Periodicities of Radio Flares in RS CVn and Algol Binaries

Richards, Mercedes T.; Waltman, E. B.; Ghigo, F. D.; Richards, Donald St. P.

doi:10.1017/s0074180900182105

Cited by 25 publications

(60 citation statements)

References 3 publications

(2 reference statements)

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“…<256 days). These are the periodicities discussed in Massi et al (1998) and Richards et al (2003). In the optical data these shorter periodicities are significant (within black contour lines) but with little power, therefore, they will not be taken into account in the following discussion which focuses on the periodicities occurring in the interval of 256-512 days.…”

Section: Methods Of Timing Analysis: Wavelets and Pdmmentioning

confidence: 92%

“…Massi et al (1998) analyzed the data set (JD 2 448 965.17+) 0÷1000 and determined periods of 14, 25, 159 and 56 (circular polarization data) days. Richards et al (2003) analyzing the GBI data identified periods of 53, 83, 141 and 280-300 days. This is very similar to the Sun, where together with the Rieger period (152-158 days) several other periodicities with time scales of months appear and disappear and slightly change in frequency (see references in Oliver & Ballester 1995;Bai 2003).…”

Section: The Datamentioning

confidence: 99%

“…The flaring activity of UX Arietis shows some periodicities: 3-yr monitoring with the Effelsberg 100-m radio telescope revealed a cycle of several months modulated by shorter cycles (Massi et al 1998) and later 3-yr radio monitoring with the Green Bank Interferometer not only confirmed the existence of such a cyclic flaring activity in UX Arietis, but also indicated periodical activity in other stars (Richards et al 2003).…”

Section: Introductionmentioning

confidence: 96%

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Discovery of Solar Rieger periodicities in another star

Massi

Neidhoefer

Carpentier

et al. 2005

A&A

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Abstract. The Rieger periods are solar cycles with a time scale of months, which are present in both flaring activity and sunspot occurrence. These short-term periodicities, tentatively explained by equatorially trapped Rossby-type waves modulating the emergence of magnetic flux at the surface, are considered a peculiar and not yet fully understood solar phenomenon. We chose a stellar system with solar characteristics, UX Arietis, and performed a timing analysis of two 9-year datasets of radio and optical observations. The analysis reveals a 294-day cycle. When the two 9-year datasets are folded with this period, a synchronization of the peak of the optical light curve (i.e., the minimum spot coverage) with the minimum radio flaring activity is observed. This close relationship between two completly independent curves makes it very likely that the 294-day cycle is real. We conclude that the process invoked for the Sun of a periodical emergence of magnetic flux may also be applied to UX Arietis and can explain the cyclic flaring activity triggered by interactions between successive cyclic emergences of magnetic flux.

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Section: Methods Of Timing Analysis: Wavelets and Pdmmentioning

confidence: 92%

Section: The Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

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Discovery of Solar Rieger periodicities in another star

Massi

Neidhoefer

Carpentier

et al. 2005

A&A

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“…Budding et al (1998) and Richards et al (2003) showed that the RS CVn system V711τ frequently emits radio bursts that reach 0.1 Jy at 2.3 GHz and 1 Jy at 8.4 GHz. With a distance of 29 pc and a bandwidth Δ f ≥ 8 GHz, one deduces an isotropic radio power ∼7 × 10 19−20 W. Based on estimates from Saar (1996) and Budding et al (1998), the RS CVn magnetic fields reach 1−3 × 10 3 G, which leads, based on the separation of the system V711τ (11.5 R , Richards et al 2003), to a magnetic field magnitude B ∼ 10−30 G at the interaction region. The radius of this region is at most that of the secondary companion in V711τ (∼1.3 R ).…”

Section: Brightnessmentioning

confidence: 99%

Radio emissions from pulsar companions: a refutable explanation for galactic transients and fast radio bursts

