Bibcode
Balick, Bruce; Gomez, Thomas; Vinković, Dejan; Alcolea, Javier; Corradi, R. L. M.; Frank, Adam
Referencia bibliográfica
The Astrophysical Journal, Volume 745, Issue 2, article id. 188 (2012).
Fecha de publicación:
2
2012
Revista
Número de citas
23
Número de citas referidas
19
Descripción
We present four-color images of CRL 2688 obtained in 2009 using the
Wide-Field Camera 3 on Hubble Space Telescope. The F606W image is
compared with archival images in very similar filters to monitor the
proper motions of nebular structure. We find that the bright N-S lobes
have expanded uniformly by 2.5% and that the ensemble of rings has
translated radially by 0farcs07 in 6.65 yr. The rings were ejected every
100 yr for ~4 millennia until the lobes formed 250 yr ago. Starlight
scattered from the edges of the dark E-W dust lane is coincident with
extant H2 images and leading tips of eight pairs of CO
outflows. We interpret this as evidence that fingers lie within
geometrically opposite cones of opening angles ≈30° like those in
CRL618. By combining our results of the rings with 12CO
absorption from the extended asymptotic giant branch (AGB) wind we
ascertain that the rings were ejected at ~18 km s-1
with very little variation and that the distance to CRL 2688,
v_{exp}/dot{ heta }_{exp}, is 300-350 pc. Our 2009 imaging program
included filters that span 0.6-1.6 μm. We constructed a
two-dimensional dust scattering model of stellar radiation through CRL
2688 that successfully reproduces the details of the nebular geometry,
its integrated spectral energy distribution, and nearly all of its color
variations. The model implies that the optical opacity of the lobes
>~ 1, the dust particle density in the rings decreases as
radius-3, and that the mass and momentum of the AGB
winds and their rings have increased over time.
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Antonio
Mampaso Recio