Absolute Proper Motion of IRAS 00259+5625 with VERA : Indication of Superbubble Expansion Motion

TL;DR

This study measures the proper motion of IRAS 00259+5625 to investigate its vertical movement, providing evidence for the expansion of the NGC 281 superbubble likely caused by sequential supernovae.

Contribution

First measurement of absolute proper motions of IRAS 00259+5625, revealing vertical motion consistent with superbubble expansion from supernova explosions.

Findings

Proper motion indicates vertical movement away from the Galactic plane.

Measured vertical velocity supports superbubble expansion hypothesis.

Results align with previous VLBI observations of related structures.

Abstract

We present the first measurement of the absolute proper motions of IRAS 00259+5625 (CB3, LBN594) associated with the HI loop called the "NGC281 superbubble" that extends from the Galactic plane over ~300 pc toward decreasing galactic latitude. The proper motion components measured with VERA are (mu_alpha cos(delta), mu_delta) = (-2.48 +/- 0.32, -2.85 +/- 0.65) mas yr^{-1}, converted into (mu_l cos(b), mu_b) = (-2.72 +/- 0.32, -2.62 +/- 0.65) mas yr^{-1} in the Galactic coordinates. The measured proper motion perpendicular to the Galactic plane (mu_b) shows vertical motion away from the Galactic plane with a significance of about ~4-sigma. 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 (v_{b}) of -17.9 +/- 12.2 km s^{-1} is determined with ~1.5-sigma significance. The tendency of the large vertical motion is consistent with previous VLBI results for NGC 281 associated with the same superbubble. Thus, our VLBI results indicate the superbubble expansion motion whose origin is believed to be sequential supernova explosions.