A closeup of Sirius in Canis Major, taken in moonlight, with the 130mm f/6 apo refractor. This is a stack of six 2-minute exposures and three 30-second exposures to reduce the core brilliance, with the short exposures blended in with a luminosity mask. All with the Canon 6D MkII at ISO 800. The diffraction spikes were added with Astronomy Tools Photoshop actions.
A montage of close-ups of the brightest stars of the winter season of the Northern Hemisphere, but also of the summer season of the southern hemisphere, as all these stars can be seen from southern latitudes, at least north of 35° South. However, if this were a collage of southern hemisphere “summer” stars (i.e. ones most prominent in December to February) I would have to include Canopus as well. Betelgeuse and Aldebaran, being cool red giants, are noticeably redder than the others, with Capella and Pollux being more yellow as they are cooler (in stellar terms) than the hot blue and blue-white stars such as Sirius and Rigel, buit not as cool in surface temperature as the red giants. If our yellow dwarf Sun were as far away as even nearby Sirius, it would be just magnitude 2, bright but not among the brightest stars in the sky, as seen from Sirius. Distances are as per Wikipedia, and may not reflect the latest measurements from the ESA Gaia satellite. All these stars are larger and more luminous than our Sun, but most appear very bright in our sky because they are relatively close, from 8.6 light years away for Sirius, to 65 light years away for Aldebaran. However, Betelgeuse and Rigel are truly luminous supergiants, being bright despite being much more distant at hundreds of light years away. I shot each of these on one night, November 19, 2018, using a 130mm Astro-Physics refractor at f/6 and a Canon 6D MkII at ISO 800 for a stack of 6 x 2-minute exposures blended with a stack of 3 x 30-second exposures to prevent the “core” of the star from brightening too much. I increased the vibrancy a lot to accentuate the stars’ colours. The sky is naturally deep blue as I shot these on a night with a waxing gibbous Moon in the sky. I applied similar processing steps to all the images to preserve the relative brightness of the stars, with Sirius the brightest, indeed the brightest star in the night sky. I added the diffraction spikes with the Astronomy Tools action, just for artistic effect.
Alya, Theta Serpentis, a double star in Serpens, not resolved here in this wide-field view. This is a stack of 4 x 4 minute exposures with the TMB 92mm apo refractor at f/4.4 with the Borg 0.85x field flattener/reducer and Canon 6D at ISO 800.
