Spectroscopic observations of the eclipsing Polar MN Hya (RX J0929--24)

We present low--medium resolution optical spectroscopy of the eclipsing AM Her system MN Hya (RX J0929--24). We determine the magnetic field strength at the primary accretion region of the white dwarf to be 42MG from the spacing of cyclotron features visible during ~0.4--0.7. From spectra taken during the eclipse we find that the secondary has a M3--4 spectral type. Combined with the eclipse photometry of Sekiguchi, Nakada & Bassett and an estimate of the interstellar extinction we find a distance of ~300--700pc. We find unusual line variations at phase ~0.9: Halpha is seen in absorption and emission. This is at the same point in the orbital phase that a prominent absorption dip is seen in soft X-rays.Comment: accepted by MNRAS, 7 pages, 5 fig

RX J0806+15: the shortest period binary?

The X-ray source RX J0806+15 was discovered using ROSAT , and shows an X-ray light curve with a prominent modulation on a period of 321.5 s. We present optical observations in which we report the detection of its optical counterpart. We find an optical period consistent with the X-ray period. We do not find convincing evidence for a second period in the data: this implies the 321.5-s period is the orbital period. As such it would be the shortest period stellar binary system yet known. We discuss the nature of this system. We conclude that an isolated neutron star and an intermediate polar interpretation is unlikely and that a double degenerate interpretation is the most likely

XMM-Newton observations of the complex spin pulse of the intermediate polar PQ~Geminorum

The intermediate polar PQ Geminorum shows a complex pulsation, caused by a spinning white dwarf, which varies markedly with wavelength. We report XMM-Newton observations, including the soft and hard X-ray bands and the first UV lightcurves of this star. We update the ephemeris for PQ Gem allowing us to align these data with a compilation of lightcurves from the optical to the X-ray. Building on work by previous authors, we show how a model in which accretion flows along skewed field lines, viewed at the correct inclination, can explain the major features of the lightcurves in all bands. We discuss how the skew of the field lines relates to the spinning down of the white-dwarf rotation.Comment: 7 pages, 7 figures, accepted for publication in MNRA

Cytological studies on mosses from Papua New Guinea : 1., introduction and the family Orthotrichaceae.

Chromosome numbers with information on meiotic behaviour are recorded for the first time for the following taxa in the family Orthotrichaceae from Papua New Guinea - Desmotheca apiculata (Dozy & Molk.) Lindb. ex Card. n=6; Macromitrium incurvifolium (Hook. & Grev.) Schwaegr. n=9, M. longicaule C. Muell. n=6 (5+X/y), M. orthostichum Nees ex Schwaegr. n=7 (6+ X/y), M. salakanum C. Muell. n=9, M. similirete Bartr. n=9. M. streimannii Vitt n=9 (8+m); Schlotheimia emarginato-pilosa Herz. n=9 and S. macgregorii Broth. & Geh. n=11

Phonon sidebands of color centers in hexagonal boron nitride

Low temperature photoluminescence spectra of a color center in hexagonal boron nitride are analyzed. The acoustic phonon sideband can be described by a deformation coupling proportional to strain to a phonon bath that is effectively two dimensional. The optical phonon band is described by Frohlich coupling to the LO-branches, and a deformation coupling proportional to lattice displacement for the TO-branch. The resonances expressed in the optical band vary from defect to defect, in some emitters, coupling to out-of-plane polarized phonons is reported.Comment: 7 pages, 4 fig

The Role and Influence of Teachers in Relation to Student Decision Making Regarding Jobs and Careers

Secondary schools in most parts of Australia now conduct work experience programmes which provide for student participation in normal conditions of work. Generally, work experience is now embedded within what is termed a \u27Transition Education\u27 programme, and usually includes elements of social studies, skills associated with job acquisition, and components designed to prepare the student for transition from school to wor