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| | 3 Variable stars |
 | | Already Hachenberg (1939) noticed that this star is almost a magnitude brighter than RR Lyrae stars in M 92 and thus supposed that it might be in fact a Cepheid. | | | However, he regarded it to be the RR Lyrae variable (blended with another unresolved star) and his classification is maintained also in the CVSGC. | | | In M 53, for example, seven giants are known to be variable (Kopacki 2000). |
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http://aanda.u-strasbg.fr:2002/papers/aa/full/2001/15/aah2569/node3.html
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| | RR Lyrae variable stars |
| | At present, a large number of research programs at various levels of completion are carried out, and new projects are proposed to address the RR Lyrae distance scale and the stellar population issues, as well as the impact of the RR Lyraes on stellar evolution and pulsation theories. | | | The absolute magnitude of the RR Lyrae variables is known to depend on metallicity, but no general consensus has been reached so far both on the correct slope and on the zero-point of the Mv(RR)-[Fe/H] relation. | | | New software tools have been developed, purposely designed to allow the identification of variable stars and to perform period searches and studies of multiple periodicities of variable objects. |
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http://www.bo.astro.it/report00/node19.html
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| | BGSU Variable Star Project |
| | Programs compute the magnitude difference (RR Lyrae - comparison), add a time-tag to the observation, and write the information to a database. | | | The data reduction culminates with the student measuring on each picture the magnitude (brightness) of the RR Lyrae star along with the magnitudes of several comparison stars on the frame. | | | We are using the BGSU 0.5-meter telescope and CCD camera to monitor the brightness and color changes over time of a number of variable stars. |
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http://physics.bgsu.edu/~layden/VarStarProj/vsp_main.html
(2072 words)
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| | Interstellar Medium and the Milky Way |
| | This is because all RR Lyrae have about the same average absolute magnitude (=+0.6, or 49 solar luminosities). | | | All of the RR Lyrae stars in a cluster have the same average apparent magnitude. | | | If the cluster is more distant from us, the RR Lyrae in it will have greater apparent magnitudes (remember fainter objects have greater magnitudes!). |
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http://www.astronomynotes.com/ismnotes/s5.htm
(1165 words)
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| | AAVSO: Types of Variable Stars |
| | These are yellow supergiants having a characteristic light variation with alternating deep and shallow minima. | | | These are rare, luminous, hydrogen-poor, carbon-rich, variables that spend most of their time at maximum light, occasionally fading as much as nine magnitudes at irregular intervals. | | | The origins of these light variations define the classification system of variable stars. |
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http://www.aavso.org/vstar/types.stm
(1008 words)
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| | AAVSO: Delta Cep, September 2000 Variable Star Of The Month |
| | The variability of Polaris occurs with a 3.97 day period and fluctuates by only a tenth of a magnitude, but the change is markedly detectable particularly through photometry. | | | Investigation of delta Cep's heavenly position shows that the variable conveniently sits between two bright stars that shine at either end of its range of variability: zeta Cep at a magnitude of 3.6 and epsilon Cep at a magnitude of 4.2. | | | Delta Cep is a terrific "starter" variable star for the amateur astronomer looking a place to begin, or for the student seeking a research project for math and science courses. |
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http://www.aavso.org/vstar/vsotm/0900.stm
(3768 words)
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| | OzDASL: Magnitudes of Variable Star RR Lyrae 1198 |
| | Different classes of variable stars can be located in different regions of a plot of magnitude versus temperature or spectral type. | | | For example, Beat Cepheids and Beat RR Lyrae oscillate at more than one frequency. | | | Differential magnitude in the blue band from 4500 to 6300 Angstroms |
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http://www.statsci.org/data/oz/rrl1198.html
(749 words)
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| | T.Borkova, V.Marsakov, Subsystemsof RR Lyrae Variable Stars in Our Galaxy |
