S Molecule Search: Summing Lines Demo: Detection of Isotopomers of HC 5 N In 39-48 GHz GBT Survey of TMC Glen Langston (NSF) + Many Students
Dec 23, 2015
S
Molecule Search:
Summing LinesDemo: Detection of Isotopomers of HC5N
In 39-48 GHz GBT Survey of TMC
Glen Langston (NSF)+ Many Students
Why Molecules? - Precursors of Life
• Molecular Chemistry is Dynamic
• Diagnostic clock of star formation
• Cloud temperature
Image from Tielens (2013), Reviews of Modern Physics, vol. 85, page 1021
What Telescope?- GBT
a.k.a. Robert C. Byrd Green Bank Telescope
100m Diameter
0.3 to 90 GHz
Multi-band Spectrometer
Radio Quiet Zone
What Molecules? - Carbon
Chains
Molecules found by Hollis, Jewell, Lovas, Remijan, Mollendal, 2004 Ap. J. Let. 610, L21 Lovas, Remijan, Hollis, Jewell, Snyder (2006) Ap. J. Let. 637, L37
Confirm Molecules? - Select Carbon
Chains
Where? - Taurus Molecular Cloud (TMC)
Taurus Region Rich in Molecules
Long Carbon Chains foundin TMC and several regions
https://science.nrao.edu/science/Decadal%20Survey/tech/langston_chemistrymap_TEC_RMS.pdfCO image from Goldsmith, P. F., Heyer, M. H., Narayanan, G., Snell, R. L., Li, D., & Brunt, C., 2008
CO
What Data?
- GBT 39-48 GHz TMC Survey
Soon to be inAp. J. Supp., with all calibrateddata online
Spectral Resolution0.04 km/sec
Sensitivity 0.06 KRMS (1 Hour obs.)
Where? - TMC Cyanopolyyene Peak
HC5NH C C C C C N
Averaging Lines in velocity to increase
SNR
What Demo?
- Isotopomers of H13CC4N
All Lines Average Line
See: Langston, Turner (2007), Ap. J. 658, 455.
What Demo?
- Isotopomers of HC13CC3N
All Lines Average line
What Demo?
- Isotopomers of HC213CC2N
All Lines Average line
What Demo?
- Isotopomers of HC313CCN
All Lines Average line
What Demo?
- Isotopomers of HC413CN
All Lines Average line
What Demo?
- Average All Isotopomers HC5N
3 HC5N lines in this frequency rangePeak 3.334 +/- 0.005 K (TB)RMS 0.011 K
5 x 3 HC5N Isotopomer linesPeak 0.047 +/- 0.003 K (TB)RMS 0.007 K
What Demo!
- 12C/13C
12C/13C = 71.5 +/- 4.5
New Confirmation?- H2C3HCN
14 Strongest Lines in frequency range. No detection of any individual line.
Weighted average shows clear10 sigma detection.
New Confirmation!- H2C3HCN
0.057 +/- 0.005
Confirmation.
New Detection?- Keep Posted
Thanks!Great Summer Students
NRAO and GBT Staff
Astrochemists for Lines and Models.
Cologne Database of Molecular Spectroscopy
H?C?N
THE COLOGNE DATABASE FOR MOLECULAR SPECTROSCOPY, CDMS by H. S. P. Müller, S. Thorwirth, D. A. Roth, and G. Winnewisser; Astron. Astrophys. 370 (2001) L49 – L52.H. S. P. Müller, F. Schlöder, J. Stutzki, and G. Winnewisser, THE COLOGNE DATABASE FOR MOLECULAR SPECTROSCOPY, CDMS: A USEFUL TOOL FOR ASTRONOMERS AND SPECTROSCOPISTS, J. Mol. Struct. 742, 215–227 (2005).