NGC 7635: The Bubble Nebula

Credit & Copyright: Russell Croman
Explanation: It's the bubble versus the cloud. NGC 7635, the Bubble Nebula, is being pushed out by the stellar wind of massive central star BD+602522. Next door, though, lives a giant molecular cloud, visible above to the lower right. At this place in space, an irresistible force meets an immovable object in an interesting way. The cloud is able to contain the expansion of the bubble gas, but gets blasted by the hot radiation from the bubble's central star. The radiation heats up dense regions of the molecular cloud causing it to glow. The Bubble Nebula, pictured above in scientifically mapped colors to bring up contrast, is about 10 light-years across and part of a much larger complex of stars and shells. The Bubble Nebula can be seen with a small telescope towards the constellation of Cassiopeia.

Young Star Gets Pushy

NGC 346 in the Small Magellenic Cloud. Image credit: Hubble

This is a Hubble Space Telescope view of one of the most dynamic and intricately detailed star-forming regions in space, located 210,000 light-years away in the Small Magellanic Cloud (SMC), a satellite galaxy of our Milky Way. At the center of the region is a brilliant star cluster called NGC 346. A dramatic structure of arched, ragged filaments with a distinct ridge surrounds the cluster.A torrent of radiation from the cluster's hot stars eats into denser areas creating a fantasy sculpture of dust and gas. The dark, intricately beaded edge of the ridge, seen in silhouette by Hubble, is particularly dramatic. It contains several small dust globules that point back towards the central cluster, like windsocks caught in a gale.Energetic outflows and radiation from hot young stars are eroding the dense outer portions of the star-forming region, formally known as N66, exposing new stellar nurseries. The diffuse fringes of the nebula prevent the energetic outflows from streaming directly away from the cluster, leaving instead a trail of filaments marking the swirling path of the outflows.The NGC 346 cluster, at the center of this Hubble image, is resolved into at least three sub-clusters and collectively contains dozens of hot, blue, high-mass stars, more than half of the known high-mass stars in the entire SMC galaxy. A myriad of smaller, compact clusters is also visible throughout the region.Some of these mini-clusters appear to be embedded in dust and nebulosity, and are sites of recent or ongoing star formation. Much of the starlight from these clusters is reddened by local dust concentrations that are the remnants of the original molecular cloud that collapsed to form N66.



Mountains of Creation

Credit: Lori Allen (Harvard-Smithsonian CfA) et al., JPL-Caltech, NASA
Explanation: This fantastic skyscape lies at the eastern edge of giant stellar nursery W5, about 7,000 light-years away in the constellation Cassiopeia. An infrared view from the Spitzer Space Telescope, it features interstellar clouds of cold gas and dust sculpted by winds and radiation from a hot, massive star outside the picture (just above and to the right). Still swaddled within the cosmic clouds, newborn stars are revealed by Spitzer's penetrating gaze, their formation also triggered by the massive star. Fittingly dubbed "Mountains of Creation", these interstellar clouds are about 10 times the size of the analogous Pillars of Creation in M16, made famous in a 1995 Hubble Space Telescope view. W5 is also known as IC 1848 and together with IC 1805 it is part of a complex region popularly dubbed the Heart and Soul Nebulae. The Spitzer image spans about 70 light-years at the distance of W5.