scholarly journals New results on OGLE Cepheids and PL relations in the LMC and SMC

2004 ◽  
Vol 193 ◽  
pp. 75-82
Author(s):  
A. Udalski
Keyword(s):  
Gravitational Lensing ◽  
Variable Stars ◽  
Magellanic Clouds ◽  
Photometric Data ◽  
Second Phase ◽  
Internet Archive ◽  
Pulsating Stars ◽  
Third Phase ◽  
Pulsating Variable Stars ◽  
Star Field

AbstractWe present results of the search for pulsating variable stars in the Magellanic Cloud fields covering central parts of these galaxies. The data were collected during the second phase of the Optical Gravitational Lensing Experiment survey (OGLE-II) from 1997 to 2000. In total, several thousand pulsating stars (Cepheids, RR Lyr) were found in both Magellanic Clouds. The photometric data of all objects are available to the astronomical community from the OGLE Internet archive. We present basic properties of pulsating stars in the Magellanic Clouds including Period–Luminosity relations for Cepheids. We also discuss observational prospects for the pulsating star field in the ongoing third phase of the OGLE project (OGLE-III) which started in 2001.

scholarly journals Eclipsing Binaries in the Magellanic Clouds

2005 ◽  
Vol 13 ◽  
pp. 451-451
Author(s):  
Andrzej Udalski
Keyword(s):  
Gravitational Lensing ◽  
Direct Determination ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Eclipsing Binaries ◽  
Physical Parameters ◽  
Second Phase ◽  
Internet Archive ◽  
Pulsating Stars ◽  
Eclipsing Stars

We present results of a search for eclipsing binaries in the Magellanic Cloud fields covering central parts of these galaxies. The data were collected during the second phase of the Optical Gravitational Lensing Experiment survey (OGLE-II) in 1997-2000. In total, about 1500 and 3000 eclipsing stars were found in the Small and Large Magellanic Cloud, respectively (Udalski et al. 1998, Wyrzykowski et al. 2003). The photometric data of all objects are available to the astronomical community from the OGLE Internet archive (http://sirius.astrouw.edu.pl/~ogle/). OGLE-II data contain a full variety of classical eclipsing objects of all types: Algol EA-type, β-Lyr EB-type and W UMA EW-type stars. Large samples of stars allow to study in detail statistical properties of eclipsing objects. OGLE data also contain many very unusual eclipsing stars. Examples include eclipsing variable B-type stars (Mennickent et al. 2003), many spotted stars or eclipsing stars with a Cepheid as a component (Udalski et al. 1999). Recently three objects from the LMC revealing simultaneously RR Lyr and eclipsing binary type variability were discovered (Soszyński et al 2003). If the follow-up observations confirm that both components are physically bound and not optical blends these stars will provide a unique opportunity of direct determination of physical parameters of RR Lyr pulsating stars.

scholarly journals The OGLE-III catalog of variable stars: First results

2008 ◽  
Vol 4 (S256) ◽  
pp. 30-35
Author(s):  
Igor Soszyński
Keyword(s):  
Statistical Analysis ◽  
High Precision ◽  
Gravitational Lensing ◽  
Variable Stars ◽  
Magellanic Clouds ◽  
Large Area ◽  
The Third ◽  
Third Phase ◽  
First Results ◽  
Basic Parameters

AbstractThe third phase of the Optical Gravitational Lensing Experiment (OGLE-III) has been conducted since 2001 and regularly monitors the brightness of about 200 million stars. The OGLE-III fields cover both Magellanic Clouds and a large area in the Galactic bulge and disk. Here we describe the first parts of the OGLE-III Catalog of Variable Stars which is being prepared on the basis of these data. We present the principles of the catalog and methods used to select variable stars. We expect that the whole catalog will contain at least one million variable stars of all types. The catalog includes the list of variable sources along with their basic parameters, high precision multi-epoch I and V-band photometry and accurate astrometry. All objects are classified and cross-identified with previously published catalogs. We also carry out a preliminary statistical analysis of these huge samples of variable stars.

25 Years of the Southern Skies Monitoring by OGLE

2017 ◽  
Vol 14 (S339) ◽  
pp. 226-229 ◽  
Author(s):  
Ł. Wyrzykowski ◽  
P. Pietrukowicz ◽  
Keyword(s):  
Time Domain ◽  
Gravitational Lensing ◽  
Milky Way ◽  
Extrasolar Planets ◽  
Variable Stars ◽  
Matter Content ◽  
Magellanic Clouds ◽  
Photometric Data ◽  
Galactic Bulge ◽  
Selection Of

AbstractThe Optical Gravitational Lensing Experiment (OGLE) started at Las Campanas Observatory in 1992 with a pilot monitoring programme of two million stars in the Galactic Bulge. It is still operating today, collecting time-domain photometric data of a billion stars from the densest regions in the southern sky. Among its main achievements are discoveries of thousands of microlensing events, a few dozen extrasolar planets and candidates for black holes, a million variable stars, and thousands of quasars and supernovæ. It has made a major contribution to the studies of the dark-matter content of the Milky Way halo, the structure of the Galactic Bulge, the Magellanic Clouds, and new classes of variable stars. In this its 25th anniversary year, we presented a selection of the major scientific highlights of OGLE.

