The Magellanic Stream

We lead an international collaboration studying the Magellanic Stream, a massive tail of gas stripped out of the Magellanic Clouds and slowly falling into the Galactic halo. Our multi-wavelength research program uses the Hubble Space Telescope, the Very Large Telescope (GBT), and radio telescopes to determine the Stream's properties. This includes four funded Hubble programs to investigate gas in and around the Magellanic Clouds: 13448 in Cycle 19, 14687 in Cycle 24, 17053 in Cycle 30, and 18149 in Cycle 33.

We have made multiple contributions to understanding several key aspects of the Stream. First, we derived its metallicity and therefore origin; we used “chemical tagging” to show that gas from both Magellanic Clouds is present in the form of two interwoven filaments, one with an LMC abundance pattern and one with an SMC pattern. Second, we used customized photoionization models to derive its total mass accounting for ionized gas; we found that the Stream contains about three times as much ionized gas as neutral gas, which represented a substantial upward revision of the Stream’s mass. Third, we calculated its inflow rate onto the Galaxy, finding a higher value than the infall rate of all other HVCs combined. The Stream is now a poster child for how gas accretes from satellites onto central galaxies. Our group's Magellanic Stream research has been published in the following series of papers, many of which are based on UV spectra taken with the Cosmic Origins Spectrograph (COS) and Space Telescope Imaging Spectrograph (STIS) on Hubble:

Paper 1: Fox et al. 2010 (STIS spectroscopy of two Stream sightlines)
Paper 2: Fox et al. 2013 (COS abundance analysis in Stream)
Paper 3: Fox et al. 2014 (COS ionization survey of Stream)
Paper 4: Kumari et al. 2015 (COS analysis of Compact HVCs near Stream)
Paper 5: D'Onghia & Fox 2016 (Annual Reviews article on the Stream; see figure below)
Paper 6: Fox et al. 2018 (COS oxygen analysis in Leading Arm)
Paper 7: Richter et al. 2018 (COS & STIS abundance analysis in Leading Arm region II)
Paper 8: Fox et al. 2020 (COS kinematic analysis of Stream)
Paper 9: Krishnarao et al. 2022 (COS evidence for a warm-hot Magellanic corona)
Paper 10: Mishra et al. 2024 (COS evidence for a truncated Magellanic corona)
Paper 11: Mishra et al. 2025 (Constraints on distance to the Stream)