11 research outputs found
Formation of giant planets around intermediate-mass stars
To understand giant planet formation, we need to focus on host stars close to
, where the occurrence rate of these planets is the
highest. In this initial study, we carry out pebble-driven core accretion
planet formation modelling to investigate the trends and optimal conditions for
the formation of giant planets around host stars in the range of . We find that giant planets are more likely to form in systems with
a larger initial disk radius; higher disk gas accretion rate; pebbles of
millimeter in size; and birth location of the embryo at a moderate radial
distance of AU. We also conduct a population synthesis study of our
model and find that the frequency of giant planets and super-Earths decreases
with increasing stellar mass. This contrasts the observational peak at $1.7\
\rm M_{\odot}\sim 0.7{-}0.8\%1\ \rm
M_{\odot}$ - similar to RV observations around Sun-like stars, but drastically
decreases for higher mass stars.Comment: 21 pages, 11 figure
Determining the mid-plane conditions of circumstellar discs using gas and dust modelling: a study of HD 163296
The mass of gas in protoplanetary discs is a quantity of great interest for
assessing their planet formation potential. Disc gas masses are, however,
traditionally inferred from measured dust masses by applying an assumed
standard gas-to-dust ratio of . Furthermore, measuring gas masses
based on CO observations has been hindered by the effects of CO freeze-out.
Here we present a novel approach to study the mid-plane gas by combining
CO line modelling, CO snowline observations and the spectral energy
distribution (SED) and selectively study the inner tens of au where freeze-out
is not relevant. We apply the modelling technique to the disc around the Herbig
Ae star HD 163296 with particular focus on the regions within the CO snowline
radius, measured to be at 90 au in this disc. Our models yield the mass of
CO in this inner disc region of
M. We
find that most of our models yield a notably low , especially in the
disc mid-plane (). Our only models with a more interstellar medium
(ISM)-like require CO to be underabundant with respect to the ISM
abundances and a significant depletion of sub-micron grains, which is not
supported by scattered light observations. Our technique can be applied to a
range of discs and opens up a possibility of measuring gas and dust masses in
discs within the CO snowline location without making assumptions about the
gas-to-dust ratio.This work has been supported by the DISCSIM project, grant agreement 341137 funded by the European Research Council under ERC-2013-ADG. DMB is funded by this ERC grant and an STFC studentship. OP is supported by the Royal Society Dorothy Hodgkin Fellowship. During a part of this project OP was supported by the European Union through ERC grant number 279973. TJH is funded by the STFC consolidated grant ST/K000985/1.This is the final version of the article. It first appeared from Oxford University Press via http://dx.doi.org/10.1093/mnras/stw132
Planet Formation Imager (PFI): Science vision and key requirements
The Planet Formation Imager (PFI) project aims to provide a strong scientific vision for ground-based optical astronomy beyond the upcoming generation of Extremely Large Telescopes. We make the case that a breakthrough in angular resolution imaging capabilities is required in order to unravel the processes involved in planet formation. PFI will be optimised to provide a complete census of the protoplanet population at all stellocentric radii and over the age range from 0.1 to âŒ100 Myr. Within this age period, planetary systems undergo dramatic changes and the final architecture of planetary systems is determined. Our goal is to study the planetary birth on the natural spatial scale where the material is assembled, which is the Hill Sphere of the forming planet, and to characterise the protoplanetary cores by measuring their masses and physical properties. Our science working group has investigated the observational characteristics of these young protoplanets as well as the migration mechanisms that might alter the system architecture. We simulated the imprints that the planets leave in the disk and study how PFI could revolutionise areas ranging from exoplanet to extragalactic science. In this contribution we outline the key science drivers of PFI and discuss the requirements that will guide the technology choices, the site selection, and potential science/technology tradeoffs
Enabling planetary science across light-years. Ariel Definition Study Report
