Molecular Cloud Key Project Proposal

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  • Maryland: Lee Mundy, Shaye Storm, Peter Teuben, Marc Pound, Demerese Salter, Eve Ostriker, Hao Gong
  • Illinois: Leslie Looney, Charles Gammie, Dick Crutcher, Manuel Fernandez Lopez , Woojin Kwon, I-Jen (Katherine) Lee
  • Caltech: Andrea Isella
  • JPL: Jens Kauffmann
  • Arizona: Yancy Shirley
  • Yale: Hector Arce
  • NRAO: John Tobin
  • UBC: Erik Rosolowsky

Telecon Notes

Notes from Telecon 1

Notes from Telecon 2

Scientific and Technical Points of Discussion

1. Cloud Selection Ideas

General approach: Focus in detail on 1-2 clouds. This is a natural way to limit the scope of the project to something that be done in ~600 hours. Perseus and Serpens have subregions that cover a range of densities and activity. Plus, they are in unique enough RA ranges not to monopolize all the time near Perseus/Orion/Taurus.

Specific Clouds:

1. Perseus (Andrea, Jens, John, Shaye):

  • Contains starless cores to Class II sources. Variety of regions with different properties. Tons of complementary data: SCUBA, Bolocam, etc.
    • NGC 1333 [already complete, though at 0.6 km/s resolution]: 17' x 12' cented on SVS 13, ~1 Myr cluster age
    • ? B1: younger star formation, half-dozen starless cores, a few young YSOs, diffuse starless dust, fairly well studied objects within
    • ? L1448: younger star formation
    • ? HH211: presumably young star formation, possibly influenced by nearby IC 348, several sub-mm cores

2. Serpens (Hector, Manuel, John):

  • Serpens South getting attention because recently discovered. CARMA CO maps and GBT K-band maps exist.
    • ?
    • ?
    • ?

2. Time per cloud? Total Time Request? Semester Split?

  • Something in the ballpark of 600 hours spread over 2-3 semesters seems reasonable
  • We got ~130 hours for NGC 1333. This achieved a mean S/N across the cloud of ~15 for weakest N2H+ line, ~25 for weakest HCN line, and ~180 for HCO+.

3. 8 MHz or 31 MHz Bands?

  • 8 MHz bands with ~0.15 km/s resolution are crucial to achieve some science goals such as: tracing infall motions with HCN (1-0) if the lines are subsonic
  • General consensus to lose some outflow information and observe HCO+, HCN, N2H+ in 8 MHz bands in 3-bit mode.
  • But we will likely have to average up to ~0.3-0.4 km/s channels in the weaker emission regions.

4. Which Molecular Tracers?

Choose to go with more cloud regions rather than more tracers

  • We observed NGC 1333 in:
    • HCN (1-0) 88.632 GHz | Tracer of dense gas and infall motion
    • HCO+ (1-0) 89.188 GHz | Tracer of dense gas and outflows
    • N2H+ (1-0) 93.171 GHz | Tracer of dense, quiescent gas, depletes late

and we will observe the other clouds in the same tracers.

Other lines had good justifications, but cost of including >3 lines too much.

  • Correlator setup will be something like:
   'restfreq' : 90.8286,  # [GHz] Line rest frequency
   'sideband' : USB,    # Sideband for first LO (LSB or USB)
   'IFfreq'   : 4.986632,   # [GHz] IF frequency, 5 - 0.013368
   lo1 = 85.8286
   configastroband(1, "CARMA23", BW8, lo1 + 2.80325, USB,  88.631847, 88.631847, bits=CORR_3BIT)
   configastroband(3, "CARMA23", BW500, lo1 - 8.30255,AUTO, 94.135924, 94.135924, bits=CORR_2BIT)
   configastroband(5, "CARMA23", BW8, lo1 + 7.3448, USB, 93.173505, 93.173505, bits=CORR_3BIT)
   configastroband(7, "CARMA23", BW8, lo1 + 3.3600, USB , 89.188518, 89.188518, bits=CORR_3BIT)

6. Which arrays?

Try to match physical size scales probed between clouds

  • NGC 1333 observed in D+E arrays getting 5 arcsec resolution at 250 pc --> ~1200 AU physical size scale
  • What is the best distance estimate to Serpens??

7. Complementary Single-Dish Proposals?

Use Arizona 12-m to determine how optically thick we may be at HCO+, HCN?

8. Joint Deconvolution of Interferometer and Single-Dish Mosaics

We have been successful using the miriad task "mosmem" to do the joint deconvolution if we input the clean components of the interferometer mosaic as the model input.