Mottez

Zarka

2014

A&A

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Context. The six known highly dispersed fast radio bursts are attributed to extragalactic radio sources that are of unknown origin but extremely energetic. We propose here a new explanation that does not require an extreme release of energy and involves a body (planet, asteroid, white dwarf) orbiting an extragalactic pulsar. Aims. We investigate a theory of radio waves associated with such pulsar-orbiting bodies. We focus our analysis on the waves emitted from the magnetic wake of the body in the pulsar wind. After deriving their properties, we compare them with the observations of various transient radio signals to determine whether they could originate from pulsar-orbiting bodies. Methods. The analysis is based on the theory of Alfvén wings: for a body immersed in a pulsar wind, a system of two stationary Alfvén waves is attached to the body, provided that the wind is highly magnetised. When they are destabilised through plasma instabilities, Alfvén wings can be the locus of strong radio sources that are convected with the pulsar wind. By assuming a cyclotron maser instability operating in the Alfvén wings, we make predictions about the shape, frequencies, and brightness of the resulting radio emissions. Results. Because of the beaming by relativistic aberration, the signal is seen only when the companion is perfectly aligned between its parent pulsar and the observer, as is the case for occultations. For pulsar winds with a high Lorentz factor (≥10 4 ), the whole duration of the radio event does not exceed a few seconds, and it is composed of one to four peaks that last a few milliseconds each and are detectable up to distances of several Mpc. The Lorimer burst, the three isolated pulses of PSR J1928+15, and the recently detected fast radio bursts are all compatible with our model. According to it, these transient signals should repeat periodically with the companion's orbital period. Conclusions. The search of pulsar-orbiting bodies could be an exploration theme for new-or next-generation radio telescopes.

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“…Some difference in circular polarization fraction was attributed naturally to differences in system inclination. Some palpable differences have been found, however : Richards, Waltman, & Ghigo (2002) have recently presented evidence that apparent periodicities in radio flaring in the time from 1995 to 2000 at frequencies of 2.3 and 8.3 GHz are different, with the strongest periodicities found being 49 AE 5 days and 120 AE 5 days for Algol and HR 1099, respectively. Nevertheless, all other characteristics appearing very similar, I feel that assumption 1 is justified and that, indeed, the temperature structures of the coronae of HR 1099 and Algol are essentially the same.…”

Section: Similarities In Stellar Parameters and Coronaementioning

confidence: 99%

From the Heart of the Ghoul: C and N Abundances in the Corona of Algol B

Drake¹

2003

ApJ

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Chandra Low Energy Transmission Grating Spectrograph observations of Algol have been used to determine the abundances of C and N in the secondary star for the first time. In order to minimize errors arising from an uncertain coronal differential emission measure as a function of temperature, the analysis was performed relative to similar observations of an adopted '' standard '' star, HR 1099. It is demonstrated that HR 1099 and Algol are coronal twins in many respects and that their X-ray spectra are very similar in nearly all details, except for the observed strengths of C and N lines. The H-like 2p 2 P 3=2;1=2 ! 1s 2 S 1=2 transitions of C and N in the coronae of Algol and HR 1099 demonstrate that the surface abundances of Algol B have been strongly modified by CN processing, as shown earlier by Schmitt & Ness. It is found that N is enhanced in Algol B by a factor of 3 compared with HR 1099. No C lines are detected in the Algol spectrum, indicating a C depletion relative to HR 1099 by a factor of 10 or more. These C and N abundances indicate that Algol B must have lost at least half of its initial mass and are consistent with predictions of evolutionary models that include nonconservative mass transfer and angular momentum loss through magnetic activity. Based on Hlike and He-like transitions in O and Ne, it is estimated that Algol is slightly metal poor, by 0.2 dex in terms of the coronal abundances of light elements relative to HR 1099, while the Fe xvii 2p 5 3d 1 P 1 ! 2p 6 1 S 0 transition indicates a very similar Fe abundance. In reviewing coronal abundance results for active stars in the literature and drawing on an earlier Chandra study of the coronal abundances of HR 1099, it is concluded that Fe is very likely depleted in the coronae of both Algol and HR 1099 by 0.5 dex relative to their photospheric compositions, but that Ne is enhanced by a similar magnitude. Light elements such as C, N, and O are likely depleted in both stars by of order 0.3 dex. The similarities in these large-abundance anomalies in HR 1099 and Algol are notable. Despite such compositional fractionation in these coronae, the relative C and N abundances in HR 1099, determined by comparing observed line strengths with theoretical C/N line ratios, are consistent with recent solar values, indicating that differential fractionation between these elements is not significant and that little or no dredge-up of material subjected to CN processing has occurred on the subgiant component.

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Periodicities of Radio Flares in RS CVn and Algol Binaries

Abstract: Abstract. Periodicities of radio flaring activity from the Algol systems (3 Per and 6 Lib and the RS CVn systems V711 Tau and UX Ari were determined from a continuous 5-year survey. The radio continuum fluxes at 2.3 GHz and 8.3 GHz were monitored with the NRAO-Green Bank

Cited by 25 publications

References 3 publications

Discovery of Solar Rieger periodicities in another star

Discovery of Solar Rieger periodicities in another star

Radio emissions from pulsar companions: a refutable explanation for galactic transients and fast radio bursts

From the Heart of the Ghoul: C and N Abundances in the Corona of Algol B

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