THE REMARKABLE MOLECULAR CONTENT OF THE RED SPIDER NEBULA (NGC 6537)
Millimeter and sub-millimeter molecular-line observations of planetary nebula (PN) NGC 6537 (Red Spider) have been carried out using the Sub-Millimeter Telescope and the 12 m antenna of the Arizona Radio Observatory in the frequency range 86-692 GHz. CN, HCN, HNC, CCH, CS, SO, H{sub 2}CO, HCO{sup +} and N{sub 2}H{sup +}, along with the J = 3 {yields} 2 and 6 {yields} 5 lines of CO and those of several isotopologues, were detected toward the Red Spider, estimated to be {approx}1600 yr old. This extremely high excitation PN evidently fosters a rich molecular environment. The presence of CS and SO suggest that sulfur may be sequestered in molecular form in such nebulae. A radiative transfer analysis of the CO and CS spectra indicate a kinetic temperature of T{sub K} {approx} 60-80 K and gas densities of n(H{sub 2}) {approx} 1-8 Multiplication-Sign 10{sup 5} cm{sup -3} in NGC 6537. Column densities of the molecules in the nebula and their fractional abundances relative to H{sub 2} ranged from N{sub tot} {approx} 10{sup 16} cm{sup -2} and f {approx} 10{sup -4} for CO, to {approx}7 Multiplication-Sign 10{sup 11} cm{sup -2} and f {approx} 8 Multiplication-Sign 10{sup -9} for the least abundant species, N{sub 2}H{sup +}. For SO and CS, N{sub tot} {approx} 2 Multiplication-Sign 10{sup 12} cm{sup -2} and 10{sup 13} cm{sup -2}, respectively, with f {approx} 10{sup -7} and 2 Multiplication-Sign 10{sup -8}. It was also found that HCN/HNC Almost-Equal-To 2. A low {sup 12}C/{sup 13}C ratio of {approx}4 was measured, indicative of hot-bottom burning. These results, coupled with past observations, suggest that molecular abundances in PNe are governed principally by the physical and chemical properties of the individual object and its progenitor star, rather than nebular age.
- OSTI ID:
- 22118795
- Journal Information:
- Astrophysical Journal Letters, Vol. 770, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COSMOLOGY AND ASTRONOMY
ASTRONOMY
ASTROPHYSICS
CARBON 12
CARBON 13
CARBON MONOXIDE
CHEMICAL PROPERTIES
CYANIDES
ELEMENT ABUNDANCE
EMISSION SPECTRA
EXCITATION
GALAXIES
GHZ RANGE
HYDROCYANIC ACID
HYDROGEN
MOLECULES
NUCLEOSYNTHESIS
PLANETARY NEBULAE
RADIANT HEAT TRANSFER
STARS
TELESCOPES