NGC 7129, a reflection nebula in Cepheus

NGC 7129, a reflection nebula in Cepheus

Image Credit & Copyright: Adam Block/NOAO/AURA/NSF (

NGC 7129 is a reflection nebula of about 10 light-years across, located some 3,330 light-years away from Earth in the northern constellation of Cepheus. It is home to a young open cluster which contains more than 130 stars less than 1 million years old, very young by astronomical standards. These stars are responsible for illuminating the surrounding bluish, rosebud-shaped nebula.

The young stars have blown a large bubble in the molecular cloud that once surrounded them at their birth. Dust grains on the surface of the bubble are being heated by the intense light from the young stars within and making the nebula glow.

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.

In addition, a small number of deep red crescent shapes around NGC 7129 indicate regions where new stars are forming (but are not yet visible directly). These regions are outflows of gas called Herbig Haro (HH) objects. (The crescent shaped object near the top of the nebula is HH 103). The molecules in this gas region – H2O (water!) – are quite important (to us).

Ultimately the natal gas and dust in the region will be dispersed, the stars drifting apart as the loose cluster orbits the center of the Galaxy.

By analyzing the amount and type of (infrared) light emitted by nearly every star in the cluster within NGC 7129, scientists can find out which stars support the rings of debris, called circumstellar disks, in which planets may eventually form. Roughly half of the stars observed were found to have these disks. These observations will help astronomers determine how stellar nurseries shape the development of planetary systems similar to our own.

This image was obtained on September 23rd-26th, 2011 at Mount Lemmon SkyCenter.

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