scholarly journals The Absolute Luminosity of RR Lyrae Variables

1988 ◽  
Vol 126 ◽  
pp. 587-588
Author(s):  
C. Cacciari ◽  
G. Clementini ◽  
L. Prevot
Keyword(s):  
Surface Brightness ◽  
Radial Velocities ◽  
Photoelectric Photometry ◽  
Rr Lyrae ◽  
Metal Abundance ◽  
Metal Abundances ◽  
Complete Set ◽  
Effective Temperatures ◽  
Absolute Magnitudes ◽  
Absolute Luminosity

We have taken UBVRI photoelectric photometry and CORAVEL radial velocities for 6 field RR Lyraes, i.e. SW And, YZ Cap, SW Dra, SS For, RV Phe and V440 Sgr, with the purpose of applying the Baade-Wesselink (B-W) method and determining their absolute magnitudes. The present improvements with respect to previous applications of the method are: a) the use of the (V-I) color, which shows the smallest sensitivity to gravity and metal abundance in the color-visual surface brightness plane. b) the use of a new grid of model atmospheres by Buser and Kurucz (1986), which include an improved treatment of opacity and convection. They provide a complete set of models for the relevant values of effective temperatures, gravities and metal abundances, thus avoiding the need of inaccurate interpolations or extrapolations.

scholarly journals The Luminosities of 13 Field RR Lyrae Stars: The Correlation with Metallicities

1989 ◽  
Vol 111 ◽  
pp. 272-272
Author(s):  
T. Liu ◽  
K.A. Joens
Keyword(s):  
Surface Brightness ◽  
Large Range ◽  
Radial Velocities ◽  
Color Temperature ◽  
Clear Correlation ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Absolute Magnitudes ◽  
Lyrae Stars

AbstractWe have obtained UBVRI and JK photometry and radial velocities for 13 field RR Lyrae stars with a large range of metallicity. Our sample includes eleven ab-type and two c-type variables. The surface brightness method is applied to these RR Lyrae stars to determine their mean absolute magnitudes <MV> as well as their distances and radii. We have used the Kurucz’s model atmospheres to provide metallicity- and gravity-dependent color-temperature transformations and bolometric corrections. Our results indicate a clear correlation between the luminosities of the RR Lyrae stars and their metallicities such that metal-poor RR Lyrae stars are more luminous.

scholarly journals Absolute Magnitudes of RR Lyrae Variables

1971 ◽  
Vol 2 ◽  
pp. 788-789
Author(s):  
S. V. M. Clube
Keyword(s):  
Velocity Dispersion ◽  
Radial Velocities ◽  
Proper Motions ◽  
Photoelectric Photometry ◽  
Rr Lyrae ◽  
Solar Motion ◽  
Absolute Magnitudes ◽  
Kinematic Properties

My remarks concern the kinematics of a-type RR Lyrae variables with large ∆s(≥5), supposedly halo members, which have relatively well determined proper motions (μ) and radial velocities (ϱ) as well as accurate photoelectric photometry (m). The number of variables fulfilling these criteria is about 60. Using procedures which need not be discussed in detail here, it is possible to determine the statistical kinematic properties of these stars - that is, their solar motion (υ) and velocity dispersion (σ) - in two different ways:

scholarly journals Abundance Effects in the Classification of K Stars

1976 ◽  
Vol 72 ◽  
pp. 87-90
Author(s):  
P. M. Williams
Keyword(s):  
Spectral Type ◽  
Near Infrared ◽  
Narrow Band ◽  
Infrared Photometry ◽  
Metal Abundance ◽  
Metal Abundances ◽  
Effective Temperatures

The influence of metal abundance and gravity on the relation between spectral type and effective temperatures of late G and K type stars is investigated and calibrated using metal abundances from narrow-band photometry, near infrared photometry and independent luminosity estimates.

scholarly journals METAL ABUNDANCES, RADIAL VELOCITIES, AND OTHER PHYSICAL CHARACTERISTICS FOR THE RR LYRAE STARS IN THEKEPLERFIELD

2013 ◽  
Vol 773 (2) ◽  
pp. 181 ◽  
Author(s):  
James M. Nemec ◽  
Judith G. Cohen ◽  
Vincenzo Ripepi ◽  
Aliz Derekas ◽  
Pawel Moskalik ◽  
...  
Keyword(s):  
Physical Characteristics ◽  
Radial Velocities ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Metal Abundances ◽  
Lyrae Stars

scholarly journals The Gravitational Field of the Galaxy in the Z Direction

1977 ◽  
Vol 4 (2) ◽  
pp. 65-66
Author(s):  
R. F. Griffin
Keyword(s):  
Galactic Plane ◽  
Narrow Band ◽  
Radial Velocities ◽  
Photoelectric Photometry ◽  
Giant Stars ◽  
The North ◽  
The Galaxy ◽  
Absolute Magnitudes ◽  
North Galactic ◽  
K Giants

This is a progress report of a project designed to find the component, perpendicular to the Galactic plane, of the gravitational potential of the Galaxy. The principle is to measure the radial velocities and distances of a large number of K-giant stars near the North Galactic Pole. My student G. A. Radford is masterminding the project; collaborating with us are Drs. J. E. Gunn of the Hale Observatories and L. Hansen and K. Gyldenkerne of Copenhagen.We have measured the radial velocities of all the HD stars of type KO and later, and many of the G5 stars, within 15°of the Galactic Pole, using the Cambridge photoelectric spectrometer. In addition, we have observed all the stars classified as K giants by Upgren in his declination zones 25° to 31°, using the spectrometer on the Hale telescope. There are about 900 stars observed altogether, including about 200 Upgren stars, running down to twelfth magnitude or so, which are not in the Henry Draper Catalogue. To determine the distances of all these stars we are now trying to determine the absolute magnitudes by narrow-band photoelectric photometry in the Copenhagen system. Most of the observations have been made, thanks largely to the very generous grants of observing time given by the Hale Observatories earlier this year; but the reductions have only been completed for about 300 stars (including 244 K giants) which were observed last year at Kitt Peak, and the present, very preliminary, discussion is based on those stars alone.

