Figure 1: Milky Way as seen in the northern sky from Lac Teeples on May 14, 2023.
This is a wide-field image of the Milky Way. This is in the northern sky, and is not the brightest part of the Milky Way: We are seeing the galaxy's disk but are not looking in the direction of the galactic centre. The star near the centre of the image is Deneb, an extremely bright and hot star in the constellation of Cygnus the swan. It is one of the three stars of the “summer triangle” with Vega and Altair.
Of the brightest stars in our sky many are bright by virtue of being quite close to us. Deneb is intrinsically bright – it is relatively far away but shines brightly because it is emitting a vast amount of light. It has a magnitude of 1.25 making it the 19’th brightest star and is a blue-white supergiant. Of the 30 brightest stars Deneb is the most distant - twice as far away as any other.
Deneb is a mere baby as stars go and we know that because it is a blue-white supergiant – a type of star that burns so brightly that it cannot live very long. Wikipedia says that it’s around 100,000 times brighter than our Sun. If you ever travel in the direction of Deneb don’t forget your SPF 10million starscreen. Since Deneb will “soon” explode as a supernova I recommend staying away.
Deneb has a declination of 45 degrees, meaning that it crosses nearly overhead in Ottawa (latitude 45 north). In galaxies like ours bright stars are typically born in spiral arms, burn brightly and then die or explode within those arms. Deneb is no exception, and is located in the “Orion” spiral arm of the Milky Way. Our Sun, Polaris, the main stars of Orion, and other familiar stars are also in this spiral arm. See Figure 2.
Figure 2: Spiral arms of the Milky Way galaxy in the vicinity of the Sun. From Wikipedia "Orion Arm".
Figure 3: Another view of the Milky Way as seen in the northern sky with key objects identified. Observed at Lac Teeples on May 14, 2023.
A few of the objects in this part of the sky are identified in Figure 3. To the right of Deneb is another bright star, Sadr. Sadr is emitting 30,000 times as much light as our Sun and will also live a short but exceptionally bright life. Sadr is also in the constellation Cygnus.
Cygnus is home to these stars and also several nebulae. Below Deneb we see the North America nebula (shaped like … North America). Facing this is the Pelican nebula which appears much dimmer in this image. The two nebulae are probably one, with a dark patch of dust in the foreground blocking the light in the area between them. The bright section facing the “Caribbean” is known as the Cygnus Wall.
On the far left of the image is a faint red patch. This is the nebula IC-1396, within which is the more famous “Elephant’s Trunk Nebula”. Near Sadr is much nebulosity in the characteristic red emission of the Hydrogen Alpha line.
One more thing… along the bottom of the image, roughly 2/3 of the way to the right of centre is another faint nebula. This is the famous Veil Nebula, a supernova remnant. The right side of it, the “witch’s broom” can be seen with a bright star in the centre. Facing this, on the left, we can see some bright colours of the shell that was created when this massive star exploded.
This image of the Milky Way was captured with a ZWO ASI-294MC Pro camera, a Canon EFS 24mm pancake lens, an Astromechanics focus controller and a Sky-Watcher Star Adventurer mini mount on a tripod. A ZWO duo-band filter was used to enhance the red nebulae.
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