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).