izvcrao Изв. Крымск. Астрофиз. Обсерв. Izv. Krymsk. Astrofiz. Observ. Известия Крымской астрофизической обсерватории Izvestiya Krymskoi Astrofizicheskoi Observatorii 0367-8466 3034-4107 Киселев Н.Н., пос. Московский, Москва, РФ RU 701 Материалы конференции Сonference proceedings Unprecedentedly rapid rotational braking of the He-strong CP star HD 37776 Unprecedentedly rapid rotational braking of the He-strong CP star HD 37776 Mikulasek Z. Krticka J. Henry G.W. Zverko J. Ziznovský J. Janik J. Graf T. Institute of Theoretical Physics and Astrophysics, Masaryk University, CZ-611 37, Brno, Czech Republic; Observatory and Planetarium of J. Palisa, VSB – Technical University, Ostrava, Czech Republic Institute of Theoretical Physics and Astrophysics, Masaryk University, CZ-611 37, Brno, Czech Republic Center of Excellence in Information Systems, Tennessee State University, Nashville, Tennessee, USA Astronomical Institute, Slovak Academy of Sciences, Tatranska Lomnica, Slovak Republic Astronomical Institute, Slovak Academy of Sciences, Tatranska Lomnica, Slovak Republic Institute of Theoretical Physics and Astrophysics, Masaryk University, CZ-611 37, Brno, Czech Republic Observatory and Planetarium of J. Palisa, VSB – Technical University, Ostrava, Czech Republic 01 05 2008 104 2 15 05 2020 Copyright (c) 2008 , , , , , , Copyright (c) 2008 Mikulasek Z., Krticka J., Henry G., Zverko J., Ziznovský J., Janik J., Graf T. 2008 , , , , , , Mikulasek Z., Krticka J., Henry G., Zverko J., Ziznovský J., Janik J., Graf T. Метаданные этой статьи доступны по лицензии Creative Commons «Attribution» («Атрибуция») 4.0 Всемирная. Авторское право и право на публикацию текстов, представленных в журнале  "Известия Крымской астрофизической обсерватории", сохраняются за авторами, при этом право первой публикации предоставляется журналу. Тексты могут свободно использоваться при условии правильного цитирования с указанием авторства в соответствии с лицензией Creative Commons «Attribution» («Атрибуция») 4.0 Всемирная. The metadata for this submission is licensed under a Creative Commons Attribution 4.0 International License. Copyright and publishing rights for texts published in Izvestiya Krymskoi Astrofizicheskoi Observatorii is retained by the authors, with first publication rights granted to the journal.Texts are free to use with proper attribution and link to the licensing (Creative Commons Attribution 4.0 International).

We study long-term light variations in the well-known He-strong CP star HD 37776 = V901 Ori to search for changes in its photometric period. We analyze all published reliable photometric observations of this star, including 861 uvbyβ , BV, V and H p measurements. These observations are supplemented by 506 new BV observations obtained during the last two observing seasons. All the observations are treated simultaneously in our analysis. We confirm a previously suspected lengthening of the photometric period in HD 37776 and measure the rate of increase to be 52.4 ± 2.1 s per century (!). We interpret this ongoing period increase to be the slowing of the star's surface rotation, most likely due to momentum loss through a magnetically confined stellar wind.