The chromosphere of Beta Cassiopeiae

Teays, T. J.; Schmidt, Edward G.; Fracassini, L. E. Pasinetti; Fracassini, M.

doi:10.1086/167761

Cited by 8 publications

(9 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…On the other hand, while Lya shows a trend of elevated intensity between phases 0.25 and 0.75 compared with the phases around maximum light-similar to the behavior of the Mg ii emission suggested by Teays et al (1989)-the periodogram analysis indicates that the chromospheric emission is not persistently correlated with the ö Set cycle. The Lya flux, although affected slightly by the uncertain correction for geocoronal light, should be a much more reliable tracer of the chromospheric response to pulsational heating than the Mg n doublet: the latter is a low-contrast feature in the early F stars, and its measurement in LWP echellograms is subject to a variety of uncertainties (see Teays et al).…”

Section: The Variability Of the Ultraviolet Continuum Of Caphsupporting

confidence: 74%

“….7O4A ROTATIONAL MODULATION STUDY OF F STARS 707 No. 2, 1991Teays et al (1989 found phase-dependent emission in the Mg it doublet of Caph, but peaking near minimum light, contrary to the behavior cited previously for p Pup and the Cepheids.…”

Section: Caphcontrasting

confidence: 54%

“…Thus, no significant periodic modulations appear in the chromospheric emissions of any of the program stars. Figure 6 illustrates the ultraviolet continuum (and H i Lya) of Caph phased according to the P = 0.101 days adopted by Teays et al (1989; the authors monitored the Mg n emission of Caph with the IUE about a month after my observing program), and a zero epoch (maximum visual light) of JD 2,447,072.838 ± 0.003, as measured at McDonald Observatory during the IUE campaign (communicated by S. L. Hawley 1987).…”

Section: Quantitative Evaluation : Periodogram Analysismentioning

confidence: 99%

See 2 more Smart Citations

The many faces of F stars - A rotational modulation study of Capella, Procyon, and Caph with the International Ultraviolet Explorer

Ayres

1991

ApJ

View full text Add to dashboard Cite

I monitored the far-ultraviolet emissions of three bright "F" stars-the Capella secondary (a Aur Ah: GO III), Procyon (a CMi A: F5 IV-V), and Caph (ß Cas: F2 III-IV)-over one or more rotational cycles with the International Ultraviolet Explorer. Strong rotational modulations produced by isolated "active regions" are a characteristic signature of the hydromagnetic dynamo, believed to be the root of the nonclassical hot outer atmospheres-chromospheres and coronae-of late-type stars. Although all three stars are regarded as chromospherically "active" (with C iv A1549 surface flux densities up to 20 times solar), none exhibited any sensible rotational modulations, even at the high sensitivity achieved by pseudo-trailing low-dispersion spectra on the SWP camera (precisions of 2%-5% [1

show abstract

Section: The Variability Of the Ultraviolet Continuum Of Caphsupporting

confidence: 74%

Section: Caphcontrasting

confidence: 54%

Section: Quantitative Evaluation : Periodogram Analysismentioning

confidence: 99%

See 1 more Smart Citation

The many faces of F stars - A rotational modulation study of Capella, Procyon, and Caph with the International Ultraviolet Explorer

Ayres

1991

ApJ

View full text Add to dashboard Cite

show abstract

“…Section 1), chromospheric activity has been reported in several other δ Scuti variables (e.g. Fracassini & Pasinetti 1982;Teays et al 1989;Fracassini et al 1991). Another apparently chromospherically active δ Scuti star, β Cas (HD 432, HR 21), is evident from Fig.…”

Section: Discussionmentioning

confidence: 60%

K2 observations of 95 Vir: δ Scuti pulsations in a chromospherically active star

Paunzen

Hümmerich

Bernhard

et al. 2017

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We have searched for photometric variability in 95 Vir, a fast rotating, chromospherically active early F-type star, which was observed in the framework of Campaign 6 of the Kepler K2 mission. Available literature information on 95 Vir were procured, and well-established calibrations were employed to verify the derived astrophysical parameters. We have investigated the location of our target star in the M Bol versus log T eff diagram, which provides information on evolutionary status. We have discussed our results in detail, drawing on literature information and the theoretical predictions of state-of-the-art pulsation models, with the aim of unraveling the underlying variability mechanisms. From an analysis of 3400 long-cadence measurements, we have identified two main frequencies and several harmonics in our target star. We attribute the main frequency, f 1 = 9.53728 d −1 , to δ Scuti pulsations. The origin of the secondary signal, f 2 = 1.07129 d −1 , is less clear. We have investigated three possible interpretations of the low-frequency variation: binarity, pulsation and rotational modulation. Current evidence favours an interpretation of f 2 as a signature of the rotational period caused by the presence of cool star spots, which goes along well with the observed chromospheric activity. However, phase-resolved spectroscopy is needed to verify this assumption. We briefly consider other chromospherically active δ Scuti stars that have been presented in the literature. A search for star spot-induced photometric variability in these objects might be of great interest, as well as an investigation of the interplay between chromospheric and pulsational activity.

show abstract

“…β Cas' chromosphere was studied using IUE spectra by Teays et al (1989) who found that its chromospheric activity is modulated by the pulsation and that the mean level of chromospheric activity is comparable to other F-type stars.…”

Section: Introductionmentioning

confidence: 99%

beta Cas: the first delta Scuti star with a dynamo magnetic field

Zwintz,

Neiner,

Kochukhov

et al. 2020

Preprint

View full text Add to dashboard Cite

Context. F type stars are characterised by several physical processes such as different pulsation mechanisms, rotation, convection, diffusion, and magnetic fields. The rapidly rotating δ Scuti star β Cas can be considered as a benchmark star to study the interaction of several of these effects. Aims. We investigate the pulsational and magnetic field properties of β Cas. We also determine the star's apparent fundamental parameters and chemical abundances. Methods. Based on photometric time series obtained from three different space missions (BRITE-Constellation, SMEI, and TESS), we conduct a frequency analysis and investigate the stability of the pulsation amplitudes over four years of observations. We investigate the presence of a magnetic field and its properties using spectropolarimetric observations taken with the Narval instrument by applying the Least Square Deconvolution and Zeeman Doppler Imaging techniques. Results. β Cas shows only three independent p-mode frequencies down to the few ppm-level; its highest amplitude frequency is suggested to be a n = 3, = 2, m = 0 mode. Its magnetic field structure is quite complex and almost certainly of a dynamo origin. β Cas' atmosphere is slightly deficient in iron peak elements and slightly overabundant in C, O, and heavier elements. Conclusions. Atypically for δ Scuti stars, we can only detect three pulsation modes down to exceptionally low noise levels for β Cas. The star is also one of very few δ Scuti pulsators known to date to show a measurable magnetic field, and the first δ Scuti star with a dynamo magnetic field. These characteristics make β Cas an interesting target for future studies of dynamo processes in the thin convective envelopes of F-type stars, of the transition region between fossil and dynamo fields, and the interaction between pulsations and magnetic field.

show abstract

The chromosphere of Beta Cassiopeiae

Cited by 8 publications

References 0 publications

The many faces of F stars - A rotational modulation study of Capella, Procyon, and Caph with the International Ultraviolet Explorer

The many faces of F stars - A rotational modulation study of Capella, Procyon, and Caph with the International Ultraviolet Explorer

K2 observations of 95 Vir: δ Scuti pulsations in a chromospherically active star

beta Cas: the first delta Scuti star with a dynamo magnetic field

Contact Info

Product

Resources

About