I'm the Principal Investigator of three HST programs studying the Galactic Center outflow in UV absorption. Our results on the properties of the biconical outflow at the center of the Milky Way are described in a series of published papers.
The Magellanic Clouds are surrounded by massive reservoirs of gas, tracing their ongoing interaction with the Milky Way. I'm the Principal Investigator of four HST HST programs to study these gas reservoirs, and have written over 10 published articles on this topic, including an Annual Reviews article.
Cloud 9 is a compact gas cloud near the spiral galaxy M94. In Anand et al. 2025 we used HST imaging to show that this cloud is starless. Cloud 9's properties make it the first confirmed example of a RELHIC, a dark-matter-dominated failed galaxy from the early Universe.
The dwarf irregular galaxy Sextans B sits on the outer frontier of the Local Group, in an isolated environment. In a recent paper (Fox et al. 2026) we used Hubble UV spectroscopy to show that Sextans B has a gaseous halo with very low metallicity.
Complex C is one of the largest high-velocity clouds (HVCs) in the sky. In Fox et al. 2023 we used UV spectroscopy to show that Complex C contains dust grains and has therefore been chemically enriched. This provides an important clue on its origin.
Cloud 9 is the first observed example of a RELHIC, a dark-matter-dominated starless cloud leftover from the early Universe. See our NASA and ESA press releases from 2026, following our deep Hubble Space Telescope imaging that showed Cloud-9 is starless.
The Galactic Center is surrounded by two giant lobes of plasma known as the Fermi Bubbles. Our Fermi Bubble program has led to two NASA press releases, one in 2015 and one in 2017, and an NRAO press release in 2025.
The Magellanic Clouds are surrounding by huge quantities of gas, including the famous Magellanic Stream, the Bridge, and a diffuse halo. We have been studying Magellanic gas for over a decade with the Hubble Spacee Telescope. See our series of NASA press releases from 2013, 2022, and 2024.
In 2019, we used observations from Hubble's Cosmic Origins Spectrograph (COS) to measure the rates at which the Milky Way is gaining and losing gas to its surroundings, finding an excess of inflow. This story was covered in 2019 by NASA, Phys.org and Universe Today.
The enigmatic Smith Cloud is a massive infalling gas cloud close to impacting the Galactic disk, where it may trigger new generations of star formation. We used Hubble to measure its chemical compostion and probe its source. See our 2016 NASA press release.
Space Telescope Science Institute
3700 San Martin Drive, Baltimore, MD 21218
Office: +1 410 338 5083
Email: afox[at]stsci.edu
Web: www.stsci.edu/~afox/
ORCID: https://orcid.org/0000-0003-0724-4115
