planetary bodies. destruction of minor evolution, and On ...

On the formation, evolution, and destruction of minor planetary bodies.

Thomas WilsonJonathan Rawling, Jay Farihi, Bruce Swinyard (UCL)

Ovidiu Vaduvescu (ING)

Outline

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Formation● Modelling the Origin of O2 in Comet 67P

Evolution● Herschel Observations of Non-Typical

Cometary Water Ortho-to-Para Ratios

Destruction● White Dwarf Planetary Debris Disks

Frequencies● Planetesimal Debris Disk Variation

Other projects I have worked on:Near-Earth Asteroids, Carbon-dominant white dwarfs, dwarf-Carbon stars.

Herschel Observations of

Non-Typical Cometary Water Ortho-to-Para

Ratios3

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Why study comets???

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Water, water everywhere

Bockelée-Morvan et al. 2004

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Using isotopic ratios as a proxy for formation location

Altwegg et al. 2015

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Observing water in the sub-millimetre

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Ortho-to-Para Ratio (OPR) as a function of temperature

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Ortho-to-Para Ratio should always be 3...

Hama et al. 2016

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H2O and NH3 Ortho-to-Para ratios

Shinnaka et al. 2016

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Herschel/SPIRE Observations

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Observations show multiple rotational lines

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Observations show an OPR less than 3...

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Observations show an OPR less than 3...

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… and OPR seems to vary with nucleocentric distance

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Conclusions

White Dwarf Planetary Debris

Disks Frequencies

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Exoplanet Zoo

Kaltenegger 2017

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Planetesimal debris disks around white dwarfs!

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Disrupted planets form disks which accretes onto the star

Jura & Young 2014

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(Exo)planetary compositions

Xu 2014

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GD 362

Xu 2014

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WD 1425+540

Xu et al. 2017

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Water, water everywhere? in GD 61

Farihi et al. 2013

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How do we find debris disks? - Atmospheric metals

van Maanen, 1917 Farihi 2016

Ca II H & K

v Ma 2

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How do we find debris disks? - Infrared excess

Zuckerman & Becklin 1987

G29-38

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Our unbiased samples

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The complete sample

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What do we know so far?

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Why do we see this? - Modeling

Mustill et al. 2014

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A white dwarf with an infrared excess...

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… and atmospheric metalsWD 1018+410

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Some white dwarfs show metals, but no infrared excess

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Infrared excess frequencies are a few percent...

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… but, the nominal atmospheric metals frequency is 47%!

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Conclusions● The only unbiased Spitzer and Hubble single hydrogen dominated white dwarf

sample over a large temperature/age range.

● 3 out of 206 stars have an infrared excess, yielding a frequency of 1.5%, whereas 61 out of 130 stars have atmospheric metals, roughly 47%.

● A significant percentage of debris disks still remain unobserved via infrared excesses.

The end

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Formation● Modelling the Origin of O2 in Comet 67P

Evolution● Herschel Observations of Non-Typical

Cometary Water Ortho-to-Para Ratios

Destruction● White Dwarf Planetary Debris Disks

Frequencies● Planetesimal Debris Disk Variation

Other projects I have worked on:Near-Earth Asteroids, Carbon-dominant white dwarfs, dwarf-Carbon stars.

Thanks for listening.

Any questions?

Extra slides

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Modelling the Origin of O2 in

Comet 67P

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Detection of O2 in Comet 67P

Bieler et al. 2015

Planetesimal Debris Disk

Variation

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WD 0959-0200 - The first variable disk

Xu & Jura 2014

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GD 56 - A highly variable disk

Farihi et al. 2018

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GD 56 - A highly variable disk

Farihi et al. 2018

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SDSS 1228

Xu et al. 2018