Linking Exoplanets and Gaps in Planet-Forming Disks
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Are the gaps observed in protoplanetary disks connected to Exoplanets?
A population study of protoplanetary disks imaged with ALMA reveals that gaps and rings are more common around higher mass stars. A comparison with exoplanet demographics indicates that Neptune and Jupiter mass exoplanets could be responsible for creating the observed disk structures. Paper: van der Marel & Mulders 2021 links: Press Release (en Español) explanatory video |
The Genesis Database of Planet Formation Models
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How do planetary systems around other stars form?
In the frame of the Earths in Other Solar Systems project our team has developed an extensive library of planet formation models, including the planetary systems that emerged from these simulations. This comprehensive library of simulated planetary systems – the Genesis Database – provides an opportunity for researchers worldwide to explore connections between the initial and boundary conditions of forming planetary systems and the final planetary system architectures. Papers: Mulders et al. 2020 Links: Genesis Database, File Archive, Example Notebooks |
The Occurrence and Architecture of Keplers Planetary Systems
What is the distribution of planetary systems around other stars?
Kepler has discover hundreds of multi-planet systems, though many planets remain undiscovered because they do not transit their stars. We use a forward model to account for these undetected planets and reconstruct the intrinsic population of planetary systems. We find that at least 42% of Sun-like stars have planetary systems. These systems have a range of properties that encompasses the Solar System terrestrial planets, except that they typically have planets closer to the star.
Papers: Mulders et al. 2018, Mulders et al. 2019
Code: epos
Kepler has discover hundreds of multi-planet systems, though many planets remain undiscovered because they do not transit their stars. We use a forward model to account for these undetected planets and reconstruct the intrinsic population of planetary systems. We find that at least 42% of Sun-like stars have planetary systems. These systems have a range of properties that encompasses the Solar System terrestrial planets, except that they typically have planets closer to the star.
Papers: Mulders et al. 2018, Mulders et al. 2019
Code: epos
A Break in the Distribution of Giant Exoplanets
What does the distribution of giant planets tell us about how planets form?
Giant planets are thought to form far away from their star outside of the snow line and migrate inwards to their current locations. Rachel Fernandes calculated how frequently giant planets occur at different distances from their star and discovered a break in the distribution near the snow line. The break explains why few planets are detected in direct imaging surveys, and matches the prediction of giant planet formation and migration models.
Papers: Fernandes et al. 2019
Tables with Exoplanet Catalog and Survey Completeness are part of EPOS
Giant planets are thought to form far away from their star outside of the snow line and migrate inwards to their current locations. Rachel Fernandes calculated how frequently giant planets occur at different distances from their star and discovered a break in the distribution near the snow line. The break explains why few planets are detected in direct imaging surveys, and matches the prediction of giant planet formation and migration models.
Papers: Fernandes et al. 2019
Tables with Exoplanet Catalog and Survey Completeness are part of EPOS
Exoplanets as Function of Stellar Properties
How do exoplanet properties vary as a function of stellar properties?
The relations between exoplanets and stellar properties can help us understand how planets form, and where to find them. In this chapter for the forthcoming Handbook of Exoplanets, I review what we know about how frequently planets are found around stars of different masses and compositions, focussing on the difference between giant planets (pink circles) and sub-Neptunes (cyan circles).
Paper: Mulders 2018
Image Credit: Handbook of Exoplanets
The relations between exoplanets and stellar properties can help us understand how planets form, and where to find them. In this chapter for the forthcoming Handbook of Exoplanets, I review what we know about how frequently planets are found around stars of different masses and compositions, focussing on the difference between giant planets (pink circles) and sub-Neptunes (cyan circles).
Paper: Mulders 2018
Image Credit: Handbook of Exoplanets
The Relation Between Accretion and Disk Mass
How is angular momentum transported in protoplanetary disks?
The relation between disk mass and accretion provides a strong constraint on the structure and evolution of protoplanetary disks. We have measured dust masses with ALMA and mass accretion rates with the VLT/X-Shooter of 145 stars in the Chamaeleon I and Lupus star forming regions. We find that the standard picture of disk evolution is not yet complete, perhaps indicating the role of disk winds in driving angular momentum transport in protoplanetary disks.
