Featured Image: A New Look at Fomalhaut


ALMA continuum image overlaid as contours on the Hubble STIS image of Fomalhaut. [MacGregor et al. 2017]

This stunning image of the Fomalhaut star system was taken by the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile. This image maps the 1.3-mm continuum emission from the dust around the central star, revealing a ring that marks the outer edge of the planet-forming debris disk surrounding the star. In a new study, a team of scientists led by Meredith MacGregor (Harvard-Smithsonian Center for Astrophysics) examines these ALMA observations of Fomalhaut, which beautifully complement former Hubble images of the system. ALMA’s images provide the first robust detection of “apocenter glow” — the brightening of the ring at the point farthest away from the central star, a side effect of the ring’s large eccentricity. The authors use ALMA’s observations to measure properties of the disk, such as its span (roughly 136 x 14 AU), eccentricity (e ~ 0.12), and inclination angle (~66°). They then explore the implications for Fomalhaut b, the planet located near the outer disk. To read more about the team’s observations, check out the paper below.


Meredith A. MacGregor et al 2017 ApJ 842 8. doi:10.3847/1538-4357/aa71ae

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