| | However, observations of field RR Lyrae stars and blue hrizontalbranch stars were used in Laydan (1998) to estimate the number ratios of these objects in different directions from the Sun. | | | This sample includes virtually all brigh RR Lyrae variables known prior to 1976 (such data were included in the satellite's input catalog). | | | The mean eccentricities in the proto-disk halo subsystens are the same, whereas, in the outer halo, the eccentricities are, on average, higher for the field stars, as expected (note that orbital eccentricities are known only for a small number of clusters, and with large uncertainties). |
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http://ip.rsu.ru/~marsakov/paper6/article6_1.htm
(5709 words)
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| | AAVSO: AAVSO Section |
| | More information on these classifications and sub-classes with examples, may be found on our Types of Variable Stars page. | | | Thus it is amateur astronomers utilizing visual, photographic, photoelectric, and now CCD techniques, who are making a real and highly useful contribution to science by observing variable stars and submitting their observations to the AAVSO International Database. | | | The brightness changes of these stars can range from a thousandth of a magnitude to as much as twenty magnitudes over periods of a fraction of a second to years, depending on the type of variable star. |
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http://www.aavso.org/vstar
(377 words)
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| | Variable Stars |
| | A variable star is characterized by a particular light curve, a diagram in which the apparent magnitude is reported versus time. | | | The pulsation period of a Cepheid star depends on its intrinsic magnitude, according to a law known as "period-luminosity relation". | | | The luminosity does not vary that much, approximately one magnitude. |
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http://www.pd.astro.it/E-MOSTRA/NEW/A3041VAR.HTM
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| | Large Magellanic Cloud Microlensing |
| | The distance distribution of the Sgr RRab, equivalent to about 0.5% of all the MACHO RRab found in the LMC, is overplotted in Figure 3 (we have actually used the reddening independent magnitudes to compute their individual distances because of the heavy differential reddening of the bulge fields). | | | These cuts are optimized to discriminate foreground RR Lyrae from LMC RR Lyrae, blends, and other variable stars. | | | The uncertainty in these individual distances is estimated to be about 10%, with the caveat that the zero point in RR Lyrae absolute magnitudes may be more uncertain (e.g., M |
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http://ecf.hq.eso.org/~ralbrech/novdec97apjl/975552.html
(3422 words)
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| | Distance to the Galactic Center |
| | It is based on the estimated distance between the Sun and the calculated center of the globular clusters surrounding the Milky Way and on distance estimates to RR Lyrae stars close to the Galactic center. | | | McNamara and colleagues recently used the Optical Gravitational Lensing Experiment (OGLE) data for Delta Scuti stars and RR Lyrae stars to determine the distance to the Galactic bulge in the direction of Baade’s window (McNamara 2000). | | | By calculating the center of the distribution of the globular clusters surrounding the Milky Way, he determined the Galactic center was in Sagittarius, and the Solar System was 13 kiloparsecs from the Galactic center (Reid 1993; Gino 2003). |
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http://www.grasslands.org/Essays2.htm
(1749 words)
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| | IngentaConnect The distance to Galactic globular clusters through RR Lyrae pulsa... |
| | This method is quite similar to the one adopted for estimating the absolute bolometric magnitude of the ZAHB but it relies only on the pulsational properties of the Lyrae variables in each cluster. | | | By adopting the same approach outlined by De Santis and Cassisi, we evaluate the absolute bolometric magnitude of the zero-age horizontal branch (ZAHB) at the level of the RR Lyrae variable instability strip in selected Galactic globular clusters. | | | As the adopted method relies on theoretical predictions on both the fundamental pulsational equation and the allowed mass range for fundamental pulsators, we give an estimate of the error affecting present results, owing to systematic uncertainties in the adopted theoretical framework. |
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http://www.ingentaconnect.com/content/bsc/mnr/2001/00000326/00000001/art00036
(334 words)
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| | IMSA Astrophysics: Distance Ladder |
| | To find the distance to the RR Lyrae star, simply determine its apparent visual magnitude, m, and solve the distance modulus equation. | | | For example, we can determine the distance to the RR Lyrae star described above using the mean apparent magnitude (remember, it varies) of 5.81. | | | Unlike Cepheids, whose periodicity is related to its absolute magnitude, RR Lyrae stars have an even simpler relationship with absolute magnitude. |
