PoS(10th EVN Symposium)063 http://pos.sissa.it/ rseus, and L1204G in bsolute proper motions and n to reveal their 3-dimensional VLBI and the new generation of radio is will also enable us to reveal the Gould Belt. l parallaxes of Orion KL in Orion, rometry with VERA, which can pro- O maser sources in nearby molecular 2 e Commons Attribution-NonCommercial-ShareAlike Licence. O maser sources in nearby 2 ∗ [email protected] Speaker. We present recent results of astrometic observations of H clouds with VERA. The main goal of our study is to measure the a IRAS16293-2422 in Ophiuchus, NGC1333 SVS13 and L1448C in Pe overall structure of the local arm of our Galaxy as well as the distances to nearby molecular cloudsstructures. within So 1 far, kpc we from have the successfully measured Su the annua Cepheus. Our results demonstrate the highvide capability most of accurate ast distances to nearby molecular clouds. Th ∗ Copyright owned by the author(s) under the terms of the Creativ c

star-forming regions with VERA National Astronomical Observatory of Japan E-mail: Tomoya HIROTA Astrometry of H 10th European VLBI Network Symposium andarrays EVN Users Meeting: September 20-24, 2010 Manchester Uk PoS(10th EVN Symposium)063 O 2 19 pc er spot ± rried out multi- RA of the H Tomoya HIROTA mical Image Pro- ns were made in the parallax. The annual h VERA ss and low-mass star- target source. Further trometry (VERA) and [10] in Table 1. ocessing, although these nd bandpass calibrations ccurate distances toward sources were observed si- ity in star-forming regions. e calibration measurements hese results are essential to 6 [11] seus [6, 8], Serpens [4], Orion 18 37 27 [7] 18 [8] 18 [6] 19 [5] , while phase calibrations were ± + − ± ± ± ± 178 5 5 . . 1 0 0.05 764 0.33 232 0.32 235 0.10 437 0.03 418 + − ± ± ± ± ± 2 1 kpc) have been developed rapidly. Annual paral- O maser source Orion KL [5]. This is one of the first < 2 0.10 mas, corresponding to the distance of 437 ± O 5.6 O 1.31 O 4.31 O 4.25 O 2.29 2 2 2 2 2 O masers (22235.080 MHz) have been carried out since 2004. The 2 Distances toward nearby star-forming regions observed wit Table 1: IRAS 16293-2422 H L1204G H Source NameL1448C Tracer Parallax (mas) Distance (pc) H Reference NGC1333 SVS13 H Orion KL H Orion KL SiO 2.39 VERA observations of H Here we briefly review our results of annual parallax measurements with VE Figure 2 shows examples of the astrometric results from VERA, in which we ca In the last decade, phase-referenced VLBI astrometry of both high-ma maser sources associated with nearby star-forming regions as summarized 2. Observations baseline length of VERA ranges fromdual-beam 1000 mode to with 2300 which km. targetmultaneously. All maser Calibration of sources and the imaging and observatio were phase-reference performed usingcessing the System NRAO (AIPS). Astrono First, we adoptedand the the results corrections of for dual-beam the phas a prioriby delay themselves model are applied not in accurate the enough correlation for pr were precise made astrometry. Amplitude for a each of a targetmade and only a for reference the source independently referencedetails source, are of described which in solutions [9, 5], were and applied references to therein. the laxes have been successfully measured with VLBI Exploration of Radio As Very Long Baseline Array (VLBA). All ofthe these molecular works clouds such provide as the the most Ophiuchus a [5, [10, 12], 11, Taurus [12], 13, Per 16], andrefine physical Cepheus and [7, dynamical properties 14] such regions as size, as mass, shown and luminos in Figure 1. T 3. Results and Discussion Astrometry of nearby SFRs with VERA 1. Introduction astrometric results obtained with VERA. One can easily find that the motion of the mas consists of a linear proper motion andparallax sinusoidal of modulation Orion due KL to is an derived annual to be 2.29 epoch VLBI observations of a well known H forming regions in nearby molecular clouds ( PoS(10th EVN Symposium)063 6 ± us Molecular uncertainties in ns of the maser with each other Tomoya HIROTA rs associated with her accuracy, 418 ources in NGC 1333 ause these two maser stematic motion of the and Cepheus (L1204G, io continuum sources in egion, we obtained the dis- Cyg Rift Cyg OB7 Cep Cloud C Cloud Vul Cep Cloud A Cloud s, Orion, Ophiuchus, and Perseus) and rcles represent the positions of molecular ey ellipse indicates the Gould Belt [17]. Cloud B Cloud Ser Sun Aql Per Galactic center Galactic Tau 3 Ori B Mon OB1 Oph R CrA Lup 10%. Thus, further monitoring observations would be 120 pc based on the VLBA observations with higher 18 pc [8] from the Sun, respectively. These values are in ∼ ∼ Ori A ± Distance from the Sun (pc) the from Distance Vel O masers [1]. Although one cannot rule out the possibility of Cha sack Coal G317-4 2 Mon R2 7 pc [13]. ± O maser source IRAS 16293-2422 [10] while those of other two radio 2 -1000 -5000 500 1000 0 18 pc [6] and 232 500

