An EXOSAT observation of 1.5 orbital cycles of the 0.7 day short-period RS CVn system ER Vul

White, N. E.; Culhane, J. L.; Parmar, A. N.; Sweeney, Marvin A.

doi:10.1093/mnras/227.3.545

Cited by 16 publications

(12 citation statements)

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“…White et al (1987) used a two-component thermal plasma model to fit the spectrum, with temperatures of 6×10 6 K and 4×10 7 K. Gunn & Doyle (1997) derived a large filling factor of 0.53, as well as a large chromospheric thickness of ≤0.42 R , for the secondary component of ER Vul. Despite the high orbital inclination of ER Vul, no eclipses have been observed so far in the UV, radio and X-ray domain (Osten et al 2002).…”

Section: Er Vulmentioning

confidence: 99%

VLA multifrequency observations of RS CVn binaries

Garcia-Sanchez¹,

Paredes²,

Ribó³

2003

A&A

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Abstract. We present multiepoch Very Large Array (VLA) observations at 1.4 GHz, 4.9 GHz, 8.5 GHz and 14.9 GHz for a sample of eight RS CVn binary systems. Circular polarization measurements of these systems are also reported. Most of the fluxes observed are consistent with incoherent emission from mildly relativistic electrons. Several systems show an increase of the degree of circular polarization with increasing frequency in the optically thin regime, in conflict with predictions by gyrosynchrotron models. We observed a reversal in the sense of circular polarization with increasing frequency in three noneclipsing systems: EI Eri, DM UMa and HD 8358. We find clear evidence for coherent plasma emission at 1.4 GHz in the quiescent spectrum of HD 8358 during the helicity reversal. The degrees of polarization of the other two systems could also be accounted for by a coherent emission process. The observations of ER Vul revealed two U-shaped flux spectra at the highest frequencies. The U-shape of the spectra may be accounted for by an optically thin gyrosynchrotron source for the low frequency part whereas the high frequency part is dominated by a thermal emission component.

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Section: Er Vulmentioning

confidence: 99%

VLA multifrequency observations of RS CVn binaries

Garcia-Sanchez¹,

Paredes²,

Ribó³

2003

A&A

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“…Eclipse studies at x-ray wavelengths have been carried out for the eclipsing RS CVn systems AR Lac (13)(14)(15), ER Vul (16), and TY Pyx (1 7), for the eclipsing dMe pair YY Gem (1 8), and for the Algol system p Per (1 9). In all previously studied eclipsing systems, with the exception of P Per (where no eclipses have been found), both components are known to contribute to the.…”

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confidence: 99%

A Spatially Resolved X-ray Image of a Star Like the Sun

Schmitt

Kürster

1993

Science

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Observations made with the x-ray satellite ROSAT (Roentgen Satellite) have produced the first spatially resolved x-ray image of a corona around a star like our sun. The star is the secondary in the eclipsing binary system alpha Coronae Borealis (CrB), which consists of one star of spectral type A0V and one of type G5V. The x-ray light curve of alpha CrB shows a total x-ray eclipse during secondary optical minimum, with the G star behind the A star. The totality of the eclipse demonstrates that the A-type component in alpha CrB is x-ray dark and that the x-ray flux arises exclusively from the later-type companion. The x-ray eclipse ingress and egress are highly asymmetric compared with the optical eclipse, indicating a highly asymmetric x-ray intensity distribution on the surface of the G star. From a detailed modeling of the ingress and egress of the x-ray light curve, an eclipse map of the G star was constructed by a method based on an optimization by simulated annealing.

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“…The high elliptical orbit of EXOSAT enabled continuous observations of a given target for up to three days. Observations of the eclipsing system Algol and of the partially eclipsing RS CVn, ER Vul, showed no strong x-ray modulation or eclipses, again suggesting a scale height for their coronae of several stellar radii (White et al 1986;White et al 1987). A detailed study of an EXOSAT observation covering one full orbit of AR Lac by White et al (1990) produced results in qualitative agreement with those of Walter et al (1983).…”

Section: Ajmentioning

confidence: 61%

EUVE Photometric Eclipse Observations of AR Lacertae

Christian¹,

Drake²,

Patterer³

et al. 1996

The Astronomical Journal

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We report on observations of the eclipsing RS CVn system AR Lac with the Extreme Ultraviolet Explorer (EUVE) scanning and deep survey (DS) telescopes. This system consists of a G2 IV star and a KO IV star separated by 9.2R 0 with an orbital period of about 1.98 days. The scanner observations consisted of a single pointing over a period of 25 hours, providing some coverage of both primary and secondary eclipses, and subsequent scanning during the all-sky survey. During the pointed observation AR Lac was detected in the EUVE Lexan/boron (Lexan/B, 50-180 Â) and Al/Ti/C (160-240 Â) bands at average count rates of 0.12 and 0.016 count s-1 , respectively. During primary eclipse, the Lexan/B count rate was at about one-third of its subsequent value at quadrature, suggesting that, in the case of a compact and relatively homogeneous corona, a minimum of 60%-70% of the extreme ultraviolet (EUV) emission originates on the G star. There was no detectable modulation corresponding to secondary eclipse in either Lexan/B or Al/Ti/C bands. Data taken several months later during the EUVE all-sky survey yield the same Lexan/B count rate as the pointed data but only an upper limit in the Al/Ti/C bandpass. AR Lac was observed again with the DS as part of a Guest Observer pointed observation. This single pointing lasted slightly more than three days and included both primary and secondary eclipses. AR Lac was detected in the DS Lexan/B band with an average count rate of 0.31 count s _1. The primary eclipse is easily visible as a-40% decrease in intensity. A dip in the light curve is present at the time of secondary eclipse, but is not readily discernible from the average level of variability. A flare corresponding to a factor of 2 increase over the quiescent emission count rate was observed during the next expected secondary eclipse. We have performed an elementary emission measure analysis and compared isothermal models that fit the EUVE data to earlier Einstein, EXOSAT, ASCA, and ROSAT two-temperature models culled from the literature. In general, the EUVE data indicate very similar emission measures to those derived in previous work, indicating that the corona of AR Lac does not vary in average x-ray or EUV luminosity over periods of years up to a decade. Assuming an isothermal model with r~10 7 K, as indicated by the emission measure analysis, the total Lexan/B count rate at quadrature implies an EUV luminosity of 1.1 X10 30 ergs-1 in the 50-180 Â bandpass.

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An EXOSAT observation of 1.5 orbital cycles of the 0.7 day short-period RS CVn system ER Vul

Cited by 16 publications

References 0 publications

VLA multifrequency observations of RS CVn binaries

VLA multifrequency observations of RS CVn binaries

A Spatially Resolved X-ray Image of a Star Like the Sun

EUVE Photometric Eclipse Observations of AR Lacertae

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