NASA takes a closer look at Orion's belt and uncover mysterious.
One of the most recognizable constellations in the sky is Orion, the Hunter. Among Orion’s best-known features is the “belt,” consisting of three bright stars in a line, each of which can be seen without a telescope.
The westernmost star in Orion’s belt is known officially as Delta Orionis. (Since it has been observed for centuries by sky-watchers around the world, it also goes by many other names in various cultures, like “Mintaka”.)
Modern astronomers know that Delta Orionis is not simply one single star, but rather it is a complex multiple star system.
Delta Orionis is a small stellar group with three components and five stars in total including Delta Ori A which is actually two closely separated stars orbit around each other every 5.7 days, while a third star orbits this pair with a period of over 400 years.
This special class of star system is known as an “eclipsing binary,”.
By observing this eclipsing binary component of Delta Orionis A (dubbed Delta Ori Aa) with NASA’s Chandra X-ray Observatory for the equivalent of nearly six days, a team of researchers gleaned important information about massive stars and how their winds play a role in their evolution and affect their surroundings. The Chandra image is seen in the inset box in context with an optical view of the Orion constellation obtained from a ground-based telescope.
Since Delta Ori Aa is the nearest massive eclipsing binary, it can be used as a decoder key for understanding the relation between the stellar properties derived from optical observations, and the properties of the wind, which are revealed by X-ray emission.
The researchers also found that the X-ray emission from certain atoms in the wind of Delta Ori Aa changes as the stars in the binary move around. This may be caused by collisions between winds from the two stars, or from a collision of the wind from the primary star with the surface of the secondary star. This interaction, in turn, obstructs some of the wind from the brighter star.
Parallel optical data from the Canadian Space Agency’s Microvariability and Oscillation of Stars Telescope (MOST) revealed evidence for oscillations of the primary star produced by tidal interactions between the primary and companion star as the stars travel in their orbits. Measurements of the changes of brightness in optical light plus detailed analysis of optical and ultraviolet spectra were used to refine the parameters of the two stars. The researchers were also able to resolve some previously claimed inconsistencies between the stellar parameters and models of how the stars are expected to evolve with time.
Read NASA's article here.
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
 "Credits: NASA")
)
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}
)
){kind=small}
){kind=small}
)
)
)
)
)
){kind=small}
){kind=small}
){kind=small}
){kind=small}
){kind=small}