scholarly journals The kinematics and zero point of the log P –〈MK〉 relation for galactic field RR Lyrae variables via statistical parallax

2004 ◽  
Vol 193 ◽  
pp. 128-132 ◽  
Author(s):  
A.K. Dambis ◽  
O.V. Vozyakova
Keyword(s):  
Zero Point ◽  
Log P ◽  
Distance Modulus ◽  
Proper Motions ◽  
Galactocentric Distance ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Solar Galactocentric Distance ◽  
Lyrae Stars ◽  
Maximum Likelihood Technique

AbstractThe kinematical parameters of the local field RR Lyrae population and the zero point of the log P –〈MK〉 relation for these variables are inferred by applying the statistical parallax (maximum-likelihood) technique to a sample of 379 RR Lyrae stars with known periods, radial-velocities, metallicities, K-band photometry, and absolute proper motions on the ICRS system. Hipparcos, Tycho-2, SPM, UCAC1 and NPM1 were used as the sources of proper motions. The K-band magnitudes were adopted from the 2MASS All-Sky Data Release. The parameters of the velocity distribution are found to be (U0 = −13 ± 9, V0 = −41 ± 7, W0 = −19±4) kms−1, (σU = 66±9, σV = 47±7, σW = 23±5) km s−1 and (U0 = −11±10, V0 = −224±8, W0 = −8±6) km s−1 (σU = 158±9, σV = 95±5, σW = 88±5) km s−1 for the thick-disk (the purest disk sample, 56 stars) and halo (the purest halo sample, 264 stars) objects, respectively. The zero point of the infrared PL relation of Jones et al. (1992 – based on the results obtained using the Baade-Wesselink method) is confirmed: we find 〈MK〉 = −2.33⋅log PF−0.89±0.09, which is only brighter than found using the Baade-Wesselink method (Jones et al. 1992). A conversion of the resulting log P –〈MK〉 relation to V-band luminosities yields the metallicity-luminosity relation 〈MV〉 = +1.12 + 0.18 ⋅ [Fe/H] ± 0.10. Our results imply a solar Galactocentric distance of R0 = 7.8±0.4 kpc and an LMC distance modulus of DMLMC = 18.17 ±0.10 (cluster RR Lyraes) or DMLMC = 18.10±0.10 (field RR Lyraes), thereby favoring the so-called short distance scale.

scholarly journals Optical and Near-infrared Pulsation Properties of RR Lyrae and Population II Cepheid Variables in the Messier 15 Globular Cluster

2021 ◽  
Vol 922 (1) ◽  
pp. 20
Author(s):  
Anupam Bhardwaj ◽  
Marina Rejkuba ◽  
G. C. Sloan ◽  
Marcella Marconi ◽  
Soung-Chul Yang
Keyword(s):  
Globular Cluster ◽  
Near Infrared ◽  
Variable Stars ◽  
Log P ◽  
Distance Modulus ◽  
Distance Measurements ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Cepheid Variables ◽  
Lyrae Stars

Abstract Messier 15 (NGC 7078) is an old and metal-poor post core-collapse globular cluster that hosts a rich population of variable stars. We report new optical (gi) and near-infrared (NIR, JK s ) multi-epoch observations for 129 RR Lyrae, 4 Population II Cepheids (3 BL Herculis, 1 W Virginis), and 1 anomalous Cepheid variable candidate in M15 obtained using the MegaCam and the WIRCam instruments on the 3.6 m Canada–France–Hawaii Telescope. Multi-band data are used to improve the periods and classification of variable stars, and determine accurate mean magnitudes and pulsational amplitudes from the light curves fitted with optical and NIR templates. We derive optical and NIR period–luminosity relations for RR Lyrae stars which are best constrained in the K s band, m K s = − 2.333 ( 0.054 ) log P + 13.948 ( 0.015 ) with a scatter of only 0.037 mag. Theoretical and empirical calibrations of RR Lyrae period–luminosity–metallicity relations are used to derive a true distance modulus to M15: 15.196 ± 0.026 (statistical) ± 0.039 (systematic) mag. Our precise distance moduli based on RR Lyrae stars and Population II Cepheid variables are mutually consistent and agree with recent distance measurements in the literature based on Gaia parallaxes and other independent methods.

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 Standard Galactic field RR Lyrae II: a Gaia DR2 calibration of the period–Wesenheit–metallicity relation

2019 ◽  
Vol 490 (3) ◽  
pp. 4254-4270 ◽  
Author(s):  
Jillian R Neeley ◽  
Massimo Marengo ◽  
Wendy L Freedman ◽  
Barry F Madore ◽  
Rachael L Beaton ◽  
...  
Keyword(s):  
Near Infrared ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Distance Modulus ◽  
Rr Lyrae Stars ◽  
Galactic Field ◽  
Rr Lyrae ◽  
Lyrae Stars ◽  
Distance Indicators ◽  
Made In

ABSTRACT RR Lyrae stars have long been popular standard candles, but significant advances in methodology and technology have been made in recent years to increase their precision as distance indicators. We present multiwavelength (optical UBVRcIc and Gaia G, BP, RP; near-infrared JHKs; mid-infrared [3.6], [4.5]) period–luminosity–metallicity (PLZ), period–Wesenheit–metallicity (PWZ) relations, calibrated using photometry obtained from the Carnegie RR Lyrae Program and parallaxes from the Gaia second data release for 55 Galactic field RR Lyrae stars. The metallicity slope, which has long been predicted by theoretical relations, can now be measured in all passbands. The scatter in the PLZ relations is on the order of 0.2 mag, and is still dominated by uncertainties in the parallaxes. As a consistency check of our PLZ relations, we also measure the distance modulus to the globular cluster M4, the Large Magellanic Cloud and the Small Magellanic Cloud, and our results are in excellent agreement with estimates from previous studies.

