uvby Paper Abstracts
Balona L.A. (1984, MNRAS 211, 973)
Using the Kurucz model atmospheres as a guide, we calibrate effective
temperatures and bolometric corrections for early-type stars in terms of
the Stromgren co and beta indices. These are placed on an empirical scale by
adjusting the zero points for best agreement with measurements by Code et
al. The form of the mass calibration is determined from evolutionary
calculations and the zero point adjusted for best agreement with empirical
determinations. A mass discrepancy problem arises when these masses are
compared with those determined from model atmospheres.
Balona L.A. (1994, NMNRAS 268, 119)
We discuss the determination of effective temperature, bolometric
correction and surface gravity using Stromgren indices. We use synthetic
colours to define the functional relationship over a wide range of surface
gravity, and calibrate the relationship by means of stars with well-determined
effective temperatures and surface gravities. The calibrations are presented
as interpolation formulae, valid for O-F stars. We find that the latest
evolutionary computations predict masses that agree with those from detached
eclipsing binaries to within 7 per cent. We discuss the position of the
zero-age main sequence from the models relative to that observed in two
young open clusters. There is a serious discrepancy between the surface
gravity calculated from model atmospheres and from evolutionary models.
Gray R.O. (1991, A&A 252, 237)
This paper is the second in a series of papers which derives an empirical
calibration of the Stromgren uvby beta photometric system for the A, F and
early G supergiants. This paper considers the F and early G supergiants.
A calibration which gives the intrinsic colour (b-y)o in terms of a
temperature parameter, [m1] and a gravity parameter delta [c1] is derived.
This calibration is subjected to tests to determine the presence of
systematic errors. It is also used to derive colour excesses for a set of
classical Cepheid variable stars, which are compared to other estimates in
the literature. Finally, the (b-y)o index is calibrated against the
effective temperatures of Luck & Bond (1989), and the sensitivity of the
calibration to metal abundance is discussed.
Gray R.O. (1992, A&A 265, 704)
This paper, the third in a series, deals with calibration of Stromgren
photometry for the A and early F supergiants. We derive a gravity parameter,
delta G, which can be used to separate photometrically supergiants of
different luminosity classes. delta G is used in conjunction with [m1] to
derive a simple calibration which gives the intrinsic colour, (b-y)o of
the supergiant. This calibration is tested and compared with other reddening
estimates for A and F supergiants in the literature. Finally, we derive a
semi-empirical effective temperature calibration for the A and F supergiants.
Napiwotzki R., et al. (1993, AA 268, 653)
The determination of stellar temperatures and surface gravities by means of
the Stromgren photometric system is examined in the region. We used a sample
of stars with independently derived temperature and gravities. We compare our
results with Castelli (1991) and present new temperature calibrations for normal
stars ([u-b],(b-y)o, and Johnson (B-V)o) and for Ap stars ([u-b] and [c1]).
The use of integrated fluxes and especially the infrared flux method (IRFM) for
determining stellar temperatures is discussed. SDurface gravities of B and A stars,
derived by fitting theoretical profiles to the Balmer lines, are used to check the
Olsen E.H. (1988, AA 189, 173)
Several calibrations of Stromgren uvby-beta photometry with respect to the intrinsic
colour (b-y)o exist for F-type stars. These calibration are complementary,
since they are valid for different ranges of heavy element abundance. A new
comprehensive intrinsic colour calibration is presented. It is valid for all
F0-G2 stars of luminosity classes III-V, except possibly the most extreme
population II stars. The calibration is based on 1231 stars. The rms scatter
around the calibration is 0.009 (one star).
Schuster W.J., Nissen P.E. (1989, A&A 221, 65)
The uvby beta photometry of 711 hight-velocity and metal-poor stars by Schuster
and Nissen (1988, Paper I) has been used to derive new (b-y)o - beta and [Fe/H]
calibrations. The interstellare color excess, E(b-y), can be determined with a
standard deviation of 0.01 for beta values down to 2.55. The standard deviation
of [Fe/H] increases from about 0.15 dex at [Fe/H]~-0.5 to about 0.30 dex at
[Fe/H]~-2.5. The calibrations are particularly useful for metal-poor, late-F
and G stars, and will be used to study the age-metallicity-kinematic relations
of halo and old disk population stars. The error of E(b-y) for unresolved binary
stars is shown to be negligible whereas the error of [Fe/H] is of the order of
+0.10 to + 0.25 dex. Errors in beta due to radial velocity shifts of the H Beta
line are shown to be negligible for the particular set of beta observations in
Paper I. The derived reddenings and metallicities for stars from Paper I agree
very well with data from the survey of proper motions stars by Laird et al.
(1988) for the large majority of the 132 stars in common between the two works.
However, about 10% of the stars have significant differences in the derived
reddenings, which lead to differences in [Fe/H] of typically +0.40 dex. The
[Fe/H] values for stars in Paper I do not agree particularly well with the
[Fe/H] values of Sandage and Fouts (1987). From a comparison of data for 258
stars in common the standard deviation of the [Fe/H] values of Sandage and Fouts
is estimated to be 0.35 dex. This error should be taken into account when
deriving the intrinsic relations between kinematical parameters and metallicity
from the data of Sandage and Fouts.
Smalley B., Dworetsky M.M. (1995, A&A 293, 446)
We present an investigation into the determination of fundamental values of
Tefff and log g. A re-evaluation of the fundamental values of T eff determined
by Code et al. (1976) using modern flux measurements is presented, but there
are no significant changes. A determination of fundamental values of Tefff for
four binary systems with fundamental log g value has been performed.
Medium-resolution Hbeta profiles of the fundamental stars have been obtained
and compared to theoretical profiles in order to provide estimates of the
parameters that have not been obtained in a fundamenta manner.
We have calculated a table of synthetic beta indices which explicitly include
the effects of metal-line blocking. We find that these beta indices are in
good agreement with the photometric values. A comparison of theoretical uvby
colours is also presented, and found to be in very good agreement with the
Last update: 7 Novembre 1995