A Grid of NLTE Line‐blanketed Model Atmospheres of Early B‐Type Stars

Lanz, T.; Hubený, I.

doi:10.1086/511270

Cited by 600 publications

(499 citation statements)

References 46 publications

Supporting

Mentioning

490

Contrasting

Unclassified

Order By: Relevance

“…), the theoretical spectra computed by Kunze do not include the metal line blanketing. This indicates that they probably overestimate the effective temperatures by as much as ∼2000 K. Even when one compares the synthetic spectra from the O-star grid, and the later published spectra from the B-star grid (Lanz & Hubeny 2007) in the overlapping temperature range, it turns out that the two sets of model spectra differ from each other since the B-star values are based on somewhat improved input physics. Clearly, without further progress in the model spectra, one cannot do any better.…”

Section: Discussionmentioning

confidence: 99%

Revised physical elements of the astrophysically important O9.5+O9.5V eclipsing binary system Y Cygni

Harmanec

Holmgren²,

Wolf

et al. 2014

A&A

View full text Add to dashboard Cite

Context. Rapid advancements in light-curve and radial-velocity curve modelling, as well as improvements in the accuracy of observations, allow more stringent tests of the theory of stellar evolution. Binaries with rapid apsidal advance are particularly useful in this respect since the internal structure of the stars can also be tested. Aims. Thanks to its long and rich observational history and rapid apsidal motion, the massive eclipsing binary Y Cyg represents one of the cornerstones of critical tests of stellar evolutionary theory for massive stars. Nevertheless, the determination of the basic physical properties is less accurate than it could be given the existing number of spectral and photometric observations. Our goal is to analyse all these data simultaneously with the new dedicated series of our own spectral and photometric observations from observatories widely separated in longitude. Methods. We obtained new series of UBV observations at three observatories separated in local time to obtain complete light curves of Y Cyg for its orbital period close to 3 days. This new photometry was reduced and carefully transformed to the standard UBV system using the HEC22 program. We also obtained new series of red spectra secured at two observatories and re-analysed earlier obtained blue electronic spectra. Reduction of the new spectra was carried out in the IRAF and SPEFO programs. Orbital elements were derived independently with the FOTEL and PHOEBE programs and via disentangling with the program KOREL. The final combined solution was obtained with the program PHOEBE. Results. Our analyses provide the most accurate value of the apsidal period of (47.805 ± 0.030) yr published so far and the following physical elements: M 1 = 17.72 ± 0.35 M , M 2 = 17.73 ± 0.30 M , R 1 = 5.785 ± 0.091 R , and R 2 = 5.816 ± 0.063 R . The disentangling thus resulted in the masses, which are somewhat higher than all previous determinations and virtually the same for both stars, while the light curve implies a slighly higher radius and luminosity for star 2. The above empirical values imply the logarithm of the internal structure constant log k 2 = −1.937. A comparison with Claret's stellar interior models implies an age close to 2 × 10 6 yr for both stars. Conclusions. The claimed accuracy of modern element determination of 1-2 per cent still seems a bit too optimistic and obtaining new high-dispersion and high-resolution spectra is desirable.

show abstract

Section: Discussionmentioning

confidence: 99%

Revised physical elements of the astrophysically important O9.5+O9.5V eclipsing binary system Y Cygni

Harmanec

Holmgren²,

Wolf

et al. 2014

A&A

View full text Add to dashboard Cite

show abstract

“…The analysis makes use of grids of model atmospheres calculated using the  and  codes (Hubeny 1988;Hubeny & Lanz 1995;Hubeny et al 1998;Lanz & Hubeny 2007). Details of the methods adopted can be found in Hunter et al (2007), while a more detailed discussion of the grids can be found in Ryans et al (2003), Dufton et al (2005) 2 .…”

