamical star–star interactions or external photoevaporation by nearby massive stars 9 . It is challenging to quantify how the architecture of planetary sysems is affected by these environmental processes, because stellar groups spatially disperse within less than a billion years 10 , well below the ages of most known exoplanets. Here we identify old, co-moving stellar groups around exoplanet host stars in the astrometric data from the Gaia satellite 11 , 12 and demonstrate that the architecture of planetary systems exhibits a strong dependence on local stellar clustering in position-velocity phase space. After controlling for host stellar age, mass, metallicity and distance from the star, we obtain highly significant differences (with p values of 10 −5 to 10 −2 ) in planetary system properties between phase space overdensities (composed of a greater number of co-moving stars than unstructured space) and the field. The median semi-major axis and orbital period of planets in phase space overdensities are 0.087 astronomical units and 9.6 days, respectively, compared to 0.81 astronomical units and 154 days, respectively, for planets around field stars. ‘Hot Jupiters’ (massive, short-period exoplanets) predominantly exist in stellar phase space overdensities, strongly suggesting that their extreme orbits originate from environmental perturbations rather than internal migration 13 , 14 or planet–planet scattering 15 , 16 . Our findings reveal that stellar clustering is a key factor setting the architectures of planetary systems.

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Section: Methodsmentioning

confidence: 77%

Stellar clustering shapes the architecture of planetary systems

Winter

Kruijssen

Longmore

et al. 2020

Nature

109

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“…If that is true, we can set the iron abundance to be equal for all stars in the system. This notion is supported by the simulations (Kamdar et al 2019a) and studies (Kamdar et al 2019b) of field stars showing that close stars are very likely to be co-natal if their velocity separation is small.…”

Section: Fitting Proceduresmentioning

confidence: 64%

The GALAH survey: unresolved triple Sun-like stars discovered by the Gaia mission

Čotar

Zwitter

Traven

et al. 2019

Monthly Notices of the Royal Astronomical Society

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The latest Gaia data release enables us to accurately identify stars that are more luminous than would be expected on the basis of their spectral type and distance. During an investigation of the 329 best solar twin candidates uncovered among the spectra acquired by the GALAH survey, we identified 64 such overluminous stars. In order to investigate their exact composition, we developed a data-driven methodology that can generate a synthetic photometric signature and spectrum of a single star. By combining multiple such synthetic stars into an unresolved binary or triple system and comparing the results to the actual photometric and spectroscopic observations, we uncovered 6 definitive triple stellar system candidates and an additional 14 potential candidates whose combined spectrum mimics the solar spectrum. Considering the volume correction factor for a magnitude-limited survey, the fraction of probable unresolved triple stars with long orbital periods is ∼2 per cent. Possible orbital configurations of the candidates were investigated using the selection and observational limits. To validate the discovered multiplicity fraction, the same procedure was used to evaluate the multiplicity fraction of other stellar types.

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“…Simulations [121] have demonstrated that co-moving stars, even those that are widely separated (∼10 pc), are mostly co-natal. This picture is further borne out by observations [9,215], supporting the idea co-moving stars are "clusters of two."…”

Section: Co-moving Starsmentioning

confidence: 99%

All-sky visible and near infrared space astrometry

et al. 2021

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The era of all-sky space astrometry began with the Hipparcos mission in 1989 and provided the first very accurate catalogue of apparent magnitudes, positions, parallaxes and proper motions of 120 000 bright stars at the milliarcsec (or milliarcsec per year) accuracy level. Hipparcos has now been superseded by the results of the Gaia mission. The second Gaia data release contained astrometric data for almost 1.7 billion sources with tens of microarcsec (or microarcsec per year) accuracy in a vast volume of the Milky Way and future data releases will further improve on this. Gaia has just completed its nominal 5-year mission (July 2019), but is expected to continue in operations for an extended period of an additional 5 years through to mid 2024. Its final catalogue to be released $\sim $ ∼ 2027, will provide astrometry for $\sim $ ∼ 2 billion sources, with astrometric precisions reaching 10 microarcsec. Why is accurate astrometry so important? The answer is that it provides fundamental data which underpin much of modern observational astronomy as will be detailed in this White Paper. All-sky visible and Near-InfraRed (NIR) astrometry with a wavelength cutoff in the K-band is not just focused on a single or small number of key science cases. Instead, it is extremely broad, answering key science questions in nearly every branch of astronomy while also providing a dense and accurate visible-NIR reference frame needed for future astronomy facilities.

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A Dynamical Model for Clustered Star Formation in the Galactic Disk

Cited by 31 publications

References 162 publications

Stellar clustering shapes the architecture of planetary systems

Stellar clustering shapes the architecture of planetary systems

The GALAH survey: unresolved triple Sun-like stars discovered by the Gaia mission

All-sky visible and near infrared space astrometry

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