Hemisphere:  Northern  ·  Constellation: Cepheus (Cep)  ·  Contains:  21 zet Cep  ·  22 lam Cep  ·  B174  ·  NGC 7261  ·  PK104+00.1  ·  Sh2-134  ·  Sh2-135  ·  The star ζCep  ·  The star λCep
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Part II: Lambda Cephei (λ Cephei), Sh2-134 and the Cep OB2 Association, 


            Daniel Erickson
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Part II: Lambda Cephei (λ Cephei), Sh2-134 and the Cep OB2 Association

Getting plate-solving status, please wait...
Part II: Lambda Cephei (λ Cephei), Sh2-134 and the Cep OB2 Association, 


            Daniel Erickson
Powered byPixInsight

Part II: Lambda Cephei (λ Cephei), Sh2-134 and the Cep OB2 Association

Imaging telescopes or lenses: Williams Optics RedCat 51

Imaging cameras: ZWO ASI183 MC PRO

Mounts: Sky-Watcher HEQ5

Guiding telescopes or lenses: ZWO 30F4 Miniscope

Guiding cameras: ZWO ASI 120 mini

Software: Starnet ++  ·  Adobe Creative Cloud  ·  Siril

Filters: Optolong L-Pro 2"

Accessory: ZWO AsiAir Pro

Dates:June 2, 2021

Frames:Optolong L-Pro 2": 120x240" (8h) (gain: 53.00) -15C

Integration: 8h

Darks: 30

Flats: 30

Flat darks: 30

Avg. Moon age: 22.33 days

Avg. Moon phase: 48.12%

Bortle Dark-Sky Scale: 6.00

RA center: 22h14m31s.653

DEC center: +58°4317.64

Pixel scale: 1.994 arcsec/pixel

Orientation: -9.082 degrees

Field radius: 1.671 degrees

More info:Open 

Resolution: 5091x3232

Locations: Backyard, Tacoma, WA, United States

Data source: Backyard


Sometimes it's less about the image, and more about the larger context, the story.

Lambda Cephei is located in a stellar association called Cep OB2. This is a very loose, very large and widely-separated association of hot, young, luminous Class O and B stars that is surrounded by an expanding cloud of dust and gas called the Cepheus Bubble. The most prominent and well-known member of the Cep OB2 is IC1396, the Elephant Trunk Nebula.

If you have lost your bearings, orient yourself by taking a look at this beautiful Cepheus Wide Field by Jeffrey Horne. Lambda Cephei is located "next door" to IC1396 at the center of Sh2-134, which comprises the majority of the nebulosity in this image.

Other HII Ionized regions (Sharpless (Sh2) objects) associated with Cep OB2 are Sh2-129, Sh2-133 and Sh2-140, all visible on Jeff's widefield. At the center of each of these are the young hot OB stars, like Lam Cep. They emit large amounts of UV radiation and ionize the hydrogen, burning it out and creating a shockwave that radiates outward from the star. When the shockwave encounters denser areas where there are other stars and protostars, the gas and dust stacks up and creates pillars, elephant trunks and ridges--the wondrous structures we love to photograph.

Lam Cep itself is a runaway star. It is moving at high speed on a seemingly independent trajectory, creating a shockwave ahead of it, as seen in this image. The explanation for this movement is that it was ejected by a supernova from NGC 7190 (see Jeff's image again). More recent data suggests that NGC 7190 was not the origin, but that the movement of Lam Cep was still the result of a supernova ejection. IR imaging studies of the region have now begun in the hopes that this will provide the evidence to decide the issue.

Whatever the origin of Lambda Cephei's trajectory, the power of the Class O star is on full display in this image. Large sections of HII have already been fully ionized and a vague reflection nebulosity is visible near the star with the shockwave visible further to the lower left. The star will continue on its current trajectory for several million more years, before exploding in its own supernova and possibly forcing other stars onto new trajectories.

Also visible in this picture is Barnard 174, a dark nebula no doubt concealing a stellar nursery resisting Lam Cep's shockwave. Further away is the beautiful Zeta Cephei (ζ Cep), a bright orange supergiant (Class K1.5)

This area is rather faint, seldom-imaged and without a recognizable structure, making it less interesting as a photograph. Nonetheless, it is a fascinating part of sky when you consider the complex history and ongoing dynamics of the Cepheus Bubble.

Thanks for stopping by and taking the time to read the story of Lambda Cephei and part of the Cep OB2 Association. I hope you enjoyed the picture-story and that it gives you some insight and inspiration.


If you haven't already, check out the other images in my Cep OB2 Series:

Part I: The Complexity of Phenomena. IC 1396 and the Power of Stars.

Part III: HD202214, Sh2-129 and the Cep OB2 Association

Part IV: The Origins of Cep OB2, NGC7160, and Sh2-140

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Lam Cep (HD 210839)

Spectral Class: O6.5I(n)fp

Mass 51.4 M☉

Radius ~20 R☉

Luminosity 630,000 L☉

Distance: 950 parsecs (3098ly) [disputed]

Also in this Image:

Zeta Cephei: Orange Supergiant

SH2-134: HII (ionized) region being excited by Lam Cep.

B174: Dark Nebula

SH2-135: HII (ionized) region (not currently affected by Lam Cep)

NGC7261: Open cluster

PK 104+00.1: Planetary Nebula

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I'd like to thank these Astrofriends for giving me inspiration for this image.

@Jeffrey Horne (Cepheus Wide Field)

@Göran Nilsson (Sharpless in Cepheus)

@Thilo (Sh2-134)