Bibcode
Cuesta, L.; Phillips, J. P.
Bibliographical reference
Astronomy and Astrophysics Suppl. 104, 169-177 (1994)
Advertised on:
4
1994
Citations
18
Refereed citations
16
Description
We have observed 77 evolved planetary nebulae in the J, H, K, L', and M
photometric bands. As a consequence, we note that most PN fall into a
range -0.6 < (J-H)_0_ < 0.2 mag , and 0.0 < (H-K)_0_ <
1.2mag , whilst a few sources have also been detected in the range 1.0
< (K-L)_0_ < 5.3 mag . Most indices (J-H)_0_ are almost certainly
depressed through the influence of HeI 2^3^ S 2^3^ P emission, whilst
stellar continua appear to dominate ~ 6 sources, and components of high
temperature dust enhance (J-H)_0_ in several others. Fully 60% of
sources having (J-H)_0_ >=0.0 appear to be type I nebulae. Finally,
we note that H_2_S(1) and Q band quadrupole emission may be important in
enhancing K band fluxes for several of the nebulae, and the mean value
(H-K)_0_ =~ 0.88 mag for H_2_S(1) emission sources is significantly in
excess of the mean. As a consequence, the parameter (H-K)_0_ may prove a
useful tool in the prior selection of nebulae having shocked, neutral
gas. By contrast, the various L' band detections are likely to derive
from a mix of mechanisms, including emission from grains having a broad
range of temperatures.