Ge/Ay133

What can comets tell us about the early S.S.?

Deep Impact (Comet Tempel 1)

Comet Hale-Bopp

Sharp drop off suggests amin~1.7 x 104 AU, unlikely to be bound over S.S. history?

How are bodies placed into the Oort Cloud? Jupiter most important dynamically, but Neptune is the most efficient.

What forces are most important in perturbing the Oort Cloud?

versus ?

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

For species with dipole moments, use rotational spectra:

Infrared spectroscopy gives access to pivotal non-polar species (CO2, CH4), and in many cases, water.

ISO spectra:

Water “spin” temp.~25 K

Ground-based data can also provide constraints, on a much larger number of comets, but must fight through the Earth’s atmosphere!

Isotope ratios? D/H most important to date…

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

Astronomically, we only have spectroscopy to probe the dust.

Comet dust assembled from sub- micron sized components.

IDPs can be analyzed in the lab!

Samples ofknownprovenance!

Crystalline silicates do seem to be formed in the inner parts of disks. How to transport to comet-forming zone?

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.

Sun-grazing comets as seen by SOHO (look for “metals”):

http://sohowww.estec.esa.nl/bestofsoho/Movies/movies2.html#comets