Astrobiology
Two Columns
Theme II
Overview 06.18.2005
Organic Materials?
Theme II investigates the processes affecting the origin and evolution of organics in planetary systems.
What processes were involved in the creation of organic materials in protoplanetary disks and stellar surroundings? The primary focus of Theme II is uncovering the answer to this question.
Projects 06.18.2005
Research by the Blake group centers on an investigation of the evolution of molecular complexity in the star-forming cores of molecular clouds. Both laboratory and observational studies are carried out. This work began with an observational search for dihydroxyacetone, or DHA, the simplest three carbon ketose sugar. Over ten transitions have now been detected toward the galactic center source Sgr B2(N-LMH), which is shown in the image below. The top portion of the figure depicts the molecular structure and a portion of the laboratory spectrum assigned in our laboratory, while the bottom panel shows one of the DHA lines observed near 1.3mm toward Sgr B2(N-LMH). The rest velocities of the lines are nicely centered on that expected for complex molecules from detailed mapping with the Very Large Array, and a rotation diagram analysis of the integrated intensities yields excitation temperatures consistent with those of acetone and other organics. The column densities are also in line with chemical expectations from the earlier detections of chemically related compounds such as glycoaldehyde (the simplest, two carbon, sugar) and acetone.ss
Sgr B2 (N-LMH).
Jeff Pedelty and Lee Mundy have been awarded time on the Very Large Array to observe the hot molecular core in the young stellar object IRAS 16293-2422. Four telescope sessions were scheduled in July 2004 to observe ethyl cyanide, methyl formate, and formic acid with approximately 2" spatial resolution in order to provide additional constraints on the molecular abundances and rotational temperatures in this low mass star forming region. A VLA proposal for high resolution (A array), multi-frequency, and high sensitivity observations of the OMC1-S, Trapezium, and BN region is pending, but if successful would lead to observing time in late 2004. A poster entitled "Radio Interferometric Searches for the Amino Acid Glycine in High Mass Star Formation Regions" was presented at AbSciCon 2004; a poster entitled "NRAO VLA Searches for the Amino Acid Glycine in OMC-1 and SgrB2(N-LMH) and Other Molecular Explorations" was presented at the ALMA Science Workshop in College Park, MD.
Very Large Array. Image courtesy of NRAO/AUI.
Mike DiSanti, Neil Dello Russo, and Mike Mumma conduct studies of parent volatiles in comets through ground-based high-resolution spectroscopy at near-IR wavelengths (~ 1 – 5 µm). This has been an exciting year with the availability of 2P/Encke (a short-period comet and member of Jupiter’s dynamical family) in Fall 2003, and of two long-period (Oort cloud) comets (C/2001 Q4 NEAT and C/2002 T7 LINEAR) in Spring 2004. Our observations of Encke permitted the volatile chemistry of a Jupiter Family comet to be characterized in unprecedented detail. Our studies of Q4 and T7 exploited their large geocentric Doppler shifts to conduct detailed studies of emissions that are normally obscured by atmospheric extinction, in particular transitions of CH4 and, to a lesser extent, CO. Our research emphasizes the volatile carbon-oxygen chemistry, in particular the efficiency of converting CO to formaldehyde and methyl alcohol on the surfaces of icy grain mantles prior to their incorporation into the nucleus. This process is expected to be temperature-dependent, and comet T7 in particular displayed very strong signatures of both H2CO and CH3OH, yet relatively weak CO, suggesting high conversion efficiency. Such measurements are important for establishing the role of comets in replenishing Earth’s oceans and for delivery of the seed organic molecules from which life emerged. Along with HCN and NH3 (both of which we also study), H2CO is thought to play a particularly significant role in the latter process.
Parent volatiles in comets
More Research
NASA Fact
On March 16, 1926, Dr. Robert H. Goddard successfully launched the first liquid fueled rocket. The launch took place at Auburn, Massachusetts, and is regarded by flight historians to be as significant as the Wright Brothers flight at Kitty Hawk.
