Revisiting the Rigidly Rotating Magnetosphere model for Ori E - I. Observations and data analysis★

Oksala, M. E.; Wade, G. A.; Townsend, R. H. D.; Owocki, S. P.; Kochukhov, O.; Neiner, C.; Alécian, E.; Grunhut, J.

doi:10.1111/j.1365-2966.2011.19753.x

Cited by 83 publications

(93 citation statements)

References 42 publications

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“…Such emissions are normally observed to be in phase with the rotation of the stars (e.g. Oksala et al 2010Oksala et al , 2012Grunhut et al 2012). In Fig.…”

Section: Hα Magnetospheric Signaturesmentioning

confidence: 99%

Discovery of new magnetic early-B stars within the MiMeS HARPSpol survey

Alécian

Kochukhov

Petit

et al. 2014

A&A

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Context. The Magnetism in Massive Stars (MiMeS) project aims at understanding the origin of the magnetic fields in massive stars as well as their impact on stellar internal structure, evolution, and circumstellar environment. Aims. One of the objectives of the MiMeS project is to provide stringent observational constraints on the magnetic fields of massive stars; however, identification of magnetic massive stars is challenging, as only a few percent of high-mass stars host strong fields detectable with the current instrumentation. Hence, one of the first objectives of the MiMeS project was to search for magnetic objects among a large sample of massive stars, and to build a sub-sample for in-depth follow-up studies required to test the models and theories of fossil field origins, magnetic wind confinement and magnetospheric properties, and magnetic star evolution. Methods. We obtained high-resolution spectropolarimetric observations of a large number of OB stars thanks to three large programs (LP) of observations that have been allocated on the high-resolution spectropolarimeters ESPaDOnS, Narval, and the polarimetric module HARPSpol of the HARPS spectrograph. We report here on the methods and first analysis of the HARPSpol magnetic detections. We identified the magnetic stars using a multi-line analysis technique. Then, when possible, we monitored the new discoveries to derive their rotation periods, which are critical for follow-up and magnetic mapping studies. We also performed a first-look analysis of their spectra and identified obvious spectral anomalies (e.g., surface abundance peculiarities, Hα emission), which are also of interest for future studies. Results. In this paper, we focus on eight of the 11 stars in which we discovered or confirmed a magnetic field from the HARPSpol LP sample (the remaining three were published in a previous paper). Seven of the fields were detected in early-type Bp stars, while the last field was detected in the Ap companion of a normal early B-type star. We report obvious spectral and multiplicity properties, as well as our measurements of their longitudinal field strengths, and their rotation periods when we are able to derive them. We also discuss the presence or absence of Hα emission with respect to the theory of centrifugally-supported magnetospheres.

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“…Such emissions are normally observed to be in phase with the rotation of the stars (e.g. Oksala et al 2010Oksala et al , 2012Grunhut et al 2012). In Fig.…”

Section: Hα Magnetospheric Signaturesmentioning

confidence: 99%

Discovery of new magnetic early-B stars within the MiMeS HARPSpol survey

Alécian

Kochukhov

Petit

et al. 2014

A&A

Self Cite

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“…In addition to the detection of planets around pulsars and other pulsating stars, it was the primary diagnostic tool that helped earn Hulse and Taylor the Nobel Prize in Physics for their indirect detection of gravitational wave emission (Taylor et al 1979). The O − C diagram remains a critical tool across time domain astronomy (see, e.g., Oksala et al 2012;Barlow et al 2011;Mullally et al 2008;Hermes et al 2012). For pulsating white dwarf stars and other short-period variables, it is convenient to describe O − C as a time-varying absolute phase.…”

Section: Introduction and Formalismmentioning

confidence: 99%

PERIODIC VARIATIONS IN THEO–CDIAGRAMS OF FIVE PULSATION FREQUENCIES OF THE DB WHITE DWARF EC 20058–5234

Dalessio

Sullivan

Provençal

et al. 2013

ApJ

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Variations in the pulsation arrival time of five independent pulsation frequencies of the DB white dwarf EC 20058−5234 individually imitate the effects of reflex motion induced by a planet or companion but are inconsistent when considered in unison. The pulsation frequencies vary periodically in a 12.9 year cycle and undergo secular changes that are inconsistent with simple neutrino plus photon-cooling models. The magnitude of the periodic and secular variations increases with the period of the pulsations, possibly hinting that the corresponding physical mechanism is located near the surface of the star. The phase of the periodic variations appears coupled to the sign of the secular variations. The standards for pulsation-timing-based detection of planetary companions around pulsating white dwarfs, and possibly other variables such as subdwarf B stars, should be re-evaluated. The physical mechanism responsible for this surprising result may involve a redistribution of angular momentum or a magnetic cycle. Additionally, variations in a supposed combination frequency are shown to match the sum of the variations of the parent frequencies to remarkable precision, an expected but unprecedented confirmation of theoretical predictions.

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“…Oksala et al 2012;Grunhut et al 2012a;Rivinius et al 2013). As illustrated by several recent studies (e.g.…”

Section: Magnetically Confined Winds and Magnetospheresmentioning

confidence: 79%

Magnetic fields in early-type stars

Henrichs¹,

Neiner

Geers³

2014

Proc. IAU

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Abstract. For several decades we have been cognizant of the presence of magnetic fields in early-type stars, but our understanding of their magnetic properties has recently (over the last decade) expanded due to the new generation of high-resolution spectropolarimeters (ESPaDOnS at CFHT, Narval at TBL, HARPSpol at ESO). The most detailed surface magnetic field maps of intermediate-mass stars have been obtained through Doppler imaging techniques, allowing us to probe the small-scale structure of these stars. Thanks to the effort of large programmes (e.g. the MiMeS project), we have, for the first time, addressed key issues regarding our understanding of the magnetic properties of massive (M > 8 M⊙) stars, whose magnetic fields were only first detected about fifteen years ago. In this proceedings article we review the spectropolarimetric observations and statistics derived in recent years that have formed our general understanding of stellar magnetism in early-type stars. We also discuss how these observations have furthered our understanding of the interactions between the magnetic field and stellar wind, as well as the consequences and connections of this interaction with other observed phenomena.

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Revisiting the Rigidly Rotating Magnetosphere model for Ori E - I. Observations and data analysis★

Cited by 83 publications

References 42 publications

Discovery of new magnetic early-B stars within the MiMeS HARPSpol survey

Discovery of new magnetic early-B stars within the MiMeS HARPSpol survey

PERIODIC VARIATIONS IN THEO–CDIAGRAMS OF FIVE PULSATION FREQUENCIES OF THE DB WHITE DWARF EC 20058–5234

Magnetic fields in early-type stars

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