Dengel-Hartl 5 in Cepheus

Dengel-Hartl 5 in Cepheus

Ancient Planetary Nebula

Constellation: Cepheus
Ra: 22h 19m 34s
Dec: +70d 56m 01s
Distance: 1300 - 1600 light years
Image Size: 11' x 9'
North: Right



Dengel-Hartl 5 is a large, ancient planetary nebula (PN) in Cepheus at RA 22h 19m 34s and DEC +70d 56m 01s. It is also designated as PK 111 + 11.1.
It was discovered in 1979 in a survey of Palomar Observatory Sky Survey (POSS) plates (#559) and described in the 1980 Astron. Astrophys. Research Note “A Search for Planetary Nebula on the “POSS””, vol 85, pp 356-358 by J. Dengel, H. Hartl and R. Weinberger. It is designated as DeHt 5, and not to be confused by DHW5, which is a different PN altogether (this is still a point of confusion for me). North is toward the right. The blue star in the center of the blue-green OIII-rich region is the central star of the PN: UCA3 322:74172 (white dwarf WD 2218+706). Beverly Lynds catalogued the brighter portion as LBN 538 in 1965.
Many PN are circular. The lower portion (below the H-a-rich region near the top of the object) is roughly circular. However, this deep image including that upper region indicates that it has a very unusual shape. It is ~ 9′ EW (up-down) and 7′ NS (right-left), but there is a faint halo extending north (right) beyond the brighter portion of the nebula, increasing the NS apparent size to 11′. DeHt 5 is estimated to be 1300 – 1600 light years distant, making it one of nearest known PN according to Dengel et al. Some reports suggest that the intrinsic morphology of DeHt5 was destroyed in interacting with the interstellar medium (ISM). It is suggested that it has been interacting with the ISM for > 74,000 years. Radio polarization images reveal a long “tail” behind DeHt5 in a direction opposite of the movement of its white dwarf star.

It is near the often-imaged reflection nebula, vdB 152, in the large molecular cloud, B175 (Bok globule) and can be seen at the upper left of Bernhard Hubl’s image of vdB 152 as a faint, red, crescent-shaped object.

My image contains 17 hours of exposures taken over several nights. The high contrast from very narrow (3 nm) H-alpha and OIII filters was utilized to bring out structure in this faint PN. H-a was mapped to red/magenta and OIII was mapped to blue-green (teal) to represent the color we would see if this object were bright enough to activate the cone sensors in our eyes. 1 hour of RGB data were added for star colors using a G2V (sunlike star) white point balance.

Please read my description of PN Abell 36 for a more detailed discussion of PN as markers for the end of life of star.

Exposure: 17 hrs Total: 8.5 hrs H-a, 7.5 hrs OIII, 1 hr RGB
Telescope: RCOS 16
Mount: Software Bisque Paramount ME
Oag: Astrodon MonsterMOAG
Acquisition: CCD AutoPilot4
Calibration: CCDStack2
Observatory Site: Sierra-Remote Observatories, Shaver Lake, CA
Camera: Apogee U16M
Filters: Astrodon 3nm OIII, H-a, Gen 2 RGB
Guider: SBIG ST-402
Camera Operation: MaximDL4.62
Processing: Photoshop CS5 Extended
Image Date: 06/17/2011 - 06/21/2011

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