GRS Press Release Images
Principal Investigator:  Dr. James Jackson
Images and Captions compiled by Drs. Ronak Shah & Jill Rathborne
March 2006






A team of Boston University astronomers has produced the clearest map to-date of the giant gas clouds in the Milky Way that serve as the birthplaces of stars:  the Galactic Ring Survey shown at top.  An expanded view of a large swath is included to demonstrate the richness and detail seen by the GRS:  the densest, richest star forming regions are shown in white and red, while the other areas contain more quiescent gas.  The BU team, along with colleagues from the University of Cologne (Germany) and the University of Massachusetts, Amherst, spent nearly a decade charting the gas using a radio telescope tuned to a frequency of 110 GHz, which allowed them to trace a rare isotope of carbon monoxide, ¹³CO, found within molecular clouds.  The advanced technologies of the telescope allowed them to obtain a map of much finer detail than previously possible.  Furthermore, the choice of studying the emission from ¹³CO, rather than the more common ¹²CO, allowed the team to peer more deeply into the interiors of molecular clouds.









An expanded view of the top most image, displaying the densest condesations as well as filamentary structure of the molecular clouds charted by the GRS.




A blow-up of one region of intense star formation known as W51, located at about 15,000 light-years from the Earth.  W51 is roughly 260 light-years, or nearly 16 million times the mean Sun-Earth distance.  The total amount of molecular gas involved in the star formation process can be estimated using the GRS data.  For W51, the GRS team estimates that nearly 100,000 times the mass of the Sun's worth of material is taking part in the formation of stars.  Although it takes tens of thousands of years to produce a new star, the GRS team estimates that somewhere between 100 and 1000 stars are likely to form out of W51.  Most will be similar in mass to our own Sun, but a small number will become behemoths, weighing in as much as 10 times the mass of our Sun.  Such stars are probably located deep in the bright region at lower left, and are responsible for sculpting the wispy tendrils and sharp features through their intense ultraviolet radiation found throughout W51.   In addition to the dense region of molecular gas in the lower left, the GRS provides the contrast to view these faint, wispy tendrils in the Milky Way's gas clouds.  In fact, the GRS team estimates that most of the molecular gas they charted is found in less concentrated forms such as the wispy tendrils seen above.  Studying these less dense regions will allow the GRS team to understand how molecular gas clouds assemble and produce stars like those we see in the Milky Way.




A molecular cloud referred to as the "backwards Nike swoosh", showing a deep arch, located at about 12,000 light-years from the Earth.  Once considered unusual, such features are now commonly found by the GRS team.

The vast quantity of data acquired by GRS team requires them to carefully chose a naming convention for individual molecular clouds.  This naming convention is typically based on a coordinate system quite similar to Earth's latitude-longitude.  The cloud at left, for example, is properly termed GRS45.46+0.05;  that's a lot like referring to Boston, MA by its longitude and latitude (US 71° W+42°20' N, in case you were wondering).  But much like naming shapes from clouds in our own sky, astronomers adapt pop-culture for the categorizing of the night sky, as well.  The GRS team generally refers to GRS45.46+0.05 as the "Klingon" because of its strong similarity to an enemy spaceship found in the Star Trek television series.  Not to be outdone by science fiction, the "Klingon", at 6.5 kpc, possesses some of the brightest, densest star forming regions in the Galactic Ring Survey.  Before the GRS, many molecular clouds such as the Klingon were virtually unknown.  Now their impact on the Milky Way can be better understood.




A 2°×1° region of the GRS displaying emission from molecular clouds located within the Galactic Ring.  Previously identified as one of the most massive gravitational structures in the Milky Way, astronomers believe that this Galactic Ring is a signature feature of our home Galaxy: if alien civilizations from other galaxies were to peer down on the Milky Way, they would note the immense concentration of starforming molecular clouds located in donut-like distribution about the Galactic Center.  The radius of this donut is estimated to be about 15,000 light-years, about half the distance between the Sun and Milky Way's center;  it is also as thick as 3000 light-years in some places.  The concentration of molecular gas is spawning copious numbers of stars.   An interesting result obtained from studying such active regions of star formation is that all of the molecular clouds studied so far have similar lumpy structures, regardless of their size, mass, and star-forming activity.  These lumps will eventually become stars and, according to the researchers, this similarity suggests that all clouds form stars of various masses in roughly the same proportion.