The light variability of the helium strong star HD 37776 as a result of its inhomogeneous elemental surface distribution We simulate light curves of the helium strong chemically peculiar starHD 37776 assuming that the observed periodic light variations originateas a result of inhomogeneous horizontal distribution of chemicalelements on the surface of a rotating star. We show that chemicalpeculiarity influences the monochromatic radiative flux, mainly due tobound-free processes. Using the model of the distribution of silicon andhelium on HD 37776 surface, derived from spectroscopy, we calculate aphotometric map of the surface and consequently the uvby light curves ofthis star. Basically, the predicted light curves agree in shape andamplitude with the observed ones. We conclude that the basic propertiesof variability of this helium strong chemically peculiar star can beunderstood in terms of the model of spots with peculiar chemicalcomposition.
Merged catalogue of reflection nebulae Several catalogues of reflection nebulae are merged to create a uniformcatalogue of 913 objects. It contains revised coordinates,cross-identifications of nebulae and stars, as well as identificationswith IRAS point sources.The catalogue is only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (184.108.40.206) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/399/141
The large system of molecular clouds in Orion and Monoceros Emission is noted over about one-eighth of an 850-sq deg region centeredon Orion and Monoceros that has been surveyed in the J = 1 to 0 line ofCO; most of the emission arises from giant molecular clouds associatedwith Orion A and B, and Mon R2. A much smaller area was surveyed forC-13O emission. A comparison of cloud masses obtained by threeindependent methods indicates that CO luminosity is as accurate ameasure of cloud mass as other indicators. The possible relationshipsamong clouds in the survey are discussed, including the conjecture thatthe overall Orion complex of clouds is a much larger system thanpreviously considered, incorporating most of the clouds in the presentsurvey.