Occultation of a Large Star by the Large Plutino (28978) Ixion on 2020 October 13 UTC

• Published in: The Astronomical journal Vol. 161; no. 5; p. 210
• Main Authors: Levine, Stephen E., Zuluaga, Carlos A., Person, Michael J., Sickafoose, Amanda A., Bosh, Amanda S., Collins, Michael
• Format: Journal Article
• Language: English
• Published: Madison IOP Publishing 01.05.2021
• Subjects: Astronomy; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; Diameters; ILLUMINANCE; MAGNETIC MIRRORS; MARS PLANET; Occultation; Parallax; Pressure; Spectral classification; STARS; Surface pressure; TELESCOPES; Titan
• ISSN: 0004-6256; 1538-3881; 1538-3881
• DOI: 10.3847/1538-3881/abe76d

Abstract We observed the occultation of the star Gaia DR2 4056440205544338944 by (28978) Ixion. The event was observed from two Lowell Observatory sites, using the 4.3 m Lowell Discovery Telescope (LDT), near Happy Jack, AZ, USA, and a 0.32 m telescope co-mounted with the Titan Monitoring telescope on Lowell’s Mars Hill campus in Flagstaff, AZ. The LDT chord, at 44.86 s, was roughly 30% longer than the longest predicted possible chord. Under the assumption of a spherical body, Ixion’s fitted diameter D = 709.6 ± 0.2 km. The LDT light-curve profile was used to place an upper limit on the surface pressure P < 2 μ bar on any possible atmosphere of Ixion. At the distance of Ixion, the occulted star had a fitted projected diameter of 19.25 ± 0.3 km assuming uniform disk illumination, giving a stellar angular diameter of 0.675 ± 0.010 mas. Using the Gaia EDR3 parallax of 0.565 mas, the stellar radius is . The measured size is consistent with prior spectral classification of this star as a reddened mid-M giant. This is one of only a modest number of M5 III stars to have a directly measured diameter, and is more distant than most.