scholarly journals Cluster Distances using Delta Scuti Stars; The Open Clusters Praesepe and NGC 7062

2002 ◽  
Vol 207 ◽  
pp. 135-137
Author(s):  
Torben Arentoft ◽  
Lars M. Freyhammer
Keyword(s):  
Chemical Composition ◽  
Open Cluster ◽  
Large Population ◽  
High Amplitude ◽  
Open Clusters ◽  
Distance Scale ◽  
Stellar Clusters ◽  
Delta Scuti ◽  
Scuti Stars ◽  
Δ Scuti Stars

Asteroseismology of multiperiodic δ Scuti stars is a powerful tool for providing estimates of distances to the stars being analyzed. Especially δ Scuti stars in clusters offer good possibilities for determining asteroseismic distances, as the stellar models are constrained by assuming common values for chemical composition, age and distance. Recently, we detected a large population of δ Scuti stars in the open cluster NGC 7062. On the basis of these results, we discuss the potential of extending the asteroseismic distance scale for δ Scuti stars to include extra-galactic stellar clusters. Especially high-amplitude δ Scuti stars, pulsating in at least 2 radial modes, offer promising possibilities for doing this.

scholarly journals Delta Scuti Stars in Open Clusters: w2 and w20 in NGC 2264 and h501 and h906 in α Per

2000 ◽  
Vol 176 ◽  
pp. 465-466
Author(s):  
J. H. Peña ◽  
R. Peniche ◽  
F. Cervantes ◽  
R. M. García ◽  
J. P. Sareyan
Keyword(s):  
Chemical Composition ◽  
Effective Temperature ◽  
Variable Stars ◽  
Open Clusters ◽  
Early Type ◽  
Early Type Stars ◽  
Delta Scuti ◽  
Scuti Stars ◽  
Δ Scuti Stars

There are many advantages to studying variable stars in open clusters; the parameters that determine the evolution of the stars, such as chemical composition and age, can be considered to be the same for all the stars in the cluster. These data, along with the mass, effective temperature and superficial gravity, allow us to better determine the physics which explain the pulsation mechanisms. In the present paper the variable stars h501 and h906 in α Per and w2 and w20 in NGC 2264 are studied. In particular, the reasons why δ Scuti stars coexist with early type stars in NGC 2264 is examined.

scholarly journals Seismology of δ Scuti stars in stellar clusters

1995 ◽  
Vol 10 ◽  
pp. 343-344
Author(s):  
Y. Lebreton ◽  
E. Michel
Keyword(s):  
Chemical Composition ◽  
Stellar Clusters ◽  
Unknown Parameters ◽  
Physical Description ◽  
Star Mass ◽  
Oscillation Modes ◽  
Stellar Models ◽  
F Stars ◽  
Scuti Stars ◽  
Δ Scuti Stars

Several δ Scuti stars (A/F stars) have been observed during multi-site campaigns of observations and have been found to be multiperiodic pulsators. They are thus good candidates for asteroseismology from ground based observations. Observations provide the position of the star in the H-R diagram and some frequencies (about 5 for the STEPHI campaigns). Comparisons with models should then allow to identify the oscillation modes of the star and then give information on the unknown parameters of the star (mass, age, chemical composition). However the situation is complicated, since stellar models are based on a physical description of the stellar material, which is not well known in many respects. In particular A/F stars have convective cores, the extent of which depends on the amount of overshooting considered and on the description of this process.

scholarly journals Dwarf Cepheid Radii and the Distance Scale

2002 ◽  
Vol 185 ◽  
pp. 112-115 ◽  
Author(s):  
C.D. Laney ◽  
M. Joner ◽  
L. Schwendiman
Keyword(s):  
High Amplitude ◽  
Distance Scale ◽  
Distance Modulus ◽  
Classical Cepheid ◽  
Rr Lyrae ◽  
Classical Cepheids ◽  
Delta Scuti ◽  
Absolute Magnitudes ◽  
Scuti Stars ◽  
Ir Photometry

AbstractBaade-Wesselink radii for dwarf Cepheids (High Amplitude Delta Scuti stars) can give luminosities and distances independent of the classical Cepheid distance scale. Using optical and IR photometry together with precision radial velocities, the authors have obtained radii and luminosities for 7 stars, and combined these with two from the literature, obtaining results consistent with the luminosities of the 3 dwarf Cepheids with good Hipparcos parallaxes. Classical Cepheids and dwarf Cepheids appear to fit the same PL and PR relations. The results imply ‘bright’ RR Lyrae absolute magnitudes giving an LMC distance modulus of 18.51-18.54, in agreement with the distance derived from classical Cepheids.

