A Chandelier of Blue Stars


Maybe it’s because I did a lot of research on protostars, but I never cease to be amazed by the extreme beauty of the regions of star formation, in particular the one recently observed by the Hubble Space Telescope in the Tarantula Nebula, which is found in the Great Magellanic Cloud (satellite galaxy of ours) at about 160.000 light-years away from us.

In the midst of these dusts and gases so many new stars were formed by gravitational collapse, induced by shock waves of supernovae that exploded long before and by stellar winds of nearby stars. In this case they are stars of the class of blue supergiants and O spectral type (the hottest stars that exist in the universe). They are stars with a mass that is 25-50 times greater than that of the Sun, with a photospheric temperature up to 10 times higher, and with a radius up to 50 times greater. They are stars that literally prefer to live one day like a lion rather than 100 as a sheep; in fact, by burning hydrogen thermonuclearly much more quickly than stars like the Sun, they live very little: only a few hundred million years (about 10 times less than stars of solar type). But their short life is bright in blue and very high in its intrinsic brightness. They are sparks that have to be “immortalized instantly” (in astrophysical terms, we mean), but not to be slowly sipped in time as in the case of solar-type stars or the case of very cold but long-lived brown dwarfs.

Even their death will be worth of a lion, because such blue supergiants, instead of giving rise to slow expansions that culminate in planetary nebulae (that which will happen to the Sun, for example), will all explode as supernovae. Since this cluster of blue supergiants – there are about a hundred of them within a radius of only 15 light-years, in short, a real blue chandelier – could have been born roughly in the same time period (+/- 10.000 years) from a collapsed piece of the interstellar mother nebula, if the stars have a comparable mass, even their death could be a quasi-synchronous firework for astronomers who will see them explode in a few hundred million years (presumably using spatial interferometers with a 1-year baseline).

I therefore expect that in more or less 500 million years that area where at the moment these stars shine glorious, can become a multiple remnant of supernovae, made of strange arcs of light born from the interaction of different dynamically interacting shock fronts.

A kind of work of cosmic art made of various colors of glaze depending on the chemical composition of the excited gases, and with their dark collapsed residues hidden inside them, which depending on the mass could be neutron stars / pulsars / magnetars or black holes.

If then binary star systems are formed either by intrinsic nature or by gravitational capture, then I expect that one day two black holes will merge together, which would shake spacetime like when we hit a sheet to remove dust. And so in more or less one billion years astronomers will observe events – probably multiple but not synchronous – of gravitational waves, but with an accuracy in their measurement which presumably will be one million times greater than that obtained by the recent discovery of LIGO.
By the way, returning to the blue supergiant stars that it is possible to see in this beautiful image of HST, can they host Life? Not at all: too many ultraviolet and X-ray emissions.

I’m sorry to disappoint the new age lovers of the “Nordic Plejadian aliens”, but life in the biological sense of the term here is impossible in any form, even if these stars could host planets (however very difficult to find due to various reasons, among which the resolution in radial speed of the spectra and the limited dynamic range of the CCD cameras in this specific case). The only thing that matters here is the radiance of their resplendent but short life as they furiously burn Hydrogen to form Helium through thermonuclear reactions. Life, possibly even intelligent, can only be hosted in much colder stars (spectral types G> M).