The center of our galaxy is a complex environment, which is unlike anywhere else in the galaxy. It is home to the supermassive black hole, Sgr A*, as well as numerous massive stars and several high-density molecular clouds. Even though the Galactic center is relatively small (less than ~1% of the volume of the Milky Way), it holds ~5% of the cold molecular gas in the Milky Way. With all of this molecular gas, which is the key ingredient to form new stars, one would expect this region to be very efficient at forming stars. However, the Galactic center is actually much less efficient at forming stars than we would expect based on studies of other regions in our galaxy. The reason for this star formation inefficiency is unknown, though it could be related to the gravitational tidal forces produced by Sgr A*, the observed turbulence that appears to be effecting clouds in the region, or the higher average temperatures for the 'cold' gas in the region. Much of my research on the Galactic center focuses on studying infrared emission from dust associated with molecular clouds and massive stars to better understand stars which have recently formed in the region and search for newly forming stars.

The Milky Way galaxy is a very dusty place. If you've ever been outside on a very dark night and looked up at the Milky way, its possible to see the dusty features that trace the plane of our galaxy. Because of all of this dust, it is difficult, if not impossible, to look through parts of the galaxy in visible light. On the other hand, infrared light is able to travel through relatively opaque dust, which allows us to observe different parts of the sky that can't be viewed in optical light. The direction of the Galatic center is one of the dustiest places in our galaxy. Infrared observations are one of the few (but certainly not the only) ways we can study objects in this region. Below I feature some of the more spectacular observations that our group has taken with the SOFIA telescope, including material orbiting Sgr A* and molecular clouds surrounding two large stellar clusters.

Sgr A* has a large disk of gas and dust in a close orbit around it (radius ~ 3 light-years). FORCAST mid-infrared maps of the region (shown above) trace warm dust on the inner edge of the disk. We refer to this inner edge, which is illuminated by nearby massive stars, as the ring in order to specify it from the full disk. The origin of the disk and its ultimate fate are unknown. Over million-year timescales, the material in the disk might be pulled into the black hole, though the disk could be more stable and survive longer than this. Observations of the region show 'streamers' near the disk (the white 'v' shaped structure, which is known as the 'minispiral') which are thought to be material that is being funneled in closer to Sgr A*. These observations provide support to the idea that material is currently falling into the black hole. Our group is currently working on new SOFIA/FORCAST observations tracing emission from molecules in the ring, which will help us better understand the structure of the ring, including several of the interesting clumpy structures present in the western arc.

There are three main stellar clusters in the Galactic center. They are the Central cluster, the Quintuplet cluster, and the Arches cluster. The Central cluster is in close orbit around Sgr A* and is responsible for heating the dust in the circumnuclear ring. The other two clusters are located further away from Sgr A* (~60 - 90 light-years). These clusters contribute to the heating of nearby molecular clouds which are very bright in the infrared. The FORCAST map of the region around the Quintuplet cluster is shown above. The molecular cloud associated with this region is known as the 'Sickle'. This is a somewhat unusual name, which originates from earlier radio maps of the region. The Quintuplet cluster is home to several bright infrared sources. These sources are discussed in more detail on my massive evolved stars page.

The Arched filaments is one of the most interesting regions in the Galactic center. The size of the filamentary structures stretch ~ 40 light-years, which is rather large for what appear to be contiguous features. The filaments are thought to be the edges of molecular clouds which are being heated by hot stars in the Arches cluster. The FORCAST maps of the region (shown above) show many intricate details of the clouds' morphology. Studying the infrared emission from this region allows us to constrain properties of the dust in the molecular cloud, as well as properties of the Arches cluster. We were able to able to constrain the total luminosity of the Arches cluster and infer the 3D structure of the clouds with respect to the cluster. Our group continues to study the Galactic center by observing new regions with SOFIA and studying the emission at different wavelengths.