There isn't a special name for a first magnitude star. The magnitude system is a way to classify stars based on their brightness as seen from Earth.

Here's how it works:

* Lower magnitude numbers indicate brighter stars. So, a 1st magnitude star is brighter than a 2nd magnitude star, and so on.

* The system is logarithmic. This means a difference of one magnitude corresponds to a brightness difference of about 2.5 times.

* There are negative magnitudes. The brightest stars in the night sky have negative magnitudes, like Sirius (-1.46).

So, while there's no specific name for a first magnitude star, you can say it's a "bright star" or refer to it by its specific name (like Vega or Altair).