helium and hydrogen
Scientists know of 91 "natural" elements and several additional elements that have been created in the laboratory. It's likely that many of the "artificial" elements do exist, at least momentarily, in the aftermath of supernova explosions where even exceptionally heavy elements are thought to be created, but with half-lives that cause them to decay to nothingness before they actually get far enough from the star to be detected.
Very low. Such a companion would have been detected by now, even if only through its gravitational effects.
Yes, Sirius is a binary star system composed of two stars, Sirius A and Sirius B. As of now, there have been no confirmed exoplanets detected in orbit around either star.
The emission spectrum of each element has characteristic lines for each element. Analyzing the spectrum of a star, you can figure out what elements are present, and also get an estimate on how much there is of each element. For more information, check the Wikipedia article on "emission spectrum".
Hydrogen and helium are the most abundant elements in a star.
The sun belongs to the star class G-type main-sequence star, also known as a G dwarf star.
Hydrogen and helium are the most abundant elements in a star.
You would expect to find them in both.
Arcturus is in class A.
They can for sure be detected by GM. I would doubt a repo man would have that capability unless they are working for GMAC.
They Belong to the class asteroidea
Yes it a G class star