KaVA Large Programs of Circumstellar Masers
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KaVA Large Programs of Circumstellar Masers KaVA Evolved Stars sub-Working Group Hiroshi Imai *1 , Se-Hyung Cho *2 , Miyako Oyadomari 1 , Gabor Orosz 1 , Akiharu Nakagawa 1 , Youngjoo Yun 2 , Jaeheon Kim 2 , Yoon-Kyong Choi 2 , Taehyun Jung 2 , Soon-Wook Kim 2 , Naoko Matsumoto 3 , Cheul-Hong Min 3 , Jeong-Sook Kim 3 , Yoshiharu Asaki 4 , Fujika Watari 5 , Maria J. Rioja 6 , Richard Dodson 6 , and Tao An 7 * co-chair of sub-WG; 1 Kagoshima Univ.; 2 KVN/KASI; 3 NAOJ Mizusawa; 4 ISAS/JAXA; 5 Yokohama City Univ.; 6 ICRAR/UWA; 7 SHAO Specification of the Large Programs Phase 1: ESTEMA (Expanded Study on Stellar Masers) during 20152016, ~200 hours Snapshot imaging of H 2 O and SiO masers in circumstellar envelopes (Figure 1) around ~80 stars ● statistics of stellar masers i. maser spot sizes and phapes ii. distributions of H 2 O masers with respect to locations of SiO masers iii. correlation with kinematic parameters of circumstellar envelopes and stars ● yielding a larger sample of stars as targets of the Phase 2 project Phase 2: Intensive monitoring campaign during 20162024, 400500 hours/year 16—20 pulsating stars (P=300—1600 days) monitoring SiO and H2O masers in every 1/20 pulsation cycle over a few pulsation cycles for “stellar maser movie” synthesis ● detecting (both or either) i) propagation of pulsation-driven shock waves (Figure 2) ii) periodic change in physical conditions affected by stellar radiation ● Comprehensive synergy with ALMA, VLTI, Nano-JASMINE Figure 3 (top left) H2O maser map in S Per taken with KaVA (by K. Kusuno, Y. Asaki) Figure 4 (bottom left) SiO maser map in BX Cam taken with KaVA/KJCC (by H. Imai) v=1 peak flux = 53.7 Jy channel /beam Levs = 0.54*(1, 2.6, 6.6, 16.8, 43, 69) Decl. offset (milliarcsecond) R.A. offset (milliarcsecond) 430 425 420 415 410 405 400 -235 -240 -245 -250 -255 -260 v=2 peak flux = 87.4 Jy channel /beam Levs = 0.88*(1, 2.600, 6.600, 16.80, 43, 69) SiO v=1 J=1→0 SiO v=2 J=1→0 BX Cam Figure 1 Schematic view of the spatial and density structure of a circumstellar envelope of an oxygen-rich (intermediate-mass) long-period pulsating star that hosts SiO and H2O masers. Gas ejected from the stellar surface forms molecules, then oxygen/silicon-rich dust (e.g. silicate and olivine). The dust particles are accelerated by stellar radiative pressure received through scattering of stellar infrared radiation. The microscopic (dust condensation) and macroscopic (turbulence, shock waves) process should be linked and explored in the KaVA projects. H 2 O maser SiO v=1 maser SiO v=2 maser VLBI position uncertainty SiO maser ring HIPPARCOS stellar position and its uncertainty Distance from the star (stellar radus) Expansion velocity [km/s] 0 5 10 15 0 5 10 15 20 With shock waves SiO masers H 2 O masers shock wave propagation per year KaVA angular resolution at 1 kpc Without shock waves Figure 2 Schematic view of the radial velocity field of a circumstellar envelope of a pulsating star and the locations of the hosting SiO and H2O masers. Pulsation driven shock waves will be detectable by directly finding the velocity field and its time variation in the intensive KaVA monitoring program over a few stellar pulsation cycles. Current progress towards the Large Programs Imaging feasibility image quality comparable to that with the VLBA (figure 3, 4) Snapshot imaging feasibility Focused image in <2 hour integration time with a good (u,v) coverage Feasibility of maser map registration onto a common coordinate system Feasible in the source-frequency phase-referencing technique (Figure 5) Now testing it in KaVA operation Feasibility of maser source astrometry feasible with VERA dual beam, testing in antenna fast-nodding mode Scheduling of single observation session testing hybrid operation (KaVA imaging + VERA astrometry + KVN SFPR) Modeling of long-term campaign Confirming the reality of biweekly-monthly monitoring operation, including scheduling, array operation, correlation, data processing, and archive S Per on 2012 March 30 Peak flux = 0.24 Jy channel /beam Levs = 0.024* (-10, -9, -8, -7, -6, -5, -4, -3, -2, -1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10) Decl. offset (mas) R.A offset (mas) 100 50 0 -50 -100 100 80 60 40 20 0 -20 -40 -60 -80 -100 Figure 5 Demonstration of the source-frequency phase-referencing technique (SFPR) with KVN (Dodson et al. 2014). This technique will be adopted in the KaVA Large Programs. Note that this request high precision maser source astrometry as made with VERA as well.
