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 Plus annual

Presents the access of premium content as premium feature

Premium Content

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 annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Strong meridional mixing induced by rapid rotation is one reason why all hotmain-sequence stars are not chemically peculiar. However, the finding that theHe-strong CP star HR 7355 is a rapid rotator complicates this concept. Our goalis to explain the observed behaviour of HR 7355 based on period analysis of allavailable photometry. Over two years, we acquired 114 new BV observations of HR7355 at observatories in Arizona, U.S.A and Cape Town, South Africa. Weperformed period analyses of the new observations along with new analyses of732 archival measurements from the Hipparcos and ASAS projects. We find thatthe light curves of HR 7355 in various filters are quite similar, withamplitudes 0.035(4), 0.036(4), and 0.038(3) mag in B, Hp and V, respectively.The light curves are double-peaked, with unevenly deep minima. We substantiallyrefine the rotational period to be P=0.5214410(4) d, indicating that HR 7355 isthe most rapidly rotating CP star known. Our period analyses reveal a possiblelengthening of the rotational period with dP/dt/P = 2.4(8)x 10^-6/yr. Weconclude that the shape and amplitude of HR 7355 light curves are typical ofmagnetic He-strong CP stars, for which light variations are the result ofphotospheric spots on the surface of a rotating star. We hypothesise that thelight variations are caused mainly by an uneven distribution of overabundanthelium on the star's surface. We briefly describe and discuss the cause of therapid rotational braking of the star.

HR 7355 - another rapidly braking He-strong CP star?