MK Spectral Types for Bright Southern OB Stars

Hiltner, W. A.; Garrison, R. F.; Schild, Rudolph E.

doi:10.1086/150069

Cited by 151 publications

(103 citation statements)

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“…T eff and Log(L * /L ) from Humphreys & McElroy (1984); ve sin(i) from Howarth et al (1997). Spectral types from Walborn (1972Walborn ( , 1976, Garrison et al (1977), Hiltner et al (1969), and Morgan et al (1955). N − refers to stars whose spectra are nitrogen deficient.…”

Section: The Iue Time-series Data Setsmentioning

confidence: 99%

Wind variability of B supergiants

Prinja

Massa²,

Fullerton

2002

A&A

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Abstract. We present the most suitable data sets available in the International Ultraviolet Explorer (IUE) archive for the study of time-dependent stellar winds in early B supergiants. The UV line profile variability in 11 B0 to B3 stars is analysed, compared and discussed, based on 16 separate data sets comprising over 600 homogeneously reduced high-resolution spectrograms. The targets include "normal" stars with moderate rotation rates and examples of rapid rotators. A gallery of grey-scale images (dynamic spectra) is presented, which demonstrates the richness and range of wind variability and highlights different structures in the winds of these stars. This work emphasises the suitability of B supergiants for wind studies, under-pinned by the fact that they exhibit unsaturated wind lines for a wide range of ionization. The wind activity of B supergiants is substantial and has highly varied characteristics. The variability evident in individual stars is classified and described in terms of discrete absorption components, spontaneous absorption, bowed structures, recurrence, and ionization variability and stratification. Similar structures can occur in stars of different fundamental parameters, but also different structures may occur in the same star at a given epoch. We discuss the physical phenomena that may be associated with the spectral signatures. The diversity of wind patterns evident likely reflects the role of stellar rotation and viewing angle in determining the observational characteristics of azimuthally extended structure rooted at the stellar surface. In addition, SEI line-synthesis modelling of the UV wind lines is used to provide further information about the state of the winds in our program stars. Typically the range, implied by the line profile variability, in the product of mass-loss rate and ion fraction (Ṁ qi) is a factor of ∼1.5, when integrated between 0.2 and 0.9 v∞; it can however be several times larger over localised velocity regions. At a given effective temperature the mean relative ion ratios can differ by a factor of 5. The general excess in predicted (forward-scattered) emission in the low velocity regime is discussed in terms of structured outflows. Mean ion fractions are estimated over the B0 to B1 spectral classes, and trends in the ionic ratios as a function of wind velocity are described. The low values obtained for the ion fractions of UV resonance lines may reflect the role of clumping in the wind.

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Section: The Iue Time-series Data Setsmentioning

confidence: 99%

Wind variability of B supergiants

Prinja

Massa²,

Fullerton

2002

A&A

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“…The works of Morgan et al (1955), Hiltner (1956), and Lesh (1968) provided original accurate spectral classifications for ''northern'' ( k À20 ) stars that, taken together, constitute a quite uniform catalog for that part of the sky. The southern equivalent can be obtained by merging the spectral classifications obtained by Hiltner et al (1969) and Garrison et al (1977). Those catalogs, though, are far from complete and most of their spectral classifications were done before the introduction of spectral types O3 (Walborn 1971b) and O2 .…”

Section: Introductionmentioning

confidence: 99%

A Galactic O Star Catalog

Maíz‐Apellániz¹,

Walborn²,

Galué³

et al. 2004

ASTROPHYS J SUPPL S

227

206

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We have produced a catalog of 378 Galactic O stars with accurate spectral classifications that is complete for V < 8 but includes many fainter stars. The catalog provides cross-identifications with other sources; coordinates (obtained in most cases from Tycho-2 data); astrometric distances for 24 of the nearest stars; optical (Tycho-2, Johnson, and Strömgren) and NIR photometry; group membership, runaway character, and multiplicity information; and a Web-based version with links to on-line services.

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“…First reported as a Be object in 1925 (Merrill et al 1925), it was later recognised as a true Oe star (Hiltner et al 1969;Conti & Leep 1974) of type O7.5IIIe or V[n]e 2 . HD 155806 indeed displays Balmer lines in emission (with a multiple-peak structure in Hα, see, e.g.…”

Section: The Oe Categorymentioning

confidence: 99%

Hot and cool: two emission-line stars with constrasting behaviours in the same XMM-Newtonfield

Nazé

Rauw

ud‐Doula

2010

A&A

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High-energy emissions are good indicators of peculiar behaviours in stars. We have therefore obtained an XMM-Newton observation of HD 155806 and 1RXS J171502.4−333344, and derived their spectral properties for the first time. The X-ray spectrum of HD 155806 appears soft, even slightly softer than usual for O-type stars (as shown by a comparison with the O9 star HD 155889 in the same XMM-Newton field). It is well-fitted with a two-component thermal model with low temperatures (0.2 and 0.6 keV), and it shows no overluminosity (log[L X /L BOL ] = −6.75). The high-resolution spectrum, though noisy, reveals a few broad, symmetric X-ray lines (FWHM ∼ 2500 km s −1 ). The X-ray emission is compatible with the wind-shock model and therefore appears unaffected by the putative dense equatorial regions at the origin of the Oe classification. 1RXS J171502.4−333344 is a nearby flaring source of moderate X-ray luminosity (log[L X /L BOL ] = −3), with a soft thermal spectrum composed of narrow lines and presenting a larger abundance of elements (e.g. Ne) with a high first ionization potential (FIP) compared to lower-FIP elements. All the evidence indicates a coronal origin for the X-ray emission, in agreement with the dMe classification of this source.

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MK Spectral Types for Bright Southern OB Stars

Cited by 151 publications

References 0 publications

Wind variability of B supergiants

Wind variability of B supergiants

A Galactic O Star Catalog

Hot and cool: two emission-line stars with constrasting behaviours in the same XMM-Newtonfield

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