This is Melotte 15, an Open Cluster in the constellation of
Cassiopeia, probably better known as "The Heart of the Heart"; it is
the centre cluster of stars within The Heart Nebula, IC1805 (also known as
Sharpless 2-190). Melotte 15 is about 7,500 light years away from Earth.
When photographed under visible wavelength, the nebula's
intense red colour and its configuration are driven by the Hydrogen Alpha
radiation emanating from a small group of stars near the nebula's centre. This
open cluster of stars, known as Melotte 15, contains a few bright stars nearly
50 times the mass of our Sun, and many more dim stars that are only a fraction
of our Sun's mass. The grouping is only about 1.5 million years old and its
lifespan is expected to be as short as 3-6 million years.
This image was created by adopting the Hubble false-colour
palette for mapping narrowband emissions from Sulphur, Hydrogen Alpha and
Oxygen atoms to the red, green and blue channels respectively. So, the
cyan/blue colours are the intense reds (Hydrogen Alpha) that you would normally
see when photographed under visible wavelength, with the yellow/orange colours
representing the Sulphur.
Imaged over two nights, with just over 6 hours of total
integration time.
25x5mins Ha, 25x5mins Sii, 25x5mins Oiii, plus Darks Flats
and Flat Darks. Stacked and processed in PixInsight, with final colour
balancing in Photoshop.
