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名稱Title
2018天文年會
國立金門大學
5月18日至20日

論文摘要

Discovery of an O-type Runaway Star in the Superbubble N160 in the Large Magellanic Cloud

[ Poster PS15 ]

Chen-Hung Chen ( Academia Sinica Institute of Astronomy and Astrophysics); You-Hua Chu( Academia Sinica Institute of Astronomy and Astrophysics )

Using the Spitzer Space Telescope observations and the Magellanic Cloud Photometric Survey of the Large Magellanic Cloud (LMC), we have found ~100 stars with U-B < 0 and 8μm or 24 μm excesses. To determine the nature of these blue stars with IR excesses, we have obtained long-slit medium-dispersion spectra of these stars. While most stars in HII regions show stellar absorption lines at radial velocities similar to those of the ambient interstellar medium (ISM), one star shows a 150 km/s offset between the stellar velocity and the ambient interstellar velocity. This star, 053949.2-693747.7, is projected within the superbubble N160. We speculate that this star is a runaway star. The UBV photometry and spectral features of this star are consistent with those of an O7-8 main sequence star. A massive runaway star moving through the ISM is expected to produce a bow shock. We have searched the Hubble Space Telescope (HST) archive and found continuum and line images of this star. The HST [O III] and H-alpha images indeed show an arc around the star, indicating a bow shock structure and supporting the runaway nature of the star. This runaway star's mass, ~25 Msun, provides a lower mass limit to its companion that have exploded as supernova. We have further used the H-alpha surface brightness of the bow-shock structure to determine its rms density, assess the nature of the shock and ambient density, and use the bow shock geometry to infer stellar