scholarly journals Stellar Temperature Scale and Bolometric Corrections

1973 ◽  
Vol 54 ◽  
pp. 231-271 ◽  
Author(s):  
J. R. W. Heintze
Keyword(s):  
Temperature Scale ◽  
Main Sequence ◽  
Main Sequence Stars ◽  
Correction Formula ◽  
Stellar Temperature ◽  
Effective Temperatures ◽  
Future Work ◽  
Intrinsic Colour

In chapter 1 basic methods are reviewed, and applications and suggestions for future work are presented. In chapter 2 a revision is given of the intrinsic-colour relation in the U, B, V system of hot main-sequence stars. Some temperature-colour relations are discussed in chapter 3, where also a correction formula is given for the effects of interstellar reddening on the effective temperatures of hot main-sequence stars. An empirical mass-luminosity relation is given in chapter 4.

scholarly journals A test for radial mixing using local star samples

2012 ◽  
Vol 10 (H16) ◽  
pp. 357-357
Author(s):  
Jincheng Yu ◽  
Jerry Sellwood ◽  
Carlton Pryor ◽  
Li Chen ◽  
Jinliang Hou
Keyword(s):  
Angular Momentum ◽  
Main Sequence ◽  
Milky Way ◽  
Galactic Center ◽  
Thin Disk ◽  
Main Sequence Stars ◽  
Radial Gradient ◽  
Stellar Temperature ◽  
Effective Temperatures ◽  
Constant Gradient

AbstractWe use samples of local main-sequence stars to show that the radial gradient of [Fe/H] in the thin disk of the Milky Way decreases with mean effective stellar temperature. We use the angular momentum of each star about the Galactic center to eliminate the effects of epicyclic motion, which would otherwise blur the estimated gradients. We use the effective temperatures as a proxy for mean age, and conclude that the decreasing gradient is consistent with the predictions of radial mixing due to transient spiral patterns. We find some evidence that the trend of decreasing gradient with increasing mean age breaks to a constant gradient for samples of stars whose main-sequence life-times exceed the likely age of the thin disk.

scholarly journals Colours and Teff of Main Sequence Stars Covering the Galactic Metallicity Range

1995 ◽  
Vol 164 ◽  
pp. 368-368
Author(s):  
A. Alonso ◽  
S. Arribas ◽  
C. Martínez-Roger
Keyword(s):  
Temperature Scale ◽  
Main Sequence ◽  
Main Sequence Stars ◽  
Flux Method ◽  
Absolute Flux ◽  
The Galaxy ◽  
Effective Temperatures ◽  
Bolometric Correction ◽  
Flux Calibration ◽  
Hr Diagram

We present the results of a general programme aimed to study the effects of metallicity on the temperature scale of late main sequence stars (F0-K5). A sample of approximately 400 stars with published UBV(RI) and ubvy – β photometry has been collected from the literature. A three years campaign of observations (Alonso et al. 1994b) was carried out to obtain JHK photometry in order to apply the InfraRed Flux Method (IRFM) to derive effective temperatures. The effect of metallicity on Colour-Colour IR diagrams is discussed. The absolute flux calibration in the IR was revised in Alonso et al. (1994a). The effect of metallicity on the bolometric correction has been studied in Alonso et al. (1995) in order to derive bolometric fluxes. The temperatures have been derived by applying the IRFM using new Kurucz models. Teff = f(Colours, [Fe/H], log(g)) relations are obtained for dwarfs covering the ranges 4000K ≤ Teff ≤ 8000K, 3.5 ≤ logg ≤ 5.00, +0.5 ≤ [Fe/H] ≤ −3.00 which expands considerably the database of previous works. These relations are used to check atmosphere models through the analysis of UBV RIJH Kubvy – β synthetic photometry in combination with the IRFM. The transformation from the theoretical HR diagram into an observational one is analyzed with the new relations. The influence of these points on the study of the evolution of the Galaxy is briefly discussed.

Temperatures and radii of O stars

1979 ◽  
Vol 83 ◽  
pp. 103-108
Author(s):  
A. B. Underhill ◽  
L. Divan ◽  
V. Doazan ◽  
M.L. Prévot-Burnichon
Keyword(s):  
Main Sequence ◽  
Near Infrared ◽  
Stellar Atmosphere ◽  
Class Iii ◽  
Main Sequence Stars ◽  
Class V ◽  
Intermediate Band ◽  
B Stars ◽  
Luminosity Class ◽  
Effective Temperatures

Angular diameters have been estimated for 18 O and 142 B stars using absolute intermediate-band photometry in the near infrared and they have been combined with integrated fluxes to yield effective temperatures. The effective temperatures of the O stars lie in the range 30000 K to about 47000 K. For a given subtype, the luminosity class I stars have lower effective temperatures than the main-sequence stars by about 1000 K. The absorption-line spectral types of the supergiants of types O and B reflect electron temperatures which are higher than can be maintained by the integrated flux which flows through the stellar atmosphere. Distances have been estimated for all the stars and linear diameters found. The average radius for an 08 to 09.5 supergiant is about 23.3 R⊙; the radii for luminosity class III and Class V O stars lie in the range 6.8 to 10.7⊙ R.

scholarly journals The stellar temperature scale from angular diameters and flux distributions

1997 ◽  
Vol 189 ◽  
pp. 147-152
Author(s):  
A.J. Booth
Keyword(s):  
Temperature Scale ◽  
Current Situation ◽  
Stellar Temperature ◽  
Uv Visible ◽  
Effective Temperatures ◽  
Angular Diameters

