Astronomy and Astrophysics – Astrophysics
Scientific paper
2008-10-28
Astronomy and Astrophysics
Astrophysics
6 pages, 5 figures, 2 tables
Scientific paper
10.1051/0004-6361:200810542
The existence and origin of large spatial temperature fluctuations in HII regions and planetary nebulae are assumed to explain the differences between the heavy element abundances inferred from collisionally excited and recombination lines, although this interpretation remains significantly controversial. We investigate the spatial variation in electron temperature inside NGC 346, the brightest HII region in the Small Magellanic Cloud. Long slit spectrophotometric data of high signal-to-noise were employed to derive the electron temperature from measurements derived from localized observations of the [OIII]($\lambda4959 + \lambda5007)/\lambda4363$ ratio in three directions across the nebula. The electron temperature was estimated in 179 areas of 5$^{\prime\prime}\times1.5^{\prime\prime}$ of size distributed along three different declinations. A largely homogeneous temperature distribution was found with a mean temperature of 12 269 K and a dispersion of 6.1%. After correcting for pure measurements errors, a temperature fluctuation on the plane of the sky of $t^2_{\rm s} = 0.0021$ (corresponding to a dispersion of 4.5%) was obtained, which indicates a 3D temperature fluctuation parameter of $t^2 \approx 0.008$. A large scale gradient in temperature of the order of $-5.7\pm1.3$ K arcsec$^{-1}$ was found. The magnitude of the temperature fluctuations observed agrees with the large scale variations in temperature predicted by standard photoionization models, but is too small to explain the abundance discrepancy problem. However, the possible existence of small spatial scale temperature variations is not excluded.
Copetti Marcus V. F.
Krabbe Angela C.
Oliveira V. A.
No associations
LandOfFree
Electron temperature fluctuations in NGC 346 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Electron temperature fluctuations in NGC 346, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electron temperature fluctuations in NGC 346 will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-485505