Paper: Mulders et al., in press, Pascucci et al. 2016, Manara et al. 2017
Table with dust mass and mass accretion rates
Image Credit: NASA/JPL-Caltech
The relation between disk mass and accretion provides a strong constraint on the structure and evolution of protoplanetary disks. We have measured dust masses with ALMA and mass accretion rates with the VLT/X-Shooter of 145 stars in the Chamaeleon I and Lupus star forming regions. We find that the standard picture of disk evolution is not yet complete, perhaps indicating the role of disk winds in driving angular momentum transport in protoplanetary disks.
Paper: Mulders et al., in press, Pascucci et al. 2016, Manara et al. 2017
Table with dust mass and mass accretion rates
Image Credit: NASA/JPL-Caltech
Hot Rocky Planets Around Heavy Metal Stars
How common are rocky planets around stars that are enriched in heavy elements?
The metallicity of a star provides a measure how much solid material was present in the protoplanetary disk during planet formation. Planet formation models predict that planets form more efficiently if more solids are available, and giant planets are indeed found more often around metal-rich stars.
In this project we explore how the presence rocky planets depends on the stellar metallicity, using spectra from the LAMOST telescope. We find that hot rocky planets are three times more common around metal-rich stars, but find no trend for colder planets.
Paper: Mulders et al. 2016
Image Credit: NASA/CXC/M.Weiss
The metallicity of a star provides a measure how much solid material was present in the protoplanetary disk during planet formation. Planet formation models predict that planets form more efficiently if more solids are available, and giant planets are indeed found more often around metal-rich stars.
In this project we explore how the presence rocky planets depends on the stellar metallicity, using spectra from the LAMOST telescope. We find that hot rocky planets are three times more common around metal-rich stars, but find no trend for colder planets.
Paper: Mulders et al. 2016
Image Credit: NASA/CXC/M.Weiss
Stellar Mass dependencies in the Exoplanet population
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Do the architectures of planetary systems vary with the mass of their host star?
In this project we investigate how the planet populations unearthed by the Kepler spacecraft vary with stellar mass. I've written a Python code that calculates the occurrence of planets for different subsets of stars. We find that planet occurrence is anti-correlated with stellar mass, and that the population of planets extends closer in around lower mass stars. Papers: Mulders et al. 2015a, Mulders et al. 2015b Posters: XXIX IAU General Assembly Press Release AASNova highlight Table with occurrence rates per spectral type Image credit: NASA/JPL-Caltech |
Water Delivery To Planets around low-mass stars
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Water delivery to terrestrial planets in the habitable zones around low-mass stars is less efficient than around low-mass stars. But exactly how much less efficient? In this series of papers with Fred Ciesla, we explore which factors influence water delivery to the habitable zones of low-mass stars using Nbody simulations. We explore the effects of water-loss in asteroids, the inclusion of planetesimals in the simulations, and the location of the snow line. We find that the majority of water-rich planets may still be found around M stars, despite less efficient water delivery.
Papers: Ciesla et al. 2015, Mulders et al. 2015 ScienceNews article AstroBites watch my talk at the EBI 2014 conference planet formation movies Image credit: www.mysciencework.com |
Signatures of planet formation in the LkCa 15 protoplanetary disk
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The LkCa 15 protoplanetary disk exhibits an annular disk gap that is thought to be carved out by a forming giant planet. We have imaged both the inner and outer disk for the first time in scattered light. These observations constrain the disk geometry and help us understand how forming giant planets affect the evolution and observational appearance of these disks.
Papers: Thalmann et al. 2010, Thalmann et al. 2014, Thalmann et al. 2015, Thalmann et al. 2016 Image credit: Karen L. Teramura, UH IfA |
Dust Radiative Transfer Models of Protoplanetary disks
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I obtained my PhD at the astronomical institute at the University of Amsterdam in the Netherlands, working with Carsten Dominik and Michiel Min on dust radiative transfer modeling of protoplanetary disks with MCMax.
PhD thesis Papers: Mulders et al. 2010, Mulders et al. 2011, Mulders & Dominik 2012, Mulders et al. 2013a, Mulders et al. 2013b Image credit: NASA |
