Sh2-155 - Cave Nebula (Ara Jerahian)

Celestial hemisphere: Northern · Constellation: Cepheus (Cep)

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Sh2-155 - Cave Nebula

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Sh2-155 - Cave Nebula

Sh2-155, The Cave Nebula, is an ionized H II region, part of the Cepheus molecular cloud, residing at roughly 2400 ly away from us. It is another wonderful example of triggered star formation, mainly from the radiation emitted by the hot O-type star HIP 113306 (HD 217086), labelled in the annotation.

Also captured (albeit poorly given I only shot NB) in this image is the reflection nebula vdB 155, appearing in the upper right corner. There is conflicting information as to whether the reflection is illuminated by the star in the center of the vdB 155 annotation circle, HD 216659, or by the star, HD 216658, which is off-center.

Confusingly and by coincidence, both objects share the same entry number (155) in their respective catalogs, though they are unrelated.

Lastly, although not annotated, on the right-side mid-way down is Herbig-Haro 168 (HH 168). These bright nebulous objects are regions of hot newborn stars.

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Sh2-155 - Cave Nebula

Sh2-155 - Cave Nebula

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