Eta Carinae Nebula
Photo montage: HST/NASA
The most massive explosion ever recorded by humans on planet Earth occurred 12.2 billion light years distant, sometime after September 15, 2008 in the southern hemisphere constellation Carina - ‘The Ship’s Keel’. Of particular interest within Carina is NGC 3372, the Eta Carinae Nebula, which was discovered by Nicolas Louis de Lacaille in 175152 as he searched the night skies from the Cape of Good Hope in South Africa. The Eta Carinae Nebula is between 6500 and 10,000 light years from earth. This beautiful, false color, photographic montage portrays a region of the nebula 50 light years wide. Red indicates sulfur, green represents hydrogen and blue reveals oxygen emission.
Star Birth Regions in Eta Carinae Nebula
Composite Photograph: NASA
There are several star birth regions in the Eta Carinae Nebula and astronomers are just beginning to understand the connection between massive stars that produce massive bursts of gamma ray radiation, and the creation of new stars.
GRB 080916C / gamma ray burst
Video: NASA/DOE/Fermi LAT Collaboration
Most of the extreme energy of this massive explosion was contained in the gamma ray region of the electromagnetic spectrum. The explosion was detected by the Fermi telescope satellite that was launched June 11, 2008 with specialty instruments to survey the gamma ray spectrum in the universe. The ‘name’ given to the star that exploded is GRB 080916C, and once again one prays for a more user friendly id for the general public. This image is a still photo taken from a NASA video. “The blue dots represent lower-energy gamma rays (less than 100 million eV); green, moderate energies (100 million to 1 billion eV); and red, the highest energies (more than 1 billion eV)” (Source 5).
To get a sense of the immense distance to this star note that the sun is 8 light minutes from earth, and Pluto, whose recent planetary status demotion this scribe refuses to acknowledge, is 12 light hours away from us. A light year, the distance covered by photons moving at the speed of light in one year, is 9.46 trillion kilometers (5.88 trillion miles), assuming a Julian Year and the speed of light = 299,792,458 m/s. At 12.2 billion light years away (1,154,120,000,000,000,000,000,000 km!), this stupendous gamma ray explosion occurred when the universe was only 1.5 billion years old.
GRB 080916C is likely a hypergiant, or super massive star whose mass exceeds 80X the sun’s and produces more than a million times as much light as the sun on average, explosive events excepted. Such giant stars are very rare; there may be only a few dozen among the 400 billion stars in the Milky Way. These super massive, giant stars exist near the Eddington Limit; that is, the outward pressure of their radiation is almost strong enough to exceed their gravitational field, thereby ensuring that their lives will end in a massive supernovae.
GRB 080916C / gamma ray burst afterglow
Video: NASA/DOE/Fermi LAT Collaboration
A Research Group at the Max Planck Institute for Extraterrestrial Physics in Germany found the afterglow of the GRB 080916C explosion. When that data was added to other observations, a calculation was possible to estimate the massive energy produced by this explosion. Visible light from our sun has an energy range of 2 to 3 electron volts. The GRB 080916C explosion lasted for 23 minutes and is the biggest gamma ray event on record. By comparison, it produced millions to billions of electron volts and was stronger than 9,000 supernovae. Furthermore, this explosion had the greatest total energy, fastest particle motion and highest energy for initial emission of any astrophysical event yet observed at any wavelength. The atomic particles emitting these high powered gamma rays must have been moving at 99.9999X the speed of light, likely the most extreme velocity of anything in the universe yet recorded. Click on Source #5 below to see a video of the GRB 080916C explosion at gamma ray wavelengths.
Eta Carinae - Massive Star Explosion to Black Hole
Artist: Nicolle Rager Fuller/NSF
Stupendous gamma ray bursts are two seconds or longer in duration, have no equal and are generated when massive stars run out of nuclear fuel and implode into black holes. The time delay between highest and lowest energy explosions in GRB 080916C is mysterious and not yet understood. As the star’s core collapsed into the black hole, jets of material bore through the collapsing star and blasted outward. Interactions with gas previously blown off the massive star generated bright afterglows that slowly faded. The mechanism behind the jets is poorly understood; the energy from something not yet precisely identified may be spinning, then collapsing, into the black hole to drive the jets outward. After they rip through the star, a supernovae follows and astronomers have a spectacular event at visible wavelengths to study.
