42 citations · 76 across the 12 of their papers we have counts for
12 papers · 1 filter
Searching for low-mass stars with magnetically-induced hyper-inflated radii
D. J. Mullan, J. MacDonald
Precise empirical estimates of stellar radii have revealed that the radii of certain low-mass stars are inflated relative to stellar structure predictions: the largest inflations o…
New Insights from Revisiting the Rotation Period of the Strongly Magnetic O Star, NGC 1624-2
S. Seadrow, V. Petit, G. A. Wade +5
NGC 1624-2 hosts the strongest surface magnetic field found on an O star thus far. When applied across several epochs of observations, the star's currently accepted rotation period…
Empirical measures of the largest amounts of magnetically-induced radius inflation in low-mass stars
D. J. Mullan, J. MacDonald
Access to precise empirical estimates of stellar radii in recent decades has revealed that the radii of certain low-mass stars are inflated relative to stellar structure prediction…
The Role of the Convective Kissing Instability in Cataclysmic Variable Evolution
Conor M. Larsen, James MacDonald
The convective kissing instability (CKI) is postulated to occur in low mass stars around the fully convective transition. Non-equilibrium He burning leads to the merging of c…
A plasmoid-model for mass loss from stars on the upper red giant branch: The mass loss rate is controlled by the number of density scale heights in the convection zone
J. MacDonald, D. J. Mullan
Recent asteroseismic determinations of ΔM, the integrated mass loss on the red giant branch (RGB), for fields stars show a trend of ΔM decreasing as metallicity increases. This tre…
Early Post Asymptotic Giant Branch Instability: Does it Affect White Dwarf Hydrogen Envelope Mass?
James MacDonald
Although most white dwarf stars have hydrogen-dominated atmospheres, a significant fraction have atmospheres in which hydrogen is spectroscopically absent, with the fraction of hyd…
The Effects of Magneto-Convection on Short Period Cataclysmic Variables
Conor M. Larsen, James MacDonald
Many of the current problems related to the evolution of cataclysmic variables revolve around the magnetic nature of the main sequence secondary. It is known that magnetic fields a…
Using ZDI maps to determine magnetic forces and torques at the photospheres of Early-type stars
James MacDonald, Tali Natan, Véronique Petit +2
We use the magnetic field components measured by Zeeman Doppler imaging (ZDI) to calculate the stellar surface force and torque due to magnetic stresses for the fast rotators O…
Mechanical energy fluxes associated with saturated coronal heating in M dwarfs: comparison with predictions of a turbulent dynamo
D. J. Mullan, J. MacDonald
Empirically, the X-ray luminosity LX from M dwarfs has been found to have an upper limit of about 0.2% of the bolometric flux Lbol. In the limit where magnetic fields in M dwarfs a…
Magneto-convective models of red dwarfs: constraints imposed by the lithium abundance
J. MacDonald, D. J. Mullan
Magnetic fields impede the onset of convection, thereby altering the thermal structure of a convective envelope in a low mass star: this has an effect on the amount of lithium depl…
An Empirical Measure of the Rate of White Dwarf Cooling in 47 Tucanae
R. Goldsbury, J. Heyl, H. B. Richer +8
We present an empirical determination of the white dwarf cooling sequence in the globular cluster 47 Tucanae. Using spectral models, we determine temperatures for 887 objects from…
Magneto-Convection and Lithium Age Estimates of the βPictoris Moving Group
J. Macdonald, D. J. Mullan
Although the means of the ages of stars in young groups determined from Li depletion often agree with mean ages determined from Hertzsprung - Russell diagram isochrones, there are…