Astronomy and Astrophysics – Astrophysics – Solar and Stellar Astrophysics
Scientific paper
2010-08-06
Astronomy and Astrophysics
Astrophysics
Solar and Stellar Astrophysics
35 pages, 21 figures, 6 tables, accepted by Astrophysical Journal
Scientific paper
We present a detailed analysis of Spitzer-IRAC images obtained toward six Herbig-Haro objects (HH 54/211/212, L 1157/1448, BHR 71). Our analysis includes: (1) comparisons in morphology between the four IRAC bands (3.6, 4.5, 5.8 and 8.0 um), and H2 1-0 S(1) at 2.12 um for three out of six objects; (2) measurements of spectral energy distributions (SEDs) at selected positions; and (3) comparisons of these results with calculations of thermal H2 emission at LTE (207 lines in four bands) and non-LTE (32-45 lines, depending on particle for collisions). We show that the morphologies observed at 3.6 and 4.5 um are similar to each other, and to H2 1-0 S(1). This is well explained by thermal H2 emission at non-LTE if the dissociation rate is significantly larger than 0.002-0.02, allowing thermal collisions to be dominated by atomic hydrogen. In contrast, the 5.8 and 8.0 um emission shows different morphologies from the others in some regions. This emission appears to be more enhanced at the wakes in bow shocks, or less enhanced in patchy structures in the jet. These tendencies are explained by the fact that thermal H2 emission in the 5.8 and 8.0 um band is enhanced in regions at lower densities and temperatures. Throughout, the observed similarities and differences in morphology between four bands and 1-0 S(1) are well explained by thermal H2 emission. The observed SEDs are categorized into:- (A) those in which the flux monotonically increases with wavelength; and (B) those with excess emission at 4.5-um. The type-A SEDs are explained by thermal H2 emission, in particular with simple shock models with a power-law cooling function. Our calculations suggest that the type-B SEDs require extra contaminating emission in the 4.5-um band. The CO vibrational emission is the most promising candidate, and the other contaminants discussed to date are not likely to explain the observed SEDs.
Chen How-Huan
Karr Jennifer L.
Koh Haegon
Lee Hsu-Tai
Takami Michihiro
No associations
LandOfFree
A Detailed Study of Spitzer-IRAC Emission in Herbig-Haro Objects (I): Morphology and Flux Ratios of Shocked Emission 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 A Detailed Study of Spitzer-IRAC Emission in Herbig-Haro Objects (I): Morphology and Flux Ratios of Shocked Emission, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A Detailed Study of Spitzer-IRAC Emission in Herbig-Haro Objects (I): Morphology and Flux Ratios of Shocked Emission will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-230531