D Eridani

d Eridani, also known as HD 27563, is a single star in Eridanus, in the direction of the Orion–Eridanus Superbubble, that is faintly visible to the naked eye at a magnitude of about 5.84. classifies this star as spectral type B5III, but catalog it as B7II.
File:EMEriLightCurve.png|thumb|left|A light curve for EM Eridani, plotted from Transiting Exoplanet [Survey Satellite|TESS data]. The 3.8 day period is marked in red.
It was used as a comparison star for 46 Eridani in four separate runs at La [Silla Observatory] in the 1970s and 1980s, but in 1989, both stars were found to be variable with similar periods of about four days, and d Eridani was assigned the designation EM Eridani. Despite the lack of reliable comparisons for EM Eridani, it was found that the power spectrum of its light curve is remarkably noisy, with two or four prominent oscillation periods centered around, and is classified as a slowly pulsating [B-type star].