9. Why CARMA-23 and CARMS Single-Dish?

  • CARMA Single-Dish will make this project self-contained within CARMA, and we can help commission the mode. Plus, with CARMA-23 mode having the SZA dishes at "medium" spacings, we only need a ~10-m dish to get the shortest spacings
  • CARMA-23 mode will give us the SZA spacings, which will help with the fact that our single-dish is only 10-m. We don't have easy access to any ~30-m single-dish, right?
    • (these reasons for CARMA-23 and Single-Dish are not independent of one another ...)

Science Areas

Key Projects need to have lasting value. We need to provide data products of value to the general community. Good to probe regions that have already been worked on.

Science to do with 3 dense gas molecular tracers:

1. Kinematics

  • Trace parsec scale kinematics down to ~1200 AU scale kinematics
  • Comparisons with stellar content

2. Testing Global Models of Star Formation

  • Turbulence
  • Magnetic Fields
    • We won't be able to say anything directly about the magnetic fields, but we can observe the kinematic structure and determine whether it is a better match to star formation models with or without magnetic fields and turbulence.
    • Collaborate with a project that is doing polarization measurements of individual cores in Perseus and Serpens. Dick is doing something with this.

3. Core Identification and Properties

4. Core Formation

5. ALMA Connection

Management Plan

"This section should provide a plan for the overall management of the project. This should include (i) a description of the data products and data release plans, (ii) key benchmarks covering the duration of the project against which progress may be gauged, and (iii) how the project team will contribute to CARMA operations and provide regular feedback on data quality."

(i) Descriptions of Data Products and Data Release Plans (Shaye)

  • 3 months after final track of cloud has been observed:
  • 1. Fully calibrated interferometric data cubes for each cloud
  • 2. Fully calibrated visibility datasets for each cloud
  • 3. Final single-dish maps for each cloud
  • 6-9 months after final track of cloud has been observed:
  • 4. Combined SD+int data cubes for each cloud 6-months after the final track

(ii) Key Benchmarks (Shaye)

  • Observation Benchmarks/ Real-time adjustments to observing strategy
  • 1. Our MIS pipeline provides daily full assessment of data quality and project progress
  • 2. Keep colorful integration maps updated on our website. And uvcoverage movies. Sensitivity maps. More area in different cloud? Reduce are of current cloud if not sensitive enough?

We have queue of goals, we can make real-time adjustments and MAXIMIZE SCIENCE OUTPUT!

  • Science Goal Benchmarks
  • 3. Pipeline/quick turnaround spectral line fitting? Only in the peaky positions.
  • 4. Each science goals needs custom scripting; develop as data comes in so we are ready when final int+SD is done. Examples are: spectral line fitting, comparison of neutral to ionized species ......

(iii) Project Team Contributions to CARMA operations

  • 1. CARMA Single-Dish Mode (Peter)

Balanced off Averaging of offs When to go to OFF to minimize overhead of slewing Improve sinbad: currently takes OFF before current int, want to average OFFs on either side of integration. Algorithm improvements to single-dish miriad codes. Improve algorithms for combining single-dish maps: reduce striping; out of 20 tracks, only could use 10 tracks without degrading SD map. Antenna based anomolies? Trends in antenna based results? Different surface accuracy? Only did this experiment for 10-m, could now work on other dishes.

  • 2. Collaborative Scripting and Data Reduction Environment (Peter)

An improved version of the the previously used MIS pipeline, enabling multi-track data reduction in a collaborative scripting environment. MIS infrastructure to organize large number of project tracks. Easily tailored to similar large project. Egnogg is currently using adapted version of MIS. Provide code, documentation, wiki support for teams that want this collaborative environment.

  • 3. Mosaic Overhead Improvements (Marc)

Testing of continuous integration mode as a way of reducing overhead without doing a full implementation of on-the-fly mosaics. This is a new idea discussed by people in the RTS group. Full accounting of overhead for traditional mosaic. Where is all time going? Modify observing script. Do continous integrations during maintancence day. We will investigate how much overhead can be reduced. Is doing that substantial enough to get most of the way to full on the fly mapping? What fraction of overhead is recouped as compared with full on the fly implementation. Save time waiting for pipeline to startup (couple of sec per integration). Not wasting time when 6-m are there already, waiting for 10-m to arrive. When do you move on? After slowest has completed desired time? Average of antennas have acquired enough time? 80% antennas have at least desried time. Flag visibility data. Does this get us better time on source?? If looks promising, we can adopt it for some Key science tracks. Get the real, full statistics from those Key science tracks. Use that to present argument to CARMA as to whether to offer as full observing mode.

per field penatly of 6 s -- kills large mosaics. 60% overhead. we can get back some of this with continuous integration. Pipeline people want 1.5 s. 3/12 frames from pipeline wait.

due to 3.5-m?

just don't tsys every 5 minutes!

why were spending 90 seconds going from OFF back to source? slew+tsys not = to 90 sec.

Payment Plan





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