Sh 2-155, Cave Nebula

Sharpless 2-155
Sharpless 2-155: Cave Nebula in Auriga; Meade Schmidt-Newton 254mm f/4; Canon EOS 20Da; ISO 1600; 15 x 362s; Observatory Oberes Schlierental, Obwalden; © 15. 7. 2007 Eduard von Bergen
Sharpless 2-155
Sharpless 2-155: Cave Nebula in Auriga; Celestron RASA 11" f/2.22; ZWO ASI6200 Pro; Tentlingen; © 2020 Peter Kocher

Object Description

Sharpless 155 (Sh2-155, LBN 529) is a bright H-II region of a major nebula complex (Cepheus B molecular cloud) consisting of emission nebulae, reflection nebulae and dark nebulae, stretching over the constellation Cepheus. The nebula, about 2400 light-years away, is an active star-forming region. Young stars of the OB3 asterism are responsible for the ionization of the gas. Radiation from the hot O-type star HD 217086 is thought to be compressing gas in the region, triggering new star formation.

Sh2-155
Sh2-155: In visible light (DSS) and infrared (WISE) [147]

In the animated fig. 3 one can see how in the infrared (section WISE, Wide-field Infrared Survey Explorer) the dust clouds emerge brightly, which appear dark in visible light (section DSS, STSci Digitized Sky Survey).

The name "Cave Nebula" probably goes back to the English amateur astronomer and book author Sir Patrick Moore and his Caldwell catalogue, which was published in Sky & Telescope in 1995. The arch in the nebula looks like the entrance of a cave. Sh2-155 is called Caldwell 9 here. The name «Cave Nebula» was also used for the reflection nebula Ced 201 and VdB 152. [299]

Further infos at CDS: Sh2-155

RA    : 22h 57m 05.9s
Dec   : +62° 38' 09"
Mag   : 7.7 mag
Grösse: 50' x 30'

Finder Chart

Sh2-155 is located in the eastern part of the Cepheus constellation. It is circumpolar for Central Europe. The best observation time is May to December.

Chart Sh 2-155
Chart created using SkySafari 6 Pro and STScI Digitized Sky Survey. [149, 160]

References

147Aladin Lite; aladin.u-strasbg.fr/AladinLite (2020-12-23)
149SkySafari 6 Pro, Simulation Curriculum; skysafariastronomy.com
160The STScI Digitized Sky Survey; archive.stsci.edu/cgi-bin/dss_form
299Sh2-155; en.wikipedia.org/wiki/Sh2-155 (2021-03-25)