A Study of the Near‐Ultraviolet Spectrum of Vega

García‐Gil, Alejandro; López, R. J. García; Prieto, C. Allende; Hubený, I.

doi:10.1086/428279

Cited by 16 publications

(21 citation statements)

References 35 publications

(38 reference statements)

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“…metal-deficient object (Hill & Landstreet 1993;García-Gil et al 2005) -shows, as expected, a reduced ∆a value. Otherwise, the standard lines and observations of Vega fit the synthetic values very closely.…”

Section: Results and Conclusionsupporting

confidence: 77%

On theλ Bootis spectroscopic binary hypothesis

Stütz¹,

Paunzen²

2006

A&A

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Context. It is still a matter of debate whether the group of λ Bootis stars have been homogeneously defined. A widely discussed working hypothesis postulates that two apparent, solar-abundant stars of an undetected spectroscopic binary system mimic a single metal-weak spectrum thus preventing any reliable analysis of the group characteristics. Aims. We investigate whether the proposed spectroscopic binary model can explain the observed abundance pattern as well photometric metallicity indices and what the percentage of undetected spectroscopic binary systems is. Methods. We used the newest available stellar atmospheres to synthesize 105 hypothetical binary systems in the relevant astrophysical parameter range. These models were used to derive photometric indices. As a test, values were generated for single stellar atmospheres, Vega and two typical λ Bootis stars, HD 107233 and HD 204041. Results. The synthesized indices fit the standard lines and the observations of the three stars excellently. For about 90% of the group members, the spectroscopic binary hypothesis cannot explain the observations. Conclusions. A careful preselection of λ Bootis stars results in a homogeneous group of objects that can be used to investigate the group characteristics.

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Section: Results and Conclusionsupporting

confidence: 77%

On theλ Bootis spectroscopic binary hypothesis

Stütz¹,

Paunzen²

2006

A&A

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“…In order to account for the possibility that the metallicity of Vega might differ from that adopted by us, an alternative model with [M/H] = −1.0 (cf. Garcia-Gil et al 2005) was used to check for the influence of a different metallicity on the derived calibration. At least for the Johnson photometric system, the differences in the corresponding fluxes turned out to lie always below 1%.…”

Section: Absolute Flux Calibrationmentioning

confidence: 99%

Bright OB stars in the Galaxy

Puls¹,

Маркова²,

Scuderi³

et al. 2006

A&A

286

391

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Context. Recent results strongly challenge the canonical picture of massive star winds: various evidence indicates that currently accepted mass-loss rates,Ṁ, may need to be revised downwards, by factors extending to one magnitude or even more. This is because the most commonly used mass-loss diagnostics are affected by "clumping" (small-scale density inhomogeneities), influencing our interpretation of observed spectra and fluxes. Aims. Such downward revisions would have dramatic consequences for the evolution of, and feedback from, massive stars, and thus robust determinations of the clumping properties and mass-loss rates are urgently needed. We present a first attempt concerning this objective, by means of constraining the radial stratification of the so-called clumping factor. Methods. To this end, we have analyzed a sample of 19 Galactic O-type supergiants/giants, by combining our own and archival data for H α , IR, mm and radio fluxes, and using approximate methods, calibrated to more sophisticated models. Clumping has been included into our analysis in the "conventional" way, by assuming the inter-clump matter to be void. Because (almost) all our diagnostics depends on the square of density, we cannot derive absolute clumping factors, but only factors normalized to a certain minimum. Results. This minimum was usually found to be located in the outermost, radio-emitting region, i.e., the radio mass-loss rates are the lowest ones, compared toṀ derived from H α and the IR. The radio rates agree well with those predicted by theory, but are only upper limits, due to unknown clumping in the outer wind. H α turned out to be a useful tool to derive the clumping properties inside r < 3. . .5 R . Our most important result concerns a (physical) difference between denser and thinner winds: for denser winds, the innermost region is more strongly clumped than the outermost one (with a normalized clumping factor of 4.1 ± 1.4), whereas thinner winds have similar clumping properties in the inner and outer regions. Conclusions. Our findings are compared with theoretical predictions, and the implications are discussed in detail, by assuming different scenarios regarding the still unknown clumping properties of the outer wind.

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“…These may very likely be attributed to NLTE effects in metals, such as C, Mg, Si, and perhaps Fe, which could be alleviated by fine-tuning abundances, using NLTE line blanketed models. For a detailed discussion see García-Gil et al (2005). We did not embark on such a study since our aim here is not to perform detailed fitting of individual UV spectral features but instead to show overall agreement of predicted and observed spectra for synthetic photometry.…”

Section: A Vega Modelmentioning

confidence: 99%

Binary Star Synthetic Photometry and Distance Determination Using Binsyn

Linnell

DeStefano

Hubený

2013

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This paper extends synthetic photometry to components of binary star systems. The paper demonstrates accurate recovery of single star photometric properties for four photometric standards, Vega, Sirius, GD153, and HD209458, ranging over the HR diagram, when their model synthetic spectra are placed in fictitious binary systems and subjected to synthetic photometry processing. Techniques for photometric distance determination have been validated for all four photometric standards.

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A Study of the Near‐Ultraviolet Spectrum of Vega

Cited by 16 publications

References 35 publications

On theλ Bootis spectroscopic binary hypothesis

On theλ Bootis spectroscopic binary hypothesis

Bright OB stars in the Galaxy

Binary Star Synthetic Photometry and Distance Determination Using Binsyn

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