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http://staff.imsa.edu/science/astro/astrometry/rung3.html
(256 words)
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| | Calvin College - Physics and Astronomy |
| | All RR Lyrae stars have a same average absolute magnitude of 0.6. | | | The apparent magnitude of our variable star (C-V), and the magnitude of the reference stars (Norm C-K) were plotted against the elapsed time in hours. | | | RR Lyrae variable stars are known for having a short period of variability of less than a day in length. |
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http://www.calvin.edu/academic/phys/observatory/images/Astr212.Fall2002/SWAnd
(697 words)
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| | RR Lyrae Stars and the Distance to M4 |
| | Plot apparent magnitude vs. time (where the time is given in the fraction of the day since the observations started) on a apparent magnitude of star 42 versus time graph. | | | REMINDER IF YOU ARE USING YOUR OWN GRAPH PAPER: the graph must have the smallest magnitude value (for brightest) at the top of the "y" axis and the largest magnitude value (for dimmest) at the bottom of the "y" axis. | | | The RR Lyrae stars have a mean absolute magnitude (M) of 0.75. |
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http://www.astro.washington.edu/labs/clearinghouse/labs/DistM4/m4.html
(1106 words)
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| | [No title] |
| | Smith, H., "CCD Photometry of Variable Stars in a Sophomore Level Astronomy Course", Journal of the AAVSO, 22, 35. | | | 1991, "CCD Photometry of the RR Lyrae Star SS Leonis", Journal of the AAVSO, 20, 28. | | | Much of the observing is carried out by students, both graduate students and undergraduates. |
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http://www.pa.msu.edu/astro/observ/research.html
(521 words)
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| | Evolution of V79 in M3 |
| | Since we now know that at least one Blazhko variable, V79 in M3, has exhibited mixed-mode pulsations, we consider the first possibility to be more feasible. | | | We determined the primary periods for V68 and V79 with a computer program that utilized Stellingwerf's (1978) phase dispersion minimization (PDM) technique with a (5, 2) bin structure. | | | The RR Lyrae variables in type II clusters should switch modes at longer periods, and as a result, their mean periods will be longer than those in the type I clusters. |
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http://ecf.hq.eso.org/~ralbrech/novdec97apjl/975521.html
(2814 words)
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| | The RR Lyrae Variable Stars in the Globular Cluster M15 |
| | New CCD photometry is presented for RR Lyrae variable stars in the globular cluster M15. | | | However, this result depends upon the adopted mass, bolometric correction, and color-temperature relation, which remain significantly uncertain. | | | The observable parameters of the light curves are used, in conjunction with theoretical photometric indices, to obtain effective temperatures and bolometric magnitudes in the RR Lyrae stars. |
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http://www.cs.wisc.edu/niagara/data/nasa/AJ_110_704.xml
(569 words)
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| | BGSU Variable Star Project |
| | Development of observation planning and image processing software. | | | Now in PhD program in Physics/Astronomy at Univ of Toledo, specialty in comets. | | | I enjoy computers, Seti@home, and reading Science Fiction and Fantasy. |
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http://physics.bgsu.edu/~layden/VarStarProj/People/vsp_people.htm
(755 words)
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| | Catalog of RR Lyrae stars in the LMC |
| | If any of these objects were an eclipsing binary system containing RR Lyr star, then for the first time the direct determination of the mass of RR Lyr variable would be possible. | | | PLEASE cite the following paper when using the data or referring to these OGLE results: Soszynski et al. | | | The mean observed V-band magnitudes of RR Lyr stars in the LMC are 19.36 mag and 19.31 mag for ab and c types, respectively, while the extinction free values are 18.91 mag and 18.89 mag. |
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http://bulge.princeton.edu/%7Eogle/ogle2/rrlyr_lmc.html
(373 words)
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| | * RR Lyrae Variable - (Astronomy): Definition |
| | The absolute magnitude of all RR Lyrae variables seems to be nearly constant at <MV = 0.75 ± 0.1. | | | RR Lyrae variables are old type A stars with periods less than one day, and most of them change brightness by less than one magnitude. | | | There may be as many as fifty RR Lyrae variables in the cluster. |
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http://en.mimi.hu/astronomy/rr_lyrae_variable.html
(273 words)
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| | Research Endeavours (Christine Clement) |
