B fields in OB stars (BOB): on the detection of weak magnetic fields in the two early B-type stars<i>β</i> CMa and<i>ϵ</i> CMa

Fossati, L.; Castro, N.; Morel, Thierry; Langer, N.; Briquet, Maryline; Carroll, T. A.; Hubrig, S.; Nieva, M. F.; Oskinova, L. M.; Przybilla, N.; Schneider, F. R. N.; Schöller, M.; Simón‐Díaz, S.; Ilyin, I.; Koter, A. de; Reisenegger, Andreas; Sana, H.

doi:10.1051/0004-6361/201424986

Cited by 69 publications

(90 citation statements)

References 84 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is consistent with an evolutionary age (see Table 3) that compares reasonably well with the age of the parent open cluster NGC 3293, 10.7 Myr (Lotkin & Matkin 1994). There is also reasonably good agreement between the spectroscopic distance of CPD −57 • 3509 (d spec = 2630 ± 370 pc) and the cluster distance of ∼2460 pc (Briquet et al 2013;Petit et al 2013;Alecian et al 2014;Neiner et al 2014;Fossati et al 2014Fossati et al , 2015aSikora et al 2015;Castro et al 2015, grey circles), and CPD −57 • 3509 (black dot). Error bars are 1σ uncertainties.…”

Section: Discussionsupporting

confidence: 53%

B fields in OB stars (BOB): Detection of a magnetic field in the He-strong star CPD −57° 3509

Przybilla

Fossati

Hubrig

et al. 2016

A&A

Self Cite

View full text Add to dashboard Cite

Aims. We report the detection of a magnetic field in the helium-strong star CPD −57 • 3509 (B2 IV), a member of the Galactic open cluster NGC 3293, and characterise the star's atmospheric and fundamental parameters. Methods. Spectropolarimetric observations with FORS2 and HARPSpol are analysed using two independent approaches to quantify the magnetic field strength. A high-S/N FLAMES/GIRAFFE spectrum is analysed using a hybrid non-LTE model atmosphere technique. Comparison with stellar evolution models constrains the fundamental parameters of the star. Results. We obtain a firm detection of a surface averaged longitudinal magnetic field with a maximum amplitude of about 1 kG. Assuming a dipolar configuration of the magnetic field, this implies a dipolar field strength larger than 3.3 kG. Moreover, the large amplitude and fast variation (within about 1 day) of the longitudinal magnetic field implies that CPD −57 • 3509 is spinning very fast despite its apparently slow projected rotational velocity. The star should be able to support a centrifugal magnetosphere, yet the spectrum shows no sign of magnetically confined material; in particular, emission in Hα is not observed. Apparently, the wind is either not strong enough for enough material to accumulate in the magnetosphere to become observable or, alternatively, some leakage process leads to loss of material from the magnetosphere. The quantitative spectroscopic analysis of the star yields an effective temperature and a logarithmic surface gravity of 23 750 ± 250 K and 4.05 ± 0.10, respectively, and a surface helium fraction of 0.28 ± 0.02 by number. The surface abundances of C, N, O, Ne, S, and Ar are compatible with the cosmic abundance standard, whereas Mg, Al, Si, and Fe are depleted by about a factor of 2. This abundance pattern can be understood as the consequence of a fractionated stellar wind. CPD −57 • 3509 is one of the most evolved He-strong stars known with an independent age constraint due to its cluster membership.

show abstract

Section: Discussionsupporting

confidence: 53%

B fields in OB stars (BOB): Detection of a magnetic field in the He-strong star CPD −57° 3509

Przybilla

Fossati

Hubrig

et al. 2016

A&A

Self Cite

View full text Add to dashboard Cite

show abstract

“…On the other hand, the Ap component of HD 5550 has a higher temperature than the samples analysed in those works. Polar field strengths of 10-100 G have been recently found in early-B type stars (above B3) (Fossati et al 2015;Briquet et al 2016). While the limit of 100 G appears to be strict at temperatures lower than 10 000 K, it may decrease with increasing temperatures.…”

