Notes from Telecon 1
Key Project Proposal Telecon 1, November 28th
- Maryland: Shaye, Lee, Hao, Marc, Peter, Demerese
- Illinois: Leslie, Dick, Manuel, Woojin
- Caltech: Andrea
- Arizona: Yancy
- OVRO: Nikolaus
- UBC: Erik
- NRAO: John
- Yale: Hector
- JPL: Jens
---Start with some Science goals----
1. Testing Global Models of Star Formation:
- Can't say anything directly about the magnetic fields
- But can determine whether the observed kinematic structure better matches models with or without magnetic fields
- It is a reasonable idea to coordinate with dust polarization projects if Dick is looking at sources in Perseus or Serpens
2. Optically thick in NGC 1333?
- Lines in NGC 1333 are not horribly optically thick
- Overall optical depths of several, but not such that hyperfine components are of comparable strength to the center line
- Don't know this explicitly for HCO+ without isotopic observations. Perhaps Yancey can get us 12-m observations to estimate how optically thick we might be.
---Conversation opened up to discuss targets-----
3. John discusses OMC2/3
- 50 Class 0/I protostars + more Class II sources in ~100 arcmin^2 field
- Herschel maps exist and SCUBA2 will eventually exist
- Ask if filament is consistent with magnetic quasi-static formation? or dynamic even is densest gas?
- 5-6 arcsec resolution gets individual envelopes kinematics --- how connects with large scale cloud
---Lee discusses broad goals of Key----
4. Lasting value, data products of value to general community, regions others have worked on, good for complete data sets, data to justify ALMA followup.
---Continue discussing clouds----
5. Hector discusses Serpens
- Serpens Main and Serpens South
- Mapped by Stuart Corder for thesis with CARMA in 13CO and C18O
- Serpens South getting attention because recently discovered
- K band GBT data
---Do we want do probe clouds with different evolutionary stages?----
- Probably not any nearby, large IRDCs
7. California Cloud
- Talk to John B(?) with Charles Lada
- Large section mapped 12CO and 13CO and followup with NIR
- 12-m observed cores
- A few degrees of cloud mapped by end of project
- GBT proposal: 60 hour proposal to use KFPA to map 3 degree filament in NH3 (1-1) (2-2), CCS (?)
- Hub of 1495: 20' x 20' region -- starless, class 0/I
- Low density regions have magnetic field strength measured
---Where in cloud do you choose to map??----
9. Not obvious what types of regions we go after
- Do we go after clustered star formation?
- Parts where not many stars have not formed yet?
- Observe dense gas proceeding towards filament?
---Put things in perspective with time----
10. How much time can we justify?
- Multi-semester Key Project
- 400-500 hour level, not hurting ourselves
- 1000 hour level is too big
- 2-3 semesters at the least
- This is one of areas for array to concentrate on overall several years so 150-200 hours per semester for 3 semester not crazy
---Discussion of alternatives to CARMA-23---
11. Why need CARMA-23 + SD?
- CARMA-15 kills kinematics science due to negatives
- Need good line profiles filled in with all spacings
- But lose LSB :(
12. Does 3.5-m data make a huge difference?
- 3.5-m doing important things in theory
- The 3.5-3.5 and 3.5-6 baselines get important spacings
- More effort has been put into pointing at 3.5-m at 3mm
13. "Time share" with 3.5-m?
- Time share with 3.5-m uvcell distance?
- Can't observe USB and LSB with 3.5-m since 3.5-m only USB.
- No great alternatives found
---Go back to cloud approach---
14. Andrea suggests focusing on Perseus
- Starless cores to class II sources
- Variety of regions with different properties
- Tons of complementary data: scuba, bolocam, ..,
- Makes link to 1333 clear from point of view of evaluating proposal
15. Do 4 major subregions of Perseus?
- Hurt us to be in same RA range, sucks up a lot of Orion time.
- Scheduling array --- better to have two distinct RA spots.
16. Serpens or Oph?
- Oph has signal-to-noise penalty
- Serpense near equator so we get bad beam; straight lines in UV plane
- Advantage, it is accessible to ALMA
---Consensus view: 2 clouds ! ---------------
17. Need large enough area to get context of surrounding material
- trends in chemistry, not noticed across less than 1 pc.
- still with ~10' scale
18. Advocate for 8 MHz mode with higher spectral resolution
- Science goal of tracing infall motions with HCN(1-0) using hyperfine lines that are subsonic-- velocity resolution needs to be ~0.1-0.2 km/s
19. C18O comparison to HCN and N2H+ is chemical measure of depletion
20. N2H+/C18O crude chemical evolution tracer
21. C18O is interesting near protostars; it is peaked at protostars due to liberation from grains; it is probe of the inner envelope
- Is that worth doing 1/2 the number of clouds?
22. Probing wide variety and disparity of different star forming regions
23. What science can be done with few lines?
- kinematics, large scale down to 1200 AU scale
- trace morphology from parsec scale to 1200 AU scale
- comparisons with stellar content
- test models for how stars are forming
- figure out how multiple tracers give you unique information
- kinematics very different in regions --- no one core is alike, having kinematics of many
- these 3 tracers probe dense gas between 10^4-6 -- nice range of densities traced here
24. Focus on Perseus and Serpens
- Oph only up 4-5 hours tops at a time
- 2-3 regions in each cloud
25. Who would like to help by choosing clouds?
- Serpens: Hector, Manuel, John
- Perseus: Andrea, Shaye, Jens, John
26. Need management plan
27. Next telecon Wednesday