scholarly journals Review of Observational Data on RR Lyrae Stars

1971 ◽  
Vol 2 ◽  
pp. 781-787
Author(s):  
G. van Herk
Keyword(s):  
Radial Velocity ◽  
Observational Data ◽  
Proper Motion ◽  
Point Of View ◽  
Proper Motions ◽  
Physical Point ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Complete Set ◽  
Lyrae Stars

The data on which my work on the secular parallaxes of RR Lyrae stars is based (Bull. Astron. Inst. Neth.18) were in many respects so incomplete that I have tried to interest astronomers to get a more complete set of data. The number of stars for which I had a proper motion was only 168, and for which a radial velocity was known, was 180, with an overlap of only 138 stars. The accuracy of the proper motions was certainly unsatisfactory for 43% of the total. The greatest trouble in dealing with such insufficient numbers arises when one wants to subdivide the material into groups which are homogeneous from a physical point of view. Many subdivisions, in making up my paper, were not tried at all, simply because the material was inadequate.In recent years plenty of work has been done by various investigators, of which I will at this point only mention the work on proper motions done at the Leander McCormick Observatory, and the great number of radial velocities determined by Dr. Clube and his associates. I do not, however, believe we are yet in a position to consider the whole subject as finished. Discussions about space motions, as given by Professor Oort in the book Stellar Structures, Volume V, will, at this time, be hardly improved upon. I still feel we should increase the number of stars substantially in order to get a better statistical discussion possible. This means we have to go to fainter stars. Plenty of these stars will be found on the plates which have served to make the Charts of the Carte du Ciel, which means we have at least one old position available for proper motions. At Leiden we are now engaged in the determination or redetermination of the proper motions of 430 RR 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 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.

scholarly journals The Lick Observatory Program on Proper Motions of RR Lyrae Stars

1971 ◽  
Vol 2 ◽  
pp. 790-791
Author(s):  
A. R. Klemola
Keyword(s):  
Proper Motions ◽  
Rr Lyrae Stars ◽  
Mean Error ◽  
Rr Lyrae ◽  
Star Catalogue ◽  
Homogeneous Set ◽  
The Mean ◽  
Year 2000 ◽  
Lyrae Stars

It is the purpose of this note to reveal the nature and progress of a long term astrometric program at the Lick Observatory (see references by S. Vasilevskis in Trans. Int. Astron. Union, XI B, 404, 1962). One of its many goals is the measurement of absolute proper motions of RR Lyrae stars with respect to faint galaxies. The first-epoch photographs, obtained in 1947-54 by Shane and Wirtanen for the sky north of declination – 23°, were supplemented later by plates of poorer quality down to –33° with the 20-in. astrograph. This means that first-epoch plates are now on hand which cover three-fourths of the sky and on which stars of 9-17 mag. may be measured for proper motions. Since these photographs represent the largest and most homogeneous set that will be available in the foreseeable future, we shall try to estimate the number of RR Lyrae stars which may be measured on them.As a guide we take the 1968 edition of the Russian Variable Star Catalogue, which contains a little over 4400 RR Lyrae stars. For the sky north of —33° nearly 2000 of these stars are brighter than average magnitude 17.0, 1000 brighter than 15.0, and about 350 brighter than 12.0. Experience with the Lick program shows that 80% of these stars should be measurable, after account is made for losses due to plate defects, blended images, and other factors.An important limitation to the usefulness of the measured motions is imposed by the size of the mean errors, which amount to 0.”7/century for an epoch difference of 20 yr. This mean error is the same size as the proper motion of a typical RR Lyrae star of 13.0 mag. But for an epoch difference of 50 yr the mean error drops to 0.”3/century, which is comparable to the motion of an RR Lyrae star of 15.0 mag. Useful results for the fainter RR Lyrae stars will not be possible until after a third epoch about the year 2000.

scholarly journals Erratum: Photometric and radial-velocity time-series of RR Lyrae stars in M3: analysis of single-mode variables

2018 ◽  
Vol 481 (2) ◽  
pp. 2778-2778
Author(s):  
J Jurcsik ◽  
P Smitola ◽  
G Hajdu ◽  
Á Sódor ◽  
J Nuspl ◽  
...  
Keyword(s):  
Time Series ◽  
Radial Velocity ◽  
Single Mode ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Lyrae Stars

Measures of RR Lyrae Stars

1984 ◽  
Vol 88 ◽  
pp. 399-403
Author(s):  
G. Burki ◽  
G. Meylan ◽  
M. Mayor
Keyword(s):  
Radial Velocity ◽  
General Information ◽  
Radial Velocities ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Lyrae Stars ◽  
Pulsation Cycle

Four RR Lyrae stars have been measured in Oct.-Nov. 1983 from the Observatoire de Haute Provence in France (radial velocities with CORAVEL) and from La Silla Observatory in Chile (Geneva 7-color photometry). General information on these stars is listed in the following table. The quantities N and σ are the number of measurements and the typical precision of one measurement.The variation of the radial velocity with the pulsation cycle of each star is shown in Fig. 1. Especially noteworthy is the very quick decrease of the radial velocity in the cases of RR Cet and DX Del.

scholarly journals The Absolute Magnitude Of RR Lyrae Stars

1998 ◽  
Vol 11 (1) ◽  
pp. 580-580
Author(s):  
T. Tsujimoto ◽  
M. Miyamoto ◽  
Y. Yoshii
Keyword(s):  
Hubble Constant ◽  
Likelihood Estimation ◽  
Absolute Magnitude ◽  
Proper Motions ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Trigonometric Parallaxes ◽  
The Absolute ◽  
Age Of The Universe ◽  
Lyrae Stars

The present determination of the absolute magnitude .Mv(RR) of RR Lyrae stars is twofold, relying upon Hipparcos proper motions and trigonometric parallaxes separately. First, applying the statistical parallax method to the proper motions, we find < Mv(RR)>= 0.69 ± 0.10 for 99 halo RR Lyraes with <[Fe/H]> = -1.58. Second, applying the Lutz-Kelker correction to the RR Lyrae HIP95497 with the most accurately measured parallax, we obtain Mv(RR) = 0.57-0.74 at [Fe/H]=-1.6. Furthermore, allowing full use of low accuracy and negative parallaxes as well for 125 RR Lyraes with - 2.49≤[Fe/H]≤0.07, the maximum likelihood estimation yields the relation, Mv(RR)= (0.59±0.37)+(0.20±0.63)([Fe/H]+1.60), which formally agrees with the recent preferred relation. The same estimation yields again My (RR) = 0.65 ± 0.33 for the 99 halo RR Lyraes. Although the formal errors in the latter two estimates are rather large, all of the four results suggest the fainter absolute magnitude, My(RR)=0.6-0.7 at [Fe/H]=-1.6. The present results still provide the lower limit on the age of the universe which is inconsistent with a fiat, matter-dominated universe and current estimates of the Hubble constant.

scholarly journals Photometric and radial-velocity time series of RR Lyrae stars in M3: analysis of single-mode variables

2017 ◽  
Vol 468 (2) ◽  
pp. 1317-1337 ◽  
Author(s):  
J. Jurcsik ◽  
P. Smitola ◽  
G. Hajdu ◽  
Á. Sódor ◽  
J. Nuspl ◽  
...  
Keyword(s):  
Time Series ◽  
Radial Velocity ◽  
Single Mode ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Lyrae Stars
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