Galactic Cycle of Gas

If left alone, galaxies form stars until they run out of gas in their disks. Our own galaxy, the Milky Way, is scheduled to run out of gas in only 2 billion years—a blink of an eye for a galaxy. Many galaxies are surrounded by ecosystems of gas clouds that might be able to sustain their voracious star-forming appetites.

Recycling Gas

Energetic and explosive events, such as supernova explosions, can rocket gas out of galaxies. If the galaxy is very massive, then its gravitational pull will slow the ejected gas down and pull it back to its disk in what is known as a “galactic fountain” process. Small galaxies do not pull as hard and the gas can instead escape. 

TCU Magazine Article

Swapped Gas

Galaxies often live in pairs or groups that interact. If the galaxies are close together, then gravitational tides can cause the gas within them to rise and fall. If the tides are strong enough, the gas can be ripped out of the galaxy completely and strewn far from the galaxy. This provides opportunities for neighboring galaxies to gravitationally steal gas that was tossed their way.  

Lingering Gas

When the Universe first formed, there were no particles, no stars, and no galaxies. Everything had to slowly build itself up. Some of the gas clouds that were created, never formed stars or found their way into galaxies. Today there is still low density gas in the nearly empty voids between galaxies. This lingering gas is slowly gravitationally drawn to galaxies. 

The Large Magellanic Cloud’s Galactic Wind through the Eyes of ULLYSES

We are conducting a comprehensive survey of the galaxy-scale outflows from the LMC using Ultraviolet Legacy Library of Young Stars as Essential Standards ( ULLYSES) STIS and COS spectra of 140 massive stars.  Using these UV absorption-line observations with optical and radio emission-line observations, radiative transfer models, and hydrodynamical simulations, we are characterizing the LMC’s stellar-driven galactic wind with more detail than is possible for any other galaxy. We are in the process of mapping the mechanical feedback from this actively star-forming galaxy and assessing its impact on the galaxy’s environment. This is the largest campaign to resolve the galactic wind of a single galaxy and has the potential to revolutionize the field as the winds of external galaxies are typically only sampled along 1 down-the-barrel sightline per galaxy.


We are looking for a Post Doc & Grad student to join the Team in Fall 2022

We seek new team members to  assist us in charactering the properties of the Large Magellanic Cloud’s galactic winds using UV absorption-line and optical and radio emission-line spectroscopy.  We are looking for highly motivated individuals that work well others to join our team. We are especially interested in individuals who are committed to fostering a diverse, equitable, and inclusive working and learning environment and we welcome applicants from groups that are underrepresented in Physics and Astronomy. These new team members will work closely with all of the project leaders, which include Kat Barger at Texas Christian University (Project PI),  Andrew Fox at Space Telescope Science Institute, Elena D’Onghia at University of Wisconsin-Madison, Nicolas Lehner at the University of Notre Dame, Dhanesh Krishnarao at Colorado College, and Naomi McClure-Griffiths at the Australian National University. 

TCU is a member of the Sloan Digital Sky Surveys IV and V. Although this project does not explicitly use data from those surveys, new team members will have access to them.

Smith Cloud might be recycled Milky Way gas

Using observations taken with the Hubble Space Telescope, we measured the chemical composition of the Smith Cloud. We were surprised to find that it is made out of material that is very similar to our galaxy. This cloud may have been ejected out of the Milky Way and is now on a return journey to its disk.

Gas Flows of the Milky Way and Magellanic Cloud galaxy

Galactic winds of the Large Magellanic Cloud galaxy

We find that supernova explosions occurring in the Large Magellanic Cloud galaxy are kicking out more than 10 million times the mass of the Sun in gas. Some of this gas could escape the clutches of this galaxy only to be captured by our galaxy, the Milky Way.

TCU Magazine Article

Ionizing light escaping from the Magellanic Cloud galaxies

Contained within galaxies are numerous stars that shine light. The massive stars emit light that is energetic enough to pop electrons off of hydrogen. We find that the less than 4% of the ionizing light escapes out of the large galaxy and less than 6% out of the small galaxy. 

The Small Magellanic Cloud looses the galactic tug-of-war

LA_tug of_war

The Large and Small Magellanic Clouds gravitationally tug at each other, and one of them has pulled out a huge amount of gas from its companion. This shredded and fragmented gas, called the Leading Arm, is being devoured by the Milky Way and is feeding new star birth in our galaxy. Using Hubble data, we have now which dwarf galaxy is doing the pulling: the Large Magellanic Cloud. This larger bully has stripped the smaller galaxy of a few hundred million times the mass of our Sun in gas. This gas is currently crashing into our galaxy, where it will it could be used to make millions of new stars like our Sun.  

NASA Hubble News Article