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 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 Photometry of early type stars in open clusters (NGC 1444, NGC 1662, NGC 2129, NGC 2169 and NGC 7209)

1994 ◽  
Vol 162 ◽  
pp. 303-304
Author(s):  
J. H. Peña ◽  
R. Peniche
Keyword(s):  
Open Clusters ◽  
Early Type ◽  
Number Of Clusters ◽  
Pulsating Stars ◽  
Blue Stragglers ◽  
Chemical Enrichment ◽  
Short Period ◽  
The Galaxy ◽  
Early Type Stars ◽  
Delta Scuti

This is part of a series which has the purpose of examining the nature of the stars belonging to open clusters. The aim of this series is, among others things, to study short period pulsating stars, mainly of the Delta Scuti type, by first establishing the membership of each star to the cluster, to determine the abundance of the Be and Ap phenomena and blue stragglers in open clusters for clusters of different ages and metalicities and, eventually, to study the chemical enrichment of the galaxy when age, dynamics and metalicity are known for a fair number of clusters.

scholarly journals Do the Pre-Main Sequence δ Scuti Stars Really Exist?

2002 ◽  
Vol 185 ◽  
pp. 346-347
Author(s):  
J.H. Peña ◽  
R. Peniche ◽  
J.C. Plascencia ◽  
M.A. Hobart ◽  
C. de la Cruz ◽  
...  
Keyword(s):  
Main Sequence ◽  
Variable Stars ◽  
Current Status ◽  
Excellent Review ◽  
Scuti Stars ◽  
Δ Scuti Stars

Recently, new views of the current status of δ Scuti stars have been developed by Rodríguez & Breger (2001) who carried out an excellent review, listing 8 pre-main-sequence (PMS) δ Scuti candidates and examined the possibility of the existence of PMS δ Scuti variable stars. Here we discuss the nature of 4 stars from their list: 2 said to be members of NGC 2264 and 2 of NGC 6823.

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 Is Delta Scuti Star Seismology Possible?

1989 ◽  
Vol 111 ◽  
pp. 271-271
Author(s):  
G. Kovacs
Keyword(s):  
Sampling Rate ◽  
Efficient Tool ◽  
Scuti Star ◽  
Delta Scuti Star ◽  
Delta Scuti ◽  
Stellar Seismology ◽  
Ap Stars ◽  
Scuti Stars ◽  
Δ Scuti Stars ◽  
Nonradial Pulsation

AbstractThe direct fit of theoretical pulsation frequencies to the observations (i.e. stellar seismology) proved to be a very efficient tool in the study of solar oscillations. In the case of other multiperiodic variables, like δ Scuti stars, Ap stars and white dwarfs the method suffers from the disturbing abundance of possible nonradial modes. Colour and/or radial velocity (or line profile) measurements can narrow down the number of possibilities, but these kinds of data are not often available with the desired accuracy and sampling rate. Since pulsational frequencies are the most readily and accurately computed and measured quantities of pulsation, we address the question of the accurate fit of the nonradial pulsation frequencies to the observations in the case of δ Scuti stars.

scholarly journals The hard life of clumps in atmospheres of early-type stars

1994 ◽  
Vol 162 ◽  
pp. 505-506
Author(s):  
A.F. Kholtygin
Keyword(s):  
Shock Waves ◽  
Effective Temperature ◽  
Density Ratio ◽  
Gravitational Attraction ◽  
Early Type ◽  
Number Density ◽  
Gas Jets ◽  
Early Type Stars

As has been recently established, the atmospheres of early-type stars are strongly disheveled. These atmospheres consist of dense clumps and a more rarefied interclump medium. We consider the forces that determine the motion of the clumps. We show that the main force is gravitational attraction of the clumps to the star. For stars with a high effective temperature (Teff ≥ 6 · 104 K) it appears that the clump/interclump gas number density ratio is ≥ 30. In this case we can conclude that the clumps are formed by shock waves. Some evidence as to the existence of gas jets in the atmospheres of Wolf-Rayet stars have recently been presented. We propose that such jets may be a common feature of all early-type stars. Profiles of HeI lines in spectra of clumped atmospheres with jets have been calculated.

scholarly journals Oscillation Patterns of SX Phœnicis Variables in Globular Clusters

2000 ◽  
Vol 176 ◽  
pp. 497-498
Author(s):  
J. O. Petersen ◽  
M. Quaade ◽  
M. I. Andersen ◽  
L. M. Freyhammer
Keyword(s):  
Life History ◽  
Globular Clusters ◽  
Open Clusters ◽  
Light Curves ◽  
Standard Field ◽  
Blue Straggler ◽  
Scuti Stars ◽  
Δ Scuti Stars

AbstractBased on new analyses of light curves of SX Phœnicis variables in globular clusters and on results taken from the literature, an overview of oscillation patterns in this subgroup of δ Scuti variables is given. Belonging to the Blue Straggler stars, they are expected to have a more complicated life history than “normal” δ Scuti stars in the field or in open clusters. The overall picture is that the patterns found in this SX Phe group seem to be similar to the patterns that are well established for standard field δ Set stars.

scholarly journals Re-classification of ROTSE-I δ Scuti stars

2004 ◽  
Vol 193 ◽  
pp. 279-282
Author(s):  
H. Jin ◽  
S.-L. Kim ◽  
C.-U. Lee ◽  
D.-J. Lee ◽  
K.-S. Kim
Keyword(s):  
Decomposition Analysis ◽  
Variable Stars ◽  
Fourier Decomposition ◽  
Eclipsing Variable Stars ◽  
Scuti Stars ◽  
Δ Scuti Stars

AbstractWe present new multiband photometric results for ROTSE-I δ Sct stars and the Fourier decomposition analysis. Our result shows that most of the stars classified as ROTSE-I δ Sct stars seem to be W UMa type eclipsing variable stars.

Sign in / Sign up

Export Citation Format

Share Document