Milky Way from Cygnus to Perseus: Many prominent emission nebulae

A 45°×60° view of the Milky Way in the constellations Cygnus, Cepheus, Cassiopeia, Camelopardalis, and Perseus is presented. This region is full of prominent emission nebulae that lie in the Local Arm and the Perseus Arm of the Milky Way, see section Remarks.

Images

Click on the image to load a high resolution (363 MP) version using a JavaScript viewer.

Remarks

This section provides additional information about some objects visible in the images. The nebulae are grouped by distance. Click on the links to load JavaScript presentations:

Objects at a distance of about 850 to 1100 pc

These objects lie in the local Orion Arm of the Milky Way.

• Cepheus bubble and nebulae that may be associated with it. These objects are located at a distance of about 1000 pc and are ionized by stars of the Cep OB2 association.
• Three other possible bubbles. Many nebulae in this direction are ionized to the Cep OB3 and OB2 associations at a distance of about 850 pc to 1000 pc. In the image, it appears that these objects, together with the Cepheus bubble, belong to a larger superstructure. High-resolution images of the center of the OB3 association are shown on the page SH2-155 (Cave Nebula).
• SH2-171 region, ionized by the CEP OB4 association and located at a distance of about 1100 pc.
• SH2-205 and IRAS 03306+5825 at distances of 1000 pc and 1050 pc, respectively.

Objects at a distance of about 2100 to 3400 pc

These objects lie in the Perseus Arm of the Milky Way.

• Nebulae in the Perseus Arm (western part), located at a distance of about 2900 pc to 3300 pc. For several of these objects, high-resolution images are also available in pages: SH2-142 (Wizard Nebula), SH2-162 (Bubble nebula), and SH2-170.
• SH2-190 and W4 superbubble/chimney: SH2-190 (also known as Heart Nebula) with a faint loop extending from it. This structure is the W4 superbubble, sometimes referred to as the W4 chimney, as it is believed that hot gas is transferred from the galactic disc to the halo through such structures (see Lagrois et al., 2009). The brightest region (SH2-190) is ionized by the cluster IC 1805, located in a distance of about 2100 pc (Gaia DR3). At this distance, the W4 structure has similar dimensions to the much closer Orion-Eridanus superbubble.
• Nebulae in the Perseus Arm (eastern part) located at distances between 2100 pc and 3400 pc. High-resolution images of SH2-184 (Pacman Nebula) can be found here.

Objects at other distances

• SH2-129 is located at a distance of about 712 pc (Corradi et al., 2014). A part of this nebula, designated as SH2-129B in the presentation, might be a separate object at a distance of about 1600 pc.
• The HII region ionized by γ Cas is located at a distance of about 170 pc and thus one of the closest emission nebulae. Its brightest part, SH2-185 (Ghost of Cassiopeia), also contains reflection nebulae.
• Si 3 is a faint but large HII region ionized by the blue supergiant α Cam, located at a distance of about 1700 pc. The stellar wind of this star appears to form a bubble.
• SI 2 is usually considered to be an HII region ionized by the spectroscopic binary AO Cas at a distance of about 1300 pc. However, the image shows that there are also significant [OIII] emissions and faint [SII] emissions in about the same direction. In the presentation, it can be seen that the Hα emissions (greenish) do not correlate well with the [SII] emissions (blue) and that AO Cas is not located in the center of the (highly ionized) OIII region. Thus, we might be seeing two different nebulae: an HII region ionized by AO Cas in its center, and another object that also emits [OIII] and [SII]. The second nebula has a typical morphology of an ancient planetary nebula. Due to its apparent size, such an object would have to be very nearby. SIMBAD reports several white dwarfs (and no OB stars) within the OIII region. (In the JavaScript viewer, they can be queried from SIMBAD by plotting a circle and pressing the shortcut 'O' or via the menu.) One candidate, which is not too far away and is close to the center, is Gaia DR3 395618925224225920 at a distance of 170 pc to 200 pc.

Image data

This image was calculated using data from the Northern Sky Narrowband Survey, DR0.2. Click the link for detailed information or visit the instruments page for information about the equipment. Here is some additional image-specific information:

Center position:	RA: 1:02h, DEC: 66°
FOV:	60°×45° (RA×DEC, through center)
Orientation:	JavaScript viewer: North is up Above: North is right
Scale:	10 arcsec/pixel (in center at full resolution)
Projection type:	Stereographic

References

 

Dominic Lagrois and Gilles Joncas. On the Dynamical Evolution of H II Regions: An Investigation of the Ionized Component of W4, A Galactic Chimney Candidate. II. Kinematics and Dynamics in the Latitude Range 3°; < b <= 7°. ApJ, 693(1):186–206, March 2009. [ DOI | http ]

 

Romano L. M. Corradi, Nicolas Grosso, Agnès Acker, Robert Greimel, and Patrick Guillout. Gas physical conditions and kinematics of the giant outflow Ou4. A&P, 570:A105, October 2014. [ DOI | arXiv | http ]

This work made use of the SIMBAD database, maintained by CDS, Strasbourg, France, and the Gaia public archive.