| | The current version of the catalogue is available in ascii files - one file for each cluster. | | | Frequency Analysis of the First Overtone RR Lyrae Stars and the Indication for Nonradial Pulsations, Astrophysical Journal, 542, 257-280 | | | Most of my recent work involves the study of RR Lyrae variables. |
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http://www.astro.utoronto.ca/~cclement/papers.html
(1259 words)
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| | Rr Lyrae Stars In The Macho Database (ResearchIndex) |
| | 0.5: Discovery and Classification of Variable Stars - William Patrick Clarke (2001) | | | 0.5: Variable Stars in the MACHO Collaboration - Database Kem | | | These variables are excellent distance indicators, and are used as tools to study the structure of the Large Magellanic Cloud and the bulge. |
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http://citeseer.ist.psu.edu/41151.html
(342 words)
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| | RR Lyrae Variables in the Globular Cluster M15 |
| | The new CCD data are used to construct a color-magnitude diagram of M15, including the RR Lyrae stars. | | | New 1991-1993 CCD data for M15 have been obtained and are used to construct new B, V and R lightcurves for the variables. | | | Phase diagrams for 40 of the RR Lyrae have been contructed to study the evolution of the variables over the past 100 years. |
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http://www.aas.org/publications/baas/v25n4/aas183/abs/S12301.html
(215 words)
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| | Energy Citations Database (ECD) - Energy and Energy-Related Bibliographic Citations |
| | Availability information may be found in the Availability, Publisher, Research Organization, Resource Relation and/or Author (affiliation information) fields and/or via the "Full-text Availability" link. | | | Energy Citations Database (ECD) Document #4264453 - Unusual RR Lyrae-type variable | | | N56200 --Physics (Astrophysics & Cosmology)--Stars; VARIABLE STARS-- STAR EVOLUTION;LUMINOSITY;TEMPERATURE DEPENDENCE |
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http://www.osti.gov/energycitations/product.biblio.jsp?osti_id=4264453
(65 words)
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| | What is an RR Lyrae? |
| | The star RR Lyrae as it appears in the Deep Sky Survey | | | The first known RR Lyrae variable was the star RR Lyrae. | | | RR Lyraes are much hotter than our Sun. |
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http://etacar.umn.edu/~martin/rrlyrae/rrlyrex.htm
(594 words)
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| | Duke Physics: Senior Thesis - Strader |
| | We used a sophisticated image subtraction method (ISM) to determine which stars were variable.First, a composite reference image of several of the best images was created. | | | We also made the firstperiod determinations for thirty-six previously known variables. | | | We discovered twelve new variables, ten of which were RR Lyraes. |
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http://www.phy.duke.edu/ugrad/thesis/strader?print
(300 words)
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| | [No title] |
| | An analysis of more than 2000 CCD observations of the field RR Lyrae star NSV 09295 shows that the star is a double-mode RR Lyrae (RRd) variable with P | | | This brings the total of known field RRd stars in the Milky Way galaxy to four. | | | These four variables are compared with the RRd stars in galactic globular clusters and with the field RRd stars in the LMC, and in the Draco and Sculptor dwarf galaxies. |
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http://www.aip.org/anjtest/stix/ANJOAA_114_3_1190_1/1190_1.html
(236 words)
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| | Physics 110 Notes Thomas Arny Explorations Chapter 13 |
| | The number one task for which the Hubble Space Telescope was built was to spot Cepheid variable stars in other galaxies so that accurate distances could be determined. | | | The first examples of these two types of stars were stars named Delta Cephei and RR Lyrae respectively (these are just catalog names). | | | So, the Cepheid variables and RR Lyrae stars with longer periods are also more luminous. |
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http://www.cs.csubak.edu/Physics/phys110/NotesCh13.html
(4900 words)
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| | [No title] |
| | Many of the stars are sufficiently far from the Sun that the UVW coordinate system becomes misaligned with the principal galactocentric axes. | | | =1995AJ....110.2288L ================================================================================ Abstract: We investigate the kinematics and spatial distribution of a sample of 302 nearby RR Lyrae variable stars with the goal of learning more about the formation history and present-day structure of the galaxy. | | | We find the kinematics of the halo RR Lyraes to be uncorrelated with abundance over the range -2.2 |
