ge/ay133
DESCRIPTION
What can comets tell us about the early S.S.?. Comet Hale-Bopp. Deep Impact (Comet Tempel 1). Ge/Ay133. Sharp drop off suggests a min ~1.7 x 10 4 AU, unlikely to be bound over S.S. history?. How are bodies placed into the Oort Cloud? Jupiter most important dynamically, - PowerPoint PPT PresentationTRANSCRIPT
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Ge/Ay133
What can comets tell us about the early S.S.?
Deep Impact (Comet Tempel 1)
Comet Hale-Bopp
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Sharp drop off suggests amin~1.7 x 104 AU, unlikely to be bound over S.S. history?
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How are bodies placed into the Oort Cloud? Jupiter most important dynamically, but Neptune is the most efficient.
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What forces are most important in perturbing the Oort Cloud?
versus ?
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What are comets made of? Dust/ice~1
Spitzer+Keck studies are mapping out both gas phase & grain mantle composition, comparable to that found in massive YSOs, comets.
How are these ice components determined?
HH46 W33A Hale-BoppWater 100 100 100CO 20 1 23CO2 30 3 6CH4 4 0.7 0.6H2CO … 2 1CH3OH 7 10 2HCOOH 2 0.5 0.1 NH3 9 4 0.7OCS … 0.05 0.4
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For species with dipole moments, use rotational spectra:
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Infrared spectroscopy gives access to pivotal non-polar species (CO2, CH4), and in many cases, water.
ISO spectra:
Water “spin” temp.~25 K
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Ground-based data can also provide constraints, on a much larger number of comets, but must fight through the Earth’s atmosphere!
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Isotope ratios? D/H most important to date…
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Latest wrinkle: D/H in JFCs appears to be terrestrial…
Hartogh et al. 2011, Nature
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Latest wrinkle: D/H in JFCs appears to be terrestrial…
Hartogh et al. 2011, Nature
Two additional JFC’s in hand withHerschel data, consistent with theHartley 2 D/H results.
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What about “exo-zodii’s? That is, dust in ~1 AU range?
Rare!
Only one convincing case so far, in large aperture searches. Need to get closer to the star….
Beichman et al., ApJ, 626, 1061
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Astronomically, we only have spectroscopy to probe the dust.
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Comet dust assembled from sub- micron sized components.
IDPs can be analyzed in the lab!
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Samples ofknownprovenance!
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Crystalline silicates do seem to be formed in the inner parts of disks. How to transport to comet-forming zone (>10 AU)?
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FEBs = Falling Evaporative Bodies
See transient redshited absoprtion against stellar continuum. Evaporating comets?For the brightest sources (e.g. Pic), you can actually image things like Na I line emission and map the disk.
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Sun-grazing comets as seen by SOHO (look for “metals”):
http://sohowww.estec.esa.nl/bestofsoho/Movies/movies2.html#comets