What is "fractional abundance" (X) explicitly when talking about molecules?

It's X/H₂.

see Jørgensen et al. (2002).

Summary of meeting with Ted on 4/20

Today I had Ted read my "Section 3" of my paper draft. Some thoughts and action items that fell out of that:

• The paper will really have to deal with the ammonia issue head-on. Probably with a dedicated section.
• We'll have to relate *why* hot cores tell you anything about ices.
• References: the early HDO detection by Jacq, T
  & Nathan's HDO/H2O paper in Orion. (tsr – actually it appears that this is Justin's paper. )
  D/H in Orion is enhanced, inconsistent with the observed temperature, indicating that it was created in an "earlier phase". That's also a big reason why we think the rich organics are found.
• There *may* be a gas-phase reshuffle of the evaporated ices, but we expect this won't ruin the overall nitrogen accounting.
• We tried to see if the DCN/HCN ratio told us anything. It's inconclusive. We couldn't find strong DCN vibrational lines in the hexos spectra. (Lines @ 507ish GHz.)
• Revision of the central point of this work: Ammonia and HCN are the carriers to follow. HCN is the organic carrier. Ammonia needs to be chemically processed before it could be the key progenitor of N in rocks.
• Actually – amendment to the above point – Scott Messenger mentions "Organic globules" from the planetary science / meteoritics literature that contain possibly ammonia-formaldehyde polymers, so maybe ammonia can be a direct progenitor after all.
• So to bring it back – Tom, can we use the following statement as an argument for HCN over NH3?
• "Nh3 doesn't have the right 15N enrichment to be a progenitor of Earth's nitrogen"
• Tom: check the Hily-Blant paper for anything pointing to this.
• NH3 *is* present in the ices, but it's not clear whether it's with the water or the organic material... separate or together. (Tom doesn't fully get this last point.)

First approaches towards getting silicates out of TSC model parameters

So. I'm interested in getting silicon measurements out of my SED models.

I wrote down two approaches in my notebook, for transcription here. For some context: The SED-generating models I'm looking into are consisting of some parameters like this:

• Version "zero" is to not even assume a gas-to-dust ratio. Version 0 is "take the total mass of the disk/envelope model inside of a relevant radius, assume that *all* the mass is apportioned among elements along cosmic abundance ratios, and take the Si directly from that."
• Version 1:
• Assume a gas/dust ratio* (by mass?) within the envelope/disk model.
• For the dust component of that mass, assume a composition distribution following some vaguely credible reference (e.g. Poteet 2015), and figure out what fraction of the dust mass is in silicon atoms.

followup from a Sweetland Writing Center workshop

Today I met with a writing coach at Sweetland. Some major takeaways for my RIRA statement:

start it like this...

an exectuvie summary [
 consisting of:
Who I am
What I study
What this trip is, with whom, and what I'll get from it.
], then...
----------
Start BIG - how solar system, planets, Earth-like planets form.

& how do they get elements necessary for life? (given certain expectations)

Thesis of others -- dry planets get asteroided.

My dissertation -- what is in those asteroids and how do they form?

What I have -- measurements, data, numbers.

What I need -- expertise from these guys & starplan.

----

also... I should cut everything but the last paragraph from my "scientific context" section - too detailed for the audience in question.

More items, too, but I'll start with this...

Some successful "correction factor" plots

Again, everything is being compared to Goldsmith/Bergin/Lis '97

so this is good!

 

figs 10 and 11 above.

A minimal pyradex example

I got the following code to produce the above plot (an intentional reproduction/bookmark against Goldsmith, Bergin, Lis 1997)

https://github.com/tomr-stargazer/nitrogen-accounting-plots/blob/7cb1f84f42c5173eb3ffa61a03e64b738e231cb1/pyradex_experiment.py

How to calculate optical depth from line ratios of molecule isotopologues

From Schwarz et al. (2016)  




further notes: there doesn't seem to be a closed-form solution for tau_13CO, so you gotta solve it numerically (using simple root-finding techniques).