The Circumstellar Gas of Phi Leonis in the UV

HST UV spectra were obtained to study whether the φ Leo system has one or more stellar companions, as shown for A-star dwarf, HR10, pulsation, transiting exocomets. During five partial observation sets spread over 13 months, redshifted gas with radial velocities up +245 km s−1 was observed on occasion, lower velocity infalling material seen twice. Blueshifted features high −150 three in two also seen. Low-mass companions late A stars are coronal sources. Assuming an age of 450 Myr, G-K Leo, and multiple M-star would have been detected ROSAT All-Sky Survey data, but not Further, star shows only 1 major pulsation component, suggesting it is single, excluding A- early F-star companion. Low covering factor absorption ∣v∣ ≤ 200 reported optical variation timescales consistent nonradial pulsation. However, highest infall feature a broader, continuous profile extending from s−1, ∼25% which transit by body star-grazing orbit.