StDr 158 - The Smaug Nebula
NEW DISCOVERY: Strottner-Drechsler 158 / the Smaug nebula
Strottner-Drechsler 158 is a new candidate of a planetary nebula in the constellation Serpens.
It was discovered by my friends and teammates Xavier Strottner and Marcel Drechsler in 2021.
This photo was taken in collaboration with Sven Eklund from Sweden and was processed by Marcel Drechsler It is the first official image of this faint object. However, StDr 158 is visible as a pale structure in numerous widefield photos of the region.
Strottner-Drechsler 158 is a new candidate of a planetary nebula in the constellation Serpens.
It was discovered by my friends and teammates Xavier Strottner and Marcel Drechsler in 2021.
This photo was taken in collaboration with Sven Eklund from Sweden and was processed by Marcel Drechsler It is the first official image of this faint object. However, StDr 158 is visible as a pale structure in numerous widefield photos of the region.

Description
This emission shell around the star V343 Serpentis is a symbiotic Mira system consisting of an M3 star and a white dwarf.
However, since we detected a relatively strong OIII signal in the emission shell around V343 Serpentis and a white dwarf is part of the system, it is possible that this structure is a former planetary nebula. Ordinary emission shells around a symbiotic Mira system usually show little to no OIII, so it is possible that this shell is from a PN phase of the white dwarf.
Given V343 Serpentis' distance of about 2700 parsecs, the emission shell appears to be very large, but is still within the realm of possibility for a planetary nebula.
Another explanation is that the OIII emission results from the ejecta of the symbiotic star, which is ionised when excited to luminate by the white dwarf. In the optical spectrum, these nebulae look like classical planetary nebulae - there seems to be no difference.
However, in terms of physics (and lifetimes) they are completely different systems.
Detailed information about the binary star system V343 Serpentis:
Distance:
Mean distance between PC = 2729.0, 2472.3 near and 3043.7 far (geometric).
Mean PC distance = 2665.7, 2364.3 near and 3362.6 far (photogeometric).
Kenyaon et al. 1987 give the companion as an M3-4 III giant in the optical spectrum.
This means that the system has a very large Roche lobe, but it is only weakly gravitationally bound.
The WD must be relatively bright so that it is not completely eclipsed by the giant star M.
The catalogue of spectroscopic double orbits even gives a fairly accurate period (450 days) and velocity of the companion's orbit.
https://vizier.cds.unistra.fr/viz-bin/VizieR-5?-out.add=.&-source=B/sb9&Seq=1795
The orbit is relatively eccentric with e = 0.13 - i.e. it changes its orbit from 0.86 to 1.135 of the semi-axis.
Distance:
Mean distance between PC = 2729.0, 2472.3 near and 3043.7 far (geometric).
Mean PC distance = 2665.7, 2364.3 near and 3362.6 far (photogeometric).
Kenyaon et al. 1987 give the companion as an M3-4 III giant in the optical spectrum.
This means that the system has a very large Roche lobe, but it is only weakly gravitationally bound.
The WD must be relatively bright so that it is not completely eclipsed by the giant star M.
The catalogue of spectroscopic double orbits even gives a fairly accurate period (450 days) and velocity of the companion's orbit.
https://vizier.cds.unistra.fr/viz-bin/VizieR-5?-out.add=.&-source=B/sb9&Seq=1795
The orbit is relatively eccentric with e = 0.13 - i.e. it changes its orbit from 0.86 to 1.135 of the semi-axis.
TARGET
Nomenclature: StDr 158, PNG 018.0+03.1, Smaug Nebula
Right Ascension: 18:12:22.14
Declination: -11:40:7.12
Size: 13.5 arc minutes
EQUIPMENT USED
Twin APM TMB LZOS 152 refractors, Celestron C14 EdgeHD
10Micron GM2000 HPS mount, iOptron CEM120
Twin QSI6120 CCD cameras, ZWO ASI1600MM Pro
Astrodon and Chroma filters
Nomenclature: StDr 158, PNG 018.0+03.1, Smaug Nebula
Right Ascension: 18:12:22.14
Declination: -11:40:7.12
Size: 13.5 arc minutes
EQUIPMENT USED
Twin APM TMB LZOS 152 refractors, Celestron C14 EdgeHD
10Micron GM2000 HPS mount, iOptron CEM120
Twin QSI6120 CCD cameras, ZWO ASI1600MM Pro
Astrodon and Chroma filters
IMAGE CAPTURE
Blue: 26x300"
Green: 20x300"
Red: 21x300"
Ha: 44x900" bin 1x1, 127x300" bin 2x2
OIII: 95x900" bin 1x1, 200x300" bin 2x2
Total Integration: 67 hours 35 minutes
Pixel scale: 0.564 arcsec/pixel
Field radius: 0.209 degrees
Capture dates: 7-27 June 2022
Capture location: Fregenal de la Sierra, Spain
Blue: 26x300"
Green: 20x300"
Red: 21x300"
Ha: 44x900" bin 1x1, 127x300" bin 2x2
OIII: 95x900" bin 1x1, 200x300" bin 2x2
Total Integration: 67 hours 35 minutes
Pixel scale: 0.564 arcsec/pixel
Field radius: 0.209 degrees
Capture dates: 7-27 June 2022
Capture location: Fregenal de la Sierra, Spain
IMAGE PROCESSING:
PixInsight and Photoshop CS2, Image stacked by Sven Eklund and processed by Marcel Drechsler
PixInsight and Photoshop CS2, Image stacked by Sven Eklund and processed by Marcel Drechsler