Ariel, the Atmospheric Remote-sensing Infrared Exoplanet Large-survey, was adopted as the fourth medium-class mission in ESA's Cosmic Vision programme to be launched in 2029. During its 4-year mission, Ariel will study what exoplanets are made of, how they formed and how they evolve, by surveying a diverse sample of about 1000 extrasolar planets, simultaneously in visible and infrared wavelengths. It is the first mission dedicated to measuring the chemical composition and thermal structures of hundreds of transiting exoplanets, enabling planetary science far beyond the boundaries of the Solar System. The payload consists of an off-axis Cassegrain telescope (primary mirror 1100 mm x 730 mm ellipse) and two separate instruments (FGS and AIRS) covering simultaneously 0.5-7.8 micron spectral range. The satellite is best placed into an L2 orbit to maximise the thermal stability and the field of regard. The payload module is passively cooled via a series of V-Groove radiators; the detectors for the AIRS are the only items that require active cooling via an active Ne JT cooler. The Ariel payload is developed by a consortium of more than 50 institutes from 16 ESA countries, which include the UK, France, Italy, Belgium, Poland, Spain, Austria, Denmark, Ireland, Portugal, Czech Republic, Hungary, the Netherlands, Sweden, Norway, Estonia, and a NASA contribution
Planet Formation Imager (PFI): science vision and key requirements
The Planet Formation Imager (PFI) project aims to provide a strong scientific vision for ground-based optical astronomy beyond the upcoming generation of Extremely Large Telescopes. We make the case that a breakthrough in angular resolution imaging capabilities is required in order to unravel the processes involved in planet formation. PFI will be optimised to provide a complete census of the protoplanet population at all stellocentric radii and over the age range from 0.1 to ~100 Myr. Within this age period, planetary systems undergo dramatic changes and the final architecture of planetary systems is determined. Our goal is to study the planetary birth on the natural spatial scale where the material is assembled, which is the "Hill Sphere" of the forming planet, and to characterise the protoplanetary cores by measuring their masses and physical properties. Our science working group has investigated the observational characteristics of these young protoplanets as well as the migration mechanisms that might alter the system architecture. We simulated the imprints that the planets leave in the disk and study how PFI could revolutionise areas ranging from exoplanet to extragalactic science. In this contribution we outline the key science drivers of PFI and discuss the requirements that will guide the technology choices, the site selection, and potential science/technology tradeoffs.S.K. acknowledges support from an STFC Rutherford Fellowship (ST/J004030/1) and Philip Leverhulme Prize (PLP-2013-110). Part of this work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration
Size-selective accretion of dust on to CPDs: low CPD masses and filtration of larger grains
The major satellites of Jupiter and Saturn are believed to have formed in circumplanetary discs (CPDs), which orbit forming giant protoplanets. Gas and dust in CPDs have different distributions and affect each other by drag, which varies with grain size. Yet simulations of multiple dust grain sizes with separate dynamics have not been done before. We seek to assess how much dust of each grain size there is in CPDs. We run multifluid 3D hydrodynamical simulations including gas and four discrete grain sizes of dust from 1 mu m to 1 mm, representing a continuous distribution. We consider a 1M(Jup) protoplanet embedded in a protoplanetary disc around a 1 M-circle dot star. Our results show a truncated MRN (Mathis-Rumpl-Nordsieck) distribution at smaller grain sizes, which starts to tail off by a = 100 mu m and is near zero at 1 mm. Large dust grains, which hold most of the dust mass, have very inefficient accretion to the CPD, due to dust filtration. Therefore, CPDs' dust masses must be small, with mass ratio similar to a few x 10(-6) to the protoplanet. These masses and the corresponding millimetre opacities are in line with CPD fluxes observed to date
Planet Formation Imager (PFI): science vision and key requirements
International audienceThe Planet Formation Imager (PFI) project aims to provide a strong scientific vision for ground-based optical astronomy beyond the upcoming generation of Extremely Large Telescopes. We make the case that a breakthrough in angular resolution imaging capabilities is required in order to unravel the processes involved in planet formation. PFI will be optimised to provide a complete census of the protoplanet population at all stellocentric radii and over the age range from 0.1 to about 100 Myr. Within this age period, planetary systems undergo dramatic changes and the final architecture of planetary systems is determined. Our goal is to study the planetary birth on the natural spatial scale where the material is assembled, which is the "Hill Sphere" of the forming planet, and to characterise the protoplanetary cores by measuring their masses and physical properties. Our science working group has investigated the observational characteristics of these young protoplanets as well as the migration mechanisms that might alter the system architecture. We simulated the imprints that the planets leave in the disk and study how PFI could revolutionise areas ranging from exoplanet to extragalactic science. In this contribution we outline the key science drivers of PFI and discuss the requirements that will guide the technology choices, the site selection, and potential science/technology tradeoffs
