Antonio G. Solalinde

Doyle, Henry Grattan

doi:10.1111/j.1540-4781.1937.tb00570.x

Cited by 5 publications

(7 citation statements)

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“…Debates linger about the precise latitudinal location and distribution (e.g., Güdel et al 2001) of star spots, but spots contained below mid-latitude (between 45 • and 50 • ) appear to be favored (Güdel et al 2001;Hussain et al 2012). The components display strong Balmer emission (Young et al 1989;Montes et al 1995b) and X-ray emission (Güdel et al 2001;Stelzer et al 2002;López-Morales 2007;Hussain et al 2012) during quiescence and have been observed to undergo frequent flaring events Doyle & Mathioudakis 1990;Hussain et al 2012). Furthermore, YY Gem has been identified as a source of radio emission, attributed to partially relativistic electron gyrosynchrotron radiation (Güdel et al 1993;McLean et al 2012).…”

Section: Analysis Of Individual Deb Systemsmentioning

confidence: 99%

Magnetic Inhibition of Convection and the Fundamental Properties of Low-Mass Stars. I. Stars With a Radiative Core

Feiden

Chaboyer

2013

ApJ

156

171

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Magnetic fields are hypothesized to inflate the radii of low-mass stars-defined as less massive than 0.8M ⊙in detached eclipsing binaries (DEBs). We investigate this hypothesis using the recently introduced magnetic Dartmouth stellar evolution code. In particular, we focus on stars thought to have a radiative core and convective outer envelope by studying in detail three individual DEBs: UV Psc, YY Gem, and CU Cnc. Our results suggest that the stabilization of thermal convection by a magnetic field is a plausible explanation for the observed model-radius discrepancies. However, surface magnetic field strengths required by the models are significantly stronger than those estimated from observed coronal X-ray emission. Agreement between model predicted surface magnetic field strengths and those inferred from X-ray observations can be found by assuming that the magnetic field sources its energy from convection. This approach makes the transport of heat by convection less efficient and is akin to reduced convective mixing length methods used in other studies. Predictions for the metallicity and magnetic field strengths of the aforementioned systems are reported. We also develop an expression relating a reduction in the convective mixing length to a magnetic field strength in units of the equipartition value. Our results are compared with those from previous investigations to incorporate magnetic fields to explain the low-mass DEB radius inflation. Finally, we explore how the effects of magnetic fields might affect mass determinations using asteroseismic data and the implication of magnetic fields on exoplanet studies.

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Section: Analysis Of Individual Deb Systemsmentioning

confidence: 99%

Magnetic Inhibition of Convection and the Fundamental Properties of Low-Mass Stars. I. Stars With a Radiative Core

Feiden

Chaboyer

2013

ApJ

156

171

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“…On the other hand, the binary nature of the system comprising KIC 8414845 could hint at an alternative scenario. Doyle & Mathioudakis (1990) reported photometric observations of repetitive apparently periodic (P = 48 ± 3 min) flares on the binary star YY Gem. Supported by 2.5D MHD numerical simulations, Gao et al (2008) later attributed such periodicity to fastmode magnetoacoustic waves trapped in the space between the surfaces of the two stars that modulated the magnetic reconnection responsible for the flaring.…”

Section: Discussion and Interpretationmentioning

confidence: 99%

Possible evidence of induced repetitive magnetic reconnection in a superflare from a young solar-type star

Mancuso

Barghini

Telloni

2020

A&A

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We report the detection of multiple quasi-periodic pulsations (QPPs) observed during the flaring activity of KIC 8414845, a young, active solar-type star observed by the Kepler mission launched by NASA. We analyzed the QQP signal using a data-driven, nonparametric method called singular spectrum analysis (SSA), which has never been utilized previously for analyzing solar or stellar QPPs. Because it is not based on a prescribed choice of basis functions, SSA is particularly suitable for analyzing nonstationary, nonlinear signals such as those observed in QPPs during major flares. The analysis has revealed that the apparent anharmonic shape of the QPP in this superflare results from a superposition of two intrinsic modes of periods of 49 min and 86 min, which display quasi-harmonic behaviors and different modulation patterns. The two reconstructed signals are consistent with slow-mode transverse and/or longitudinal magnetohydrodynamic oscillations excited in a coronal loop inducing periodic releases of flaring energy in a nearby loop through a mechanism of repetitive reconnection. The peculiar amplitude modulation of the two modes evinced by SSA favors the interpretation of the observed QPP pattern as due to the excitation in a coronal loop of the second harmonic of a standing slow-mode magnetoacoustic oscillation and a global kink oscillation periodically triggering magnetic reconnection in a nearby loop. Concurrent interpretations cannot however be ruled out on the basis of the available data.