scholarly journals Asteroseismology from Dome A, Antarctica

2013 ◽  
Vol 9 (S301) ◽  
pp. 409-410
Author(s):  
J. N. Fu ◽  
W. K. Zong ◽  
Y. Yang ◽  
A. Moore ◽  
M. C. B. Ashley ◽  
...  
Keyword(s):  
Time Series ◽  
Variable Stars ◽  
Photometric Data ◽  
Dome A ◽  
Pulsating Variable Stars ◽  
Scientific Potential

AbstractGattini and CSTAR have been installed at Dome A, Antarctica, which provide time-series photometric data for a large number of pulsating variable stars. We present the study for several variable stars with the data collected with the two facilities in 2009 to demonstrate the scientific potential of observations from Dome A for asteroseismology.

scholarly journals Confirmation of monoperiodicity above 20 s for two blue large-amplitude pulsators

2020 ◽  
Vol 496 (2) ◽  
pp. 1105-1114 ◽  
Author(s):  
Paul Ross McWhirter ◽  
Marco C Lam ◽  
Iain A Steele
Keyword(s):  
Gravitational Lensing ◽  
Large Amplitude ◽  
Variable Stars ◽  
Light Curves ◽  
Driving Mechanism ◽  
New Class ◽  
Pulsating Variable Stars ◽  
Short Period ◽  
Filter Frequency ◽  
High Cadence

ABSTRACT Blue large-amplitude pulsators (BLAPs) are a new class of pulsating variable stars. They are located close to the hot subdwarf branch in the Hertzsprung–Russell diagram and have spectral classes of late O or early B. Stellar evolution models indicate that these stars are likely radially pulsating, driven by iron group opacity in their interiors. A number of variable stars with a similar driving mechanism exist near the hot subdwarf branch with multiperiodic oscillations caused by either pressure (p) or gravity (g) modes. No multiperiodic signals were detected in the OGLE (Optical Gravitational Lensing Experiment) discovery light curves since it would be difficult to detect short-period signals associated with higher order p modes with the OGLE cadence. Using the RISE instrument on the Liverpool Telescope, we produced high-cadence light curves of two BLAPs, OGLE-BLAP-009 (mv = 15.65 mag) and OGLE-BLAP-014 (mv = 16.79 mag), using a 720 nm longpass filter. Frequency analysis of these light curves identifies a primary oscillation with a period of 31.935 ± 0.0098 min and an amplitude from a Fourier series fit of 0.236 mag for BLAP-009. The analysis of BLAP-014 identifies a period of 33.625 ± 0.0214 min and an amplitude of 0.225 mag. Analysis of the residual light curves reveals no additional short-period variability down to an amplitude of 15.20 ± 0.26 mmag for BLAP-009 and 58.60 ± 3.44 mmag for BLAP-014 for minimum periods of 20 and 60 s, respectively. These results further confirm that the BLAPs are monoperiodic.

scholarly journals Pulsating variable stars in the Magellanic Clouds

2008 ◽  
Vol 4 (S256) ◽  
pp. 373-384 ◽  
Author(s):  
Gisella Clementini
Keyword(s):  
Structure Formation ◽  
Variable Stars ◽  
Magellanic Clouds ◽  
Evolution Of Galaxies ◽  
Pulsating Variable Stars ◽  
Formation And Evolution ◽  
Near Future ◽  
Magellanic System

AbstractPulsating variable stars can be powerful tools to study the structure, formation and evolution of galaxies. I discuss the role that the Magellanic Clouds' pulsating variables play in our understanding of the whole Magellanic System, in light of results on pulsating variables produced by extensive observing campaigns like the MACHO and OGLE microlensing surveys. In this context, I also briefly outline the promise of new surveys and astrometric missions which will target the Clouds in the near future.

scholarly journals Photometry of Pulsating Stars in the Magellanic Clouds as Observed in the MOA Project

2000 ◽  
Vol 176 ◽  
pp. 31-37
Author(s):  
J. B. Hearnshaw ◽  
I. A. Bond ◽  
N. J. Rattenbury ◽  
S. Noda ◽  
M. Takeuti ◽  
...  
Keyword(s):  
Ccd Camera ◽  
Wide Band ◽  
Variable Stars ◽  
Magellanic Clouds ◽  
Eclipsing Binaries ◽  
Light Curves ◽  
Agb Stars ◽  
Ccd Photometry ◽  
Pulsating Stars ◽  
Large Numbers

AbstractA review of the MOA (Microlensing Observations in Astrophysics) project is presented. MOA is a collaboration of approximately 30 astronomers from New Zealand and Japan established with the aim of finding and detecting microlensing events towards the Magellanic Clouds and the Galactic bulge, which may be indicative of either dark matter or of planetary companions. The observing program commenced in 1995, using very wide band blue and red filters and a nine-chip mosaic CCD camera.As a by-product of these observations a large database of CCD photometry for 1.4 million stars towards both LMC and SMC has been established. In one preliminary analysis 576 bright variable stars were confirmed, nearly half of them being Cepheids. Another analysis has identified large numbers of blue variables, and 205 eclipsing binaries are included in this sample. In addition 351 red variables (AGB stars) have been found. Light curves have been obtained for all these stars. The observations are carried out on a 61-cm f/6.25 telescope at Mt John University Observatory where a new larger CCD camera was installed in 1998 July. From this latitude (44° S) the Magellanic Clouds can be monitored throughout the year.

