Comment on "Can there be a quark-matter core in a magnetar?"

We comment on the paper by Tanusri Ghosh and Somenath Chakrabarty, Phys. Rev. D63, 043006 (2001). In that paper it was argued that a first-order transition to quark matter in the core of a magnetar is absolutely forbidden if its magnetic field strength exceeds $10^{15}$ G. However, we show in this comment that if the quark anomalous magnetic moment and the population of higher Landau levels is taken into account, it may still be possible for a first-order phase transition from nuclear matter to quark matter to occur in the core of a magnetar. These effects may also obscure the question of whether beta equilibrium favors strange quark matter in the core of a magnetar.