Ten colour photometry of twelve ap‐stars

Musielok, B.; Lange, D.; Schöneich, W.; Hildebrandt, G.; Želwanowa, E.; Hempelmann, A.; Salmanov, G.

doi:10.1002/asna.2103010205

Cited by 27 publications

(29 citation statements)

References 26 publications

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“…Babcock (1958) reported a magnetic field of 483 ± 221 G. Adelman & Knox (1994) determined a period of 16.840 days from their set of 87 FCAPT Strömgren photometry combined with the V values of Winzer. This result is close to those of Bartolini et al (1974) and Musielok et al (1980). Table 3).…”

Section: Mw Vulsupporting

confidence: 93%

uvby FCAPT photometry of the mCP stars HR 2258, MW Vul, and HR 9017 and the HgMn star 46 ρ Aqr

Adelman¹,

Young²

2004

A&A

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Section: Mw Vulsupporting

confidence: 93%

uvby FCAPT photometry of the mCP stars HR 2258, MW Vul, and HR 9017 and the HgMn star 46 ρ Aqr

Adelman¹,

Young²

2004

A&A

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“…Other references to changes of the shape of light curves with wavelength are, e.g. Musielok et al (1980), Kurtz & Martinez (2000), Mikulasek & Ziznovsky (2001), Mikulasek et al (2004). Abundance anomalies on the surfaces of magnetic CP stars, which imprint their signatures on the light curves and spectral line profiles, produce changing redistributions of stellar flux (primarily from short to longer wavelengths).…”

Section: Discussionmentioning

confidence: 99%

The roAp starα Circinus as seen by BRITE-Constellation

Weiß¹,

Fröhlich²,

Pigulski³

et al. 2016

A&A

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We report on an analysis of high-precision, multi-colour photometric observations of the rapidly-oscillating Ap (roAp) star α Cir. These observations were obtained with the BRITE-Constellation, which is a coordinated mission of five nanosatellites that collects continuous millimagnitude-precision photometry of dozens of bright stars for up to 180 days at a time in two colours (≈Johnson B and R). BRITE stands for BRight Target Explorer. The object α Cir is the brightest roAp star and an ideal target for such investigations, facilitating the determination of oscillation frequencies with high resolution. This star is bright enough for complementary interferometry and time-resolved spectroscopy. Four BRITE satellites observed α Cir for 146 d or 33 rotational cycles. Phasing the photometry according to the 4.4790 d rotational period reveals qualitatively different light variations in the two photometric bands. The phased red-band photometry is in good agreement with previously-published WIRE data, showing a light curve symmetric about phase 0.5 with a strong contribution from the first harmonic. The phased blue-lband data, in contrast, show an essentially sinusoidal variation. We model both light curves with Bayesian Photometric Imaging, which suggests the presence of two large-scale, photometrically bright (relative to the surrounding photosphere) spots. We also examine the high-frequency pulsation spectrum as encoded in the BRITE photometry. Our analysis establishes the stability of the main pulsation frequency over the last ≈20 yr, confirms the presence of frequency f 7 , which was not detected (or the mode not excited) prior to 2006, and excludes quadrupolar modes for the main pulsation frequency.

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“…Photometric variations are observed to have the same period, but to have double waves (Provin 1953;Musielok et al 1980;Pyper & Adelman 1985, etc. ) with the maximum light occurring at Ca ii minimum chosen to be the phase 0.00.…”

Section: Observationsmentioning

confidence: 97%

“…(1), ϕ Guth can be transformed to new phases according to Eq. (7), ϕ new by means of the relation ϕ new = ϕ Guth + 2.648 × 10 −6 (t − 2 431 960) (Molnar 1975), -10-color medium-band photometry (Musielok et al 1980); ubvy photometry of Pyper & Adelman (1985); ∇ − BV (Provin 1953); − Hipparcos photometry (ESA 1997), and small full circles relate to broad-band photometry of WIRE (Retter et al 2004) -each point is the median of 1600 individual time-consecutive measurements.…”

Section: Improved Ephemerismentioning

confidence: 99%

Modelling the light variability of the Ap starε Ursae Majoris

Shulyak

Krtička

Mikulášek

et al. 2010

A&A

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Aims. We simulate the light variability of the Ap star ε UMa using the observed surface distributions of Fe, Cr, Ca, Mn, Mg, Sr, and Ti obtained with the help of the Doppler imaging technique. Methods. Using all photometric data available, we specified light variations of ε UMa modulated by its rotation from far UV to IR. We employed the LLmodels stellar model atmosphere code to predict the light variability in different photometric systems. Results. The rotational period of ε UMa is refined to 5.d 088631(18). It is shown that the observed light variability can be explained as a result of the redistribution of radiative flux from the UV spectral region to the visual caused by the inhomogeneous surface distribution of chemical elements. Among seven mapped elements, only Fe and Cr contribute significantly to the amplitude of the observed light variability. In general, we find very good agreement between theory and observations. We confirm the important role of Fe and Cr in determining the magnitude of the well-known depression around 5200 Å by analyzing the peculiar a-parameter. Finally, we show that the abundance spots of considered elements cannot explain the observed variabilities in near UV and β index, which probably have other causes. Conclusions. The inhomogeneous surface distribution of chemical elements can explain most of the observed light variability of the A-type CP star ε UMa.

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Ten colour photometry of twelve ap‐stars

Cited by 27 publications

References 26 publications

uvby FCAPT photometry of the mCP stars HR 2258, MW Vul, and HR 9017 and the HgMn star 46 ρ Aqr

uvby FCAPT photometry of the mCP stars HR 2258, MW Vul, and HR 9017 and the HgMn star 46 ρ Aqr

The roAp starα Circinus as seen by BRITE-Constellation

Modelling the light variability of the Ap starε Ursae Majoris

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