This Hubble Space Telescope (HST) image reveals a pair of one-half light-year long interstellar ‘twisters’ – eerie funnels and twisted-rope structures – in the heart of the Lagoon Nebula (Messier 8) which lies 5,000 light-years away in the direction of the constellation Sagittarius.
Giant ‘Twisters’ in the Lagoon Nebula. Credit: A. Caulet (ST-ECF, ESA) and NASA
The massive, young stellar grouping, called R136, is only a few million years old and resides in the 30 Doradus Nebula, a turbulent star-birth region in the Large Magellanic Cloud (LMC), a satellite galaxy of our Milky Way. Many of the stars are among the most massive known. Several of them are over 100 times more massive than our Sun. These hefty stars are destined to become supernovae in a few million years.
Hubble Observes the Large Magellanic Cloud’s Star-Forming Region, 30 Doradus. Credit: NASA, ESA, and F. Paresce (INAF-IASF, Bologna, Italy)
The image, taken by Hubble’s Wide Field Camera 3, spans about 100 light-years. The nebula is close enough to Earth that Hubble can resolve individual stars, giving astronomers important information about the stars’ birth and evolution.
The brilliant stars are carving deep cavities in the surrounding material by unleashing a torrent of ultraviolet light, and hurricane-force stellar winds (streams of charged particles), which are etching away the enveloping hydrogen gas cloud in which the stars were born. The image reveals a fantasy landscape of pillars, ridges, and valleys, as well as a dark region in the center that roughly looks like the outline of a holiday tree. Besides sculpting the gaseous terrain, the brilliant stars can also help create a successive generation of offspring. When the winds hit dense walls of gas, they create shocks, which may be generating a new wave of star birth.
The movement of the LMC around the Milky Way may have triggered the massive cluster’s formation in several ways. The gravitational tug of the Milky Way and the companion Small Magellanic Cloud may have compressed gas in the LMC. Also, the pressure resulting from the LMC plowing through the Milky Way’s halo may have compressed gas in the satellite. The cluster is a rare, nearby example of the many super star clusters that formed in the distant, early universe, when star birth and galaxy interactions were more frequent. Previous Hubble observations have shown astronomers that super star clusters in faraway galaxies are ubiquitous. The LMC is located 170,000 light-years away and is a member of the Local Group of Galaxies, which also includes the Milky Way.
The Hubble image was taken at infrared wavelengths (1.1 microns and 1.6 microns). Hubble sees through the dusty nebula, revealing many stars that cannot be seen in visible light. The large bright star just above the center of the image is in the 30 Doradus nebula. The Hubble observations of 30 Doradus were made October 20-27, 2009.
About a month and a half after its last double flyby, NASA’s Cassini spacecraft will be turning another double play this week, visiting the geyser moon Enceladus and the hazy moon Titan. The alignment of the moons means that Cassini can catch glimpses of these two contrasting worlds within less than 48 hours, with no maneuver in between.
On the left, Saturn’s moon Enceladus is backlit by the sun, showing the fountain-like sources of the fine spray of material that towers over the south polar region. On the right, is a composite image of Titan. Image credit: NASA/JPL/SSI and NASA/JPL/University of Arizona.
Cassini will make its closest approach to Enceladus late at night on May 17 Pacific time, which is in the early hours of May 18 UTC. The spacecraft will pass within about 435 kilometers (270 miles) of the moon’s surface.
The main scientific goal at Enceladus will be to watch the sun play peekaboo behind the water-rich plume emanating from the moon’s south polar region. Scientists using the ultraviolet imaging spectrograph will be able to use the flickering light to measure whether there is molecular nitrogen in the plume. Ammonia has already been detected in the plume and scientists know heat can decompose ammonia into nitrogen molecules. Determining the amount of molecular nitrogen in the plume will give scientists clues about thermal processing in the moon’s interior.
The second of Cassini’s two flybys is an encounter with Titan. The closest approach will take place in the late evening May 19 Pacific time, which is in the early hours of May 20 UTC. The spacecraft will fly to within 1,400 kilometers (750 miles) of the surface.
Cassini will primarily be doing radio science during this pass to detect the subtle variations in the gravitational tug on the spacecraft by Titan, which is 25 percent larger in volume than the planet Mercury. Analyzing the data will help scientists learn whether Titan has a liquid ocean under its surface and get a better picture of its internal structure. The composite infrared spectrometer will also get its southernmost pass for thermal data to fill out its temperature map of the smoggy moon.
Cassini has made four previous double flybys and one more is planned in the years ahead.