Planet Formation Imager: project update
International audienceThe Planet Formation Imager (PFI) is a near- and mid-infrared interferometer project with the driving sciencegoal of imaging directly the key stages of planet formation, including the young proto-planets themselves. Here,we will present an update on the work of the Science Working Group (SWG), including new simulations of duststructures during the assembly phase of planet formation and quantitative detection efficiencies for accretingand non-accreting young exoplanets as a function of mass and age. We use these results to motivate tworeference PFI designs consisting of a) twelve 3 m telescopes with a maximum baseline of 1.2 km focused onyoung exoplanet imaging and b) twelve 8 m telescopes optimized for a wider range of young exoplanets andprotoplanetary disk imaging out to the 150 K H2O ice line. Armed with 4Ă8 m telescopes, the ESO/VLTI canalready detect young exoplanets in principle and projects such as MATISSE, Hi-5 and Heimdallr are important PFI pathfinders to make this possible. We also discuss the state of technology development needed to makePFI more affordable, including progress towards new designs for inexpensive, small field-of-view, large aperturetelescopes and prospects for Cubesat-based space interferometr
Planet Formation Imager (PFI): science vision and key requirements
International audienceThe Planet Formation Imager (PFI) project aims to provide a strong scientific vision for ground-based optical astronomy beyond the upcoming generation of Extremely Large Telescopes. We make the case that a breakthrough in angular resolution imaging capabilities is required in order to unravel the processes involved in planet formation. PFI will be optimised to provide a complete census of the protoplanet population at all stellocentric radii and over the age range from 0.1 to about 100 Myr. Within this age period, planetary systems undergo dramatic changes and the final architecture of planetary systems is determined. Our goal is to study the planetary birth on the natural spatial scale where the material is assembled, which is the "Hill Sphere" of the forming planet, and to characterise the protoplanetary cores by measuring their masses and physical properties. Our science working group has investigated the observational characteristics of these young protoplanets as well as the migration mechanisms that might alter the system architecture. We simulated the imprints that the planets leave in the disk and study how PFI could revolutionise areas ranging from exoplanet to extragalactic science. In this contribution we outline the key science drivers of PFI and discuss the requirements that will guide the technology choices, the site selection, and potential science/technology tradeoffs
Ariel: Enabling planetary science across light-years
Ariel Definition Study ReportAriel Definition Study Report, 147 pages. Reviewed by ESA Science Advisory Structure in November 2020. Original document available at: https://www.cosmos.esa.int/documents/1783156/3267291/Ariel_RedBook_Nov2020.pdf/Ariel, the Atmospheric Remote-sensing Infrared Exoplanet Large-survey, was adopted as the fourth medium-class mission in ESA's Cosmic Vision programme to be launched in 2029. During its 4-year mission, Ariel will study what exoplanets are made of, how they formed and how they evolve, by surveying a diverse sample of about 1000 extrasolar planets, simultaneously in visible and infrared wavelengths. It is the first mission dedicated to measuring the chemical composition and thermal structures of hundreds of transiting exoplanets, enabling planetary science far beyond the boundaries of the Solar System. The payload consists of an off-axis Cassegrain telescope (primary mirror 1100 mm x 730 mm ellipse) and two separate instruments (FGS and AIRS) covering simultaneously 0.5-7.8 micron spectral range. The satellite is best placed into an L2 orbit to maximise the thermal stability and the field of regard. The payload module is passively cooled via a series of V-Groove radiators; the detectors for the AIRS are the only items that require active cooling via an active Ne JT cooler. The Ariel payload is developed by a consortium of more than 50 institutes from 16 ESA countries, which include the UK, France, Italy, Belgium, Poland, Spain, Austria, Denmark, Ireland, Portugal, Czech Republic, Hungary, the Netherlands, Sweden, Norway, Estonia, and a NASA contribution