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http://www.journals.uchicago.edu/AAS/cdrom/volume5/volume5/aj/v110/p2288/table.doc
(219 words)
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| | Lesson |
| | Once we have the luminosity of a star and have measured its apparent magnitude, we have its distance through the now familiar magnitude equation: m – M = 5 log(d) – 5. | | | Supernovae remnants, Sagittarius A, filamentary structures, and other identifiable as well as enigmatic objects can be seen. | | | A special kind of variable star, the RR Lyrae variable, have played an important role in our knowledge of the Galaxy. |
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http://astro.washington.edu/larson/Astro101/LecturesFraknoi/astro101s11.html
(4776 words)
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| | New Periods and Reclassification of Selected RR Lyrae Stars |
| | I also thank the W. Keck Foundation for providing the CCD camera, workstation, and funding several undergraduates through the grant to the Keck Northeast Astronomy Consortium and NSF grant AST-9417359 for support of this project. | | | As part of the variable star research at Wellesley College, we have observed several stars which are classified as RR or RR: in the GCVS, but which have no periods listed. | | | We conclude that many stars which have been classified as RR Lyrae stars but for which light curves have not been determined are not actually RR Lyrae stars. |
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http://www.aas.org/publications/baas/v28n4/aas189/abs/S081012.html
(217 words)
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| | Publications |
| | Wade, R.A., Donley, J., Fried, R., and R.E. White 1999, "A Timing Model for the RR Lyrae Variable Star TU Ursae Majoris, a Probable Member of a Binary System," Astron. | | | White, R.E. 1968, "Density Distribution of the Field RR Lyrae-type Variable Stars," Astron. | | | White, R.E. 1981, "Asymptotic Giant Branch Variable Stars" in "Astrophysical Parameters for Globular Clusters," I.A.U. Colloq. |
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http://ethel.as.arizona.edu/~white/mypage/my_cv2.htm
(1524 words)
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| | [83.04] GALEX Satellite Observes Large-Amplitude NUV and FUV Light Curves of an RR Lyrae Variable Star |
| | A series of GALEX Deep Imaging Survey observations well distributed in phase within the star's 0.564 day period shows an AB~4.5 magnitude variation in FUV (1350-1800Å) and an AB~2.0 magnitude variation in NUV (1800-2800Å), compared with 0.75 magnitude in the ROTSE-I visible band. | | | The large FUV brightness variation makes RR Lyrae stars easy to detect in FUV imagery and the GALEX single-orbit (~1500s) limiting AB~23 magnitude in both NUV and FUV make the detection of more RR Lyrae stars likely. | | | The GALEX (Galaxy Evolution Explorer) Mission has obtained NUV and FUV light curves of the Robotic Optical Transient Search Experiment (ROTSE-I) Catalog RR Lyrae type ab variable star J143753.84+345924.8. |
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http://www.aas.org/publications/baas/v35n5/aas203/193.htm
(256 words)
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| | AAVSO: RR Lyrae Observing Program |
| | Plans are underway to publish times of maximum and O-C curves of a number of program RR Lyrae stars. | | | The data are reduced and archived in electronic form in the RR Lyrae Stars section of the AAVSO International Database. | | | There are currently 40 stars in the program, many of them of small amplitude. |
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http://www.aavso.org/observing/programs/rrlyrae
(257 words)
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| | MSN Encarta - Search Results - RR Lyrae Variable |
| | MSN Encarta - Search Results - RR Lyrae Variable | | | collecting variables on one side of an equation, combining like terms, order of operations, simplifying with the distributive property, words to... | | | Search for books about your topic, "RR Lyrae Variable" |
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http://encarta.msn.com/encnet/refpages/search.aspx?q=RR+Lyrae+Variable
(176 words)
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| | Variable Stars |
| | The variation in the luminosity of RR Lyrae and Cepheid stars results from the fact that they pulsate in and out. | | | RR Lyrae stars can also be used to measure distances, but since they are less luminous, they can only be seen to smaller distances. | | | The two most interesting types of variable star are Cepheid variables and RR Lyrae variables. |
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http://www.stormpages.com/swadhwa/stellarevolution/lecture17.htm
(956 words)
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| | RR Lyrae - Wikipedia, the free encyclopedia |
| | As RR Lyrae variables are important standard candles, knowing the precise distance of this star is necessary to determine its luminosity, and hence that of other stars in its class. | | | It has a period of about 13 hours, and oscillates between apparent magnitudes 7 and 8. | | | If accurate, this gives RR Lyrae an absolute magnitude of 0.61, roughly 49 times solar luminosity. |
