VERA Tomoya Hirota (Mizusawa-VLBI, NAOJ) 2 - - PowerPoint PPT Presentation
1 VERA Tomoya Hirota (Mizusawa-VLBI, NAOJ) 2 Nearby SFRs project Astrometry of H 2 O masers in nearby SFRs (<1 kpc) One of the VERA initial scientific programs Aim of this
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Astrometry of H2O masers in nearby SFRs (<1 kpc)
One of the VERA initial scientific programs
Aim of this project
Fundamental database Refine physical processes
Reveal 3-D structure of
Distribution of nearby SFRs (based on Dame et al. 1987 and Ward-Thompson et al. 2007) 2
H2O maser map with VERA (Hirota et al. 2007) Subaru NIR image (Kaifu et al. 2000)
Nearest massive star-forming region
D=480 pc (Genzel et al. 1981) Best laboratory for star-formation studies
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The first VERA result by Hirota et al. (2007)
Single H2O maser 2.29+/-0.10 mas =
Smaller than well
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VERA: H2O and SiO masers in Orion KL
437+/-19 pc (H2O maser: Hirota et al. 2007) 418+/-6 pc (SiO maser: Kim et al. 2008)
VLBA: continuum from WTTSs
389 +24/-21 pc
414+/-7 pc
Consistent with each other
Source I (masers)
1’ = 0.12pc (NIR image of ONC; Menten et al. 2007)
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NGC1333 (Hirota et al. 2008): 235+/-18 pc L1448C (Hirota et al. 2011): 232+/-18 pc
Photometric distance: 220 pc (Cernis 1990) HIPPARCOS: 318 pc for Per OB2 (de Zeeuw et al. 1999)
Proper motions similar to VLA/HIPPARCOS results
Optical image of the Perseus region (Bally et al. 2008)
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3D structure of Perseus molecular cloud
Consistent with previously suggested by photometric
Taurus B1 IC348 NGC1333 PerOB2 Schematic view proposed by Cernis (1993)
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New distance to L1204G/IRAS22198+6336
1.3 kpc 0.7 kpc; MYSO? Intermediate-mass YSO 3D structure ranging from 0.7-3 kpc
2kpc 2-3kpc 1kpc 3kpc 0.7kpc 0.7kpc
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CO map (Yonekura et al. 1997) VLBI astrometry (compiled by Chibueze et al. 2014)
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Ophiuchus
VERA: 178 +18/-37 pc (Imai et al. 2007) VLBA: 120.0 +4.5/-4.2 pc (Loinard et al. 2008)
Orion-Monoceros
VERA: 738 +57/-50 pc for NGC2264 (Kamezaki et al. 2014)
VLBA Bessel project (Wu et al. 2014)
Nearby sources (including ~1 kpc) in Sagittarius Arm
VLBA Gould belt survey (Loinard et al. )
Continuum sources in nearby SFRs surveyed by JVLA Taurus, Perseus, Ophiuchus, Orion, Serpens, (Cepheus)
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Non-thermal radio emitting stars
Magnetic activities Strong shock by stellar wind
Possible target sources
Pulsar Micro quasar Supernovae (remnant) X(g)-ray binary RS CVn binary Weak-line T-Tauri star (WTTS) O star, Wolf-Rayet star
Relationship between X-ray and radio luminosity (Gudel 2002)
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Japanese VLBI Network (JVN)
OCTAVE (Optically ConnecTed
Usuda 64 m, Tsukuba 32 m,
Maximum baseline ~ 900 km 10 mas resolution at 8 GHz Recording rate = 2 Gbps
Real-time data transfer to Mitaka
筑波32m 臼田64m 日立32m 山口32m
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Survey of young stellar objects and massive stars
Date: 2008 March, 3 stations (WTTSs, HAeBe) Date: 2011 November/December, 3 stations (O/WR stars)
Source selection
Relatively compact/strong radio emission detected with VLA Time variation Negative spectral energy distribution Polarization Association of X-ray Not systematic samples
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Example of the results (for VLBI experts)
FRING (solint=1) solutions with SNR=10-30 for ~10mJy Detection of 3 sources (V773 Tau, GMR-12, VSSG14)
Many non-detection
Insufficient calibration Insufficient position accuracy Extended thermal sources
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Detected 5/23 sources of O/WR stars
No flux calibration applied
SNR=40 Hitachi Usuda Yamaguchi Hitachi Tsukuba Yamaguchi
Cep-A HW9 Cyg OB2 NO9 WR146 WR140 GMR-12 GMR- 12
Time=30min Time=1hr
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Summary of VERA
Maser astrometry revealed 3D structure of molecular clouds
Summary of JVN/OCTAVE
Radio emitting stars will be new probes of astrometry Complete survey of WR stars is on-going
Future astrometry with VLBI, ALMA and SKA
Star-forming regions not only with masers but also with
Stellar radio astrometry will be developed for various
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