scholarly journals Revised Baade–Wesselink Analysis of RR Lyrae Stars

2000 ◽  
Vol 176 ◽  
pp. 176-181 ◽  
Author(s):  
Carla Cacciari ◽  
Gisella Clementini1 ◽  
Fiorella Castelli ◽  
Fabrizio Melandri
Keyword(s):  
Radial Velocity ◽  
Zero Point ◽  
Absolute Magnitude ◽  
Mean Value ◽  
Physical Parameters ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Proper Comparison ◽  
The Mean ◽  
Lyrae Stars

AbstractWe have applied the Baade–Wesselink method to two field RR Lyrae stars, i.e. SW And and RR Cet, and derived their distances and physical parameters. With respect to previous B–W analyses we have applied the following improvements: i) use of all sets of available data, after proper comparison for homogeneity and compatibility; ii) use of the most recent and accurate model atmospheres, with turbulent velocity Vturb = 4 km s−1 and the no-overshooting approximation, and comparison with other treatments of convection; iii) use of the instantaneous gravity along the pulsation cycle rather than the mean value; iv) comparison with modified radial velocity curves according to various assumptions on radial velocity gradients in the atmosphere; and v) careful reanalysis of the temperature scale. The main aim of this study is to evaluate the effect of the above items on the B–W results and verify whether any (or a combination) of them can possibly account for the discrepancy of the absolute magnitude zero-point with respect to other independent determinations.

scholarly journals RR Lyrae in M15: Fourier Decomposition and Physical Parameters

2006 ◽  
Vol 2 (S240) ◽  
pp. 605-612
Author(s):  
G. García Lugo ◽  
A. Arellano Ferro ◽  
Patricia Rosenzweig
Keyword(s):  
Globular Clusters ◽  
Light Curves ◽  
Physical Parameters ◽  
Rr Lyrae Stars ◽  
Mean Values ◽  
Fourier Decomposition ◽  
Rr Lyrae ◽  
Blazhko Effect ◽  
The Mean ◽  
Lyrae Stars

AbstractThe V and R light curves for 30 RR Lyrae stars in M15 were used to calculate their physical parameters. The Blazhko effect, previously reported in V12, was not detected. The determined values of the iron content and distance of the cluster are: [Fe/H] = −1.98 ± 0.24 and d = 8.67 ± 0.41 kpc, respectively. The mean values of the physical parameters determined for the RR Lyrae stars place the cluster precisely into the sequences Oosterhoff type – metallicity and metallicity – effective temperature, valid for globular clusters.

scholarly journals Double-Mode RR Lyrae Stars in IC 4499

1988 ◽  
Vol 126 ◽  
pp. 591-592
Author(s):  
Christine M. Clement ◽  
James M. Nemec ◽  
Robert J. Dickens ◽  
Elizabeth A. Bingham
Keyword(s):  
Zero Point ◽  
Distance Modulus ◽  
Type I ◽  
Rr Lyrae Stars ◽  
Average Mass ◽  
Rr Lyrae ◽  
Cluster Distance ◽  
Metal Abundances ◽  
The Mean ◽  
Lyrae Stars

Thirteen double-mode RR Lyrae (RRd) stars, with mean magnitudes c = 18.30 ± 0.10 and <V>c = 17.80 ± 0.15, have been identified in the variable-rich Oosterhoff type I globular cluster IC 4499. The stars have surprisingly uniform properties, and are considerably different from RRd stars found in Oo II systems. The mean first-overtone period (Fig.1) is <P1>=0.357d ± 0.005d (cf. <P1>=0.40d for Oo II RRd stars), and the mean ratio of the first-overtone period to the fundamental period is <P1/P0>= 0.7443 ± 0.0002. The mean double-mode pulsation mass for the 13 stars, using the King Ia (Y=0.279, Z=0.001) mass calibration, is 0.535 ± 0.003 M⊙. Such an average mass is 0.11 M⊙ smaller (i.e. ~17% smaller) than that for RRd stars found in Oo II systems, and possibly ~0.01 M⊙smaller than the mean mass for the two RRd stars in M3 (it is important to note that the zero point of these mass determinations is uncertain by at least 15%). The metal abundances for the RRd stars, and for the system of RR Lyrae stars as a whole, are found to be consistent with <[Fe/H]>=-1.38 ± 0.20, determined from δS spectroscopy. In the Peterson diagram (Fig.2), all known RRd stars now divide (apparently by mass) into two groups (split according to Oosterhoff type). With a reddening of EB-V=0.26 ± 0.03, the cluster distance modulus is (m-M)o=16.23m ± 0.23m.

scholarly journals The Zero Point of Extinction toward Baade's Window from RR Lyrae Stars

