NGC 7129

{{Short description|Reflection nebula in the constellation Cepheus}}

{{More citations needed|date=December 2012}}

{{Infobox nebula

| image = NGC_7129_(Spitzer_Space_Telescope).jpg

| caption= An image of NGC 7129 by the Spitzer Space Telescope.

| credit= SIRTF/NASA

| name = NGC 7129

| type = reflection

| epoch = J2000.0

| ra = {{RA|21|42|56}}

| dec = {{DEC|+66|6|12}}

| dist_ly = 3,300

| dist_pc = 1,010

| appmag_v = 11.5

| size_v = 7{{prime}} x 7{{prime}}

| radius_ly = 3distance × sin( diameter_angle / 2 ) = 3 ly. radius

| absmag_v =

| constellation = Cepheus

| notes =

| names = Cr 441, OCL 240, LBN 497

}}

NGC 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.{{Cite web | url=http://apod.nasa.gov/apod/ap070913.html | title=APOD: 2007 September 13 - NGC 7129 and NGC 7142}} A recent survey indicates the cluster contains more than 130 stars less than 1 million years old.{{Citation needed|date=October 2011}} 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.{{Citation needed|date=October 2011}}

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.{{Citation needed|date=October 2011}}