scholarly journals Luminosity of δ Scuti Stars After Hipparcos Satellite

1998 ◽  
Vol 11 (1) ◽  
pp. 567-567
Author(s):  
E. Antonello ◽  
L. Mantegazza ◽  
E. Poretti
Keyword(s):  
Globular Clusters ◽  
Rotational Velocity ◽  
High Amplitude ◽  
Empirical Dependence ◽  
Trigonometric Parallaxes ◽  
Nearby Stars ◽  
Observational Errors ◽  
Absolute Magnitudes ◽  
Scuti Stars ◽  
Δ Scuti Stars

The absolute magnitudes of δ Scuti stars derived from parallaxes measured by the Hipparcos satellite were compared with the previous estimates based on photometric uvby² indices, and significant differences were found which are related to photometric effects of metallicity and rotational velocity. A reliable calibration of Mv in terms of the photometric indices shall include an estimate of these effects. It is important also to take into account the possible presence of unresolved close companions in order to fully exploit the accuracy of Mv of nearby stars derived from the trigonometric parallaxes. The Mv of few bright SX Phe stars support the period-luminosity relation obtained with ground based observations of globular clusters, while it does not seem to confirm the empirical dependence of this relation on the metallicity. Some high amplitude δ Scuti stars with intermediate or normal metallicity and small and uncertain parallax have apparently a very low luminosity. Simulations of Mv determinations from observed parallaxes based on the discussion of observational errors by Lutz and Kelker (1973) have shown that the low luminosity could be an effect related to these errors.

The MACHO Project Sample of Galactic Bulge High‐Amplitude δ Scuti Stars: Pulsation Behavior and Stellar Properties

2000 ◽  
Vol 536 (2) ◽  
pp. 798-815 ◽  
Author(s):  
C. Alcock ◽  
R. A. Allsman ◽  
D. R. Alves ◽  
T. S. Axelrod ◽  
A. C. Becker ◽  
...  
Keyword(s):  
High Amplitude ◽  
Galactic Bulge ◽  
Stellar Properties ◽  
Scuti Stars ◽  
Δ Scuti Stars

scholarly journals Bulge δ Scuti stars in the MACHO database

1997 ◽  
Vol 189 ◽  
pp. 293-298
Author(s):  
D. Minniti ◽  
C. Alcock ◽  
D.R. Alves ◽  
T.S. Axelrod ◽  
A.C. Becker ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
High Amplitude ◽  
Light Curves ◽  
Evolutionary Status ◽  
Absolute Magnitudes ◽  
Scuti Stars ◽  
Δ Scuti Stars

We describe the search for δ Scuti stars in the MACHO database of bulge fields. Concentrating on a sample of high amplitude δ Scutis, we examine the light curves and pulsation modes. We also discuss their spatial distribution and evolutionary status using mean colors and absolute magnitudes.

scholarly journals Multimode δ Scuti stars in the open cluster NGC 7062

2001 ◽  
Vol 368 (2) ◽  
pp. 580-592 ◽  
Author(s):  
L. M. Freyhammer ◽  
T. Arentoft ◽  
C. Sterken
Keyword(s):  
Open Cluster ◽  
Scuti Stars ◽  
Δ Scuti Stars

scholarly journals Delta Scuti Stars: Selected Recent Highlights

2000 ◽  
Vol 176 ◽  
pp. 408-414
Author(s):  
G. Handler
Keyword(s):  
Recent Progress ◽  
Open Problems ◽  
Delta Scuti ◽  
Scuti Stars ◽  
Δ Scuti Stars

AbstractAn overview of recent progress in the research on δ Scuti stars is given. Some intriguing results and open problems are pointed out, and some ideas for future investigations are provided.

scholarly journals Cepheid distances from the Baade–Wesselink method

2012 ◽  
Vol 8 (S289) ◽  
pp. 138-144 ◽  
Author(s):  
Wolfgang Gieren ◽  
Jesper Storm ◽  
Nicolas Nardetto ◽  
Alexandre Gallenne ◽  
Grzegorz Pietrzyński ◽  
...  
Keyword(s):  
Excellent Agreement ◽  
Surface Brightness ◽  
Recent Progress ◽  
Main Sequence ◽  
Near Infrared ◽  
Open Cluster ◽  
Open Clusters ◽  
Distance Scale ◽  
Systematic Uncertainties ◽  
Classical Cepheids

AbstractRecent progress on Baade–Wesselink (BW)-type techniques to determine the distances to classical Cepheids is reviewed. Particular emphasis is placed on the near-infrared surface-brightness (IRSB) version of the BW method. Its most recent calibration is described and shown to be capable of yielding individual Cepheid distances accurate to 6%, including systematic uncertainties. Cepheid distances from the IRSB method are compared to those determined from open cluster zero-age main-sequence fitting for Cepheids located in Galactic open clusters, yielding excellent agreement between the IRSB and cluster Cepheid distance scales. Results for the Cepheid period–luminosity (PL) relation in near-infrared and optical bands based on IRSB distances and the question of the universality of the Cepheid PL relation are discussed. Results from other implementations of the BW method are compared to the IRSB distance scale and possible reasons for discrepancies are identified.

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