Eta Carinae is one the most massive and luminous star system in the vicinity of 10000 light years around the solar system. The Eta Carinae star is known for its violet behaviours in the past. In the mid 19th century, it had become so violet and bright that it had become the second brightest star in the sky. During that time it ejected huge amount of mass that can be used to create 10 new Suns. The reason of that tremendous outburst is still not clear. The nebula created by outbursts of stars is still moving outward. The astronomers at NASA’s Goddard Space Flight Center in Greenbelt, Maryland are using telescope on Earth and NASA’s satellites to observe the behaviour of Eta Carinae to understand the activities happening there and predict the future activities. A 3D model of Eta Carinae is also proposed by them.
Eta Carinae is a binary star system present at the distance of 7500 light years from the sun which have two massive stars. The smaller one is having mass equal to 30 solar masses and it’s one million times brighter than our sun. The bigger one is nearly 90 times massive than our sun and in 5 million times brighter. The both massive star revolve around Each other. Both stars eject large amount of ionized gases into the space which is also called stellar wind. The both stars are surrounded by dense gases and nebula which makes their observation difficult.
The orbit of secondary star is highly elliptical that is not usually seen. The smaller star comes closer to bigger star in every 5.5 years, at this time the stars are at their closest distance which is also called periastron. The periastron is not more than the distance between the planet Mars and Sun. During periastron, the solar winds of both stars collide with each other and create amazing structures which are still mysterious to astronomers.
The stellar winds produced by both stars are not same. The stellar wind of primary star consists of thick gases and produced at the rate of 1.6 million km/h and the secondary star produces stellar wind of lesser density and having mass lesser by 100 times but with the speed 6 times that of primary.
When the stars are at the farthest distance from each other the stellar wind from both star undergo head on collision and produces large cavity towards the side of smaller star just like bow shock. But when they reach periastron, the smaller star carves out cavity in the denser gases of primary star. You can understand this by viewing video released by NASA’s Goddard space flight center. They have simulated a 3D model of the Eta Carinae showing this amazing activity and structures which projects outward.
The stars are near their end of life and will explode either as supernova or hypernova. As the stars are very massive, the supernova will be very powerful and they will end up into the black hole. The effect of supernova on Earth and its life is a great concern. Some astronomers have said that the supernova produces Gamma Ray Bursts which have ability to deplete ozone layer. The depletion of ozone layer will lead to exposer to UV radiation from the sun and acid rain.
Many astronomers believe that the distance between star and Earth is very large and we need not to worry about. As an estimate, the normal distance of supernova should be less than 26 light year from Earth to destroy half of its ozone layer but as this supernova is 7500 light years away from us we need not to worry. The atmosphere and magnetosphere of Earth will protect us from radiations. But the satellite and other communication system may get affected due to high level of radiation. The astronauts in the space will also be at risk.
The technical details of the above points can be obtained from the following reference. The video is also released by NASA Goddard Space Flight Center which shows their current model of Eta Carinae.