A multiwavelength study of the M dwarf binary YY Geminorum

Butler, C. J.; Erkan, N.; Budding, E.; Doyle, J. G.; Foing, B. H.; Bromage, G. E.; Kellett, B. J.; Frueh, M.; Huovelin, J.; Brown, Alexander; Neff, J. E.

doi:10.1093/mnras/stu2398

Cited by 13 publications

(6 citation statements)

References 55 publications

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“…Some of the most extensive simultaneous radio and optical monitoring has been on active M dwarfs. During flares the optical component is seen to evolve on a much shorter timescale than its radio counterpart (Osten et al 2005;Butler et al 2015). The prolonged radio decay is attributed to magnetic mirroring near footpoints where field lines converge, increasing the field strength and reflecting synchrotron-producing electrons (e.g., Aschwanden et al 1998).…”

Section: Colliding Magnetospheresmentioning

confidence: 99%

Accretion and Magnetic Reconnection in the Classical T Tauri Binary Dq Tau

Tofflemire

Ardila

Akeson

et al. 2017

ApJ

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The theory of binary star formation predicts that close binaries (a<100 au) will experience periodic pulsed accretion events as streams of material form at the inner edge of a circumbinary disk (CBD), cross a dynamically cleared gap, and feed circumstellar disks or accrete directly onto the stars. The archetype for the pulsed accretion theory is the eccentric, short-period, classical T Tauri binary DQ Tau. Low-cadence (∼daily) broadband photometry has shown brightening events near most periastron passages, just as numerical simulations would predict for an eccentric binary. Magnetic reconnection events (flares) during the collision of stellar magnetospheres near periastron could, however, produce the same periodic, broadband behavior when observed at a one-day cadence. To reveal the dominant physical mechanism seen in DQ Tau's low-cadence observations, we have obtained continuous, moderate-cadence, multiband photometry over 10 orbital periods, supplemented with 27 nights of minute-cadence photometry centered on four separate periastron passages. While both accretion and stellar flares are present, the dominant timescale and morphology of brightening events are characteristic of accretion. On average, the mass accretion rate increases by a factor of five near periastron, in good agreement with recent models. Large variability is observed in the morphology and amplitude of accretion events from orbit to orbit. We argue that this is due to the absence of stable circumstellar disks around each star, compounded by inhomogeneities at the inner edge of the CBD and within the accretion streams themselves. Quasiperiodic apastron accretion events are also observed, which are not predicted by binary accretion theory.

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Section: Colliding Magnetospheresmentioning

confidence: 99%

Accretion and Magnetic Reconnection in the Classical T Tauri Binary Dq Tau

Tofflemire

Ardila

Akeson

et al. 2017

ApJ

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“…The ubiquitous manifestations of the magnetic activity of YY Gem, including frequent flaring, broad-band photometric and emission line variability, non-thermal X-ray and ultraviolet emission, have been investigated by many authors. Since the seminal work by Kron (1952), the out-of-eclipse photometric variation of YY Gem was interpreted in the context of the rotational modulation caused by a patchy, nonuniform surface brightness distribution on one or both components (Torres & Ribas 2002;Butler et al 2015). Large and frequent flare events have been reported for the system and investigated with the help of multiwavelength monitoring campaigns spanning the frequency range from X-ray to radio (Butler et al 2015, and references therein).…”

Section: Introductionmentioning

confidence: 99%

“…However, literature contains little direct, quantitative information on the magnetic field properties and surface structure morphology of YY Gem A and B. Several studies attempted to model the out-of-eclipse photometric time series observations of the combined light from the system in terms of dark surface spots (Torres & Ribas 2002;Butler et al 2015). Such analyses generally require strong assumptions regarding the spot characteristics (e.g.…”

Section: Introductionmentioning

confidence: 99%

Magnetic Field of the Eclipsing M-dwarf Binary YY Gem

Kochukhov

Shulyak

2019

ApJ

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YY Gem is a short-period eclipsing binary system containing two nearly identical, rapidly rotating, very active early-M dwarfs. This binary represents an important benchmark system for calibrating empirical relations between fundamental properties of low-mass stars and for testing theories of interior structure and evolution of these objects. Both components of YY Gem exhibit inflated radii, which has been attributed to poorly understood magnetic activity effects. Despite a long history of magnetic activity studies of this system no direct magnetic field measurements have been made for it. Here we present a comprehensive characterisation of the surface magnetic field in both components of YY Gem. We reconstructed the global field topologies with the help of a tomographic inversion technique applied to high-resolution spectropolarimetric data. This analysis revealed moderately complex global fields with a typical strength of 200-300 G and anti-aligned dipolar components. A complementary Zeeman intensification analysis of the disentangled intensity spectra showed that the total mean field strength reaches 3.2-3.4 kG in both components of YY Gem. We used these results together with other recent magnetic field measurements of M dwarfs to investigate the relation between the global and small-scale fields in these stars. We also assessed predictions of competing magnetoconvection interior structure models developed for YY Gem, finding that only one of them anticipated the surface field strength compatible with our observations. Results of our star spot mapping of YY Gem do not support the alternative family of theoretical stellar models which attempts to explain the radii inflation by postulating a large spot filling factor.

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“…Recently, a multiwavelength study of YY Gem was presented by Butler et al (2015). They included broad-band optical, nearinfrared, ultraviolet, and radio data to determine the physical parameters and transient spots located near quadrature longitudes.…”

Section: Yy Gemmentioning

confidence: 99%

Possible substellar companions in low-mass eclipsing binaries: GU Bootis and YY Geminorum

Wolf

Kučáková

Zasche

et al. 2018

A&A

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We present the next results of our long-term observational project to analyze the variations in the orbital periods of low-mass eclipsing binaries. About 70 new precise mid-eclipse times recorded with a CCD were obtained for two eclipsing binaries with short orbital periods: GU Boo (P = 0.d49) and YY Gem (0.d81). Observed-minus-calculated diagrams of the stars were analyzed using all reliable timings, and new parameters of the light-time effect were obtained. We derived for the first time or improved the short orbital periods of possible third bodies of 11 and 54 years for these low-mass binaries, respectively. We calculated that the minimum masses of the third components are close to 50 MJup, which corresponds to the mass of brown dwarfs. The multiplicity of these systems also plays an important role in the precise determination of their physical parameters.

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A multiwavelength study of the M dwarf binary YY Geminorum

Cited by 13 publications

References 55 publications

Accretion and Magnetic Reconnection in the Classical T Tauri Binary Dq Tau

Accretion and Magnetic Reconnection in the Classical T Tauri Binary Dq Tau

Magnetic Field of the Eclipsing M-dwarf Binary YY Gem

Possible substellar companions in low-mass eclipsing binaries: GU Bootis and YY Geminorum

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