English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

The O9.7 V star HD 54879 is currently the only massive magnetic star whosemagnetic field geometry and rotation period are not constrained. Over the lastthree years, we gathered additional observations of this star, obtained usingvarious instruments at several astronomical facilities with, the aim toconstrain the rotation period and the magnetic field geometry. The new datainclude the first full Stokes vector observations with the PEPSIspectropolarimeter, installed at the Large Binocular Telescope. The acquiredspectropolarimetric observations show a very slow magnetic field variabilityrelated to the extremely slow rotation of HD 54879, which is also indicated ina dynamical spectrum, displaying variability of the H$\alpha$ line. The mostintriguing result of our study is the discovery of differences in longitudinalmagnetic field strengths measured using different LSD masks containing linesbelonging to different elements. It is the first time that such a differentialanalysis of the field strength in dependence of the used lines is carried outfor a magnetic O-type star. Since the LSD Stokes $I$ profiles of the studied O,Si, and He line masks remain stable over all observing epochs, we conclude thatthe detection of different field strengths using lines belonging to theseelements is related to the different formation depths, with the He lines formedmuch higher in the stellar atmosphere compared to the silicon and the oxygenlines, and NLTE effects. Our numerical magnetospherical model suggests thepresence of enhanced gas density that fills the volume inside the field linesclose to the star.

Detection of anomalous element distribution in the extremely slowly rotating magnetic O9.7 V star HD 54879