NGC 654

NGC 654 in Cassiopeia. Image credit: Antonio F. Sánchez  

NGC 654 is a small family of between 60 and 80 stars that were born about 15 - 20 million years old, similar to the previous clusters, which suggests that all have had a similar origin. Its central stars, the largest, are in a very dense interstellar medium, while a certain amount of gas has been detected in the periphery. This suggests that interstellar gas has been able to be displaced from the central zones due to the wind formed by the more massive stars, or by the effect of a supernova that, as a fan, has dissipated much of the gas. This cluster suffers an important and peculiar phenomenon that is called extinction, basically consisting of the dust that stands between its stars and us obscures the image that reaches our retina, causing its color to deviate to reddish wavelengths. Thus, it has been possible to estimate the presence of two intermediate nebulae at a distance of 600 and 3000 light years, capable of reducing the brightness of their stars in various magnitudes, which are located about 7800 light-years.

Visually, NGC 654 is a beautiful open cluster in which, at low magnification, it is distinguished as a nebulous patch of rounded shape that accompanies a bright star, and on the surface of which spreads a score of tiny stars, flickering in the distance. If we use greater increases we can appreciate them more easily, and some more appear among the main stars, shining timidly.

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NGC 278

NGC 278 by HST. Image source: (1)

Although NGC 278 has a quiet appearance, it is actually going through a stage of great stellar production. Such production is visible in regions plagued with blue 'knots', mainly in the spiral arms of the galaxy. In these knots are newly formed stars.

However, stellar production of NGC 278 is unusual; Does not extend to the outermost regions of the galaxy, but only occurs within an inner ring with a diameter of 6,500 light-years. These two regions are visible in the image, with the galactic center and surrounding regions shining, in contrast to the darkened areas at the edges. This strange configuration seems to have been created by the fusion of NGC 278 with a smaller, gas rich galaxy that unleashed star formation in the central regions while the remnant dust of the small galaxy dispersed outwards. Whatever the cause, this kind of star formation ring, known as the 'nuclear ring', is extremely unusual in galaxies without bars at its center, making NGC 278 a very rare object.

More details here: NGC 278

NGC 278 is in the northern constellation of Cassiopeia. Image source: (2)