NGC 3596 is a sleeping galaxy in the constellation Leo
My colleague is an astronomer Alexey Kudrya — I recently assembled another Galaxy. This sounds fantastic. But we are talking about processing “raw” monochrome images obtained by the James Webb Space Telescope – combining different spectral channels into one watchable picture long before the official release from NASA or ESA. Or it may happen that there will be no release, because most of the images taken by the Hubble and Webb telescopes remain only accessible to scientists. But Alexey periodically gets something from there for us.
So, before us seems to be a typical spiral galaxy from the constellation Leo – NGC 3596. There are many galaxies in the constellation Leo, because not far from it Virgo and Coma Berenices are constellations in which the largest clusters of galaxies are located, partially extending into neighboring constellations. Plus, somewhere here lies the direction to the north pole of our galaxy, and therefore these are the most distant areas of the sky from the Milky Way strip, and outer space here is minimally dusty – nothing prevents us from seeing intergalactic distances.
What is interesting about the galaxy NGC 3596?
Discovered by William Herschel in 1784, it is a fairly faint object – about 11th magnitude – making it a hard-to-see galaxy for amateurs. And astronomers did not spoil her with attention for a long time. If you look for it on the Internet, the most decent picture will be something like this:
But it’s good that at least one was found
Attempts to find out the distance to NGC 3596 by redshift initially yielded a result of 74 million light years, which was quite consistent with its dim, featureless appearance – a distant star city – hence it is not really visible.
But subsequent measurements using a number of other markers (such as variable and supernovae, red giants and globular clusters) reduced the distance to this galaxy by almost one and a half times – to 55-57 million light years. NGC 3596 “closer” to the boundaries of the Local Group of Galaxies, and turned out to be a member of a galactic group known as the “Leo Triplet,” consisting of such famous galaxies as M65, M66, and NGC 3628. However, the distance to this trio was previously considered twice as close – about 35 million light years.
Having studied this group of galaxies as a complex, and not one at a time, astronomer from the Byurakan Astrophysical Observatory (Armenia) Abraham Makhtesyan and his research team came to the conclusion that this is a single group of galaxies that demonstrates noticeable dynamics of its members. The relative speed of these galaxies is quite high, and this does not allow us to rely on the redshift value when measuring the distance to them. As a result, the distances to these galaxies, including NGC 3596, were revised. As a result, ideas about the galaxies of this group have changed greatly. They turned out to be much larger and brighter than previously expected, but the heroine of today’s story, NGC 3596, on the contrary, turned out to be a “low surface brightness galaxy.” Any other galaxy in its place would shine 2-3 times more intensely. Although in its structure it is a fairly typical barred spiral galaxy.
However, in infrared images the bridge is barely noticeable, and one even gets the impression that the spiral branches do not reach the bulge, breaking off on the approach to it.
What could cause such a low absolute luminosity of the galaxy NGC 3596?
A meager number of stars, or an insufficient number of massive stars?
There may be a huge number of dwarf stars, but the luminosity of a galaxy is primarily determined by the giant stars. After all, the dependence of luminosity on mass is not linear. If a star has a mass 10 times the mass of the Sun, its luminosity at different periods of its evolution can exceed the solar luminosity by tens of thousands of times and even hundreds of thousands of times.
Imagine, if a cloud of hydrogen with a mass of 10 suns gives birth to 10 stars like the Sun, they will shine like 10 Suns.
Nothing special
But if this same cloud collapses into one single star with a mass of 10 suns, then this star will shine like 100 thousand suns. True, it will burn faster.
Could it be that all the giant stars in the NGC 3596 galaxy have already burned out?
It would be weird
Another thing is more likely – that for some reason in this galaxy there have not been any violent cataclysms for a long time, leading to the emergence of multiple centers of star formation – very few of these are visible in the photograph. This means that stars are formed here calmly, slowly, and mostly of modest size and mass.
Well, this gives hope that the relatively quiet evolution of this galaxy will provide a chance for the emergence of life on many planets around many stars like the Sun, of which there are probably many.
The calm may also be temporary. Being at some distance from the Leo Triplet, this galaxy does not yet experience tidal disturbances from other stellar cities. But inside it most likely there is a supermassive black hole with a mass of about 10 million solar masses, which is now “sleeping” – not showing vigorous activity. The sleep of a supermassive black hole is a poorly understood phenomenon. Our Galaxy also has a sleeping supermassive black hole, and no one knows when it will wake up and how it will turn out for the entire Milky Way Galaxy. Therefore, we look with interest at other galaxies and try to unravel such patterns in advance.