The current situation for the measurement of effective temperatures from interferometrically determined angular diameters and spectrophometry in the UV, visible and IR is considered. Accuracies and reliabilities of the resulting temperatures are assessed and coverage of stellar types is discussed.

scholarly journals A Tale on Two Close Binaries in Pegasus

2014 ◽  
Vol 23 (2) ◽  
Author(s):  
H. V. Şenavcı ◽  
M. Yılmaz ◽  
Ö. Baştürk ◽  
İ. Özavcı ◽  
Ş. Çalışkan ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Main Sequence ◽  
Curve Analysis ◽  
Velocity Curve ◽  
Close Binaries ◽  
Main Sequence Stars ◽  
Radial Velocity Curve ◽  
Contact Binaries ◽  
Effective Temperatures

AbstractWe present the simultaneous light and radial velocity curve analysis of two contact binaries in Pegasus using the Wilson-Devinney code. The following absolute astrophysical parameters are determined: masses, radii and effective temperatures. BB Peg is a W-subtype W UMa-type binary, components of which are main sequence stars with 0.50

Some Remarks on Young Clusters and Peculiar A Stars Associated with them

1967 ◽  
Vol 1 (1) ◽  
pp. 14-15 ◽  
Author(s):  
A. R. Hyland
Keyword(s):  
Effective Temperature ◽  
Temperature Scale ◽  
Main Sequence ◽  
Atmospheric Parameters ◽  
Main Sequence Stars ◽  
B Stars ◽  
Excellent Opportunity ◽  
Young Clusters

A study has been made of the upper main-sequence stars in several young clusters, in an attempt to determine a well-defined effective temperature scale for the B stars, and to compare the observed atmospheric parameters with the recent theoretical evolutionary tracks in the H-R diagram (Iben, 1965, Hofmeister et al, 1964, Kippenhahn et al., 1965). Each of the clusters studied contains at least one peculiar A star of the Si λ-4200 type, and this afforded an excellent opportunity for a study of the evolution of these stars.

scholarly journals Mathematical Assessment of Physical and Chemical Processes from the Middle B to the Early F Type Main Sequence Stars

2017 ◽  
Vol 12 (S330) ◽  
pp. 362-363
Author(s):  
Kutluay Yüce ◽  
Saul J. Adelman
Keyword(s):  
Main Sequence ◽  
Stellar Atmospheres ◽  
Stellar Winds ◽  
Main Sequence Stars ◽  
Energy Distributions ◽  
Elemental Abundances ◽  
Effective Temperatures ◽  
Evolutionary Paths ◽  
Physical And Chemical ◽  
Hr Diagram

AbstractThe middle B to the early F Main Sequence stars have some of the most quiet stellar atmospheres. In this part of the HR diagram we find stars with atmospheres in radiative equilibrium. They lack the convective circulations of the middle F and cooler stars and the massive stellar winds of hotter stars. When stars of different mass evolve off the Main Sequence in this part of the HR Diagram their evolutionary paths do not cross initially. Thus stars with the same effective temperature and surface gravity have the same luminosity and mass. By comparing their elemental abundances, we might be able to identify physical processes which cause any differences in their abundances. Here we begin with stars whose effective temperatures and surface gravities are similar, and which have been analyzed by us using spectra obtained from the Dominion Astrophysical Observatory (DAO). Improvements in our knowledge of the energy distributions of stars (for example via GAIA measurements) should lead to improved estimates of stellar effective temperatures and surface gravities.

scholarly journals Empirical bolometric correction coefficients for nearby main-sequence stars in the Gaia era

2020 ◽  
Vol 496 (3) ◽  
pp. 3887-3905 ◽  
Author(s):  
Z Eker ◽  
F Soydugan ◽  
S Bilir ◽  
V Bakış ◽  
F Aliçavuş ◽  
...  
Keyword(s):  
Main Sequence ◽  
Eclipsing Binaries ◽  
The Other ◽  
Accurate Data ◽  
Quadratic Relation ◽  
Main Sequence Stars ◽  
Data Release ◽  
Trigonometric Parallaxes ◽  
Bolometric Correction ◽  
Intrinsic Colour

ABSTRACT Nearby detached double-lined eclipsing binaries with most accurate data were studied and 290 systems were found with at least one main-sequence component having a metallicity of 0.008 ≤ Z ≤ 0.040. Stellar parameters, light ratios, Gaia Data Release 2 trigonometric parallaxes, extinctions and/or reddening were investigated and only 206 systems were selected as eligible to calculate empirical bolometric corrections. NASA/IPAC Galactic dust maps were the main source of extinctions. Unreliable extinctions at low Galactic latitudes |b| ≤ 5° were replaced with individual determinations, if they exist in the literature, else associated systems were discarded. The main-sequence stars of te remaining systems were used to calculate the bolometric corrections (BCs) and to calibrate the BC–Teff relation, which is valid in the range 3100–36 000 K. De-reddened (B − V)0 colours, on the other hand, allowed us to calibrate two intrinsic colour–effective temperature relations; the linear one is valid for $T_{\rm eff}\gt 10\, 000$ K, while the quadratic relation is valid for $T_{\rm eff}\lt 10\, 000$ K; that is, both are valid in the same temperature range in which the BC–Teff relation is valid. New BCs computed from Teff and other astrophysical parameters are tabulated, as well.

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