EAVN WS, Aug 24-26, 2019, Ibaraki University, Mito, Japan

Astrometric observation ofExtreme-OH/IR stars with VERAAkiharu NAKAGWA(1), Atsushi MORITA(1), Tomoharu KURAYAMA(2), Hiroshi SUDOU(3)(1)Kagoshima University, (2)Teikyo University of Science, (3)Gifu University(1): VLBI astrometry of LPVs with VERA,
from Miras to Extreme-OH/IR stars.
(2): H2O maser in an individual star “NSV17351”.

AGB, OH/IR star and Extreme-OH/IR star
Understanding of stellar parameters and evolution based on precise VLBI astrometry

Hofner & Olofsson(2018)

SiO

H2OOHa few aua few×10 aua few×1000au

・Mass 1～8 M◎ （Typical Mira:1～2.5 M ）・C/O-core, He-shell, H-rich envelope →O-rich/C-rich・Period 100～1000 d, P>1000 d
・High mass loss ratio →Chemical evolution
・P-M relation → Distance estimator◎65 project sources, ~30 parallaxes were measured.
ID

Src.

TypeR.A.

Dec.

ID

Src.

TypeR.A.

Dec.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
1920
21
22
23
24
25
26
27
28
29
30
31
3233

W Hya
T Lep
RX_BooS_Crt
AP LynR UMa
WX_PscZ Pup
SY SclY Lib
VX UMaGX Mon
U Lyn
T UMa
S CrB
SW Lib
FS Lib
IRC-20540
IRC+10374
X Hya
R Cnc
FV_BooRU_Ari
RW_Lep
BW_CamBX_CamU_Ori
QX_Pup
RS_VirSY_AqlSV_Peg
R_Tau
OZ_Gem

SR
Mira
SR
SR
Mira
Mira
Mira
Mira
Mira
Mira
Mira
Mira
Mira
Mira
Mira
Mira
Mira
Mira
Mira
Mira
Mira
SR
SR
SR
Mira
Mira
Mira
Mira
Mira
Mira
SRb
Mira
Mira

13h49m01.9980s
05h04m50.7999s
14h24m11.5998s
11h52m45.1000s
06h34m33.8999s
10h44m38.3999s
01h06m25.8998s
07h32m38.1000s
00h07m36.2000s
15h11m41.2999s
10h55m39.8999s
06h52m46.8999s
06h40m46.5000s
12h36m23.5000s
15h21m24.0000s
15h55m33.3999s
16h00m23.8000s
19h08m56.0000s
18h43m36.7000s
09h35m30.3000s
08h16m33.7999s
15h08m25.8000s
02h44m45.5000s
05h38m52.7000s
05h19m52.5600s
05h46m44.2999s
05h55m49.2000s
07h42m16.8298s
14h27m16.3998s
20h07m05.4000s
22h05m42.0850s
04h28m18.0000s
07h33m57.7500s-28d22m03.488-21d54m16.500+25d42m13.000-07d35m48.100+60d56m26.199+68d46m32.298+12d35m53.000-20d39m29.199-25d29m40.000-06d00m41.399+71d52m09.800+08d25m19.000+59d52m01.600+59d29m13.000+31d22m02.600-12d51m05.099-12d20m57.500-22d14m19.399+13d57m22.800-14d41m28.600+11d43m34.500+09d36m18.199+12d19m03.000-14d02m27.199+63d15m55.798+69d58m24.199+20d10m30.699-14d42m52.100+04d40m41.100+12d57m06.299+35d20m54.536+10d09m44.798+30d30m37.798

34
35
36
37
38
39
40
4142
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
5960
61
62
6364
65

V353_Pup
HU_PupHS_UMaR_LMi
BX_EriV637_Per
U_CVn
RU_HyaNSV17351
R_Peg
R_Hya
OH127.8
NSV25875
UU_Peg
R_Cas
S_Ser
W_Leo
OH32.8-0.3
V391CYGRAFGL5201
OH83.4-0.9
OH141.7+3.5
CU_Cep
DU_PupRAFGL2445
OH39.7+1.5
EUAND
AWTAU
I17411-3154
OH26.5+0.6
OH42.3-0.1
TXCAM

SR
SR
LPV
Mira
SR
SR
Mira
Mira
OHIR
Mira
Mira
OHIR
OHIR
Mira
Mira
Mira
Mira
OHIR
Mira
OHIR
OHIR
OHIR
OHIR
Mira
OHIR
OHIR
C
Mira
Mira
OHIR
OHIR
Mira

