EXPANDED VERY LARGE ARRAY OBSERVATIONS OF THE H66{alpha} AND He66{alpha} RECOMBINATION LINES TOWARD MWC 349A

Journal Article · Sun Oct 10 04:00:00 EDT 2010 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/722/1/L100· OSTI ID:21457032

Loinard, Laurent

We have used the greatly enhanced spectral capabilities of the Expanded Very Large Array to observe both the 22.3 GHz continuum emission and the H66{alpha} recombination line toward the well-studied Galactic emission-line star MWC 349A. The continuum flux density is found to be 411 {+-} 41 mJy in good agreement with previous determinations. The H66{alpha} line peak intensity is about 25 mJy, and the average line-to-continuum flux ratio is about 5%, as expected for local thermodynamic equilibrium conditions. This shows that the H66{alpha} recombination line is not strongly masing as had previously been suggested, although a moderate maser contribution could be present. The He66{alpha} recombination line is also detected in our observations; the relative strengths of the two recombination lines yield an ionized helium to ionized hydrogen abundance ratio y {sup +} = 0.12 {+-} 0.02. The ionized helium appears to share the kinematics of the thermally excited ionized hydrogen gas, so the two species are likely to be well mixed. The electron temperature of the ionized gas in MWC 349A deduced from our observations is 6300 {+-} 600 K.

• OSTI ID: 21457032
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 1 Vol. 722; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABUNDANCE
AMPLIFIERS
ELECTRON TEMPERATURE
ELECTRONIC EQUIPMENT
ELEMENTS
EMISSION
EQUILIBRIUM
EQUIPMENT
FLUIDS
FLUX DENSITY
FREQUENCY RANGE
GASES
GHZ RANGE
GHZ RANGE 01-100
HELIUM
HYDROGEN
LTE
MASERS
MICROWAVE AMPLIFIERS
MICROWAVE EQUIPMENT
NONMETALS
RARE GASES
RECOMBINATION
STARS