VLBI Observations and NH₃ Mapping of the Star-forming Region NGC2264

Abstract

We have measured the annual parallax of the water maser source associated with star forming region NGC2264 from observations with VLBI Exploration of Radio Astrometry (VERA). We detected masers at V L SR = 7.2 km s −1 . We discussed its driving sources of detected maser spots. One of the maser spots was associated with a centimeter continuum source observed with VLA. Neither optical, infrared nor X-ray sources is catalogued near the spot. The other maser spot is located close to an X-ray source, although there is no optical or infrared counterpart. The proper motion of the former spot was (μ α , μ δ ) = (23. 91 ± 4.29, −29.81 ± 4.27) and the proper motion of latter spot was (μα , μ δ ) = (−0.96 ± 0.58, −6.05 ± 3.06). For the latter spot, the peculiar motion is ∼ 150 km s −1 and it has the high velocity and this may be a jet or an outflow from a young star. The observed parallax is 1.365 ± 0.098 mas, corresponding to the distance of 738 + 57 −50 pc. This value is constant with the photometric distance of NGC2264 previously measured. The fitting result of the parallax is shown in figure 1. We also observed in NH3 (1,1), (2,2), (3,3) lines of NGC2264 with the Kashima 34m telescope. We estimated the star formation efficiency (SFE) of NGC2264 from the dense molecular mass of NH3 and the stellar mass calculated by Teixeira et al.(2012). The SFE is 9 -12 % which is consistent with previous results.

TheGaia-ESO Survey: Stellar radii in the young open clusters NGC 2264, NGC 2547, and NGC 2516

“…In this paper we adopt the distance 777 ± 12 pc given by Turner (2012) based on model isochrone fitting. This is consistent with a distance of 760 ± 49 pc from fitting the ZAMS (Sung et al 1997) and the parallax-based distance of 738±45 pc obtained from two maser sources thought to be located in NGC 2264 (Kamezaki et al 2013). Having adopted the distance given by Turner (2012) we also adopt their average reddening of E(B − V) = 0.075 ± 0.003 mag and age of ∼5.5 Myr.…”

VLBI Observations and NH3 Mapping of the Star-forming Region NGC2264

“…We also observed in NH3 (1,1), (2,2), (3,3) lines of NGC2264 with the Kashima 34m telescope. We estimated the star formation efficiency (SFE) of NGC2264 from the dense molecular mass of NH3 and the stellar mass calculated by Teixeira et al(2012). The SFE is 9 -12 % which is consistent with previous results.…”