The visual surface brightness relation and the absolute magnitudes of RR Lyrae stars. II - RR Lyrae and X ARIETIS

1981 ◽  
Vol 250 ◽  
pp. 312 ◽  
Author(s):  
A. Manduca ◽  
R. A. Bell ◽  
T. G., III Barnes ◽  
T. J. Moffett ◽  
D. S. Evans
Keyword(s):  
Surface Brightness ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
The Absolute ◽  
Absolute Magnitudes ◽  
Lyrae Stars

scholarly journals The Contribution of Hipparcos to the Study of the Stellar Metal-Rich Population in the Solar Neighbourhood

1998 ◽  
Vol 11 (1) ◽  
pp. 566-566
Author(s):  
G. Cayrel de Strobel ◽  
C. Soubiran ◽  
Y. Lebreton
Keyword(s):  
High Resolution ◽  
Interstellar Medium ◽  
Evolved Stars ◽  
Spectroscopic Analyses ◽  
The Galaxy ◽  
Solar Metallicity ◽  
Metal Abundances ◽  
The Mean ◽  
Effective Temperatures ◽  
Absolute Magnitudes

The ‘1996 Edition’ of the Catalogue of [Fe/H] determinations by Cayrel de Strobel et al. (1997, A&A S 124,1) and two recent papers by Castro et al. (1997, AJ Vol.114, N.1) and by Feltzing and Gustafsson (A&A in press) have made possible to increase in the theoretical HR diagram (log Teff, Mbol the number of SMR stars. The SMR Stars of this new enlarged sample had to have reliable absolute magnitudes, coming all from Hipparcos parallaxes, precise bolometric corrections, effective temperatures and metal abundances from high resolution detailed spectroscopic analyses. With the help of an appropriate grid of isochrones computed by Lebreton (1997, Perryman et al. A&A, in press), ‘turn-off ages’could then be attributed to the slightly evolved stars (subgiants) of the sample. The (log Teff, Mbol) diagram constituted by the new sample of SMR stars, shows that the conclusions in a former paper by Cayrel de Strobel (1987, A&AJ 8,141) remain valid: the SMR stars areold stars in spite of their higher than solar metallicity. The result, that metal-rich stars were in the mean old stars, was interpreted in the 1987 paper as due to a more chemical uniformity of the nowadays interstellar medium of the Galaxy with respect of the older much more active interstellar medium.

scholarly journals The Absolute Magnitudes of RR Lyrae Stars

1980 ◽  
Vol 58 ◽  
pp. 509-509
Author(s):  
A. Manduca ◽  
R. A. Bell
Keyword(s):  
Radial Velocity ◽  
Surface Brightness ◽  
Variable Stars ◽  
Velocity Curve ◽  
Private Communication ◽  
Radial Velocity Curve ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Absolute Magnitudes ◽  
Lyrae Stars

AbstractA theoretical counterpart to the Barnes-Evans relation between stellar surface brightness and V-R color has been calculated from model atmospheres for parameters appropriate to RR Lyrae stars. Such a relation can be used to derive stellar angular diameters from V,R photometry and, when applied to variable stars and combined with a radial velocity curve,, to derive radii, distances, and absolute magnitudes by the method of Barnes et al. (1977, MNRAS,178, 661). This was done for RR Lyr and X Ari using the photometry of Moffett and Barnes (1980, private communication) and radial velocities from the literature. The resulting absolute magnitudes are <MV> ± + 0.59 + 0.25 for X Ari and <MV> = 0.61 + 0.35 for RR Lyr. The method is shown to be a very accurate way of determining radii, distances, and absolute magnitudes for RR Lyrae stars which compares very favorably to the variations of the Baade-Wesselink technique currently in use.

scholarly journals Observed Relations Between Physical Properties and MK Classification as Functions of Metal Abundance for F5-K4 Stars

1976 ◽  
Vol 72 ◽  
pp. 75-78
Author(s):  
M. Grenon
Keyword(s):  
Physical Properties ◽  
Spectral Range ◽  
Spectral Type ◽  
Photometric System ◽  
Luminosity Class ◽  
Empirical Relations ◽  
Metal Abundance ◽  
Systematic Effects ◽  
The Absolute ◽  
Absolute Magnitudes

The Geneva photometric system has been calibrated in terms of [M/H], θeff, Mv in the spectral range F5 to K4. As the spectral type is a datum generally available, we derive empirical relations showing the coupling of θeff and [M/H] at given spectral type and luminosity class. Similar relations are offered for the absolute magnitudes and provide a more accurate means for deriving spectroscopic parallaxes. Systematic effects on the estimation of the luminosity class are also shown.

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