Harvard Smithsonian Center for Astrophysics | 2020 Aug 17
The debate over the origins and molecular structure of 'Oumuamua continued today with an announcement ... that despite earlier promising claims, the interstellar object is not made of molecular hydrogen ice after all.
The earlier study — after observations by the Spitzer Space Telescope set tight limits on the outgassing of carbon-based molecules — suggested that if 'Oumuamua were a hydrogen iceberg, then the pure hydrogen gas that gives it its rocket-like push would have escaped detection. But scientists ... were curious whether a hydrogen-based object could actually have made the journey from interstellar space to our solar system. ...
Traveling at a blistering speed of 196,000mph in 2017, 'Oumuamua was first classified as an asteroid, and when it later sped up, was found to have properties more akin to comets. But the 0.2km radius interstellar object didn’t fit that category, either, and its point of origin has remained a mystery. Researchers focused on the giant molecular cloud (GMC) W51—one of the closest GMCs to Earth at just 17,000 light years away—as a potential point of origin for 'Oumuamua, but hypothesize that it simply could not have made the journey intact. ...
Destruction of Molecular Hydrogen Ice and Implications for 1I/2017 U1 ('Oumuamua) ~ Thiem Hoang, Abraham Loeb
- Astrophysical Journal Letters 899(2):L23 (2020 Aug 20) DOI: 10.3847/2041-8213/abab0c
- arXiv.org > astro-ph > arXiv:2006.08088 > 15 Jun 2020 (v1), 12 Aug 2020 (v3)