Evidence for a connection between photospheric and wind structure in HD 64760

Kaufer, A.; Prinja, R. K.; Stahl, O.

doi:10.1051/0004-6361:20011649

Cited by 10 publications

(20 citation statements)

References 16 publications

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“…In the O7.5 III star ξ Per, de Jong et al (2001) traced a ∼2 day (UV) wind modulation down to near-photospheric velocities, though they only detected pulsational periods on much shorter time-scales (∼3.5 h). Time-series analysis of line profile variability across the Hα profile of HD 64760 (B0.5 Ib) by Kaufer et al (2002) revealed a 2.4 day pattern in the velocity widths (i.e. at ± projected rotation velocity), which is in excellent agreement with the outer wind periods previous established (max) ∼22 days using IUE ultraviolet spectroscopy.…”

Section: Introductionsupporting

confidence: 82%

Photospheric and stellar wind variability in ϵOri (B0 Ia)

Prinja

Rivinius²,

Stahl³

et al. 2004

A&A

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Abstract. We provide direct observational evidence for a link between photospheric activity and perturbations in the dense inner-most stellar wind regions of the B supergiant star Ori. The results, which are relevant to our understanding of the origin of wind structure, are based on a multi-spectral line analysis of optical time-series data secured in 1998 using the HEROS spectrograph on the ESO Dutch 0.9-m telescope in La Silla. A period of ∼1.9 days is consistently identified in Balmer, He  absorption, and weak metal lines such as Si  and C . The primary characteristic is a large-amplitude swaying of the central absorption trough of the line, with differential velocities in lines formed at varying depths in the atmosphere. The variance resulting from the "S-wave" velocity behaviour of the lines is constrained within ± the projected rotation velocity (∼80 km s −1 ) in the weakest absorption lines, but extends blue-ward to over −200 km s −1 in Hα. A second (superimposed) 1.9 day signal is present at more extended blue-ward velocities (to ∼−300 km s −1 ) in lines containing stronger circumstellar components. Inspection of archival optical data from 1996 provides evidence that this modulation signal has persisted for at least 2.5 years. Non-radial pulsational modelling is carried out in an attempt to reproduce the key observational characteristics of the line profile variability. Only limited success is obtained with prograde (m = −1) modes. The principal S-wave pattern cannot be matched by these models and remains enigmatic.

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Section: Introductionsupporting

confidence: 82%

Photospheric and stellar wind variability in ϵOri (B0 Ia)

Prinja

Rivinius²,

Stahl³

et al. 2004

A&A

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“…Kaufer et al (2002) performed a large survey of the early B supergiant HD 64670 during ten nights and report periodic variability in photospheric lines. They explain it by a model of stellar oscillations.…”

Section: Notesmentioning

confidence: 99%

“…Fullerton et al (1996) conducted a survey of 30 O stars and detected variability in HeI 5876 and sometimes CIV 5802−5812 for 77% of their sample, indicating that spectroscopic variability is widespread among O stars even in the deepest parts of the atmosphere. Subsequent studies have revealed variability in both the wind and photospheric lines of O stars (de Jong et al 2001;Kaufer et al 2002;Prinja et al 2004;Prinja et al 2006).…”

Section: Introductionmentioning

confidence: 99%

Radial dependence of line profile variability in seven O9–B0.5 stars

Martins

Marcolino

Hillier

et al. 2015

A&A

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Context. Massive stars show a variety of spectral variabilities: discrete absorption components in UV P-Cygni profiles, optical line profile variability, X-ray variability, and radial velocity modulations. Aims. Our goal is to study the spectral variability of single OB stars to better understand the relation between photospheric and wind variability. For that, we rely on high spectral resolution and on high signal-to-noise ratio optical spectra collected with the spectrograph NARVAL on the Télescope Bernard Lyot at Pic du Midi. Methods. We investigated the variability of twelve spectral lines by means of the temporal variance spectrum. The selected lines probe the radial structure of the atmosphere from the photosphere to the outer wind. We also performed a spectroscopic analysis with atmosphere models to derive the stellar and wind properties and to constrain the formation region of the selected lines. Results. We show that variability is observed in the wind lines of all bright giants and supergiants on a daily timescale. Lines formed in the photosphere are sometimes variable, sometimes not. The dwarf stars do not show any sign of variability. If variability is observed on a daily timescale, it can also (but not always) be observed on hourly timescales, albeit with lower amplitude. There is a very clear correlation between amplitude of the variability and fraction of the line formed in the wind. Strong anti-correlations between the different parts of the temporal variance spectrum are observed. Conclusions. Our results indicate that variability is stronger in lines formed in the wind. A link between photospheric and wind variability is not obvious from our study, since wind variability is observed regardless of the level of photospheric variability. Different photospheric lines also show different degrees of variability.

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“…The signal-to-noise ratio was >100 and the spectral resolution was 0.7 Å. Finally high resolution time-averaged blue and red spectra of HD 64760 were provided by RKP (see Kaufer & Stahl 2002, for more details). These spectra were taken in 1996 on the HEROS fiber-linked echelle spectrograph, which was mounted on the ESO 50-cm telescope at the La Silla, Chile.…”

Section: Observationsmentioning

confidence: 99%

Quantitative studies of the optical and UV spectra of Galactic early B supergiants

Searle

Prinja

Massa

et al. 2008

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117

187

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Aims. We undertake an optical and ultraviolet spectroscopic analysis of a sample of 20 Galactic B0−B5 supergiants of luminosity classes Ia, Ib, Iab, and II. Fundamental stellar parameters are obtained from optical diagnostics and a critical comparison of the model predictions to observed UV spectral features is made. Methods. Fundamental parameters (e.g., T eff , log L * , mass-loss rates and CNO abundances) are derived for individual stars using CMFGEN, a nLTE, line-blanketed model atmosphere code. The impact of these newly derived parameters on the Galactic B supergiant T eff scale, mass discrepancy, and wind-momentum luminosity relation is examined. Results. The B supergiant temperature scale derived here shows a reduction of about 1000−3000 K compared to previous results using unblanketed codes. Mass-loss rate estimates are in good agreement with predicted theoretical values, and all of the 20 B0−B5 supergiants analysed show evidence of CNO processing. A mass discrepancy still exists between spectroscopic and evolutionary masses, with the largest discrepancy occurring at log (L/L ) ∼ 5.4. The observed WLR values calculated for B0−B0.7 supergiants are higher than predicted values, whereas the reverse is true for B1−B5 supergiants. This means that the discrepancy between observed and theoretical values cannot be resolved by adopting clumped (i.e., lower) mass-loss rates as for O stars. The most surprising result is that, although CMFGEN succeeds in reproducing the optical stellar spectrum accurately, it fails to precisely reproduce key UV diagnostics, such as the N v and C iv P Cygni profiles. This problem arises because the models are not ionised enough and fail to reproduce the full extent of the observed absorption trough of the P Cygni profiles. Conclusions. Newly-derived fundamental parameters for early B supergiants are in good agreement with similar work in the field. The most significant discovery, however, is the failure of CMFGEN to predict the correct ionisation fraction for some ions. Such findings add further support to revising the current standard model of massive star winds, as our understanding of these winds is incomplete without a precise knowledge of the ionisation structure and distribution of clumping in the wind.

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Evidence for a connection between photospheric and wind structure in HD 64760

Cited by 10 publications

References 16 publications

Photospheric and stellar wind variability in ϵOri (B0 Ia)

Photospheric and stellar wind variability in ϵOri (B0 Ia)

Radial dependence of line profile variability in seven O9–B0.5 stars

Quantitative studies of the optical and UV spectra of Galactic early B supergiants

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