# How bright could Gliese 710 appear in 1.35 million years?

I read this article on Gliese 710 that stated it would come within about 1.1 ly (+/- 0.577 ly) of earth in 1.35 million years. Wikipedia states it would have an apparent magnitude of 0.5, and the original paper abstract states it would have a -2.7 apparent magnitude.

From reading the list of brightest stars, apparent magnitude of 0.5 would make it about the 10th brightest star, and -2.7 would make it the brightest (besides the sun).

I'm curious about the discrepancy between these sources.

How bright would Gliese 710 appear if it were at the near end (0.523 ly) and far end (1.677 ly) of the expected closest approach to us?

• Calculate it yourself: you can treat it as a point source, so irradiance goes as the square of the distance; magnitudes are a log scale. – Carl Witthoft Jan 6 '17 at 14:30

$$D_l = 10^{{m-M \over 5} +1} pc$$
where $D_l$ = luminosity distance, $m$ = apparent magnitude, $M$ = absolute magnitude, $pc$ = parsec.