Nebulae are perhaps as famous for being identified with familiar shapes as cats are for getting into trouble. Still, no known cat could have created the vast Cat's Paw Nebula visible in Scorpius. At 5,500 light years distant, Cat's Paw is an emission nebula with a red color that originates from an abundance of ionized hydrogen atoms. Alternatively known as the Bear Claw Nebula or NGC 6334, stars nearly ten times the mass of our Sun have been born there in only the past few million years (text adapted from APOD). Apo TEC140 (140/f7.2) - FLI Proline 16803 - Ha (310m) OIII (300m) R (180m) G (180m) B (180m) - Warrumbungle Observatory, Coonabarabran, NSW, Australia
Like black ink spilt on a galactic beach, the twisting filamentary tendrils of the dark nebula Sandqvist 169 snake across a glittering field of bright Milky Way stars in the constellation of Circinus. It forms the western part of the giant Circinus Cloud complex, which measures a whopping 2x5 degrees in total! The series of filaments that seemingly emanate outwards from the dense central part of Sandqvist 169 (also known as Circinus-W) are indicative of past violent activity. The filamentary appearance of the cloud is likely to be the result of multiple outflows from young stars, whose formation might have been triggered by a supernova that exploded in close proximity to the cloud. If star formation has ensued for a few hundred thousand years, then the cloud has produced many dozens of young stars, whose outflows have torn the cloud apart. The filaments and cavities provide a fossil record of past star formation as they trace the boundaries of the outflows. Optically visible signs of star formation in Sandqvist 169 include the tiny cometary reflection nebulae vdBH65a and vdBH65b. vdBH65a is a small nebulous patch that is near a bright yellow star that is situated towards the north of the central portion of the cloud. Its illuminating star drives a bipolar molecular outflow that includes the optical bowshock HH 139 (which cannot be seen at a widefield scale). vdBH65b is a small fan shaped cometary reflection nebula that can be seen embedded in the filaments to the right of the cloud core (which are catalogued as Sandqvist 171). It is also the source of numerous Herbig Haro outflows and objects, which are not visible at this scale. Despite its size and apparent interesting past history, the Circinus Cloud has been the subject of very few detailed studies but future investigation and observations will help unravel more of its mysteries. Since it has only received one major study since its discovery, its distance is extremely uncertain and is estimated to be 2275 light years. However, a study in 2011 with observations from the Widefield Infrared Survey Explorer (WISE) telescope uncovered an embedded infrared cluster of YSO's. The Sandqvist catalogue is a collection of 95 southern dark clouds that was published in 1977 by the Swedish astronomer Aage Sandqvist. Confusingly the numbering of the catalogue starts from the number 101 to avoid mix-up with the SL catalogue, which was published by Aage Sandqvist and K.P. Lindroos in the previous year (description provided by Sakib Rasool) Apo TEC140 (140/f7.2) - FLI Proline 16803 - Ha (690m) L (520m) R (120m) G (120m) B (120m) - Warrumbungle Observatory, Coonabarabran, NSW, Australia
Home to some of the nearest molecular clouds, the constellation of Chamaeleon is filled with many dark nebula complexes. The Chamaeleon I complex is one of three large clouds found in this southern constellation and has an age of 2 million years. The distances of the three main clouds range from 520-580 light years and are also isolated from other major star forming complexes. The Chamaeleon I complex is a site of low mass star formation, which is characterised visually by various reflection nebulae including IC 2631 to the north and the blue nebula Ced 111 and the white reflection nebula Ced 110 to the south. The great obscuring mass of thick brown dust in the region absorbs the blue light of distant stars making them appear much redder than they actually are. This process of interstellar reddening also affects the light of distant galaxies in the line of sight, making them look less blue. Despite the copious amounts of dust, the Chamaeleon I complex is regarded by astronomers to impose only a moderate level of extinction on the background starfield in comparison with other dark nebulae. The Chamaeleon I complex is near the south celestial pole and is situated at the edge of the Scorpius-Centaurus OB association. The cloud is illuminated by massive stars that belong to a subgroup of this OB association. Due to its proximity, the Chamaeleon I complex has been subjected to many searches for young stellar objects by many astronomers including Karl Henize in 1963. Recent surveys in the past two decades have also yielded a large sample of YSO's, including the first X-ray emitting brown dwarf, which was discovered in 1998. Young stellar objects have also been discovered in various infrared surveys of the clouds. The cluster of sources associated with the complex is split into two northern and southern subclusters and the cloud contains 200 known low mass YSO's. Analysis of data predicts that star formation began 3-4 million years ago in the northern half of the cloud and 5-6 million years ago in the southern half. Star formation in the cloud is still ensuing at a declining rate until eventually it will completely cease. Other optically visible signs of star formation in the cloud are represented by small Herbig Haro objects and outflows. The first Herbig Haro objects to be discovered in this complex were found in a survey for Herbig Haro objects in dark clouds by Richard Schwartz in 1977. They include HH 48-9 and HH 50. Due to its tiny size, HH 48 isn't visible in this widefield image but the bright Herbig Haro objects HH 49 and HH 50 are prominently visible in the region between Ced 110 and Ced 111. HH 49/50 are associated with the largest outflow in this complex, a giant outflow with a length of 27 arcminutes (or 6.5 light years) and its source is the protostar Cha-MMS1. Spitzer infrared images of HH 49/50 reveal infrared emission associated with them. This infrared nebula has an incredible shape of a "tornado" formed by a pair of twisting helical filaments. Deep imaging surveys in the past decade have found a total of 30 Herbig Haro objects associated with 20 separate outflows. Also visible in the image is a unique curiosity, a colourful orange nebula below the reflection nebula Ced 111. This is the Chamaeleon Infrared Nebula, a bipolar infrared reflection nebula that also happens to be visible optically. Its bipolar nature is only visible in infrared images as well as its illuminating source. Studies of the nebula have shown it to exhibit a complex geometry consisting of a disk surrounding the central source as well as bipolar lobes tracing two cavities cleared out by ouflow activity. Infrared images reveal the two bipolar lobes to be separated by a dark structure, which is a circumstellar disk around the central source (description provided by Sakib Rasool) Apo TEC140 (140/f7.2) - FLI Proline 16803 - L (580m) R (90m) G (90m) B (90m) - Warrumbungle Observatory, Coonabarabran, NSW, Australia