Section: Methodsmentioning

confidence: 99%

The VLT-FLAMES Tarantula Survey

McEvoy

Dufton

Evans

et al. 2015

A&A

View full text Add to dashboard Cite

Context. Model atmosphere analyses have been previously undertaken for both Galactic and extragalactic B-type supergiants. By contrast, little attention has been given to a comparison of the properties of single supergiants and those that are members of multiple systems. Aims. Atmospheric parameters and nitrogen abundances have been estimated for all the B-type supergiants identified in the VLT-FLAMES Tarantula survey. These include both single targets and binary candidates. The results have been analysed to investigate the role of binarity in the evolutionary history of supergiants.Methods.  non-local thermodynamic equilibrium (LTE) model atmosphere calculations have been used to determine atmospheric parameters and nitrogen abundances for 34 single and 18 binary supergiants. Effective temperatures were deduced using the silicon balance technique, complemented by the helium ionisation in the hotter spectra. Surface gravities were estimated using Balmer line profiles and microturbulent velocities deduced using the silicon spectrum. Nitrogen abundances or upper limits were estimated from the N  spectrum. The effects of a flux contribution from an unseen secondary were considered for the binary sample. Results. We present the first systematic study of the incidence of binarity for a sample of B-type supergiants across the theoretical terminal age main sequence (TAMS). To account for the distribution of effective temperatures of the B-type supergiants it may be necessary to extend the TAMS to lower temperatures. This is also consistent with the derived distribution of mass discrepancies, projected rotational velocities and nitrogen abundances, provided that stars cooler than this temperature are post-red supergiant objects. For all the supergiants in the Tarantula and in a previous FLAMES survey, the majority have small projected rotational velocities. The distribution peaks at about 50 km s −1 with 65% in the range 30 km s −1 ≤ v e sin i ≤ 60 km s −1 . About ten per cent have larger v e sin i (≥100 km s −1 ), but surprisingly these show little or no nitrogen enhancement. All the cooler supergiants have low projected rotational velocities of ≤70 km s −1 and high nitrogen abundance estimates, implying that either bi-stability braking or evolution on a blue loop may be important. Additionally, there is a lack of cooler binaries, possibly reflecting the small sample sizes. Single-star evolutionary models, which include rotation, can account for all of the nitrogen enhancement in both the single and binary samples. The detailed distribution of nitrogen abundances in the single and binary samples may be different, possibly reflecting differences in their evolutionary history. Conclusions. The first comparative study of single and binary B-type supergiants has revealed that the main sequence may be significantly wider than previously assumed, extending to T eff = 20 000 K. Some marginal differences in single and binary atmospheric parameters and abundances have been identified, possibly implying non-stand...

show abstract

“…The expression for the complex amplitudes of the light variations in a given passband within the linear and zero-rotation approximation can be found, e.g., in Daszyńska-Daszkiewicz et al (2002), and need not be repeated here. To compute the values of these observables, we used the nonadiabatic pulsational code of Dziembowski (1977) and tables of the fluxes in photometric passbands and nonlinear limb-darkening coefficients computed by Daszyńska-Daszkiewicz & Szewczuk (2011) on the basis of the NLTE atmosphere models of Lanz & Hubeny (2007).…”

Section: Photometric Amplitudes and Phases Of Pulsations In Early B-tmentioning

confidence: 99%

Pulsations in B-type supergiants with masses $\boldsymbol {M<20}\,\mathbf {M}_{\odot }$ before and after core helium ignition

Ostrowski¹,

Daszyńska‐Daszkiewicz²

2015

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

Evolutionary tracks and pulsational analysis of models with masses of 13-18 M ⊙ are presented. We address two important questions. The first one deals with one of the most unresolved problems in astrophysics, i.e., the existence of a blue loop after core helium ignition; the so called "to loop or not to loop" problem. We show that inward overshooting from the outer convective zone in the red giant phase is prerequisite for the development of the blue loop. Our second question concerns pulsational instability of models in the core helium burning phase. We present for the first time that models on the blue loop can have unstable modes driven by the κ mechanism operating in the Z−bump. Contrary to post-main sequence models in the shell hydrogen burning phases, pulsational instability of the blue loop models depends mainly on effective temperature and metallicity is of secondary importance. Finally, we try to interpret the oscillation spectrum of the blue supergiant HD 163899, the only member of the SPBsg class, and to get some clue on the evolutionary status of the star.

show abstract

A Grid of NLTE Line‐blanketed Model Atmospheres of Early B‐Type Stars

Cited by 600 publications

References 46 publications

Revised physical elements of the astrophysically important O9.5+O9.5V eclipsing binary system Y Cygni

Revised physical elements of the astrophysically important O9.5+O9.5V eclipsing binary system Y Cygni

The VLT-FLAMES Tarantula Survey

Pulsations in B-type supergiants with masses $\boldsymbol {M<20}\,\mathbf {M}_{\odot }$ before and after core helium ignition

Contact Info

Product

Resources

About