Annual Parallax Measurements of an Infrared Dark Cloud, MSXDC G034.43+00.24 with VERA

作者：Kurayama Tomoharu^*; Nakagawa Akiharu; Sawada Satoh Satoko; Sato Katsuhisa; Honma Mareki; Sunada Kazuyoshi; Hirota Tomoya; Imai Hiroshi

来源：Publications of the Astronomical Society of Japan, 2011, 63(3): 513-525.

• astrometry
• ISM: individual (MSXDC G034.43+00.24)
• stars: formation
• techniques: interferometric

We have measured the annual parallax of the H2O maser source associated with an infrared dark cloud, MSXDC G034.43+00.24, from observations with VERA (VLBI Exploration of Radio Astrometry). The parallax is 0.643 +/- 0.049 mas, corresponding to a distance of 1.56 (+0.12)(-0.11) kpc. This value is less than half of the previous kinematic distance of 3.7 kpc. We revised the core-mass estimates of MSXDC G034.43+00.24, based on the virial masses, LTE masses and dust masses, and showed that the core masses decrease from the previous estimations of similar to 1000 M-circle dot to hundreds of M-circle dot. The spectral type derived from the luminosity also changes from O9.5 to B 1 in the case of MM1. This spectral type is still consistent with that of the massive star. The radial velocity derived from the flat rotation model is smaller than the observed velocity, which corresponds to a peculiar motion of similar to 40 km s(-1) in the line-of-sight direction.

• 出版日期2011
• 单位中国科学院国家天文台