Recorded Talks

During the pandemic I have participated in several conferences for which the talks have been recorded. You can watch them below.


Exozodiacal dust and its implications for LIFE
LIFE All-Hands Meeting, November 2021


Abstract:

Many main sequence stars show excess mid-infrared emission which is inferred to be due to warm dust in the habitable zone of the star. Known as exozodiacal dust in analogy to our zodiacal cloud, this dust provides a unique opportunity to study the inner regions of planetary systems. Exozodiacal dust is of particular interest as its presence in the habitable zone poses potential difficulties for future searches for Earth-like planets. In this talk I will briefly review mid-infrared observations and what they tell us about exozodis. The origin of exozodiacal dust is uncertain, as dust grains should have a very short lifetime so close to the star. I will summarise the models proposed for the origin of exozodis. Finally, I will discuss the impact we think exozodiacal dust will have on the LIFE mission.






Comet fragmentation as a source of zodiacal dust
Europlanet Science Congress 2021, September 2021


Abstract:

Models of the thermal emission of the zodiacal cloud and sporadic meteoroids suggest that the dominant source of interplanetary dust is Jupiter-family comets (JFCs). However, comet sublimation is insufficient to sustain the quantity of dust presently in the inner solar system. It has therefore been suggested that spontaneous disruptions of JFCs may supply the zodiacal cloud.
We present a model for the dust produced in comet fragmentations and its evolution, comparing with the present day zodiacal cloud. Using results from dynamical simulations we follow individual JFCs as they evolve and undergo recurrent splitting events. The dust produced by these events is followed with a kinetic model which takes into account the effects of collisional evolution, Poynting-Robertson drag, and radiation pressure. This allows us to model both the size distribution and radial profile of dust resulting from comet fragmentation. Our model suggests that JFC fragmentations can produce enough dust to sustain the zodiacal cloud. We also discuss the feasibility of comet fragmentation producing the spatial and size distribution of dust seen in the zodiacal cloud.
By modelling individual comets we are also able to explore the variability of cometary input to the zodiacal cloud. Comets are drawn from a size distribution based on the Kuiper belt and fragment randomly. We show that large comets should be scattered into the inner solar system stochastically, leading to large variations in the historical brightness of the zodiacal light.


Predictions for exozodiacal dust dragged in from an exo-Kuiper belt
UK Exoplanet Community Meeting 2021, April 2021


Abstract:

Many nearby stars show mid-infrared excesses which are indicative of the presence of warm habitable zone dust, known as exozodiacal dust, in analogy to the zodiacal cloud. The presence of even low levels of this dust will be problematic for future attempts at detection and characterisation of Earth-like planets. Therefore, the study of exozodiacal dust allows us to better target planet detection missions and learn more about the inner regions of planetary systems. Such dust should disappear rapidly due to its proximity to the star via collisions and radiation pressure, and several mechanisms have been suggested to explain the presence of exozodiacal dust. Given the observed correlation between the presence of warm exozodiacal dust and cold planetesimal belts, we present an analytical model for exozodiacal dust dragged inwards by Poynting-Robertson drag from an exo-Kuiper belt undergoing a collisional cascade. We show that Poynting-Robertson drag should produce detectable levels of exozodiacal dust in systems which have a previously detected outer planetesimal belt, such that non-detections could imply the presence of intervening planets. Our model is applied to the HOSTS survey of exozodiacal dust for systems with known planetesimal belts, and we find that some detections can be explained by our Poynting-Robertson drag model. In particular, our model is applied in more detail to beta Leo, which hosts both warm and cold dust. We also discuss the likelihood of drag producing exozodiacal dust levels which are problematic for direct imaging of exo-Earths.

Watch at exoplanet-talks.org


Predictions for exozodiacal dust dragged in from an exo-Kuiper belt
Five Years After HL Tau: a new era in planet formation, December 2020


Abstract:

Many nearby stars show mid-infrared excesses which are indicative of the presence of warm habitable zone dust, known as exozodiacal dust, in analogy to the zodiacal cloud. The presence of even low levels of this dust will be problematic for future attempts at detection and characterisation of Earth-like planets. Therefore, the study of exozodiacal dust allows us to better target planet detection missions and learn more about the inner regions of planetary systems. Such dust should disappear rapidly due to its proximity to the star via collisions and radiation pressure, and several mechanisms have been suggested to explain the presence of exozodiacal dust. Given the observed correlation between the presence of warm exozodiacal dust and cold planetesimal belts, we present an analytical model for exozodiacal dust dragged inwards by Poynting-Robertson drag from an exo-Kuiper belt undergoing a collisional cascade. We show that Poynting-Robertson drag should produce detectable levels of exozodiacal dust in systems which have a previously detected outer planetesimal belt, such that non-detections could imply the presence of intervening planets. Our model is applied to the HOSTS survey of exozodiacal dust for systems with known planetesimal belts, and we find that some detections can be explained by our Poynting-Robertson drag model. We also discuss the likelihood of drag producing exozodiacal dust levels which are problematic for direct imaging of exo-Earths.