Section: Summary and Discussionmentioning

confidence: 96%

The magnetic field of the double-lined spectroscopic binary system HD 5550

Alécian¹,

Tkachenko²,

Neiner³

et al. 2016

A&A

View full text Add to dashboard Cite

Context. The origin of fossil fields in intermediate-and high-mass stars is poorly understood, as is the interplay between binarity and magnetism during stellar evolution. Thus we have begun a study of the magnetic properties of a sample of intermediate-mass and massive short-period binary systems as a function of binarity properties. Aims. This paper specifically aims to characterise the magnetic field of HD 5550, a double-lined spectroscopic binary system of intermediate mass.Methods. We gathered 25 high-resolution spectropolarimetric observations of HD 5550 using the instrument Narval. We first fitted the intensity spectra using Zeeman/ATLAS9 LTE synthetic spectra to estimate the effective temperatures, microturbulent velocities, and the abundances of some elements of both components, as well as the light ratio of the system. We then applied the multi-line least-square deconvolution (LSD) technique to the intensity and circularly polarised spectra, which provided us with mean LSD I and V line profiles. We fitted the Stokes I line profiles to determine the radial and projected rotational velocities of both stars. We then analysed the shape and evolution of the V profiles using the oblique rotator model to characterise the magnetic fields of both stars. Results. We confirm the Ap nature of the primary, which has previously been reported, and find that the secondary displays spectral characteristics typical of an Am star. While a magnetic field is clearly detected in the lines of the primary, no magnetic field is detected in the secondary in any of our observations. If a dipolar field were present at the surface of the Am star, its polar strength must be below 40 G. The faint variability observed in the Stokes V profiles of the Ap star allowed us to propose a rotation period of 6.84 +0.61 −0.39 d, which is close to the orbital period (∼6.82 d), suggesting that the star is synchronised with its orbit. By fitting the variability of the V profiles, we propose that the Ap component hosts a dipolar field inclined with the rotation axis at an angle β = 156 ± 17• and a polar strength B d = 65 ± 20 G. The field strength is the weakest known for an Ap star.

show abstract

“…Such fields are generally considered to be (mostly) dipolar. In addition, except for ζ Ori A (a supergiant O-star with an extremely low field, Blazère et al 2015) and β CMa (Fossati et al 2015a), the detected fields are strong, with B d larger than 0.5 kG for O and B0.5-1 stars (e.g. Petit et al 2013).…”

Section: Resultsmentioning

confidence: 98%

How unique is Plaskett’s star? A search for organized magnetic fields in short period, interacting or post-interaction massive binary systems

Nazé

Neiner

Grunhut

et al. 2017

Mon. Not. R. Astron. Soc.

View full text Add to dashboard Cite

Amongst O-type stars with detected magnetic fields, the fast rotator in the close binary called Plaskett's star shows a variety of unusual properties. Since strong binary interactions are believed to have occurred in this system, one may wonder about their potential role in generating magnetic fields. Stokes V spectra collected with the low-resolution FORS2 and high-resolution ESPaDOnS and Narval spectropolarimeters were therefore used to search for magnetic fields in 15 interacting or post-interaction massive binaries. No magnetic field was detected in any of them, with 0 G always being within 2σ of the derived values. For 17 out of 25 stars in the systems observed at high-resolution, the 90% upper limit on the individual dipolar fields is below the dipolar field strength of Plaskett's secondary; a similar result is found for five out of six systems observed at low resolution. If our sample is considered to form a group of stars sharing similar magnetic properties, a global statistical analysis results in a stringent upper limit of ∼ 200 G on the dipolar field strength. Moreover, the magnetic incidence rate in the full sample of interacting or post-interaction systems (our targets + Plaskett's star) is compatible with that measured from large surveys, showing that they are not significantly different from the general O-star population. These results suggest that binary interactions play no systematic role in the magnetism of such massive systems.

show abstract

B fields in OB stars (BOB): on the detection of weak magnetic fields in the two early B-type starsβ CMa andϵ CMa

Cited by 69 publications

References 84 publications

B fields in OB stars (BOB): Detection of a magnetic field in the He-strong star CPD −57° 3509

B fields in OB stars (BOB): Detection of a magnetic field in the He-strong star CPD −57° 3509

The magnetic field of the double-lined spectroscopic binary system HD 5550

How unique is Plaskett’s star? A search for organized magnetic fields in short period, interacting or post-interaction massive binary systems

Contact Info

Product

Resources

About