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http://en.wikipedia.org/wiki/RR_Lyrae
(173 words)
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| | Variable Star Projects |
| | I'm currently working on two separate variable star projects the first is my second year project over NGC 6304 and the second is the Type II Cepheid Project. | | | One way of studying variable stars is to look at objects that hold them. | | | NGC 6304 is unusual in that several RR Lyraes have been found in the field around it. |
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http://www.pa.msu.edu/people/delee/variable.html
(383 words)
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| | [No title] |
| | RR Lyrae: the zero point of temperature and magnitude scales. | | | The Absolute Magnitude and Kinematics of RR Lyrae Stars via Statistical Parallax | | | The Absolute Magnitude and Kinematics of RR Lyrae Stars Via Statistical Parallax |
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http://www.columbia.edu/~fms5/w438.html
(639 words)
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| | RR Lyrae Variable Stars In The CCD/Transit Instrument Survey - Storming Media |
| | The RR Lyrae space density as a function f Galactocentric distance is shown to be a power-law function (R-3 to -3.5) and consistent with an ellipsoidal distribution in the nuclear bulge and more spherically symmetric distribution in the Galactic halo. | | | This dissertation chronicles an RR Lyrae variable star survey from a thorough description of the initial observations with the CCD/ transit Instrument (CTI), to an examination of RR Lyrae space density and the Galactic mass using the discovered RR Lyrae stars. | | | Abstract: RR Lyrae variable stars have long been recognized as important tools in probing the mass, chemical distribution and kinematics of the Galaxy from the inner recesses of the nuclear bulge to the outer environs of the distant Galactic halo. |
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http://www.stormingmedia.us/83/8314/A831492.html
(197 words)
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| | Andy’s Astronomy Page |
| | Weighing Jupiter -- Computing the mass and mean density of Jupiter from simple observations of the Galillean moons. | | | Developing the tools with which to make these studies possible, including measuring distances to RR Lyrae variable stars, and the amount of interstellar dust between us and the RR Lyrae stars. | | | Bill Harris's catalogue of parameters for Milky Way Globular Clusters. |
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http://physics.bgsu.edu/~layden/astro.html
(219 words)
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| | Colloquium |
| | Tiny changes have been observed in RR Lyrae pulsation periods. | | | More than a century has passed since Solon Bailey discovered the class of RR Lyrae variable stars. | | | As Population II standard candles, RR Lyrae stars are an important tool in measuring the distances of old stellar systems. |
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http://physics.valpo.edu/colloquia/colloq_110201.html
(151 words)
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| | The Milky Way Galaxy |
| | •Instabilities in the star result in a fluctuation of the star’s luminosity.
•Characteristic period of this fluctuation is about 0.75 days.
•All RR Lyrae stars have the same luminosity which allows astronomers to determine their distance very precisely. |
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http://staff.jccc.net/dpatter/powerpoint/MilkyWay_files/slide0013.htm
(36 words)
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| | long-period variable Comparison Table |
| | physical object > natural object > celestial body > star > variable > periodic variable > long-period variable | | | Next periodic variable: RR Lyrae star Up: periodic variable Previous periodic variable: eclipsing binary | | | RR, RS, RT, RU, RV, RW, RX, RY, or RZ and the genitive of the latin constellation name when the single letter designations are exhausted |
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http://www.csi.uottawa.ca:4321/astronomy/long-periodvariable_table.html
(198 words)
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| | Cepheid Variable Stars |
| | The same applies to RR Lyrae variable stars. | | | The ``original'' Cepheid variable, Delta Cephei, is close enough that we have a parallax measurement for it. | | | Once you know that a star is an RR Lyrae variable (eg. |
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http://zebu.uoregon.edu/~soper/MilkyWay/cepheid.html
(267 words)
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| | RR Lyrae |
| | Related content from HighBeam Research on: RR Lyrae |
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http://www.infoplease.com/ce6/sci/A0918266.html
(77 words)
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