Transcript of KaVA Large Programs of Circumstellar Masers
KaVA Large Programs of Circumstellar MasersKaVA Evolved Stars sub-Working GroupHiroshi Imai*1, Se-Hyung Cho*2, Miyako Oyadomari1, Gabor Orosz1, Akiharu Nakagawa1, Youngjoo Yun2, Jaeheon Kim2, Yoon-Kyong Choi2, Taehyun Jung2, Soon-Wook Kim2, Naoko Matsumoto3, Cheul-Hong Min3, Jeong-Sook Kim3, Yoshiharu Asaki4, Fujika Watari5, Maria J. Rioja6, Richard Dodson6, and Tao An7
*co-chair of sub-WG; 1Kagoshima Univ.; 2KVN/KASI; 3NAOJ Mizusawa; 4ISAS/JAXA; 5Yokohama City Univ.; 6ICRAR/UWA; 7SHAO
Specification of the Large ProgramsPhase 1: ESTEMA (Expanded Study on Stellar Masers)during 2015̶2016, ~200 hoursSnapshot imaging of H2O and SiO masersin circumstellar envelopes (Figure 1) around ~80 stars● statistics of stellar masers i. maser spot sizes and phapes ii. distributions of H2O masers with respect to locations of SiO masers iii. correlation with kinematic parameters of circumstellar envelopes and stars● yielding a larger sample of stars as targets of the Phase 2 project
Phase 2: Intensive monitoring campaignduring 2016̶2024, 400̶500 hours/year16—20 pulsating stars (P=300—1600 days)monitoring SiO and H2O masers in every 1/20 pulsation cycle over a few pulsation cycles for “stellar maser movie” synthesis● detecting (both or either) i) propagation of pulsation-driven shock waves (Figure 2) ii) periodic change in physical conditions affected by stellar radiation● Comprehensive synergy with ALMA, VLTI, Nano-JASMINE
Figure 3 (top left) H2O maser map in S Per taken with KaVA (by K. Kusuno, Y. Asaki)Figure 4 (bottom left) SiO maser map in BX Cam taken with KaVA/KJCC (by H. Imai)
v=1 peak flux = 53.7 Jy channel /beam Levs = 0.54*(1, 2.6, 6.6, 16.8, 43, 69)
Dec
l. of
fset
(mill
iarc
seco
nd)
R.A. offset (milliarcsecond)430 425 420 415 410 405 400
-235
-240
-245
-250
-255
-260
v=2 peak flux = 87.4 Jy channel /beam Levs = 0.88*(1, 2.600, 6.600, 16.80, 43, 69)
SiO v=1 J=1→0SiO v=2 J=1→0
BX Cam
Figure 1 Schematic view of the spatial and density structure of a circumstellar envelope of an oxygen-rich (intermediate-mass) long-period pulsating star that hosts SiO and H2O masers. Gas ejected from the stellar surface forms molecules, then oxygen/silicon-rich dust (e.g. silicate and olivine). The dust particles are accelerated by stellar radiative pressure received through scattering of stellar infrared radiation. The microscopic (dust condensation) and macroscopic (turbulence, shock waves) process should be linked and explored in the KaVA projects.
H2O maserSiO v=1 maserSiO v=2 maser
VLBI position uncertainty
SiO maser ring
HIPPARCOS stellar position and its uncertainty
Distance from the star (stellar radus)
Exp
ansi
on v
elo
city
[km
/s]
0 5 10 15
0
5
10
15
20
With shock waves
SiO masers H2O masers
shock wave propagation per year
KaVA angular resolution at 1 kpc
Without shock waves
Figure 2 Schematic view of the radial velocity field of a circumstellar envelope of a pulsating star and the locations of the hosting SiO and H2O masers. Pulsation driven shock waveswill be detectable by directly finding the velocity field and its time variation in the intensive KaVA monitoring program over a few stellar pulsation cycles.
Current progress towards the Large ProgramsImaging feasibilityimage quality comparable to that with the VLBA (figure 3, 4)Snapshot imaging feasibilityFocused image in <2 hour integration time with a good (u,v) coverageFeasibility of maser map registration onto a common coordinate systemFeasible in the source-frequency phase-referencing technique (Figure 5)Now testing it in KaVA operationFeasibility of maser source astrometryfeasible with VERA dual beam, testing in antenna fast-nodding modeScheduling of single observation sessiontesting hybrid operation (KaVA imaging + VERA astrometry + KVN SFPR) Modeling of long-term campaignConfirming the reality of biweekly-monthly monitoring operation, including scheduling, array operation, correlation, data processing, and archive
S Per on 2012 March 30
Peak flux = 0.24 Jy channel /beam Levs = 0.024* (-10, -9, -8, -7, -6, -5, -4, -3, -2, -1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
Dec
l. of
fset
(mas
)
R.A offset (mas)100 50 0 -50 -100
100
80
60
40
20
0
-20
-40
-60
-80
-100
Figure 5 Demonstration of the source-frequency phase-referencing technique (SFPR) with KVN (Dodson et al. 2014). This technique will be adopted in the KaVA Large Programs. Note that this request high precision maser source astrometry as made with VERA as well.
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