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.

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.

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 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 The Absolute Magnitudes of the Nearby Stars: Calibrations of mean luminosity relations

1985 ◽  
Vol 111 ◽  
pp. 369-372
Author(s):  
W. Gliese ◽  
H. Jahreiss
Keyword(s):  
Spectral Type ◽  
Trigonometric Parallaxes ◽  
Preliminary Version ◽  
Nearby Stars ◽  
The Absolute ◽  
Absolute Magnitudes

The nearby stars are most favored for determining precise absolute magnitudes and for calibrating spectral-type, luminosity relations and color, luminosity relations. To demonstrate the main problems we discuss the (Mv,B-V) relation since (B-V) data are available for most of our candidates. At Yale Observatory van Altena is compiling a new catalog of trigonometric parallaxes. We feel deeply indebted to van Altena for making available to us a preliminary version of this catalog.

scholarly journals Hipparcos and Primary Distance Scale Indicators

1998 ◽  
Vol 11 (1) ◽  
pp. 576-577
Author(s):  
C. Turon
Keyword(s):  
Globular Clusters ◽  
Main Sequence ◽  
Open Clusters ◽  
Distance Scale ◽  
Relative Accuracy ◽  
Distance Information ◽  
Rr Lyrae ◽  
Trigonometric Parallaxes ◽  
Nearby Stars ◽  
Better Than

The Hipparcos data are providing a dramatic increase, qualitatively and quantitatively, of the basic available distance information. For example, the numbers of stars for which a relative accuracy better than 10 % is available from Hipparcos data and from ground-based data are respectively 22 396and about 1000. Moreover, the range of spectral types and luminosity classes for which precise parallaxes are available is considerably enlarged, including many stars in open clusters and a small number of Cepheids and RR Lyrae. The bottom of the main sequence is populated down to absolute Hpmagnitude 14, including a number of subdwarf stars essential to derive globular clusters distances and ages (Pont et al, 1997a). Finally, the Hipparcos data show how difficult are the calibration of photometric distances and the transformation of relative trigonometric parallaxes to absolute parallaxes. This is illustrated by the comparison of distances given in the last edition of the Catalogue of Nearby Stars (CNS3, Gliese & Jahreiß 1991), which is the best available compilation of stars said to be closer than 25 pc from ground-based data. About a third of them are found by Hipparcos to be (much) further than this limit (Perryman et ai, 1995). A second example is given by the study of (Binney et al, 1997).

scholarly journals A METHOD OF COLOR EXCESS DETERMINATION FOR HIGH AMPLITUDE δ SCUTI STARS

2009 ◽  
Vol 42 (6) ◽  
pp. 155-159
Author(s):  
Chul-Hee Kim ◽  
J.H. Choi ◽  
B.K. Moon ◽  
Soonthornthum Boonrucksar
Keyword(s):  
High Amplitude ◽  
Color Excess ◽  
Scuti Stars ◽  
Δ Scuti Stars

scholarly journals How to separate the low amplitude δ Scuti variation from the instrumental ones in CoRoT data?

2015 ◽  
Vol 11 (A29B) ◽  
pp. 529-531
Author(s):  
József M. Benkő ◽  
Margit Paparó
Keyword(s):  
Real Data ◽  
High Amplitude ◽  
Variable Stars ◽  
South Atlantic ◽  
Frequency Range ◽  
South Atlantic Anomaly ◽  
Fourier Spectra ◽  
Low Amplitude ◽  
Scuti Stars ◽  
Δ Scuti Stars

AbstractRich regular frequency patterns were found in the Fourier spectra of low-amplitude δ Scuti stars observed by CoRoT satellite (see Paparó et al. in prep.). The CoRoT observations are, however, influenced by the disturbing effect of the South Atlantic Anomaly. The effect is marginal for high amplitude variable stars but it could be critical in the case of low amplitude variables, especially if the frequency range of the intrinsic variation overlaps the interval of the instrumental frequencies. Some tests were carried out both on synthetic and real data for distinguishing technical and stars' frequencies.

scholarly journals CCD Photometry of the High‐Amplitude δ Scuti Stars V798 Cygni and V831 Tauri

1998 ◽  
Vol 110 (752) ◽  
pp. 1156-1163 ◽  
Author(s):  
F.  Musazzi ◽  
E.  Poretti ◽  
S.  Covino ◽  
A. Arellano  Ferro
Keyword(s):  
High Amplitude ◽  
Ccd Photometry ◽  
Scuti Stars ◽  
Δ Scuti Stars
Sign in / Sign up

Export Citation Format

Share Document