TY - JOUR
T1 - Detection of the simplest sugar, glycolaldehyde, in a solar-type protostar with ALMA
AU - Jørgensen, Jes Kristian
AU - Favre, Cécile
AU - Bisschop, Suzanne Elisabeth
AU - Bourke, Tyler L.
AU - van Dishoeck, Ewine F.
AU - Schmalzl, Markus
PY - 2012/9/20
Y1 - 2012/9/20
N2 - Glycolaldehyde (HCOCH2OH) is the simplest sugar and an important intermediate in the path toward forming more complex biologically relevant molecules. In this Letter we present the first detection of 13 transitions of glycolaldehyde around a solar-type young star, through Atacama Large Millimeter Array (ALMA) observations of the Class 0 protostellar binary IRAS16293-2422 at 220GHz (6 transitions) and 690GHz (7 transitions). The glycolaldehyde lines have their origin in warm (200-300K) gas close to the individual components of the binary. Glycolaldehyde co-exists with its isomer, methyl formate (HCOOCH 3), which is a factor 10-15 more abundant toward the two sources. The data also show a tentative detection of ethylene glycol, the reduced alcohol of glycolaldehyde. In the 690GHz data, the seven transitions predicted to have the highest optical depths based on modeling of the 220GHz lines all show redshifted absorption profiles toward one of the components in the binary (IRAS16293B) indicative of infall and emission at the systemic velocity offset from this by about 02 (25AU). We discuss the constraints on the chemical formation of glycolaldehyde and other organic species - in particular, in the context of laboratory experiments of photochemistry of methanol-containing ices. The relative abundances appear to be consistent with UV photochemistry of a CH3OH-CO mixed ice that has undergone mild heating. The order of magnitude increase in line density in these early ALMA data illustrates its huge potential to reveal the full chemical complexity associated with the formation of solar system analogs.
AB - Glycolaldehyde (HCOCH2OH) is the simplest sugar and an important intermediate in the path toward forming more complex biologically relevant molecules. In this Letter we present the first detection of 13 transitions of glycolaldehyde around a solar-type young star, through Atacama Large Millimeter Array (ALMA) observations of the Class 0 protostellar binary IRAS16293-2422 at 220GHz (6 transitions) and 690GHz (7 transitions). The glycolaldehyde lines have their origin in warm (200-300K) gas close to the individual components of the binary. Glycolaldehyde co-exists with its isomer, methyl formate (HCOOCH 3), which is a factor 10-15 more abundant toward the two sources. The data also show a tentative detection of ethylene glycol, the reduced alcohol of glycolaldehyde. In the 690GHz data, the seven transitions predicted to have the highest optical depths based on modeling of the 220GHz lines all show redshifted absorption profiles toward one of the components in the binary (IRAS16293B) indicative of infall and emission at the systemic velocity offset from this by about 02 (25AU). We discuss the constraints on the chemical formation of glycolaldehyde and other organic species - in particular, in the context of laboratory experiments of photochemistry of methanol-containing ices. The relative abundances appear to be consistent with UV photochemistry of a CH3OH-CO mixed ice that has undergone mild heating. The order of magnitude increase in line density in these early ALMA data illustrates its huge potential to reveal the full chemical complexity associated with the formation of solar system analogs.
U2 - 10.1088/2041-8205/757/1/L4
DO - 10.1088/2041-8205/757/1/L4
M3 - Letter
SN - 2041-8205
VL - 757
JO - The Astrophysical Journal Letters
JF - The Astrophysical Journal Letters
IS - 1
M1 - L4
ER -