Discovery of Non-radial pulsations in PQ Andromedae

We have detected pulsations in time-series photometry of the WZ Sge dwarf nova PQ And. The strongest peak in the power spectrum occurs at a period of 10.5 minutes. Similar periods have been observed in other WZ Sge systems and are attributed to ZZ Ceti type non-radial pulsations. There is no indication in the photometry of an approximately 1.7 hour orbital period as reported in previous spectroscopic observations.Comment: 7 pages, 5 figure

Magnetic White Dwarfs from the SDSS II. The Second and Third Data Releases

Fifty-two magnetic white dwarfs have been identified in spectroscopic observations from the Sloan Digital Sky Survey (SDSS) obtained between mid-2002 and the end of 2004, including Data Releases 2 and 3. Though not as numerous nor as diverse as the discoveries from the first Data Release, the collection exhibits polar field strengths ranging from 1.5MG to ~1000MG, and includes two new unusual atomic DQA examples, a molecular DQ, and five stars that show hydrogen in fields above 500MG. The highest-field example, SDSSJ2346+3853, may be the most strongly magnetic white dwarf yet discovered. Analysis of the photometric data indicates that the magnetic sample spans the same temperature range as for nonmagnetic white dwarfs from the SDSS, and support is found for previous claims that magnetic white dwarfs tend to have larger masses than their nonmagnetic counterparts. A glaring exception to this trend is the apparently low-gravity object SDSSJ0933+1022, which may have a history involving a close binary companion.Comment: 20 pages, 4 figures Accepted for publication in the Astronomical Journa

New Low Accretion-Rate Magnetic Binary Systems and their Significance for the Evolution of Cataclysmic Variables

Discoveries of two new white dwarf plus M star binaries with striking optical cyclotron emission features from the Sloan Digital Sky Survey (SDSS) brings to six the total number of X-ray faint, magnetic accretion binaries that accrete at rates < 10^{-13} Msun/yr, or <1% of the values normally encountered in cataclysmic variables. This fact, coupled with donor stars that underfill their Roche lobes and very cool white dwarfs, brand the binaries as post common-envelope systems whose orbits have not yet decayed to the point of Roche-lobe contact. They are pre-magnetic CVs, or pre-Polars. The systems exhibit spin/orbit synchronism and apparently accrete by efficient capture of the stellar wind from the secondary star, a process that has been dubbed a ``magnetic siphon''. Because of this, period evolution of the binaries will occur solely by gravitational radiation, which is very slow for periods >3 hr. Optical surveys for the cyclotron harmonics appear to be the only means of discovery, so the space density of pre-Polars could rival that of Polars, and the binaries provide an important channel of progenitors (in addition to the asynchronous Intermediate Polars). Both physical and SDSS observational selection effects are identified that may help to explain the clumping of all six systems in a narrow range of magnetic field strength around 60 MG.Comment: 25 pages, 13 figures, Accepted to Ap

The Effect on Elderly Parents in Cambodia of Losing an Adult Child to AIDS

Little systematic quantitative research is available on the parents of adults who become ill and die of AIDS despite their large number and the wide range of adverse consequences. This study, based on survey data from Cambodia, explores economic and social effects on parents in a country characterized by extreme poverty and a substantial AIDS epidemic. Results indicate that parents play a major role during the illness of an adult son or daughter, often sharing living quarters, providing care, and paying for illness-related expenses. These contributions to the societal response to AIDS come at considerable cost to parents at advanced ages. Multivariate analysis suggests lasting negative consequences for parents'economic well-being, and the consequences are more substantial if the adult child's death was from AIDS rather than from other causes. The study found little evidence of stigma associated with losing a grown child to AIDS: reactions from local community members are more likely to be sympathetic and supportive than negative. These results underscore the need for organizations dealing with AIDS to recognize the contributions older persons make in coping with the epidemic and to address the burden it imposes on them. Copyright 2007 The Population Council, Inc..