Absolute proper motion of IRAS 00259+5625 with VERA: Indication of superbubble expansion motion

Abstract

Abstract We present the first measurement of the absolute proper motions of IRAS 00259+5625 (CB3, LBN594) associated with the H i loop called the “NGC 281 superbubble” that extends from the Galactic plane over ∼ 300 pc toward decreasing galactic latitude. The proper motion components measured with VLBI Exploration of Radio Astrometry (VERA) are (μαcos δ, μδ) = (−2.48 ± 0.32, −2.85 ± 0.65) mas yr−1, converted into (μlcos b, μb) = (−2.72 ± 0.32, −2.62 ± 0.65) mas yr−1 in the Galactic coordinates. The measured proper motion perpendicular to the Galactic plane (μb) shows vertical motion away from the Galactic plane with a significance of about ∼ 4 σ. As for the source distance, the distance measured with VERA is marginal, $2.4^{+1.0}_{-0.6}$ kpc. Using the distance, an absolute vertical motion (vb) of −17.9 ± 12.2 km s−1 is determined with ∼ 1.5 σ significance. The tendency towards the large vertical motion is consistent with previous very long baseline interferometry (VLBI) results for NGC 281 associated with the same superbubble. Thus, our VLBI results indicate superbubble expansion motion whose origin is believed to be sequential supernova explosions.