GJ 841B-the second DQ white dwarf with polarized CH molecular bands

Abstract

We report a discovery of the circularly polarized CH A2Δ- X2π and B2Σ--X2π molecular bands in the spectrum of the DQ white dwarf (WD)GJ 841B. This is only the second such object since the discovery of G99-37 in the 1970s. GJ 841B is also the first WD to unambiguously show polarization in the C2 Swan bands. By modeling the intensity and circular polarization in the CH bands, we determine the longitudinal magnetic field strength of 1.3 ± 0.5 MG and the temperature of 6100 ± 200 K in the absorbing region. We also present new observations of G99-37 and obtain estimates of the magnetic field strength 7.3 ± 0.3 MG and temperature 6200 ± 200 K, in good agreement with previous results. © 2010. The American Astronomical Society. All rights reserved.