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On the formation, evolution, and destruction of minor planetary bodies.
Thomas WilsonJonathan Rawling, Jay Farihi, Bruce Swinyard (UCL)
Ovidiu Vaduvescu (ING)
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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.
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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
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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.
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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?
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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
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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