07h46m34.1510s
07h55m40.1600s
11h35m30.70408s
09h45m34.28304s
04h40m32.754s
03h54m02.28s12h47m19.61s
14h11m34.39861s
07h07m49.38s
23h06m39.16689s
13h29m42.78187s
01h33 51.21s
22h19m27.48s
21h31m04.156s
23h58m24.87336s
15h21m39.53475s
10h53m37.43245s
18h52m24.682333s
19h40m52.394300s
06h34m28.052569s
20h50m58.619647s
03h33m30.618480s
22h11m31.882483s
07h35m03.978770s
19h44m07.000754s
18h58m30.094784s
23h19m58.881502s
05h47m30.209209s
17h44m24.003874s
18h37m32.51s
19h09m07.466221s
05h00m51.156996s-32d18m16.260-28d38m54.840+34d52m04.1775+34d30m42.7839-14d12m02.39+36d32m17.6+38d22m30.5-28d53m07.4089-10d44m05.9+10d32m36.0892-23d16m52.7747+62d26m53.2+59d51m21.7+11d09m13.24 92+51d23m19.7011+14d18m53.1002+13d42m54.3666-00d14m57.612+48d47m41.52658-05d03m42.85697+42d48m11.44793+60d20m08.85024+57d02'17.46857''-23d59'14.80023''+35d14'08.25184"+06d42'57.69806"+47d14'34.57638"+27d08'12.40939"-31d55'35.42862"-05d23'59.2"+08d16'22.70258"+56d10'54.09311"

Period-Mk diagram of Miras in the Galaxy

Nakagawa et al. IAUS343 Proceeding

We need wide period coverage.

Images of Extreme-OH/IR stars

VLBI and Gaia are complementary to each other.

OH127.8+0.0

DSS colored

ALLWISE volor Red(W4), Green(W2),Blue(W1) from raw Atlas Images

NSV25875
Peak 1.97 Jy/beam

2MSS color J(1.23um),H(1.66um),K(2.16um)

・43GHz astrometric observation
with VERA from Nov. 2017
・QSO: J2231+5922, ~240mJy@43GHz
・SiOmaser(v=2), S/N=10AKARIFIS Color
WideL(140um),SideS(90um),N60(65um)

Phase referencing observation @43GHz, 2Gbps (512MHz BW for QSO)
Parallax = 0.38±0.13 mas, D = 2.60±0.85 kpc
RADEC

NSV25875

Sky plane

Parallax = 0.22±0.08 mas, D = 4.54±1.14 kpc(μx, μy) = (－1.18±0.12, －1.10±0.11) [mas/yr]

OH127.8+0.0

Sky plane

RADECPhase referencing observation of NSV17351@22GHz, 1Gbps (240MHz BW for QSO)【VLBI】・ Parallax(VERA) = 0.25±0.01 mas-> D = 3.95±0.2 kpc
・(μx, μy) = (－1.16±0.05, 1.35±0.09) [mas/yr]【Gaia】・ Parallax(DR2) = 0.35±0.23 mas
・(μx, μy) = (1.34±0.4, -0.38±0.4) [mas/yr]
Sky plane

No Gaia DR2 parallax for previous two
Extreme-OH/IR stars, NSV25875 and OH127.8.
● -> VLSR = 38.73 km/s
● -> VLSR = 40.41 km/s

P-Mk diagram with continuous period coverage
Three annual parallax of Extreme-OH/IR stars were added.

SRMiraExtreme-OH/IR

Three new sourcesin P > 1000 day

(2): H2O maser in an individual star
“NSV17351”.

Acceleration of H2O maser in NSV17351
1991, Kashima 34m(Takaba et al. 1994)

45 yrs
Acceleration
0.21±0.12 km/s/yr

2009, KVN 21m(Kim et al. 2010)

ΔVTime2018, VERA-IRIKI 20m(our result)

4060

・ΔV= ｜V_blue －V_red｜
・Very weak 1612 MHz OH maser(~400mJy in 1987)

Similarity of spectrums, H2O and OH maser
OH maser@1612MHzOH127.8+0.0

Similar characteristics
between H2O and OH
・Steep edges
・U-shaped hollow

Baud et al. 1979

H2O maser@22GHzNSV17351<Hypothesis>

H2O gas in NSV17351
has experienced anacceleration and reacheda terminal velocity in thelast 45 years.
H2O shell radius at theterminal velocity iscalculated to be >65 au.

Similarity of positions between H2O and OHmaser also supports the hypothesis
Bluest emission was found at an assumed stellar position.
OH maser @ 1612 MHz

OH138.0+7.2

Orosz et al. 2018

H2O maser @ 22 GHz

NSV17351

Our result...However, sky plane motion of the bluest masers are puzzling.

Summary:(1): VLBI astrometry of LPVs,
from Miras to Extreme-OH/IR stars.

H2O maser@22GHz, NSV17351

Fitting→ P = 1089 day・Study of evolutional relation of LPVs
・22 and 43GHz astrometric observation
・~30 parallaxes were determined・New parallaxes of 3 extreme-OH/IR stars
・Single-dish monitoring is also ongoing
Variability in 1600 days(4.4 yr)(2): H2O maser in an individual star “NSV17351”.
・Acceleration was found in H2O maser spectrum
・We detected 45 years acceleration of circumstellar H2O gas
・Similarities of spectrum shapes and positions of H2O maser supports
the hypothesis
・Single dish monitoring of H2O/SiO maser at VERA-IRIKI station
for determination of periods of Extreme-OH/IRstars