Publications (25)
Weakened Magnetic Braking Signals the Collapse of the Global Stellar Dynamo
Travis S. Metcalfe, Jennifer L. van Saders, Marc H. Pinsonneault +7
Weakened magnetic braking (WMB) was originally proposed in 2016 to explain anomalously rapid rotation in old field stars observed by the Kepler mission. The proximate cause was sug…
Magnetic and Rotational Evolution of CrB from Asteroseismology with TESS
Travis S. Metcalfe, Jennifer L. van Saders, Sarbani Basu +15
During the first half of main-sequence lifetimes, the evolution of rotation and magnetic activity in solar-type stars appears to be strongly coupled. Recent observations suggest th…
Constraints on Magnetic Braking from the G8 Dwarf Stars 61 UMa and Cet
Travis S. Metcalfe, Klaus G. Strassmeier, Ilya V. Ilyin +11
During the first half of their main-sequence lifetimes, stars rapidly lose angular momentum to their magnetized winds, a process known as magnetic braking. Recent observations sugg…
The Effect of Magnetic Variability on Stellar Angular Momentum Loss I: The Solar Wind Torque During Sunspot Cycles 23 & 24
Adam J. Finley, Sean P. Matt, Victor See
The rotational evolution of cool stars is governed by magnetised stellar winds which slow the stellar rotation during their main sequence lifetimes. Magnetic variability is commonl…
The magnetic and spin-down properties of slowly rotating fully convective M dwarfs
Victor See, Louis Amard, Stefano Bellotti +19
The evolution of the magnetism, winds and rotation of low-mass stars are all linked. One of the most common ways to probe the magnetic properties of low-mass stars is with the Zeem…
Prominence formation and ejection in cool stars
Carolina Villarreal D'Angelo, Moira Jardine, Victor See
The observational signatures of prominences have been detected in single and binary G and K type stars for many years now, but recently this has been extended to the M dwarf regime…
Peakbagging the K2 KEYSTONE sample with PBjam: characterising the individual mode frequencies in solar-like oscillators
George T. Hookway, Martin B. Nielsen, Guy R. Davies +5
The pattern of individual mode frequencies in solar-like oscillators provides valuable insight into their properties and interior structures. The identification and characterisatio…
The Effect of Magnetic Variability on Stellar Angular Momentum Loss II: The Sun, 61 Cygni A, Eridani, Bootis A and Bootis A
Adam J. Finley, Victor See, Sean P. Matt
The magnetic fields of low-mass stars are observed to be variable on decadal timescales, ranging in behaviour from cyclic to stochastic. The changing strength and geometry of the m…
Do non-dipolar magnetic fields contribute to spin-down torques?
Victor See, Sean P. Matt, Adam J. Finley +14
Main sequence low-mass stars are known to spin-down as a consequence of their magnetised stellar winds. However, estimating the precise rate of this spin-down is an open problem. T…
Estimating magnetic filling factors from Zeeman-Doppler magnetograms
Victor See, Sean P. Matt, Colin P. Folsom +15
Low-mass stars are known to have magnetic fields that are believed to be of dynamo origin. Two complementary techniques are principally used to characterise them. Zeeman-Doppler im…
The effects of stellar winds on the magnetospheres and potential habitability of exoplanets
Victor See, Moira Jardine, Aline A. Vidotto +4
Context: The principle definition of habitability for exoplanets is whether they can sustain liquid water on their surfaces, i.e. that they orbit within the habitable zone. However…
Weakened Magnetic Braking in the Exoplanet Host Star 51 Peg
Travis S. Metcalfe, Klaus G. Strassmeier, Ilya V. Ilyin +11
The consistently low activity level of the old solar analog 51 Peg not only facilitated the discovery of the first hot Jupiter, but also led to the suggestion that the star could b…
Asteroseismology and Spectropolarimetry of the Exoplanet Host Star Serpentis
Travis S. Metcalfe, Derek Buzasi, Daniel Huber +31
The bright star Ser hosts a hot Neptune with a minimum mass of 13.6 and a 15.5 day orbit. It also appears to be a solar analog, with a mean rotation period of 25.8…
The impact of stellar metallicity on rotation and activity evolution in the Kepler field using gyro-kinematic ages
Victor See, Yuxi, Lu +2
In recent years, there has been a push to understand how chemical composition affects the magnetic activity levels of main sequence low-mass stars. Results indicate that more metal…
The Origin of Weakened Magnetic Braking in Old Solar Analogs
Travis S. Metcalfe, Adam J. Finley, Oleg Kochukhov +10
The rotation rates of main-sequence stars slow over time as they gradually lose angular momentum to their magnetized stellar winds. The rate of angular momentum loss depends on the…
How much do underestimated field strengths from Zeeman-Doppler imaging affect spin-down torque estimates?
Victor See, Lisa Lehmann, Sean P. Matt +1
Numerous attempts to estimate the rate at which low-mass stars lose angular momentum over their lifetimes exist in the literature. One approach is to use magnetic maps derived from…
Estimating stellar wind parameters from low-resolution magnetograms
Moira Jardine, Aline Vidotto, Victor See
Stellar winds govern the angular momentum evolution of solar-like stars throughout their main-sequence lifetime. The efficiency of this process depends on the geometry of the star'…
Photometric variability as a proxy for magnetic activity and its dependence on metallicity
Victor See, Julia Roquette, Louis Amard +1
Understanding how the magnetic activity of low-mass stars depends on their fundamental parameters is an important goal of stellar astrophysics. Previous studies show that activity…
Slingshot prominence evolution for a solar-like star
Carolina Villarreal D'Angelo, Moira Jardine, Colin P. Johnstone +1
Although the present-day Sun rotates too slowly to exhibit centrifugally-supported 'slingshot prominences', at some time during its past it may have formed these clouds of cool gas…
Testing the Rossby Paradigm: Weakened Magnetic Braking in early K-type Stars
Travis S. Metcalfe, Pascal Petit, Jennifer L. van Saders +12
There is an intricate relationship between the organization of large-scale magnetic fields by a stellar dynamo and the rate of angular momentum loss due to magnetized stellar winds…
An abrupt change in the stellar spin-down law at the fully convective boundary
Yuxi Lu, Victor See, Louis Amard +2
The importance of the existence of a radiative core in generating a solar-like magnetic dynamo is still unclear. Analytic models and magnetohydrodynamic simulations of stars sugges…
Modelling the effect of stellar metallicity on the XUV evolution of low-mass stars and its impact on exoplanet atmospheres/habitability
Victor See, Charlotte Fairman, Louis Amard +1
Understanding how exoplanet atmospheres evolve is a key question in the context of habitability. One key process governing this evolution is atmospheric evaporation by stellar X-ra…
Weakened magnetic braking supported by asteroseismic rotation rates of Kepler dwarfs
Oliver J. Hall, Guy R. Davies, Jennifer van Saders +9
Studies using asteroseismic ages and rotation rates from star-spot rotation have indicated that standard age-rotation relations may break down roughly half-way through the main seq…
Further evidence of the link between activity and metallicity using the flaring properties of stars in the Kepler field
Victor See, Julia Roquette, Louis Amard +1
The magnetic activity level of low-mass stars is known to vary as a function of the physical properties of the star. Many studies have shown that the stellar mass and rotation are…
Alfvén-wave driven magnetic rotator winds from low-mass stars I: rotation dependences of magnetic braking and mass-loss rate
Munehito Shoda, Takeru K. Suzuki, Sean P. Matt +7
Observations of stellar rotation show that low-mass stars lose angular momentum during the main sequence. We simulate the winds of Sun-like stars with a range of rotation rates, co…