Rotanev — いるかの二重星

Rotanev, Beta Delphini, is the brightest star in the small but distinctive constellation Delphinus. It is an F-type subgiant of spectral class F5 IV about 101 light-years away, paired spectroscopically with an F-type companion in a 26.66-year orbit. The pair is just barely within the reach of speckle interferometry at its widest separation (0.5 arcseconds). Combined magnitude is 3.63.

Rotanev marks the southwest corner of the tiny diamond of Delphinus, one of the sky's most charming small constellations. Binoculars readily show the diamond pattern. The spectroscopic binary within Rotanev is too close to split visually; the primary appears as a steady pale yellow-white point. Best observed July through November.

The name Rotanev — along with its partner Sualocin at Alpha Delphini — famously hides a signature: both names read in reverse give "Nicolaus Venator," a Latinized version of the name Niccolò Cacciatore, the assistant astronomer to Giuseppe Piazzi at Palermo Observatory in the early 1800s. Cacciatore quietly named the two stars after himself in the 1814 Palermo Catalogue, and the names have stuck.