A short and sudden increase of the magnetic field strength and the accompanying spectral variability in the O9.7 V star HD 54879

Hubrig, S.; Küker, M.; Järvinen, S. P.; Холтыгин, А. Ф.; Schöller, M.; Ryspaeva, E. B.; Sokoloff, Dmitry

doi:10.1093/mnras/stz198

Cited by 10 publications

(30 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The major result of our re-analysis of the FORS2 spectra is that, in contrast to the claims of Hubrig et al (2019a), there is no evidence of any significant change in the spectrum obtained on February 17, 2018 with respect to all the other spectra of the same star, and that, consistent with what we have found with ESPaDOnS observations, there is no indication of any remarkable change of the star?s radial velocity. In Fig.…”

Section: Re-analysis Of the Fors2 Spectrasupporting

confidence: 84%

“…In addition, we have downloaded from the ESO archive the FORS2 observations discussed by Hubrig et al (2019a). Data were reduced using dedicated IRAF and FORTRAN routines as explained for instance by Bagnulo & Landstreet (2018).…”

Section: Observational Materialsmentioning

confidence: 99%

“…Data were reduced using dedicated IRAF and FORTRAN routines as explained for instance by Bagnulo & Landstreet (2018). We remind the reader that FORS2 is a Cassegrain- Hubrig et al (2019a). The derived values of the longitudinal magnetic field ( B z ) are reported in this table, and were measured using the procedure described by e.g.…”

Section: Observational Materialsmentioning

confidence: 99%

“…In this Letter we examine these claims in the light of independent spectropolarimetric observations obtained using the high-resolution spectropolarimeters Narval and ES-PaDOnS, as well as a re-examination of the FORS2 data studied by Hubrig et al (2019a).…”

Section: Introductionmentioning

confidence: 97%

“…Hence HD 54879 is inferred to be one of the most slowly-rotating O-type stars known. Hubrig et al (2019a) described their analysis of a FORS2 spectropolarimetric timeseries of this star spanning 140 days. The essential conclusions of their study can be summarized as follows: (i) HD 54879 exhibits significant (of order 100 km s −1 ) radial velocity variations on timescales of days.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

No evidence of a sudden change of spectral appearance or magnetic field strength of the O9.7V star HD 54879

Wade

Bagnulo

Keszthelyi

et al. 2019

Monthly Notices of the Royal Astronomical Society: Letters

View full text Add to dashboard Cite

It was recently claimed that the magnetic O-type star HD 54879 exhibits important radial velocity variability indicative of its presence in a spectroscopic binary. More remarkably, it was furthermore reported that the star underwent a short, sudden variation in spectral type and magnetic field. In this Letter we examine new Narval and ESPaDOnS data of this star in addition to the previously-published FORS2 data and conclude that both the reported velocity variations and the sudden spectral and magnetic changes are spurious.

show abstract

Section: Re-analysis Of the Fors2 Spectrasupporting

confidence: 84%

Section: Observational Materialsmentioning

confidence: 99%

Section: Observational Materialsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

No evidence of a sudden change of spectral appearance or magnetic field strength of the O9.7V star HD 54879

Wade

Bagnulo

Keszthelyi

et al. 2019

Monthly Notices of the Royal Astronomical Society: Letters

View full text Add to dashboard Cite

show abstract

Characterizing the dynamical magnetosphere of the extremely slowly rotating magnetic O9.7 V star HD 54879 using rotational modulation of the Hα profile

Küker,

Järvinen,

Hubrig

et al. 2024

Astron Nachr

View full text Add to dashboard Cite

The magnetic field in the O9.7 V star HD 54879 has been monitored for almost a decade. Spectropolarimetric observations reveal a rather strong mean longitudinal magnetic field that varies with a period of about 7.41 years. Observations in the H line show a variation with the same period, while the H line shows only little variation. Assuming the periodic variation to be caused by a slow rotation and a dipolar magnetic field, we find a magnetic field strength of 2 kG at the magnetic poles. With the relatively low mass loss rate of year−1, this star is a case of extremely strong magnetic confinement. Both theoretical arguments and numerical simulations indicate the presence of an extended disk of increased gas density in the equatorial plane of the magnetic field, where gas from the line‐driven stellar wind is trapped. This disk is likely to be the origin of the observed H emission, which peaks together with the strongest line‐of‐sight magnetic field. The profile of the H line is resolved in several components and shows a remarkable variability with the rotation period.

show abstract

Variability of OB stars from TESS southern Sectors 1–13 and high-resolution IACOB and OWN spectroscopy

Burssens

Simón‐Díaz

Bowman

et al. 2020

A&A

View full text Add to dashboard Cite

Context. The lack of high-precision long-term continuous photometric data for large samples of stars has impeded the large-scale exploration of pulsational variability in the OB star regime. As a result, the candidates for in-depth asteroseismic modelling have remained limited to a few dozen dwarfs. The TESS nominal space mission has surveyed the southern sky, including parts of the galactic plane, yielding continuous data across at least 27 d for hundreds of OB stars. Aims. We aim to couple TESS data in the southern sky with ground-based spectroscopy to study the variability in two dimensions, mass and evolution. We focus mainly on the presence of coherent pulsation modes that may or may not be present in the predicted theoretical instability domains and unravel all frequency behaviour in the amplitude spectra of the TESS data. Methods. We compose a sample of 98 OB-type stars observed by TESS in Sectors 1–13 and with available multi-epoch, high-resolution spectroscopy gathered by the IACOB and OWN surveys. We present the short-cadence 2 min light curves of dozens of OB-type stars, which have one or more spectra in the IACOB or OWN database. Based on these light curves and their Lomb–Scargle periodograms, we performed variability classification and frequency analysis. We placed the stars in the spectroscopic Hertzsprung–Russell diagram to interpret the variability in an evolutionary context. Results. We deduce the diverse origins of the mmag-level variability found in all of the 98 OB stars in the TESS data. We find among the sample several new variable stars, including three hybrid pulsators, three eclipsing binaries, high frequency modes in a Be star, and potential heat-driven pulsations in two Oe stars. Conclusions. We identify stars for which future asteroseismic modelling is possible, provided mode identification is achieved. By comparing the position of the variables to theoretical instability strips, we discuss the current shortcomings in non-adiabatic pulsation theory and the distribution of pulsators in the upper Hertzsprung–Russell diagram.

show abstract

A short and sudden increase of the magnetic field strength and the accompanying spectral variability in the O9.7 V star HD 54879

Cited by 10 publications

References 45 publications

No evidence of a sudden change of spectral appearance or magnetic field strength of the O9.7V star HD 54879

No evidence of a sudden change of spectral appearance or magnetic field strength of the O9.7V star HD 54879

Characterizing the dynamical magnetosphere of the extremely slowly rotating magnetic O9.7 V star HD 54879 using rotational modulation of the Hα profile

Variability of OB stars from TESS southern Sectors 1–13 and high-resolution IACOB and OWN spectroscopy

Contact Info

Product

Resources

About