1998 ◽  
Vol 494 (1) ◽  
pp. 396-399 ◽  
Author(s):  
C. Alcock ◽  
R. A. Allsman ◽  
D. R. Alves ◽  
T. S. Axelrod ◽  
A. C. Becker ◽  
...  
Keyword(s):  
Zero Point ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Lyrae Stars

scholarly journals The Virgo Stellar Stream: Extended sample

2009 ◽  
Vol 5 (S262) ◽  
pp. 131-134 ◽  
Author(s):  
S. Duffau ◽  
A. K. Vivas ◽  
R. Zinn ◽  
R. A. Méndez ◽  
M. T. Ruiz
Keyword(s):  
Radial Velocity ◽  
Spectroscopic Study ◽  
The Sun ◽  
Rr Lyrae Stars ◽  
Survey Team ◽  
Rr Lyrae ◽  
Abundance Estimates ◽  
Metal Abundance ◽  
Lyrae Stars

AbstractWe have completed a spectroscopic study of the “12.4 hr clump”, the second largest substructure in the Quasar Equatorial Survey Team (QUEST) catalog. First discovered as an over-density of RR Lyrae stars (Vivas et al. 2001, ApJL 554 33), the region containing the “12.4 hr clump” has generated much interest (Newberg et al. (2002), Martinez-Delgado et al. (2007), Juric et al. (2008), amongst many others). Our first spectroscopic study of this clump revealed the presence of a sharp peak in the radial velocity histogram for the candidate stars (Duffau et al. 2006). The combination of this result and metal abundance estimates for the sample was then interpreted as a signature of the presence of a stellar stream within the clump. This sub-structure was named the “Virgo Stellar Stream” (VSS), given its location in the direction of the Virgo Constellation, at approximately 20 kpc from the Sun. Several other groups have studied this region and have suggested that the over-density containing the VSS could extend to larger areas of the sky (outside QUEST's observing range). We present the complete spectroscopic follow up of the clump candidates present in QUEST and the composite of the studies we performed along the same l.o.s., including data at brighter magnitudes (Vivas et al. 2008). Our study confirmed the nature of the VSS, revealed its likely extent within the QUEST survey and defined a number of its relevant properties.

scholarly journals The Absolute Magnitude and Kinematics of RR Lyrae Stars Via Statistical Parallax

1996 ◽  
Vol 112 ◽  
pp. 2110 ◽  
Author(s):  
Andrew C. Layden ◽  
Robert B. Hanson ◽  
Suzanne L. Hawley ◽  
Arnold R. Klemola ◽  
Christopher J. Hanley
Keyword(s):  
Absolute Magnitude ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
The Absolute ◽  
Lyrae Stars

scholarly journals GAIA PARALLAX ZERO POINT FROM RR LYRAE STARS

2017 ◽  
Vol 50 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Andrew Gould ◽  
Juna A. Kollmeier
Keyword(s):  
Zero Point ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Lyrae Stars

scholarly journals Multiplicity of Galactic Cepheids and RR Lyrae stars from Gaia DR2

2019 ◽  
Vol 623 ◽  
pp. A116 ◽  
Author(s):  
Pierre Kervella ◽  
Alexandre Gallenne ◽  
Nancy Remage Evans ◽  
Laszlo Szabados ◽  
Frédéric Arenou ◽  
...  
Keyword(s):  
Proper Motion ◽  
Binary Systems ◽  
Variable Stars ◽  
Rr Lyrae Stars ◽  
Orbital Parameters ◽  
Rr Lyrae ◽  
Multiple Stars ◽  
Classical Cepheids ◽  
The Mean ◽  
Lyrae Stars

Context. Classical Cepheids (CCs) and RR Lyrae stars (RRLs) are important classes of variable stars used as standard candles to estimate galactic and extragalactic distances. Their multiplicity is imperfectly known, particularly for RRLs. Astoundingly, to date only one RRL has convincingly been demonstrated to be a binary, TU UMa, out of tens of thousands of known RRLs. Aims. Our aim is to detect the binary and multiple stars present in a sample of Milky Way CCs and RRLs. Methods. In the present article, we combine the HIPPARCOS and Gaia DR2 positions to determine the mean proper motion of the targets, and we search for proper motion anomalies (PMa) caused by close-in orbiting companions. Results. We identify 57 CC binaries from PMa out of 254 tested stars and 75 additional candidates, confirming the high binary fraction of these massive stars. For 28 binary CCs, we determine the companion mass by combining their spectroscopic orbital parameters and astrometric PMa. We detect 13 RRLs showing a significant PMa out of 198 tested stars, and 61 additional candidates. Conclusions. We determine that the binary fraction of CCs is likely above 80%, while that of RRLs is at least 7%. The newly detected systems will be useful to improve our understanding of their evolutionary states. The discovery of a significant number of RRLs in binary systems also resolves the long-standing mystery of their extremely low apparent binary fraction.

On the absolute magnitude of RR Lyrae stars - UU Ceti, RV Phoenicis, and W Tucanae

1992 ◽  
Vol 396 ◽  
pp. 219 ◽  
Author(s):  
C. Cacciari ◽  
G. Clementini ◽  
J. A. Fernley
Keyword(s):  
Absolute Magnitude ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
The Absolute ◽  
Lyrae Stars
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