Download Collaborations with East Asian VLBI stations

VERA
ー 最新の成果と今後の展望 ー
Mareki Honma
Mizusawa VLBI observatory, NAOJ
Galaxy-scale maser astrometry
Sun
Galaxy’s center
Parallax
Galaxy Center
D= 8 kpc
π= 125 μas
Galaxy scale astrometry requires 10μas accuracy
Galaxy scale astrometry = frontier in 21st century
(c.f., astrometric missions like SIM, GAIA, JASMINE)
VERA : VLBI Exploration of Radio Astrometry
Construction completed in 2002
Regular observations from 2004
Mizusawa
Iriki
Ishigaki-jima
Ogasawara
Target sources : Galactic masers (H2O@22GHz, SiO@43GHz)
New aspect: dual-beam for phase-referencing
Astrometric missions
• Satellite mission for Galaxy-scale astrometry
GAIA (ESA)
2012
SIM (NASA)
2015?
JASMINE (JAXA)
2018?
Target accuracy is ~10 μas, the same with VERA
Dual-beam receiving system
telescope
dual-beam receivers
Phase-referencing
Target source
reference
Dual-beam
platform
(2.2 deg max)
atmosphere
VERA station
Dual-beam phase compensation
~1 mas
W49N and OH43.8-0.1 again (on 23/Jul/2002)
Phase residual : ~8 degree in RMS
Current status of astrometry with VERA
Location of maser sources for which parallax/proper
motions are obtained
Schematic view of Galaxy
Solar neighborhood
NGC 281
ON1
G34
L1204
SY Scl
R UMa G14
WB755 NGC 1333
ρ oph
Orion
S Crt
I06058
T Lep
VY CMa
W49N
I19213 OH43
AFGL2789
I19181
WB621
NGC 281 ON2
Sgr A
S269
Sun
Illustration courtesy:
NASA/JPL-Caltech/R. Hurt (SSC/Caltech)
Parallax + proper motion
Proper motion
S 269 proper motion
S269 motion with respect to LSR : (V_l, V_b) = (-4.6, -4.1) km/s
>> similar galactic rotation velocity at the Sun and at S269
Galaxy
Center
S269
Sun
Honma et al. (2007)
Flat rotation curve out to 13 kpc, plenty of dark matter
RC from 7 – 13 kpc
• Oh et al. (2009) obtained distances for three more
sources
IRAS19213+1723
AFGL2789
IRAS06058+2138
D= 2 ~ 4 kpc
Basically cosistent with FRC
(but slightly slow rotation for Perseus arm sources)
ON 1
• ON1 has both H2O and Methanol masers
H2O maser parallax
2.4 +/- 0.1 kpc (Nagayama+ in prep)
Maser locations
c.f. ) Methanol maser parallax
2.57+0.34-0.27 kpc by EVN
(Rygl+ 2009)
IRAS19181
• D = 5.26 +/- 0.42 kpc (Nagayama + in prep.)
• Close to W51M (~5.1 kpc), though kinematic
distances differ (due to V_LSR difference)
Nearby SFRs
•
Astrometry of SFRs within ~1 kpc from the Sun
– Orion-Monoceros (Orion KL: Hirota+2007, Kim+2008)
– Perseus (NGC1333: Hirota+2008)
– Ophiuchus (rho-oph: Imai+2008)
– Cepheus (L1204, Hirota+2009)
•
Comparison of Cepheus distances
Cep-A (700+/-40 pc, Moscadelli+, VLBA)
L1204(764+/-27 pc, Hirota+, VERA)
L1206 (775+/-90 pc, Rygl+, EVN)
Dame et al.1987
G14.33-0.64 & Sgr Arm
• D = 1.12 +/- 0.13 kpc (Sato et al. 2010)
Sun
G14
Local arm and Sgr arm traced with masers
Combined analysis of VLBA/VERA
• 18 sources published by 2008
10 VLBA Methanol
maser project (Reid+)
4 VERA H2O maser
4 others from VLBA
• Pitch angle of Perseus arm
16 +/- 3 deg
four arm spiral ?
• Galactic constants
R0 = 8.4 +/- 0.6 kpc
Θ0=254 km/s +/- 16 km/s
(Ω0=30.3 +/- 0.9 km/s/kpc)
Reid+ 2009
Summary of current status and future
VERA
• Kpc-scale astrometry is already achieved with VERA
• Parallaxes and proper motions are obtained for ~20
sources
• ~70 sources have been observed, still to be analyzed
• ~1000 sources within next 15 years
VLBA large project (Reid, Menten, Brunthaler +) will also
observe ~500 sources.
Main targets should be disk sources in the northern hemisphere
> The bulge will remain to be explored with JASMINE !?
On-going up-grades of VERA
• New bands (6.7GHz) : more sources
• Array expansion : higher sensitivity, longer
baselines (=> better accuracy)
• Wide-band recording : higher sensitivity
(=> better accuracy)
6.7GHz receiver for VERA
• Developed by Osaka-pref. Univ. (Ogawa lab.)
• Installation finished in May 2009 (all stations)
• T_rx ~ 60 K
• Tsys ~ 120 K
• efficiency ~50%
Preliminary results : W3(OH)
Parallax : 0.651 +/- 0.133 mas (Matsumoto et al. in prep)
c.f., pi = 0.512±0.010mas (Xu et al.2006)
Collaborations with East Asian VLBI stations
KVN participation provides shorter and denser UV > better image
China participation expands east-west baseline > better astrometry
Collaboration with nano-JASMINE
• Calibration
VERA can provide calibration stars for which
parallax and proper motions are already obtained.
• position comparison / link of radio and IR frame,
+ down-link with Mizusawa 10m
Orion distance measurements
• GMR-A (VLBA 15 GHz)
389 +24/-21 pc
(Sandstrom et al. 2007)
• GMR A/F/G/12 (VLBA 8GHz)
414+/-7 pc
(Menten et al. 2007)
Source I
• H2O maser in Orion KL (VERA)
437+/-19 pc
(Hirota et al. 2007)
• SiO masers in source I (VERA)
419+/-6 pc
(Kim et al. 2008)
Position of radio sources
(Menten et al. 2007)
Trapezium can be observed with Nano-JASMINE ?
AGB star S Crt
• 年周視差 2.33±0.3 mas (VERA)
HIPPARCOS
Pi = 1.27 mas err 0.92
mu_a -3.37 mas/yr err 1.00
mu_d -4.67 mas/yr err 0.75
Nakagawa et al. (2008)
Period-Luminosity Relation of Mira
• VERA observations of SY Scl, T Lep, R UMa, S Crt (SR)
are used to precisely calibrate the P-L relation of Mira
Mk = -3.62 LogP +1.57
（Nakagawa et al. in prep）
Good luck for Nano-JASMINE !