2026-11-05 理化学研究所,国立天文台
大質量原始星を取り巻く円盤と円盤風、鉱物由来の分子の分布の模式図
＜関連情報＞
- https://www.riken.jp/press/2026/20261105_1/index.html
- https://iopscience.iop.org/article/10.3847/2041-8213/aeacbe
大質量原始星における塵の種となる分子―オリオン源IにおけるTiOの検出 Dust-seeding Molecules in a Massive Protostar—Detection of TiO in Orion Source I
Ziwei E. Zhang, Nami Sakai, Marcelino Agúndez, Linda Podio, Claudio Codella, Tomoya Hirota, Adam Ginsburg, Brett McGuire, Nadia M. Murillo, Yuki Okoda,…
The Astrophysical Journal Letters Published: 2026 October 23
DOI:10.3847/2041-8213/aeacbe
Abstract
We report the first detection of TiO in star-forming regions based on Atacama Large Millimeter/submillimeter Array observations of Orion Source I, a well-characterized massive protostar. Multiple rotational transitions are identified, with emission spatially resolved within ∼50 au, showing a compact distribution with a velocity structure consistent with the base of a rotating outflow. The spatial and velocity distributions of TiO are consistent with those of AlO, with both species being key dust-seeding refractory molecules. The column density of TiO is derived to be (3.0 ± 0.4) × 1015 cm−2, corresponding to XTiO/SiO ∼ 12.8 ± 1.7 × 10−3, higher than the CI chondrite XTi/Si value and indicative of efficient dust-to-gas conversion near the protostar. The detection of TiO, a key dust-seeding species, offers important constraints on refractory chemistry and the formation environments of primitive minerals, linking astrochemical processes in protostellar systems to the earliest stages of solar system material formation.
