NGC 3199 lies about 12,000 light-years away, a glowing cosmic cloud in the southern constellation of Carina. The nebula is about 75 light-years across in this haunting, false-color view. Though the deep image reveals a more or less complete ring shape, it does look very lopsided with a much brighter edge at the lower right. Near the center of the ring is a Wolf-Rayet star, a massive, hot, short-lived star that generates an intense stellar wind. In fact, Wolf-Rayet stars are known to create nebulae with interesting shapes as their powerful winds sweep up surrounding interstellar material. In this case, the bright edge was thought to indicate a bow shock produced as the star plowed through a uniform medium, like a boat through water. But measurements have shown the star is not really moving directly toward the bright edge. So a more likely explanation is that the material surrounding the star is not uniform, but clumped and denser near the bright edge of windblown NGC 3199 (text adapted from APOD). Apo TEC140 (140/f7.2) - FLI Proline 16803 - Ha (165m) OIII (210m) R (60m) G (50m) B (50m) - Warrumbungle Observatory, Coonabarabran, NSW, Australia
An intriguing and beautiful nebula, NGC 3576 drifts through the Sagittarius arm of our spiral Milky Way Galaxy. Within the region, episodes of star formation are thought to contribute to the complex and suggestive shapes. Powerful winds from the nebula's embedded, young, massive stars shape the looping filaments. Hydrogen and oxygen, energized by intense ultraviolet radiation, contribute to the nebular glow. But the glow also silhouettes dense clouds of dust and gas. For example, the two condensing dark clouds near the center of the picture offer potential sites for the formation of new stars. NGC 3576 itself is about 100 light-years across and 9,000 light-years away in the southern constellation of Carina, not far on the sky from the famous Eta Carinae Nebula. At the left of the picture is NGC 3603, a much larger but more distant star forming region (text adapted from APOD). Apo TEC140 (140/f7.2) - FLI Proline 16803 - Ha (240m) OIII (270m) R (100m) G (110m) B (140m) - Warrumbungle Observatory, Coonabarabran, NSW, Australia
vdBH80 is a small reflection nebula in the centre of the bright rimmed globule SFO 85, which is embedded in the giant emission nebula RCW 113 in the constellation of Scorpius. Both nebulae are influenced by the intense radiation of the energetic and luminous open cluster NGC 6231, which can partly be seen in the top right corner. NGC 6231 is a young cluster with an estimated age of 3-5 million years and contains more than 100 massive stars, including 15 O-type stars. It forms the heart of the Scorpius OB1 association, which is responsible for influencing the gas and dust in the surrounding area. RCW 113 is a large curved HII region that was first noticed in photographic plates in 1955 by Colin Gum and is also catalogued as Gum 55. It was also independently found in the same year by the astronomers Bart Bok, Michiel Bester and Campbell Wade. Its source of ionisation are multiple supergiant stars in NGC 6231. vdBH80 is one of 136 southern reflection nebulae that were catalogued by Sidney van den Bergh and William Herbst in 1975. However, this nebula was noticed earlier in 1962 by the legendary astronomer Karl Henize. At the heart of this nebula is the Be type supergiant star V921 Scorpii, which is directly associated with the nebulosity. This association is confirmed by both the star and the reflection nebula sharing almost identical spectra. Be type stars are intermediate mass stars that are characterised by an association with circumstellar gas and dust. This phenomenon has been observed at all evolutionary stellar stages including pre and post main sequence. A new study of the star whose results were only published this year detected a companion to V921 Scorpii. This has helped confirm a hypothesis that the Be phenomenon is related to interactions in a binary system. The orbital period has been calculated to be 35 years based on earlier observations in 2008 and 2009. High resolution observations of the nebula have detected regularly interspersed substructures, which would imply episodic mass outflow with a period of 25 years, which also corresponds roughly with the orbital period of the companion. The mass loss episodes might have been triggered by the orbital passage of the companion in the system. Another finding of the observations is that the circumstellar disk around V921 Scorpii is aligned with the surrounding nebula along its polar axis. Between vdBH80 and the bottom left corner is a small round faint nebula. This is the planetary nebula HaTr 5 and is one of 14 planetary nebulae discovered on POSS plates in 1983 by H. Hartl and S.B. Tritton and interestingly this catalogue wasn't published until 1985. It is characterised by an elliptical ring with a well defined outer edge. To the north of vdBH80 is the inky black dark nebula SL 19, which blocks the light of stars and dust behind it. It is one of 42 southern dark nebulae that were catalogued by the Swedish astronomers A. Sandqvist and K.P. Lindroos in 1976. Thanks to Sakib Rasool for suggesting me this little known object and for preparing the above object description. Apo TEC140 (140/f7.2) - FLI Proline 16803 - Ha (315m) R (80m) G (70m) B (80m) - Warrumbungle Observatory, Coonabarabran, NSW, Australia