D. The Line Spectrum of Pulsating Variable Stars

1967 ◽  
Vol 28 ◽  
pp. 207-244
Author(s):  
R. P. Kraft
Keyword(s):  
Variable Stars ◽  
The Other ◽  
Line Spectrum ◽  
Afternoon Session ◽  
Empirical Information ◽  
Pulsating Variable Stars ◽  
Almost Continuous ◽  
Informal Approach

(Ed. note:Encouraged by the success of the more informal approach in Christy's presentation, we tried an even more extreme experiment in this session, I-D. In essence, Kraft held the floor continuously all morning, and for the hour and a half afternoon session, serving as a combined Summary-Introductory speaker and a marathon-moderator of a running discussion on the line spectrum of cepheids. There was almost continuous interruption of his presentation; and most points raised from the floor were followed through in detail, no matter how digressive to the main presentation. This approach turned out to be much too extreme. It is wearing on the speaker, and the other members of the symposium feel more like an audience and less like participants in a dissective discussion. Because Kraft presented a compendious collection of empirical information, and, based on it, an exceedingly novel series of suggestions on the cepheid problem, these defects were probably aggravated by the first and alleviated by the second. I am much indebted to Kraft for working with me on a preliminary editing, to try to delete the side-excursions and to retain coherence about the main points. As usual, however, all responsibility for defects in final editing is wholly my own.)

C. The Continuous Spectrum of Pulsating Variable Stars

1967 ◽  
Vol 28 ◽  
pp. 177-206
Author(s):  
J. B. Oke ◽  
C. A. Whitney
Keyword(s):  
Continuous Spectrum ◽  
Variable Stars ◽  
Velocity Fields ◽  
The Other ◽  
Line Spectrum ◽  
Direct Information ◽  
Thermodynamic Structure ◽  
Diagnostic Interpretation ◽  
Pulsating Variable Stars ◽  
The Continuum

Pecker:The topic to be considered today is the continuous spectrum of certain stars, whose variability we attribute to a pulsation of some part of their structure. Obviously, this continuous spectrum provides a test of the pulsation theory to the extent that the continuum is completely and accurately observed and that we can analyse it to infer the structure of the star producing it. The continuum is one of the two possible spectral observations; the other is the line spectrum. It is obvious that from studies of the continuum alone, we obtain no direct information on the velocity fields in the star. We obtain information only on the thermodynamic structure of the photospheric layers of these stars–the photospheric layers being defined as those from which the observed continuum directly arises. So the problems arising in a study of the continuum are of two general kinds: completeness of observation, and adequacy of diagnostic interpretation. I will make a few comments on these, then turn the meeting over to Oke and Whitney.

PENERAPAN MODEL QUANTUM LEARNING UNTUK MENINGKATKAN HASIL BELAJAR AUTOCAD SISWA KELAS X TEKNIK PEMESINAN SMK NEGERI 1 STABAT

2013 ◽  
Vol 5 (1) ◽  
Author(s):  
Abdul Hasan Saragih
Keyword(s):  
Positive Response ◽  
Phase 1 ◽  
First Grade ◽  
Learning Model ◽  
Second Phase ◽  
Phase 2 ◽  
Phase 3 ◽  
The Third ◽  
Third Phase ◽  
Quantum Learning

This classroom research was conducted on the autocad instructions to the first grade of mechinary class of SMK Negeri 1 Stabat aiming at : (1) improving the student’ archievementon autocad instructional to the student of mechinary architecture class of SMK Negeri 1 Stabat, (2) applying Quantum Learning Model to the students of mechinary class of SMK Negeri 1 Stabat, arising the positive response to autocad subject by applying Quantum Learning Model of the students of mechinary class of SMK Negeri 1 Stabat. The result shows that (1) by applying quantum learning model, the students’ achievement improves significantly. The improvement ofthe achievement of the 34 students is very satisfactory; on the first phase, 27 students passed (70.59%), 10 students failed (29.41%). On the second phase 27 students (79.41%) passed and 7 students (20.59%) failed. On the third phase 30 students (88.24%) passed and 4 students (11.76%) failed. The application of quantum learning model in SMK Negeri 1 Stabat proved satisfying. This was visible from the activeness of the students from phase 1 to 3. The activeness average of the students was 74.31% on phase 1,81.35% on phase 2, and 83.63% on phase 3. (3) The application of the quantum learning model on teaching autocad was very positively welcome by the students of mechinary class of SMK Negeri 1 Stabat. On phase 1 the improvement was 81.53% . It improved to 86.15% on phase 3. Therefore, The improvement ofstudent’ response can be categorized good.

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