Massa's star, HD 93840 - A new extreme BN supergiant

Walborn, N. R.; Fitzpatrick, E. L.; Nichols-Bohlin, J.

doi:10.1086/132667

Cited by 11 publications

(12 citation statements)

References 6 publications

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“…N v is heavily saturated in the O3 object, while all O5 stars show a nonsaturated profile. This is in agreement with the spectrum of HD 14 947 displayed by Walborn et al (1985), although it does not agree with the newly reduced spectrum contained in the Final IUE Archive. The line weakens towards later spectral types and is no longer visible at B1.…”

Section: Description Of the Spectrasupporting

confidence: 42%

An analysis of HST UV spectra of Cyg OB2 stars

Herrero

Puls

Corral

et al. 2001

A&A

119

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Abstract.As a first step of a vigorous program to investigate the Wind Momentum -Luminosity Relationship (WLR) of Galactic O-stars by analyzing stars belonging to the same cluster we present UV HST observations of six supergiants and one giant in the Cyg OB2 association. Terminal and turbulent wind velocities, velocity laws and metal ion column densities are derived and mean ionization fractions are estimated. Turbulent velocities are mostly in the range 10-14% of v∞. The terminal velocities agree well with the average v∞ vs. spectral class relationship compiled by Kudritzki & Puls (2000). We compare the observed v∞ vs. escape velocity (depending on the diagnostics of the stellar mass) correlation with the predictions of the radiatively driven wind theory and find better agreement with the spectroscopic masses rather than with the evolutionary ones. The β velocity field exponents are in the range 0.7-0.8, without any trend towards larger values. We show that for a single luminosity class there is a tight relationship between T eff and < ρ > (the mean density at the point in the stellar wind, where half the wind terminal velocity is reached). In consequence, the ionization fractions show the same trend with both, T eff and < ρ >: we find that N v increases with T eff , Si iv decreases and C iv does not clearly correlate. As a byproduct, we also derive interestellar H i column densities towards Cyg OB2, which turn out to be quite large. For one object (Cyg OB2#2) we find inconsistencies making the association membership questionable.

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Section: Description Of the Spectrasupporting

confidence: 42%

An analysis of HST UV spectra of Cyg OB2 stars

Herrero

Puls

Corral

et al. 2001

A&A

119

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“…Morton (1979) concluded that there is no O vi in p Leonis and implied that its absence, although a strong N v wind profile is present, may be a critical ionization effect. However, p Leo is moderately nitrogen enhanced, and its Nv profile is anomalously strong compared with other B1 supergiants (Walbom et al 1990; B Atlas), so its O vi vs. N v discrepancy may also be partly a chemical abundance effect.…”

Section: Late-o Supergiantsmentioning

confidence: 94%

An Atlas of OB Spectra from 1000A to 1200A

Walborn¹,

Bohlin²

1996

PASP

Self Cite

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ABSTRACT. Copernicus low-resolution (0.2 Â) observations of 16 O stars, 10 B stars (mostly supergiants), and one WN-A star with the highest data quality between 1000 and 1200 Â are presented in the form of a classical spectral atlas. The purpose is to survey the systematic spectral-type/luminosity-class dependence of the line features, including those from the stellar winds, in this relatively less-studied wavelength range. Perhaps the most important new contribution is the demonstration of the pronounced luminosity effect in the S IV XX1063, 1073 wind profiles, identical to those previously recognized in Si IV XX1394, 1403 and Cm XI176, which share essentially the same ionization potential. The stellar-wind effects in O vi XX1032, 1038; P v XX1118, 1128; Si IV XX1122, 1128; and CfflXl 176 are also described. Attention is redrawn to the unidentified feature at 1099 Â, which is one of the strongest absorption lines in this range of mid-0 through early-B spectra. The atlas will facilitate interpretations of recent Hopkins Ultraviolet Telescope and future Far Ultraviolet Spectroscopic Explorer observations in this wavelength range, as well as sharpen the stellar-wind phenomenology for astrophysical analysis.

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“…We compare the WR 140 WC7pd+O4-5 IUE spectrum with that of the single WC star WR 90 in Willis et al (1986), and with those of single O4-5 stars presented in Walborn et al (1985). We measured the equivalent widths of absorption and emission parts of the P-Cygni profiles at around 1400Å (Si iv) and 1720Å (N iv), and list them in Table 3.…”

Section: The Luminosity Of the O Componentmentioning

confidence: 99%

Multi-frequency variations of the Wolf-Rayet system HD 193793 (WC7pd+O4-5)

Gunawan

Hucht

Williams³

et al. 2001

A&A

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Abstract. The colliding-wind binary system WR 140 (HD 193793, WC7pd+O4-5, P = 7.94 yr) was monitored in the ultraviolet by IUE from 1979 to 1994 in 35 short-wavelength high-resolution spectra. An absorption-line radial-velocity solution is obtained from the photospheric lines of the O component, by comparison with a single O star. The resulting orbital parameters, e = 0.87 ± 0.05, ω = 31• ± 9• and KO star = 25 ± 15 km s −1 , confirm the large eccentricity of the orbit, within the uncertainties of previous optical studies. This brings the weighted mean UV-optical eccentricity to e = 0.85 ± 0.04. Occultation of the O-star light by the WC wind and the WC+O colliding-wind region results into orbital modulation of the P-Cygni profiles of the C ii, C iv and Si iv resonance lines. Near periastron passage, the absorption troughs of those resonance-line profiles increase abruptly in strength and width, followed by a gradual decrease. In particular, near periastron the blue black-edges of the P-Cygni absorption troughs shift to larger outflow velocities. We discuss that the apparently larger wind velocity and velocity dispersion observed at periastron could be explained by four phenomena: (i) geometrical resonance-line eclipse effects being the main cause of the observed UV spectral variability, enhanced by sightline crossing of the turbulent wind-wind collision zone; (ii) the possibility of an orbital-plane enhanced WC7 stellar wind; (iii) possible common-envelope acceleration by the combined WC and O stellar radiation fields; and (iv) possible enhanced radiatively driven mass loss due to tidal stresses, focused along the orbiting line of centers.

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Massa's star, HD 93840 - A new extreme BN supergiant

Cited by 11 publications

References 6 publications

An analysis of HST UV spectra of Cyg OB2 stars

An analysis of HST UV spectra of Cyg OB2 stars

An Atlas of OB Spectra from 1000A to 1200A

Multi-frequency variations of the Wolf-Rayet system HD 193793 (WC7pd+O4-5)

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