2 Attachment(s)
Object of the Week October 11, 2020 - The Wizard
Sharpless 142, Sh2-142, LBN 511
Constellation: Cepheus
Type: Diffuse Emission Nebula
RA: 22h 47.5m
DEC: -58° 03'
Size: 35.0’ x 18.5’
NGC 7380, Cr 452, Lund 1022, OCl 244, Mrk 48
Constellation: Cepheus
Type: Open Cluster
RA: 22h 47.3m
DEC: -58° 08'
Mag: 7.2
Size: 20’
Tucked away in the southeastern corner of the constellation Cepheus are this week’s Object of the Week pair, NGC 7380 and The Wizard. The open cluster, NGC 7380, was discovered by Caroline Herschel on August 7, 1787 on the occasion of being free from recording duties when her brother William was absent preparing for his marriage. To Caroline NGC 7380 was merely a coarsely scattered cluster of stars. She did not detect the faint nebulosity which engulfs the star cluster.
This nebulosity is The Wizard, commonly known as the Wizard Nebula, an emission nebula (HII) that surrounds the open cluster. Cataloged as Sharpless 142 or Sh2-142 for short, the name comes from a catalog of 312 emission nebulae compiled by Steward Sharpless. The first edition was published in 1953 with 142 objects (Sh1) and the second and final edition was published in 1959 with 312 objects (Sh2). Sh2-142 is a portion of the extensive Cepheus ΟB1 Association, an “old” star-forming region that extends some 2,000 light years wide. NGC 7380 has 125 members of 9th magnitude and fainter. Most are Type Ο and early Β stars that are still embedded in their natal cocoons of dust and gas. The nebula is ionized by the eclipsing binary star DH Cephei (HD215835), together with the many young energetic stars within the cluster.
Attachment 4037
Image Credit & Copyright: Dean Jacobsen (www.astrobin.com/users/deanjacobsen)
NGC 7380 is a fairly easy object for amateur telescopes under moderately dark skies. However despite being fairly large, the Wizard Nebula is a challenging object to observe and requires an OIII filter and extremely clear, dark skies. But It can be seen in a small telescope. Visually, the nebula’s size is comparable to that of the Moon.
Sue French in Deep-Sky Wonders notes the following. “The cluster has a hazy background, but am I seeing unresolved stars or nebulosity? At 28x [105mm refractor] a green oxygen III filter seems to slightly enhance and extend the haziness with an unfiltered view.”
Christian Luginbuhl and Brian Skiff share their observations in the Observing Handbook and Catalogue of Deep-Sky Objects. “Though this cluster is involved with a faint nebulosity, none is easily discernable visually in amateur instruments. 15 cm shows the cluster nestled in a circlet of bright stars. It is 10’ diameter with 20 stars resolved over haze. About 40 stars are visible in 25 cm, including a distinctive V-shaped asterism pointing N. The brightest star (V=8.6) is on the SW at one end of the V. 30 cm reveals about 30 stars, including a bright pair about 10’ to the W (ADS 16260: V=7.6, 8.6; 31”; 117°).”
So why is Sharpless 142 commonly known as the Wizard Nebula? Visually, the interplay of stars, gas, and dust has created a shape that appears to some like a fictional medieval sorcerer. Perusing some of the many photos of the nebula I was unable to make the connection at first, until I came across this incredibly striking photo by J-P Metsävainio.
Attachment 4036
Image Credit & Copyright: J-P Metsävainio (http://astroanarchy.zenfolio.com)
This image was created in HST-palette (HST=Hubble Space Telescope) from the emission of ionized elements, R=Sulfur, G=Hydrogen and B=Oxygen.
"Fillet of a fenny snake,
In the cauldron boil and bake;
Eye of newt and toe of frog,
Wool of bat and tongue of dog,
Adder's fork and blind-worm's sting,
Lizard's leg and owlet's wing,
For a charm of powerful trouble,
Like a hell-broth boil and bubble.
Double, double toil and trouble;
Fire burn and cauldron bubble."
--William Shakespeare, Macbeth (IV.i.12-21)
Happy Halloween!
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