... Many bright nebulae and star clusters in planet Earth's sky are associated with the name of astronomer Charles Messier, from his famous 18th century catalog. ... NGC 6903: The Butterfly Nebula . ... The Nebula's glowing gas surrounds hot young stars at the edge of an immense interstellar molecular cloud. Curiosity: Wheels on Mars . ... The Eagle Nebula and the Swan Nebula span this broad starscape, a telescopic view of the Sagittarius spiral arm toward the center of our Milky Way galaxy. ...

... We sometimes use the word "nebula" to refer to galaxies, various types of star clusters and various kinds of interstellar dust/gas clouds. ... Early in this century, there was a great debate as to the nature of the nebulae like this one which at that time could not be resolved into individual stars. ... A typical galaxy is 100,000 light-years in diameter. ... M 42 shown) Reflection nebulae are clouds of dust which are simply reflecting the light of a nearby star or stars. ... M 1 shown) . ...

One of my on-going research interests concerns the dust shells of proto-planetary nebulae or PPNs (also called pre-planetary nebulae, transition objects, and post-AGB objects in the literature; the latter term also applies to a wider selection of objects such as RV Tauri stars), especially the carbon-rich ones that show the unidentified "21 micron' emission feature. ... I am working to find a complete sample of proto-planetary nebulae in these satellite galaxies from the millions of detected stars. ...

Next: Carbon stars Up: OTHER HYDROGEN-DEFICIENT STARS Previous: Extreme helium stars and . V348sgr may be more closely related to about twenty hydrogen-deficient central stars of planetary nebulae which have similar carbon abundances ( ) and strong emission line spectra ([ Leuenhagen et al. 1995 ], [ Leuenhagen & Hamann 1997 ]). ... Hydrogen-deficient and carbon-rich knots are seen in the inner nebulae of at least two objects (Abell 30 and Abell 78). ...

... Science Users Information > Science Activities > PhD Thesis Topics offered by ESO Faculty Members > Thesis Topic: Planetary Nebulae and HII regions in the Elliptical Galaxy NGC 5128 . ... NGC 5128 is the closest example of a giant early type (elliptical or S0) galaxy. Although often dubbed as a peculiar elliptical galaxy since it has a dust lane with recent star formation and an active galactic nucleus, the majority of early type galaxies have similar structures as revealed by recent surveys. ...

... B. Vicini, A. Natta, A. Marconi, L. Testi, D. Hollenbach, B.T. Draine . 1998, A&A, in press . ... 1998, ApJ, in press . ... L. Testi, F. Palla, A. Natta . ... Francesco Palla . 1998, The Physics of Star Formation and Early Stellar Evolution, eds. C.J. Lada and N. Kylafis, in press . ... 1998, in "The Molecular Astrophysics of Stars and Galaxies - A Volume Honouring Alexander Dalgarno", edited by T. W. Hartquist and D. A. Williams, Oxford University Press, in press . ... Star Formation Group . ...