Object: Sh 2-155 (also designated Caldwell 9, Sharpless 155 or S155, or LBN529) is a diffuse nebula in the constellation Cepheus, within a larger nebula complex containing emission, reflection, and dark nebulosity. It is widely known as the Cave Nebula, though that name was applied earlier to Ced 201, a different nebula in Cepheus. Sh 2-155 is an ionized H II region with ongoing star formation activity, at an estimated 2400 light-years from Earth.
Sh 2-155 was first noted as a galactic emission nebula in 1959 in the extended second edition of the Sharpless catalog. It is part of the much larger Cep OB3 Association. Although Sh 2-155 is relatively faint for amateur observation, some of its structure may be seen visually through a moderately
sized telescope under dark skies.
Sh 2-155 lies at the edge of the Cepheus B cloud (part of the Cepheus molecular cloud), and is ionized by young stars from the Cep OB3 association. It has been suggested that radiation from the hot O-type star HD 217086 is compressing the region, triggering the
formation of a new generation of stars. A study of the region’s young stellar objects by the Chandra X-ray Observatory and Spitzer Space Telescope shows a progression of stellar ages in front of the cloud, supporting the hypothesis of triggered star formation.
Taken: October 19-21, 2024
Telescope: Astro-Tech 14 inch RC with Starizona Apex ED 0.65x reducer
Mount: Paramount ME II unguided
Camera: ZWO ASI2600MM-Pro (cooled to 0C; Gain: 100) Bin 1×1.
Focuser: Moonlite Nitecrawler
Rotator: Moonlite Nitecrawler
Guiding: Unguided
Filters used: Chroma Ha, OIII and SII with a ZWO 7-position Electronic Filter Wheel for 2" Filters
Exposures: 176×90 seconds Ha, 279×90 seconds OIII, and 256×90 seconds SII for a total exposure time of 17.78 hours; calibrated with 40 dark frames, 20 flat frames with 20 dark-flats.
Seeing Conditions:
Image capture and telescope control: Nighttime Imaging ‘N’ Astronomy (N.I.N.A.) and TheSkyX Pro with a SkyShed POD MAX observatory.
Processed with PixInsight, Photoshop CC 2024