± 1000 -500

-1000 Distance from the Sun (pc) Sun the from Distance pc for the H 18 37 + − Distributions of nearby molecular clouds [3, 17]. Filled ci Astrometric observations for the Ophiuchus (IRAS 16293-2422, [10]) We also obtained the distances of NGC1333 SVS13 and L1448C in the Perse internal motions of masers (e.g.whole of jets the and Perseus outflow), cloud they complex. could represent sy continuum sources were reported to be helpful to improve the results.sources in Note that NGC1333 we SVS13 measured(Figure and the 3). L1448C absolute In which proper addition, show motio is the similar consistent average velocity proper with vectors motion those of of the the radio H continuum s [7]) regions have also been carried outtance with of VERA. 178 For the Ophiuchus r sources are highly time variablethe and derived parallaxes their are lifetimes relatively large are less than a half year, the good agreement with the photometric distance of NGC1333, 220 pc [2]. Bec Cloud, which are 235 [11]. All of thesethe results Orion are Nebula consistent Cluster, with 414 those obtained for other rad Figure 1: clouds whose distances haveVLBA been (Cepheus, measured Orion, Ophiuchus, with Serpens, VERA and Taurus). (Cepheu A gr from the Sun [5].Orion KL Subsequently, (radio we source I) carried and out successfully astrometry determined the of distance the with SiO hig mase Astrometry of nearby SFRs with VERA PoS(10th EVN Symposium)063 G is 27 pc ± nal struc- -5 f a number of Tomoya HIROTA 2004/083 ard the Ophiuchus 2005/081 0 2005/057 2005/015 2004/055 with VERA, 764 93-2422 in order to con- 2004/027 2004/333 2006/061 olar neighborhood including 2006/112 th VERA for Orion KL [5]. (a) 5 RA offset [mas] RA offset 2004/203 2004/354 2006/147 2004/272 2005/354 2005/323 n of time. (b) Same as (a) in declination. (c) nt the best-fit model with the annual parallax orrelles, J. M., & Osorio, M. 2008, AJ, 136, 10 2005/264 (c) OH maser observations toward Cepheus A, of the least-squares analysis (0.36 mas in right es represent the observed positions of the maser 3 0

-5

-10 -15 -20 -25

ffset [mas] ffset Dec o Dec 4 (from 2004.000) (from 2004.000) Day Day (b) (a) 0 120 240 360 480 600 720 840 0 120 240 360 480 600 720 840

5 0 5 0 -5 -5

10 -10 -15 -20 -25

[mas] set off Dec RA offset [mas] offset RA An example of the results of annual parallax measurements wi 40 pc [14] within the mutual erros. Still, it is likely that the distance toward L1204 ˇ Cernis, K. 1990, Ap&SS, 166, 315 2238 In summary, VLBI astrometry with VERA is being used to investigate the 3-dimensio ± [1] Carrasco-Gonzárez, C., Anglada, G., Rodríguez, L. F., T [2] slightly farther than Cepheus A. tures of the localsources. molecular It clouds will be by a powerful measuringthe tool local the to arm reveal distances of the our and local Galaxy structure kinematics and of the the o Gould S Belt. References Movement of the maser feature in right ascension as a functio firm whether there existregion. two On molecular the other clouds hand, at distance towards the the different Cepheus region distances obtained tow accuracy [12]. We need further astrometric observations of IRAS 162 Movement of the maser feature on the sky. Solid linesfeature represe with error barsascension indicating and the 0.74 mas standard in deviations declination). and linear proper motion for the maser feature. Filled circl 700 [7], is consistent with the VLBA result from the CH Figure 2: Astrometry of nearby SFRs with VERA PoS(10th EVN Symposium)063 Tomoya HIROTA ata [15]. Contour levels are AV =3, 5, 7, ] . D., & Plambeck, R. L. 2007, ApJ, 667, odríguez, L. F., & Torres, R. M. 2010, ApJ, . 2007, A&A, 474, 515 guez, L. F. 2008, RMxAC, 34, 14 f the maser sources and their absolute proper 5 O masers in L1448C and NGC1333 SVS13 [8]. The grey scale 2 arXiv1007.4385 Absolute proper motions of the H 718, 610 1161 [3] Dame, T. M. et al. 1987,[4] ApJ, 322, Dzib, 706 S. Loinard, L., Mioduszewski, A. J., Boden, A. F., R [5] Hirota, T. et al. 2007, PASJ, 59,[6] 897 Hirota, T. et al. 2008a, PASJ, 60,[7] 37 Hirota, T. et al. 2008b, PASJ, 60,[8] 961 Hirota, T. et al. 2011, PASJ, in press [ [9] Honma, M. et al. 2007, PASJ, 59, 889 shows the visual extinction (AV) map derived from the 2MASS d and 9 magnitude. Crosses andmotion arrows vectors, represent respectively. the position o Figure 3: Astrometry of nearby SFRs with VERA [13] Menten, K. M., Reid, M. J.,[14] Forbrich, J., Moscadelli, & L. Brunthaler, et A al. 2009, ApJ,[15] 693, 406 Ridge, N. et al. 2006, AJ,[16] 131, 2921 Sandstrom, K. M., Peek, J. E. G., Bower, G. C., Bolatto,[17] A Ward-Thompson, D. et al. 2007, PASP, 119, 855 [10] Imai, H. et al. 2007, PASJ,[11] 59, 1107 Kim, M. K. et al. 2008,[12] PASJ, 60, Loinard, 991 L., Torres, R. M., Mioduszewski, A. J., & Rodrí