If the radial velocity of a star changes in a period which is consistent with an orbiting planet, then it is now being classified as having possible planet.
I am sorry, but these rapid orbits are starting to disturb me.
This may be a new discovery of rapid pulsations of variable stars, which we have not observed before. Even the Sun, as much as it has been studied, is being suspected of being a variable star. As technology advances, our new discoveries are able to identify details that have never been observed before.
For the last few years, the discovery of new planets has excited me. However, these very short orbital periods are starting to make me wonder if we are not fooling ourselves.
Please do not get me wrong. The discovery and understanding of new stellar physics, which could simulate the rapid Doppler shifts observed, would be equally important.
Today, the study of physics and astronomy is getting very exciting. New things are being discovered almost every day.
Hi! :-)
Instead of going into pages of detail here, this link should answer your question:
http://outreach.atnf.csiro.au/education/senior/astrophysics/variable_types.html