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 (22.214.171.124) 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.
Luminosity-dependent line ratios in disks of spiral galaxies The emission-line intensity ratio of N II forbidden line double-lambda6548 + 6583 relative to S II forbidden line double-lambda 6717 + 6731averaged over a spiral disk (excluding the nucleus) increases withincreasing galaxy luminosity, M(B) in the range from -14 to -23. S IIforbidden line is strong in disks of low-luminosity spirals; N IIforbidden line is strong in disks of high-luminosity spirals. Becausethe N(+)/S(+) ratio is a good approximation to the N to S abundanceratio, it is inferred that the enhancement of N due to secondarynucleosynthetic processing in successive generations of stars is greaterin disks of high-mass spirals than in disks of low-mass spirals.
CO observations of galactic reflection nebulae Carbon monoxide emission has been observed toward about 35 galacticreflection nebulae. The peaking of CO temperatures near the hotter starsindicates substantial local heating of the gas and dust by the embeddedstars. Wide low-level emission wings are seen on several of the (C-12)Oline profiles; these are most plausibly interpreted as due to cloudmaterial accelerated by such processes as radiation pressure from thenewborn stars.