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Sorry about the scarcity of posts last week.  Ferrebeekeeper opted to enjoy an extended Fourth of July by trying not to look at the internet (which paints a less-than-rosy picture of these (dis)United States of America).  I was out experiencing summer fun in the real world.  But that doesn’t mean we have forgotten about fireworks of the past.   We have just moved our perspective farther afield.

Above is the highest resolution image of Eta Carinae taken by the NASA/ESA Hubble Space Telescope.  Between 1838 and 1844 Eta Carinae nearly went supernova and briefly became the fourth brightest star in the heavens (well really the explosion/ejection event occurred 7500 years earlier and the photons only reached Earth in the mid-nineteenth century).  Astronomers are still arguing about what exactly transpired then in this messed up stellar system: one particularly dramatic theory is that the unstable blue super giant η Car A devoured a now unknown third star in the system!

In the actual universe Eta Carinae is almost certainly gone and a vast tsunami of strange electromagnetic radiation is rushing towards Earth…but nobody knows if this is true or when the supernova afterwash will get here.  Astronomers recently pointed Hubble at the Homunculus Nebula, the hourglass shaped cloud of matter which expands approximately one light year from the binary Eta Carinae system and took the color enhanced ultraviolet photo above. It is beautiful but ominous…let’s keep it in the back of our minds as we go about our little lives. This universe is a strange & savage place.

Eta Carinae is a star system 8,000 light years from the solar system.  It contains a luminous blue hypergiant star which probably has about 100 times the mass of the sun and shines 4 million times more brightly.  For those of you keeping tally, that gives the star approximately the same mass as 33 million earths!

Eta Carinae was originally cataloged by Edmond Halley in 1677 (hence its stylish Latin name) as a comparatively dim 4th magnitude star, however astronomers noticed that its brightness varied greatly over the decades.  In 1827 it began to become significantly more luminous and by 1843 it was the second brightest star in the night sky (after Sirius, our next door stellar neighbor which is only 8.6 light years away).  The star then dimmed down to the eighth magnitude—becoming invisible to the naked eye.  Today it is believed that this strange occurrence was a supernova impostor event in which the star nearly exploded.  Looking at Eta Carinae now through the Hubble telescope reveals two huge hemispheres of material ejected from the star.   Scientists have named this cloud the Homunculus nebula and it is nearly a light year in diameter.

Eta Carinae and the Homunculus Nebula as photographed by the Hubble Space Telescope

Stars as massive as Eta Carinae are very rare.  At this stage of galactic development there are perhaps a dozen in a galaxy the size of the Milky Way (which contains 200 billion to 400 billion stars).  Eta Carinae is probably fated to die in a hypernova explosion (an immense supernova event).  A similar impostor event to Eta Carinae’s 1843 flare-up was witnessed on SN 2006jc, a star within galaxy UGC 4904 (perhaps you now appreciate the Latin and Arabic names of familiar nearby astronomical objects).  SN 2006jc went hypernova two years after its impostor nova event.  It is very possible that Eta Carinae no longer exists but was destroyed a long time ago.  The light we see now is eight thousand years old.  Who knows what happened since then?

When Eta Carinae goes hypernova it will destroy star systems nearby.  Additionally,  a massive gamma ray burst will shoot from both of its poles as its center collapses into a black hole. Any living, earth-like world caught in such a beam would be sterilized completely–although we are mercifully not currently in Eta Carinae’s polar vector…

Eta Carinae’s Fate? A Hypothetical Illustration of a Hypernova Event with Gamma Ray Burst (Credit: Nicolle Rager Fuller/NSF)

Ye Olde Ferrebeekeeper Archives

September 2020