Trigonometric Distance and Proper Motion of IRAS 20056+3350: Massive Star Forming Region on the Solar Circle

TL;DR

This study measures the distance and proper motion of IRAS 20056+3350 using maser parallax, revealing it as a young massive star-forming region on the Solar circle, and refines Galactic rotation parameters.

Contribution

First precise trigonometric distance measurement of IRAS 20056+3350, establishing its position on the Local arm and its properties as a young massive star-forming region.

Findings

Distance of 4.69 kpc, larger than previous estimates

Luminosity of 2.4 x 10^4 L_sun, forming a 16 M_sun star

Proper motion and Galactic rotation parameters consistent with other measurements

Abstract

We report our measurement of the trigonometric distance and proper motion IRAS 20056+3350, obtained from the annual parallax of H2O masers. Our distance of D = 4.69 +0.65-0.51 kpc, which is more than two times larger than the near kinematic distance adopted in the literature, places IRAS 20056+3350 at the leading tip of the Local arm, and proximal to the Solar circle. Using our distance we re-evaluate past observations to reveal IRAS 20056+3350 as a site of massive star formation at a young stage of evolution. This result is consistent with the spectral energy distribution of the source evaluated with published photometric data from UKIDSS, WISE, AKARI, IRAS and sub-millimetre continuum. Both analytical approaches reveal the luminosity of the region to be 2.4 x 10^4 Lo, and suggest that IRAS 20056+3350 is forming an embedded star of 16 Mo. We estimated the proper motion of IRAS 20056+3350 to be ($\mu_{\alpha}\cos\delta$, $\mu_{\delta}$) = ($-2.62\pm0.33$, $-5.65\pm0.52$) mas yr$^{-1}$ from the group motion of H$_{2}$O masers, and use our results to estimate the angular velocity of Galactic rotation at the Galactocentric distance of the Sun, $\Omega_{0} = 28.71\pm0.63$ km s$^{-1}$ kpc$^{-1}$, which is consistent with the values obtained for other tangent point and Solar circle objects.