Eta Carinae - 1843 Massive Explosion
Photo: CHANDRA / NASA
Another giant star in the Eta Carinae Nebula has the same name as the nebula and had a stupendous explosion in 1843 that was studied by the astronomers of that era. Eta Carinae became the second brightest star in the night sky (after Sirius) in 1843 although 7-8,000 light years away from earth. It was not destroyed by the massive explosion. It is still an extremely energetic, hypergiant, blue variable star with 100-150X the sun’s mass and luminosity 4,000,000X that of the sun.
This composite photograph above combines data from the Hubble Space Telescope and the Chandra X-Ray observatory and reveals the present state of the 1843 explosion. Blue regions are the visible light emissions thrown off from the massive star as detected by Hubble. This debris formed a bipolar shell around the star which is located at the brightest point of visible light. The bipolar shell is surrounded by a cloud of fainter material. Note the unusual jet pointing from Eta Carinae to the upper left. Chandra’s data is orange and yellow and reveals the X-ray emission produced when material thrown off from the star rams into nearby gas and dust. A hot shroud with temperatures in excess of one million degrees was created and extends far beyond the ‘cooler’ optical nebula. The circumference of this hot shroud defines the outer limit of the interactive region. X-ray data reveal that the outer material is rich in complex atoms such as nitrogen that formed deep inside Eta Carinae. The inner optical nebular glows faintly because of X-ray reflection that comes from very close to the star itself.
Recent data suggest that Eta Carinae may be a binary system, with a hot, low mass companion star providing most of the radiation output as a 5 million mph X-ray wind. Eta Carinae waxes and wains in brightness and is now barely visible to the naked eye at magnitude 5. Eta Carinae (the larger star only) is expected to undergo a final explosion/implosion into a supernovae/black hole in the near astronomical future.
Massive Star / Gamma Ray Burst Mode
Video animation artists: NASA/Fermi/Cruz deWilde
Very strong gamma ray bursts/explosions are not common. At least 1,000 strong gamma ray bursts are now detected each year, which equates to one burst every 100,000 years in a galaxy. These very strong gamma ray explosions allow astronomers to study stars at immense distances in the state they were in during earlier stages of the universe.
GLAST Satellite
Artist: SpectrumAstro / NASA
Observational data for the stupendous explosion of GRB 080916C was captured by the Fermi Gamma Ray Space Telescope satellite that was launched June 11, 2008. There are two instruments on this research satellite. The Large Area Telescope (LAT) with a field of view of 20% of the sky is conducting an all sky survey. The burst monitor within the Gamma-ray Large Area Space Telescope (GLAST) specifically studies gamma ray burst events. The Fermi Gamma Ray Space Telescope satellite is in a low orbit with a period of 95 minutes and the LAT can sweep across most of the sky 16X per day. The five year design lifetime is expected to last a decade. As does most space astronomy research, this project relies upon international cooperation. Partners include NASA, the US Department of Energy and research institutions in France, Germany, Italy, Japan, Sweden and the USA.
The Carina constellation name is Latin and translates as ‘the keel of a ship’. This obscure constellation was formerly part of Argo Navis, the large constellation representing the mythical ship ‘Argo’, in which Jason and the Argonauts set out to retrieve the Golden Fleece.
Carina in Argo - “The Ships Keel”
Engraving: Johann Hevelius 1690
As did Jason and his crew of friends in Hellenistic Greece set forth upon an epic adventure, so do today’s astronomers with telescopes of incredible design and capability situated on earth and in satellites that orbit our planet.
Argo replica sets sail
Photo: Alexey Bogdanovskiy / RIA Novosti
Many treasures have been found by those on this modern day scientific quest. One of the most recent and spectacular is this stupendously powerful, massive star explosion.
Sources:
1, 2, 3, 4, 5, 6, 7, 8
