H{alpha} variations of O9 subgiant HD57682

Among this select group, it stands out due to its sharp-lined photospheric spectrum. Since its discovery, the MiMeS Collaboration has continued to obtain spectroscopic and magnetic observations in order to refine our knowledge of its magnetic field strength and geometry, rotational period and spectral properties and variability.

In this paper we report new Echelle SpectroPolarimetric Device for the Observation of Stars (ESPaDOnS) spectropolarimetric observations of HD 57682, which are combined with previously published ESPaDOnS data and archival H{alpha} spectroscopy. This data set is used to determine the rotational period (63.5708+/-0.0057d), refine the longitudinal magnetic field variation and magnetic geometry (dipole surface field strength of 880+/-50G and magnetic obliquity of 79+/-4{deg} as measured from the magnetic longitudinal field variations, assuming an inclination of 60{deg}) and examine the phase variation of various lines.