Rotation and magnetic field in the Be star<i>ω</i>Orionis

Neiner, C.; Hubert, A. M.; Frémat, Y.; Floquet, M.; Jankov, S.; Preuss, O.; Henrichs, H.F.; Zorec, J.

doi:10.1051/0004-6361:20031086

Cited by 72 publications

(78 citation statements)

References 23 publications

(28 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The present calibration can then provide a first step for the interpretation of spectra emitted by rotating early-type objects, as already shown in Levenhagen et al (2003); Neiner et al (2003); Zorec et al (2005);Vinicius et al (2006);Frémat et al (2006); Martayan et al (2006Martayan et al ( , 2007; Floquet et al (2000Floquet et al ( , 2002.…”

Section: Effects Related To the Rotationsupporting

confidence: 59%

Fundamental parameters of B supergiants from the BCD system

Zorec¹,

Cidale

Arias

et al. 2009

A&A

Self Cite

View full text Add to dashboard Cite

Context. Effective temperatures of early-type supergiants are important to test stellar atmosphere-and internal structure-models of massive and intermediate mass objects at different evolutionary phases. However, these T eff values are more or less discrepant depending on the method used to determine them. Aims. We aim to obtain a new calibration of the T eff parameter for early-type supergiants as a function of observational quantities that are: a) highly sensitive to the ionization balance in the photosphere and its gas pressure; b) independent of the interstellar extinction; c) as much as possible model-independent. Methods. The observational quantities that best address our aims are the (λ 1 , D) parameters of the BCD spectrophotometric system. They describe the energy distribution around the Balmer discontinuity, which is highly sensitive to T eff and log g. We perform a calibration of the (λ 1 , D) parameters into T eff using effective temperatures derived with the bolometric-flux method for 217 program stars, whose individual uncertainties are on average |ΔT eff |/T f eff = 0.05. Results. We obtain a new and homogeneous calibration of the BCD (λ 1 , D) parameters for OB supergiants and revisit the current calibration of the (λ 1 , D) zone occupied by dwarfs and giants. The final comparison of calculated with obtained T eff values in the (λ 1 , D) calibration show that the latter have total uncertainties, which on average are T eff /T f eff ±0.05 for all spectral types and luminosity classes. Conclusions. The effective temperatures of OB supergiants derived in this work agree on average within some 2000 K with other determinations found in the literature, except those issued from wind-free non-LTE plane-parallel models of stellar atmospheres, which produce effective temperatures that can be overestimated by up to more than 5000 K near T eff = 25 000 K. Since the stellar spectra needed to obtain the (λ 1 , D) parameters are of low resolution, a calibration based on the BCD system is useful to study stars and stellar systems like open clusters, associations or stars in galaxies observed with multi-object spectrographs and/or spectro-imaging devices.

show abstract

Section: Effects Related To the Rotationsupporting

confidence: 59%

Fundamental parameters of B supergiants from the BCD system

Zorec¹,

Cidale

Arias

et al. 2009

A&A

Self Cite

View full text Add to dashboard Cite

show abstract

“…Moreover, the fact that the two maxima of the UV curve of Neiner et al (2003a) are unequal suggest that the dipole might be off-centred. Indeed, the maxima in the UV curve correspond to the magnetic equator seen edge-on (see Fig.…”

Section: Discussionmentioning

confidence: 99%

Detecting and modelling the magnetic field of theβ Cephei star V 2052 Ophiuchi

Neiner

Alécian

Briquet

et al. 2012

A&A

Self Cite

View full text Add to dashboard Cite

Aims. Following the indirect detection of a magnetic field in the β Cephei star V 2052 Oph by Neiner and collaborators in 2003 with the Musicos spectropolarimeter, we remeasured the magnetic field of this star to attempt to directly confirm the detection of a magnetic field and study its configuration in greater detail. Methods. We used the Narval spectropolarimeter installed at TBL (Pic du Midi, France), which is about 20 times more efficient than the Musicos spectropolarimeter. We applied the least-squares deconvolution (LSD) technique to various groups of lines to measure the circular polarisation of the light coming from V 2052 Oph. We synthesized the measured Stokes V profiles with a centred and off-centred dipole model. Results. For the first time, we clearly detect the Zeeman signature in the Stokes V profiles of V 2052 Oph and thus directly prove the presence of a magnetic field in this star. The modulation with the rotation period is also confirmed and reflects an oblique dipole field. Thanks to the small error bars on the measurements, we are able to study the behaviour of different groups of lines and the centring of the dipole in the star. We find that the dipole is most likely off-centred along the magnetic axis and that He spots are present at the surface next to the magnetic axis. Conclusions. We conclude that V 2052 Oph is a magnetic He-strong β Cep star, with a dipole field, probably off-centred, with B pol ∼ 400 G and He patches close to the magnetic poles.

show abstract

“…However, other Be stars show particular variations that cannot be modeled as non-radial pulsations (see Porter & Rivinius 2003). At least one Be star, namely ω Ori exhibits variations caused by, at the same time, pulsations and inhomogeneities rotating with the star (Neiner et al 2003b). The most likely interpretation of the variations in the CoRoT light curve of the Be star HD 175869 is the presence of stellar activity attached to the star, although a pulsational interpretation cannot be completely excluded.…”

Section: Discussionmentioning

confidence: 99%

Low-amplitude variations detected by CoRoT in the B8IIIe star HD 175869

Gutiérrez‐Soto

Floquet²,

Samadi

et al. 2009

A&A

Self Cite

View full text Add to dashboard Cite

Context. The origin of the short-term variability in Be stars remains a matter of controversy. Pulsations and rotational modulation are the components of the favored hypothesis. Aims. We present our analysis of CoRoT data of the B8IIIe star HD 175869 observed during the first short run in the center direction (SRC1). Methods. We review both the instrumental effects visible in the CoRoT light curve and the analysis methods used by the CoRoT Be team. We applied these methods to the CoRoT light curve of the star HD 175869. A search for line-profile variations in the spectroscopic data was also performed. We also searched for a magnetic field, by applying the LSD technique to spectropolarimetric data. Results. The light curve exhibits low-amplitude variations of the order of 300 μmag with a double wave shape. A frequency within the range determined for the rotational frequency and 6 of its harmonics are detected. The main frequency and its first harmonic exhibit amplitude variations of a few days. Other significant frequencies of low-amplitude from 25 to a few μmag are also found. The analysis of line profiles from ground-based spectroscopic data does not detect any variation. In addition, no Zeeman signature was found. Conclusions. Inhomogeneities caused by stellar activity in or just above the photosphere are proposed to produce the photometric variability detected by CoRoT in the Be star HD 175869. The hypothesis that non-radial pulsations are the origin of these variations cannot be excluded.

show abstract

Rotation and magnetic field in the Be starωOrionis

Cited by 72 publications

References 23 publications

Fundamental parameters of B supergiants from the BCD system

Fundamental parameters of B supergiants from the BCD system

Detecting and modelling the magnetic field of theβ Cephei star V 2052 Ophiuchi

Low-amplitude variations detected by CoRoT in the B8IIIe star HD 175869

Contact Info

Product

Resources

About