7129 is a reflection nebula located 3,300 light years away in the
constellation Cepheus. A young open cluster is responsible for
illuminating the surrounding nebula. A recent survey indicates the
cluster contains more than 130 stars less than 1 million years
old. NGC 7129 is located just half a degree from nearby
cluster NGC 7142.
The nebula is rosebud-shaped; the young
stars have blown a large, oddly shaped bubble in the molecular cloud
that once surrounded them at their birth. The rosy pink color comes from
glowing dust grains on the surface of the bubble being heated by the
intense light from the young stars within. The ultra-violet and visible
light produced by the young stars is absorbed by the surrounding dust
grains. They are heated by this process and release the energy at longer
infrared wavelengths as photographed by the Spitzer Space Telescope.
The reddish colors in the false-colour infrared image suggest the
distribution of hydrocarbon rich molecular material.
The much cooler molecular cloud outside the bubble is mostly invisible
to Spitzer. However, three very young stars near the center of the
nebula are sending jets of supersonic gas into the cloud. The collision
of these jets heats carbon monoxide molecules in the nebula. This
produces the complex nebulosity that appears like a stem of a rosebud.