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 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 RR Lyrae Stars in the Newly Discovered Ultra-faint Dwarf Galaxy Centaurus I*

2021 ◽  
Vol 162 (6) ◽  
pp. 253
Author(s):  
C. E. Martínez-Vázquez ◽  
W. Cerny ◽  
A. K. Vivas ◽  
A. Drlica-Wagner ◽  
A. B. Pace ◽  
...  
Keyword(s):  
Galactic Halo ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
Relative Rate ◽  
Distance Modulus ◽  
Rr Lyrae Stars ◽  
Full Sample ◽  
Rr Lyrae ◽  
The One ◽  
Lyrae Stars

Abstract We report the detection of three RR Lyrae (RRL) stars (two RRc and one RRab) in the ultra-faint dwarf (UFD) galaxy Centaurus I (Cen I) and two Milky Way (MW) δ Scuti/SX Phoenicis stars based on multi-epoch giz DECam observations. The two RRc stars are located within two times the half-light radius (r h ) of Cen I, while the RRab star (CenI-V3) is at ∼6 r h . The presence of three distant RRL stars clustered this tightly in space represents a 4.7σ excess relative to the smooth distribution of RRL in the Galactic halo. Using the newly detected RRL stars, we obtain a distance modulus to Cen I of μ 0 = 20.354 ± 0.002 mag (σ = 0.03 mag), a heliocentric distance of D ⊙ = 117.7 ± 0.1 kpc (σ = 1.6 kpc), with systematic errors of 0.07 mag and 4 kpc. The location of the Cen I RRL stars in the Bailey diagram is in agreement with other UFD galaxies (mainly Oosterhoff II). Finally, we study the relative rate of RRc+RRd (RRcd) stars (f cd) in UFD and classical dwarf galaxies. The full sample of MW dwarf galaxies gives a mean of f cd = 0.28. While several UFD galaxies, such as Cen I, present higher RRcd ratios, if we combine the RRL populations of all UFD galaxies, the RRcd ratio is similar to the one obtained for the classical dwarfs (f cd ∼ 0.3). Therefore, there is no evidence for a different fraction of RRcd stars in UFD and classical dwarf galaxies.

scholarly journals A DECam view of the diffuse dwarf galaxy Crater II – Variable stars

2019 ◽  
Vol 492 (1) ◽  
pp. 1061-1077 ◽  
Author(s):  
A Katherina Vivas ◽  
Alistair R Walker ◽  
Clara E Martínez-Vázquez ◽  
Matteo Monelli ◽  
Giuseppe Bono ◽  
...  
Keyword(s):  
Time Series ◽  
Dwarf Galaxy ◽  
Position Angle ◽  
Variable Stars ◽  
Distance Modulus ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
The Galaxy ◽  
Binary Evolution ◽  
Lyrae Stars

ABSTRACT Time series observations of a single dithered field centred on the diffuse dwarf satellite galaxy Crater II were obtained with the Dark Energy Camera (DECam) at the 4m Blanco Telescope at Cerro Tololo Inter-American Observatory, Chile, uniformly covering up to two half-light radii. Analysis of the g and i time series results in the identification and characterization of 130 periodic variable stars, including 98 RR Lyrae stars, 7 anomalous Cepheids, and 1 SX Phoenicis star belonging to the Crater II population, and 24 foreground variables of different types. Using the large number of ab-type RR Lyrae stars present in the galaxy, we obtained a distance modulus to Crater II of (m − M)0 = 20.333 ± 0.004 (stat) ±0.07 (sys). The distribution of the RR Lyrae stars suggests an elliptical shape for Crater II, with an ellipticity of 0.24 and a position angle of 153°. From the RR Lyrae stars, we infer a small metallicity dispersion for the old population of Crater II of only 0.17 dex. There are hints that the most metal-poor stars in that narrow distribution have a wider distribution across the galaxy, while the slightly more metal-rich part of the population is more centrally concentrated. Given the features in the colour–magnitude diagram of Crater II, the anomalous Cepheids in this galaxy must have formed through a binary evolution channel of an old population.

scholarly journals RR Lyraes in the Magellanic Clouds

1993 ◽  
Vol 139 ◽  
pp. 15-20
Author(s):  
Alistair R. Walker
Keyword(s):  
Recent Work ◽  
Galaxy Formation ◽  
Magellanic Clouds ◽  
Distance Modulus ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
Star Studies ◽  
Absolute Magnitudes ◽  
Halo Population ◽  
Lyrae Stars

AbstractRecent work on the Magellanic Cloud RR Lyrae stars is reviewed. The absolute magnitudes of LMC RR Lyraes, when calibrated from a distance modulus of 18.5 mag, disagrees with the Galactic calibration. The revised distance scale makes distances greater, and ages younger, within our galaxy. Field star studies show that the “halo” population of the LMC is very similar to that of our own Galaxy outside of the solar circle. This result supports a Searle and Zinn model of galaxy formation.

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 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.

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