If the radiance of a thousand suns were to burst at once into the sky....

Now I am become Death, the destroyer of worlds

WR-104, The Pinwheel

WR-104 in Sagittarius imaged by the WM Keck twin 10-meter telescopes

Both the title and subtitle above are from the Hindu holy book, the Bhagavad-Gita and were famously uttered by Julius Robert Oppenheimer, the American physicist whose life and career were recently featured in a full-length Hollywood production. Oppenheimer spoke these words during a 1965 television interview when discussing that first nuclear test blast at the site that would later become known as Trinity.

He is less known for his contributions to Astrophysics, however. Oppenheimer collaborated in the discovery of the upper mass limit for a Neutron star, a mass limit above which a degenerate neutron core can no longer provide a barrier to collapse and will thus, collapse to become a black hole. Known as the TOV limit, short for Tolman-Oppenheimer-Volkoff limit, this upper limit is 3 solar masses and is the analogous limit for a Neutron Star as the Chandrasekhar Limit is for White Dwarfs (1.44 Solar masses).

Imagine, if you will, a star system containing a massive, intensely hot, luminous star that’s emitting a fierce and prodigious stellar wind in a binary orbit around a 20 solar-mass O4 - O5 main-sequence star. The former, a 10 solar-mass Wolf-Rayet star, is at the very end of its productive life.

Wolf-Rayet Stars

Exemplified by broad, strong emission lines of Helium, Oxygen, Nitrogen and Carbon, Wolf-Rayet stars are stars in the last productive phase of their lives for highly evolved, massive stars (> 10 Solar Masses). Most stellar spectra exhibit absorption lines (dark lines representing elements or compounds at specific “colors” or wavelengths). Wolf-Rayet stars are known for their extremely intense stellar winds and prodigious mass loss.

Discovered by their distinctive spectra by French astronomers C.J. Wolf and Georges Rayet in 1867, many Wolf-Rayet stars present without any hydrogen in their spectra and all, with broad emission lines of ionized Carbon, Nitrogen, Oxygen and Silicon.

Classic Wolf–Rayet stars have completely lost their outer hydrogen shell and are fusing helium or heavier elements in their cores. The Wolf-Rayet phase of a high-mass star’s evolution is considered to be the last stable point before the star’s spectacular demise as a Type-II, core-collapse supernova.

Add to the “mix”, that the material being ejected from WR-104 is producing a continuous spiral 200 Astronomical Units (1 AU is the earth-sun distance) wide with a period of 242 days.

If you have imagined this, then you have a clear idea of what WR-104 is. It is a potentially lethal stellar system about 8,400 light years (2.5 Kiloparsecs) distant in the direction of Sagittarius that sports a remarkable colliding-wind pinwheel nebula.

A Lethal Star System?

Width of spiral: 200 AU with a 242-day period