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Astron. Astrophys. 323, 881-885 (1997)

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Research Note

The variations of the Bp star HD 137509 * **

G. Mathys 1 and T. Lanz 2

1 European Southern Observatory, Casilla 19001, Santiago 19, Chile
2 Astronomical Institute, Utrecht University, Princetonplein 5, P.O. Box 80000, 3508 TA Utrecht, The Netherlands

Received 12 December 1996 / Accepted 20 January 1997


A refined value [FORMULA]  d is derived for the rotation period of the Bp star HD 137509, from the simultaneous consideration of photometric data recorded in the Geneva system and of measurements of the mean longitudinal magnetic field and of the crossover. The variations of the magnetic field (one of the most intense fields known in an Ap or Bp star) show the signature of a strong quadrupolar component. This remarkable property is reflected in the brightness and line equivalent width variations.

Key words: stars: chemically peculiar – stars: magnetic fields – stars: rotation – stars: individual: HD 137509

* Based on observations collected at the European Southern Observatory (La Silla, Chile; ESO programmes Nos. 37.7-017, 39.7-089, 41.7-061, and 49.7-029)
** Table 1 is available only in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr ( or via http://cdsweb.u-strasbg.fr/Abstract.html

Send offprint requests to: G. Mathys

© European Southern Observatory (ESO) 1997

Online publication: May 26, 1998