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“…The magnetic activity of such close binaries is usually studied through their coronal and chromospheric time-averaged properties; multi-wavelength flare campaigns to study the properties of flares on solar neighborhood binaries (Stern et al 1992;Osten et al 2002Osten et al , 2004 have concentrated on ultraviolet, X-ray, and radio measurements. As discussed by Henry & Newsom (1996), there are very few observations of optical flaring on nearby active detached binaries with G and K primaries -by far the most attention has been on optical studies of late K/M dwarf binaries such as YY Gem (Doyle & Mathioudakis 1990). One notable exception is a large optical flare on the binary HR 1099 (K1IV+G5V) observed by both Zhang et al (1990) and Henry & Hall (1991), with peak enhancements noted in the V band (at different times) of 0.18 and 0.42 magnitudes, respectively.…”

Section: Discussionmentioning

confidence: 99%

“…The few optical flares seen on nearby active binaries have exhibited flare energies that can approach 10 6 times the largest solar flare energies of 10 32 ergs (Henry & Hall 1991), although the evolved nature of the flaring binary member(s) may play a role in these extremes. Doyle & Mathioudakis (1990) noted that the binary nature of YY Gem may be responsible for the change in the flare frequency distribution above 10 33.5 erg, as the increased volumes allow for more energy to be stored and released during flares. Figure 8 plots the average energy loss rate due to flares for the flaring stars in our sample and the sample of M dwarf flare stars studied by Lacy et al (1976).…”

Section: Discussionmentioning

confidence: 99%

Drafts: A Deep, Rapid Archival Flare Transient Search in the Galactic Bulge

Osten

Kowalski

Sahu

et al. 2012

ApJ

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We utilize the Sagittarius Window Eclipsing Extrasolar Planet Search (SWEEPS) HST/ACS dataset for a Deep Rapid Archival Flare Transient Search (DRAFTS) to constrain the flare rate toward the older stellar population in the Galactic bulge. During 7 days of monitoring 229,293 stars brighter than V=29.5, we find evidence for flaring activity in 105 stars between V=20 and V=28. We divided the sample into non-variable stars and variable stars whose light curves contain large-scale variability. The flare rate on variable stars is ∼ 700 times that of non-variable stars, with a significant correlation between the amount of underlying stellar variability and peak flare amplitude. The flare energy loss rates are generally higher than those of nearby well-studied single dMe flare stars. The distribution of proper motions is consistent with the flaring stars being at the distance and age of the Galactic bulge. If they are single dwarfs, they span a range of ≈ 1.0 − 0.25M ⊙ . A majority of the flaring stars exhibit periodic photometric modulations with P <3d. If these are tidally locked magnetically active binary systems, their fraction in the bulge is enhanced by a factor of ∼20 compared to the local value. These stars may be useful for placing constraints on the angular momentum evolution of cool close binary stars. Our results expand the type of stars studied for flares in the optical band, and suggest that future sensitive optical time-domain studies will have to contend with a larger sample of flaring stars than the M dwarf flare stars usually considered.Recent results from searches for deep optical fast (<1 hr) transients have indicated the prevalence of stellar flaring and bolstered support for a better quantification of the flare rate. The three transients identified in Becker et al. (2004) turned out to be Galactic flare stars; Kulkarni & Rau (2006) described this population as a foreground "fog" potentially obscuring extragalactic fast optical transients (timescales of ≈1000 s). Fresneau et al. (2001) reported results from an astrographic plate survey at low galactic latitude, covering a large field of view (520 degrees 2 ) at B magnitudes between 10 and 14; 8% of stars showed flare events greater than 0.4 mag over 20-30 minute timescales. Ramsay & Hakala (2005) performed sensitive but shallow temporal coverage observations at intermediate galactic latitude, reaching depths of

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Antonio G. Solalinde

Cited by 5 publications

References 0 publications

Magnetic Inhibition of Convection and the Fundamental Properties of Low-Mass Stars. I. Stars With a Radiative Core

Magnetic Inhibition of Convection and the Fundamental Properties of Low-Mass Stars. I. Stars With a Radiative Core

Possible evidence of induced repetitive magnetic reconnection in a superflare from a young solar-type star

Drafts: A Deep, Rapid Archival Flare Transient Search in the Galactic Bulge

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