Highest Resolution Image of Eta Carinae
An international team of astronomers have used the Very Large Telescope Interferometer to image the Eta Carinae star system in the greatest detail ever achieved. They found new and unexpected structures within the binary system, including in the area between the two stars where extremely high velocity stellar winds are colliding. These new insights into this enigmatic star system could lead to a better understanding of the evolution of very massive stars.
This colossal binary system consists of two massive stars orbiting each other and is very active, producing stellar winds which travel at velocities of up to ten million kilometres per hour . The zone between the two stars where the winds from each collide is very turbulent, but until now it could not be studied.
|This image represent the best image of the Eta Carinae star system ever made. The observations were made with the |
Very Large Telescope Interferometer and could lead to a better understanding of the evolution of very massive stars
The central area where the winds collide is so comparatively tiny -- a thousand times smaller than the Homunculus Nebula -- that telescopes in space and on the ground so far have not been able to image them in detail. The team has now utilised the powerful resolving ability of the VLTI instrument AMBER to peer into this violent realm for the first time.
image is a colour composite made from exposures from the Digitized Sky
Survey 2 (DSS2). The field of view is |
approximately 4.7 x 4.9 degrees [Credit: ESO/Digitized Sky Survey 2. Acknowledgment: Davide De Martin]
The new VLTI image clearly depict the structure which exists between the two Eta Carinae-stars. An unexpected fan-shaped structure was observed where the raging wind from the smaller, hotter star crashes into the denser wind from the larger of the pair.
In addition to the imaging, the spectral observations of the collision zone made it possible to measure the velocities of the intense stellar winds . Using these velocities, the team of astronomers were able to produce more accurate computer models of the internal structure of this fascinating stellar system, which will help increase our understanding of how these kind of extremely high mass stars lose mass as they evolve.
The findings are published in the journal Astronomy & Astrophysics.
 The two stars are so massive and bright that the radiation they produce rips off their surfaces and spews them into space. This expulsion of stellar material is referred to as stellar "wind," and it can travel at millions of kilometres per hour.
 Measurements were done through the Doppler effect. Astronomers use the Doppler effect (or shifts) to calculate precisely how fast stars and other astronomical objects move toward or away from Earth. The movement of an object towards or away from us causes a slight shift in its spectral lines. The velocity of the motion can be calculated from this shift.
Source: European Southern Observatory - ESO [October 19, 2016]