Transcript 062211_OSU_SLWW.pptx

Unraveling the Mysteries of Complex Interstellar
Organic Chemistry Using HIFI Line Surveys
^ Observational
Spectral
Susanna L. Widicus Weaver,
Mary L. Radhuber, Jay A. Kroll, Brett A. McGuire, and Jacob C. Laas
Department of Chemistry, Emory University
Darek C. Lis
California Institute of Technology
Eric Herbst
Ohio State University
Why Molecular Line Surveys?
• New astrochemical models attempt to
explain formation of complex organics
• Models require complete chemical,
physical picture for input/comparison
• Physical parameters, abundances often
educated guesses
• Few surveys access differing chemical,
physical environments
Garrod, Widicus Weaver, & Herbst, ApJ 682, 2008
Our Goals:
• Conduct surveys for many different types of sources
• Achieve high spectral sensitivity (for new molecule ID)
• Obtain full picture of chemical, physical conditions for each source
• Compare results to astrochemical models
Tracing Chemical Pathways in the ISM
H2O + hn
OH + H
H2 + O
CH3OH + hn
CH3 + OH
CH3O + H
CH2OH + H
NH3 + hn
NH2 + H
H2CO + hn
HCO + CH2OH
HCO + CH3O
HCO + OH
HCO + CH3
HCO + NH2
CH3 + CH3O
CH3 + NH2
CH3 + CH2OH
CH2OH + CH2OH
HCO + H
HOCH2CHO
CH3OCHO
HCOOH
CH3CHO
H2NCHO
CH3OCH3
CH3NH2
CH3CH2OH
HOCH2CH2OH
hn
H2O, CO, CH3OH,
NH3 , H2CO Ice mantle
(glycolaldehyde)
(methyl formate)
(formic acid)
(acetaldehyde)
(formamide)
(dimethyl ether)
(methyl amine)
(ethanol)
(ethylene glycol)
Garrod, Widicus Weaver, & Herbst, ApJ 682, 2008
CSO Orion Spectrum
3018 >3-s lines observed
59% of the lines are unassigned!
See talk FA05 (Radhuber et al.) for more information.
Results of Spectral Analysis
Residual = incomplete modeling of complex lineshapes
+ unassigned lines of known molecules + very weak lines from COMs
CSO Line Surveys
HCOOCH3 CH3OCH3
CH3OH
& CH3CN
CH3OH
HCOOCH3
& CH3OH
Ta* (K)
CH3OH
Full surveys complete for 8 sources, partial surveys complete for 5 more.
THz Observational Astronomy
Herschel Space
Observatory
Stratospheric Observatory
for Infrared Astronomy
Science observations began in 2010
Launched in 2009
500 GHz – 2.1 THz
480 GHz -1.2 THz
1.4 – 1.9 THz
ESA / AOES Medialab
background: HST, NASA/ ESA/ STScI
NASA / DLR
Atacama Large Millimeter Array
Early science observations to begin in 2011
80 GHz – 950 GHz
ESO/José Francisco Salgado
Upcoming Herschel Observations
The Importance of Follow-Up Imaging Studies
Orion-KL l = 3 mm continuum
observations with CARMA
Friedel and Widicus Weaver, in preparation.
Revealing Chemistry Through Imaging
Comparison of Methyl Formate in Orion-KL to other COMs
Methanol
Formic acid
Dimethyl ether
CARMA+
MF1
NRAO EVLA Demonstration 2009
Friedel and Widicus Weaver, CARMA, 2008
Different COMs have very different spatial distributions.
Neill et al., J. Phys. Chem., in press.
Proposed CARMA Observations
http://amandabauer.blogspot.com/2009/08/carma-telescopes.html
ALMA Changes Everything
OVRO Survey of Orion-KL
RMS = 150 mK
Integration Time ~ 27 Nights
CSO Survey of Orion-KL
RMS = 30 mK
Integration Time ~ 4 Nights
Radhuber et al., in preparation.
Blake et al. 1987, ApJ 315, 621
Full ALMA Capability
Similar coverage on Orion-KL
RMS = 30 mK
Integration Time ~ 1 Minute
eVLA Demonstration Science
Image courtesy of NRAO https://science.nrao.edu/facilities/evla/earlyscience/demoscience
Future Work
• CSO surveys at 230 GHz
8 GHz spectrometer = More sources in less time
• HIFI line surveys at 680 GHz & 1.2 THz
OT-1 observations 2011/2012
OT-2 proposals due September 15
• CARMA imaging at 230 GHz
Proposal review this week
• ALMA imaging at 680 GHz
Cycle-0 proposals due June 30
• Comparison to models
ID molecules that trace gas-phase or grain-surface chemistry
Compare relative abundances of isomers, conformers
• Future observations
CSO 345 GHz receiver + 8 GHz spectrometer
SOFIA
http://www.nasa.gov/centers/jpl/images/content/391019main_herschel-b-20091002-full.jpg
Acknowledgements
The Widicus Weaver Group:
Brian Hays, Le Zhong, Cate Levey, Jay Kroll,
Jake Laas, Brett McGuire, Mary Radhuber,
Brandon Carroll, Sophie Lang, Anne Carroll
CSO/Caltech: Jonas Zmuidzinas, Tom Phillips,
Geoffrey Blake, CSO Staff & TAC
HIFI/HEXOS: Ted Bergin, Nathan Crockett,
Claudia Comito, Peter Schilke,
Martin Emprechtinger, Steve Lord
UIUC/CARMA: Doug Friedel
NRAO/ALMA: Anthony Remijan