Glen Langston Astrobiology Review Green Bank Discoveries What Radio Astronomers Observe

1. Signs of Life: Pre-biotic Chemistry New Discoveries with the NRAO 100m Diameter Green Bank Telescope (GBT) • Glen Langston • Astrobiology Review • Green Bank Discoveries • What Radio Astronomers Observe • Future Directions NRAO glangsto@nrao.edu Glen Langston: Chautauqua 2012

2. Astrobiology Glen Langston: Chautauqua 2012 Credit: Pascal Ehrenfreund

3. Ingredients for Life Glen Langston: Chautauqua 2012

4. Miller-Urey-Type Synthese (1953) Glen Langston: Chautauqua 2012

5. Miller & Orgel:The origin of life on Earth, 1974 “It must be admitted from the beginning that we do not know how life began. It is generally believed that a variety of processes led to the formation of simple organic compounds on the primitive Earth. These compounds were combined together to give more and more complex structures until one was formed that could be called living. No one should be satisfied with an explanation as general as this.” Glen Langston: Chautauqua 2012

6. Background • Two groups of life origin theories: • Terrestrial origin. • Extraterrestrial origin. Planets are not isolated in terms of biology and exchange of organic material could occur between them. • Possibility for cosmic delivery of basic molecules: • Amount of micrometeorites (from 50 to 500 m in size) – 50-100 tons daily. • Meteorite flux - 0.03 tons per day. • Heavy bombardment in early Earth - 1000 times more than present amount. • High percentage of organic components in carbonaceous chondrites Credit: Natalia Gontareva Glen Langston: Chautauqua 2012

7. Astronomical Life Cycle Glen Langston: Chautauqua 2012 Credit: Ehrenfreund and Charnley

8. Interstellar Clouds • 5 % of the mass of the Galaxy • Lifetime: 107 - 10 8 years • Site of star formation Cosmic rays drive a rich ion-molecule chemistry supplemented by neutral-neutral processes organic molecules T ~ 10 K r ~ 106 H atoms per cm3 NGC 604 Glen Langston: Chautauqua 2012

9. Elemental abundances H 1 He 7.5 . 10-3 O 8.3 . 10-4 C 4.0 . 10-4 N 1.0 . 10-4 Ne 0.8 . 10-4 Si 4.3 . 10-5 Mg 4.2 . 10-5 S 1.7 . 10-5 Fe 4.3 . 10-5 Na 2.1 . 10-6 P 3.0 . 10-7 Glen Langston: Chautauqua 2012

10. Astronomer’s Periodic Table Credit: Ben McCall Glen Langston: Chautauqua 2012

11. Molecular Discoveries: 43m FORMALDEHYDE FORMAMIDE FORMIC ACID METHANOL CYANO- ACETYLENE ACETALDEHYDE Many organic molecules were first discovered in with the 43m telescope in Green Bank. These detections were a surprise. The experts thought interstellar space was too harsh for chemistry! Glen Langston: Chautauqua 2012

12. Interstellar Molecules • Galactic Chemistry: • Carbon Rich • Life on Earth: • Carbon based • Coincidence? Credits: Pat Thaddeus, Al Wootten Glen Langston: Chautauqua 2012

13. Field of View Sensitivity Resolution Glen Langston: Chautauqua 2012

14. Molecular Discoveries: 100m • World’s most sensitive Telescope in frequency range 10 to 50 GHz • Discovered new interstellar molecules, including propenal and propanal Glen Langston: Chautauqua 2012

15. Sugars in Space • Ethylene glycol was discovered in a massive interstellar cloud of dust and gas near the center of the Milky Way Galaxy. • Ethylene glycol (a 10-atom molecule made up of carbon, hydrogen, and oxygen) is one of the five largest molecules ever discovered in space. Glen Langston: Chautauqua 2012

16. Evidence of Astro-Chemistry Glen Langston: Chautauqua 2012

17. What do Radio Astronomers Observe? There’s no Eye piece on a Radio Telescope… Astronomers measure signal strengths as a function of frequency. With enough observations and imagination, we can see the first steps in the formation of life. Glen Langston: Chautauqua 2012

18. Intensity versus Frequency Intensity (Volts) Intensity (Volts) 80 98 116 0.0 900 1800 Frequency (MHz) Frequency (MHz) Glen Langston: Chautauqua 2012

19. Fundamental Laws HC5N HC7N HC7N Intensity (Volts) Intensity (Kelvin) HC9N 101 102 Frequency (MHz) Frequency (MHz) Physics Laws: Quantum Mechanics and Molecular Structure. (GBT observations of HC5N, HC7N and HC9N) International Law: 88.000 - 108.000 FM Broadcast (200 kHz steps) Glen Langston: Chautauqua 2012

20. GBT: Cyanopolyynes + HC13N HCN • Cyanopolyynes are ideal molecules for radio astronomy: • Simple Structure, easy to model. • Large dipole moment, strong lines. • Simple spectra. • If detected, suggest more biologically relevant molecules are present HC7N Glen Langston: Chautauqua 2012

21. Diffuse Interstellar Medium • T ~ 10 to 100 K • (-400 F) • r ~ 100-300 cm-3 • UV radiation field ~ 108 photons cm-2 s-1 photochemistry • simple di- and triatomic species: CH, CN, C2, HCN, C2H3 …. • Soot, PAHs, carbonaceous networks….. Glen Langston: Chautauqua 2012

22. GBT K-Band Ammonia Maps KFPA NH3 (1,1) Ammonia mapping of dark clouds Finn & Jackson Glen Langston: Cambridge 2011 April 26 15

23. Compare NH3 and Cyanopolyyenes Glen Langston: Chautauqua 2012

24. Cyanopolyyne Line Intensities With the GBT, observations that took many hours with the 43m, now take only minutes. Rarer, weaker, isotopic versions (13C instead of 12C) of the molecules can be discovered with the GBT. Glen Langston: Chautauqua 2012

25. Weak lines: HC7N Isotopomers Comparison of HC7N molecule 13C/12C Isotopomers: Abundance Ratio 1/80 TMC-1 is nearby (140 pc from Earth), so 13C/12C abundance is expected to be similar that abundance ratio observed on Earth. (Galactic variation observed.) We share a common history with TMC-1! Glen Langston: Chautauqua 2012

26. Future Directions • Radio Astronomers detect (in seconds) the molecules critical for life • Lower frequency (5 to 20 GHz) observations are critical for study of important large molecules. • Need *many* simultaneous lines for weak detections Glen Langston: Chautauqua 2012