Radio emissions from terrestrial planets around white dwarfs

Willes, A. J.; Wu, Kinwah

doi:10.1051/0004-6361:20040417

Cited by 37 publications

(42 citation statements)

References 41 publications

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“…Our observations of GJ 876 took place at 12 mm. The calculations of Willes & Wu (2005) suggest that any radio emission due to the UI operation would more likely be observable at shorter wavelengths. Sensitive observations at these wavelengths (<6 mm) will be possible using ALMA.…”

Section: Discussionmentioning

confidence: 98%

“…For systems with orbital periods in the range 5–10 min, the optimum observing frequency is close to 5 GHz (6 cm). For terrestrial planets orbiting around a low‐mass magnetic star, the UI model described in Willes & Wu (2005) predicted that the peak frequency is likely to be between 50 and 500 GHz (0.6–6 mm), although this was rather uncertain.…”

Section: Candidate Ui Targetsmentioning

confidence: 99%

“…It has been suggested that UI processes resembling that found in the Jovian system can occur in double‐degenerate binary systems (Wu et al 2002) and in degenerate star–planet systems (Li, Ferrario & Wickramasinghe 1998; Willes & Wu 2004, 2005). Two candidates for UI double‐degenerate binary systems are the peculiar X‐ray sources RX J0806+15 and RX J1914+24.…”

Section: Introductionmentioning

confidence: 99%

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A search for electron cyclotron maser emission from compact binaries

Ramsay

Brocksopp

et al. 2007

Monthly Notices of the Royal Astronomical Society

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Unipolar induction (UI) is a fundamental physical process, which occurs when a conducting body transverses a magnetic field. It has been suggested that UI is operating in RX J0806+15 and RX J1914+24, which are believed to be ultra-compact binaries with orbital periods of 5.4 min and 9.6 min respectively. The UI model predicts that those two sources may be electron cyclotron maser sources at radio wavelengths. Other systems in which UI has been predicted to occur are short period extra-solar terrestrial planets with conducting cores. If UI is present, circularly polarised radio emission is predicted to be emitted. We have searched for this predicted radio emission from short period binaries using the VLA and ATCA. In one epoch we find evidence for a radio source, coincident in position with the optical position of RX J0806+15. Although we cannot completely exclude that this is a chance alignment between the position of RX J0806+15 and an artifact in the data reduction process, the fact that it was detected at a significance level of 5.8 sigma and found to be transient, suggests that it is more likely that RX J0806+15 is a transient radio source. We find an upper limit on the degree of circular polarisation to be ~50%. The inferred brightness temperature exceeds 10^18 K, which is too high for any known incoherent process, but is consistent with maser emission and UI being the driving mechanism. We did not detect radio emission from ES Cet, RX J1914+24 or Gliese 876.Comment: Accepted for publication MNRA

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Section: Discussionmentioning

confidence: 98%

Section: Candidate Ui Targetsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A search for electron cyclotron maser emission from compact binaries

Ramsay

Brocksopp

et al. 2007

Monthly Notices of the Royal Astronomical Society

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“…As for exoplanets, we expect to detect either auroral emission from the exoplanetary magnetosphere itself (if the exoplanet is strongly magnetized), or emission induced by the exoplanet through interaction with the stellar magnetic field (as a giant analog of the satellite-Jupiter case) regardless of whether the exoplanet is magnetized or not. The latter case also applies to the magnetic white dwarf-planet or white dwarf-brown dwarf systems studied in the literature (Willes & Wu 2004, 2005.…”

Section: Introductionmentioning

confidence: 98%

Modeling the radio signature of the orbital parameters, rotation, and magnetic field of exoplanets

Hess

Zarka

2011

A&A

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Context. Since the first extra-solar planet discovery in 1995, several hundreds of these planets have been discovered. Most are hot Jupiters, i.e. massive planets orbiting close to their star. These planets may be powerful radio emitters. Aims. We simulate the radio dynamic spectra resulting from various interaction models between an exoplanet and its parent star, i.e. exoplanet-induced stellar emission and three variants of the exoplanet's magnetospheric auroral radio emission (full auroral oval, active sector fixed in longitude, and active sector fixed in local time). Methods. We show the physical information about the system that can be drawn from radio observations, and how this can be achieved. This information includes the magnetic field strength and the rotation period of the emitting body (planet or star), the orbital period, the orbit's inclination, and the magnetic field tilt relative to the rotation axis or offset relative to the center of the planet. For most of these parameters, radio observations provide a unique means of measuring them. Results. Our results should provide the proper framework of analysis and interpretation for future detections of radio emissions from exoplanetary systems -or from magnetic white dwarf-planet or white dwarf-brown dwarf systems -, that are expected to commence soon as part of extensive programs at large radiotelescopes such as LOFAR, UTR2 or the GMRT. Our methodology can be easily adapted to simulate specific observations, once effective detection is achieved.

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“…Alfvén wings have been observed and theorised in other astrophysical situations, for instance, the Io-Jupiter interaction in the co-rotating plasma of Jupiter's magnetosphere (Neubauer 1980;Bonfond 2010;Hess et al 2010), Saturn and Enceladus (Pontius & Hill 2006), hot-Jupiters (Preusse et al 2006), planets around white dwarfs (Willes & Wu 2005), and occasionally the Earth (Chané et al 2012).…”

Section: General Principlementioning

confidence: 99%

Towards a theory of extremely intermittent pulsars

Mottez¹,

Bonazzola²,

Heyvaerts³

2013

A&A

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Aims. We investigate whether there may be one or many companions orbiting at close distance to the light cylinder around the extremely intermittent pulsars PSR B1931+24 and PSR J1841-0500. These pulsars, behaving in a standard way when they are active, also "switch off" for durations of several days, during which their magnetospheric activity is interrupted or reduced. Methods. We constrained our analysis on eight fundamental properties of PSR B1931+24 that summarise the observations. We considered that the disruption/activation of the magnetospheric activity would be caused by the direct interaction of the star with the Alfvén wings emanating from the companions. We also considered the recurrence period of 70 days to be the period of precession of the periastron of the companions orbit. We analysed in which way the time scale of the "on/off" pseudo-cycle would be conditioned by the precession of the periastron and not by the orbital time scale, and we derived a set of orbital constraints that we solved. We then compared the model, based on PSR 1931+24, with the known properties of PSR 1841+0500. Results. We conclude that PSR B1931+24 may be surrounded at a close distance to the star by a stream of small bodies of kilometric or sub-kilometric sizes that could originate from the tidal disruption of a body of moderate size that fell at a close distance to the neutron star on an initially very eccentric orbit. This scenario is also compatible with the properties of PSR J1841-0500, although the properties of PSR J1841-0500 are, as of now, less constrained. Conclusions. These results raise new questions. Why are the asteroids not yet evaporated? What kind of interaction can explain the disruption of the magnetospheric activity? These questions are the object of two Papers in preparation that will complete the present analysis.

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Radio emissions from terrestrial planets around white dwarfs

Cited by 37 publications

References 41 publications

A search for electron cyclotron maser emission from compact binaries

A search for electron cyclotron maser emission from compact binaries

Modeling the radio signature of the orbital parameters, rotation, and magnetic field of exoplanets

Towards a theory of extremely intermittent pulsars

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