Explaining Why Medium-Class Stars Produce X-rays

Scientists have taken the first steps towards understanding the reason why the late B to mid A classes of stars emit radiation in the X-ray portion of the electromagnetic spectrum, when they shouldn't theoretically be capable of doing this.

Most types of main sequence stars produce these radiations, and, in some of them, the mechanisms that lead to the creation of X-rays have been very well understood. But some stellar types were found to release these highly-charged particles even if no discernible mechanisms of productions were found.

Massive stars, for example, produce such photons due to interaction between strong stellar winds and their extended atmospheres. The friction is sufficiently intense to create X-rays, astronomers say.

Conversely, on lower-mass types of stars, the radiation was found to be produced by the interactions between their photosphere and twisting magnetic fields. Experts had no problem figuring out this mechanism either.

But, in the late B to mid A classes of stars, none of these mechanisms should be sufficiently intense to allow for the creation of such powerful radiation. Yet observations carried out with specialized telescopes revealed that this type of light was produced nonetheless.

Studies conducted with the Einstein Observatory and the German ROSAT satellite have demonstrated in the past two decades that at least some of these type A and B stars had companions around them. That is to say, they were found to be part of binary systems, Universe Today reports.

In more recent times, experts used telescopes featuring adaptive optics (AO) technology in their attempt to unravel this mystery. However, results were mixed, in the sense that, while some of these stars revealed low-mass, hidden companions, others did not.

These findings indicate two possibilities – either the stars themselves are the source (which puts researchers back to square one), or there their companions are too small, and yet capable of influencing telescope readings.

Statistically speaking, it was found that about 43 percent of type A and B stars that are X-ray sources have hidden companions. In normal stars, that percentage drops to 12. At this point ,scientists are still weighing in the alternatives.

It could be that all X-ray stars have companions, and that not all telescopes are equipped to detect them. This will be tested in the future, as telescopes such as the NASA Chandra X-ray Observatory will begin to look more deeply into this matter.