NGC 7129

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Observation data: J2000.0 epoch
NGC 7129
A image of NGC 7129 by the Spitzer Space Telescope. Credit: SIRTF/NASA.
Right ascension	21^h 42^m 56^s
Declination	+66° 6′ 12″
Distance	3,300 ly
Apparent magnitude (V)	11.5
Apparent dimensions (V)	7′ x 7′
Constellation	Cephus
Physical characteristics
Radius	3 ly ^[1]
Absolute magnitude (V)	Unknown
Other designations	OCL 240, LBN 497
See also: Diffuse nebula, Lists of nebulae
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NGC 7129 is an open cluster star-forming region in a reflection nebula which a circa 2004 survey shows has over 130 very young stars each less than 1 million years old.

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.