2013/10/02-03
11th 水沢VLBI観測所-UM @ 三鷹, NAOJ	
山口大学	

Astrometry of the H2O Masers in
the Periodic Flux Variation Source
G12.681-0.182 (VERA11-72)	
杉山 孝一郎（山口大学 大学院理工学研究科 藤沢研究室）	
Collaborator： 元木業人, 藤沢健太 （山口大学）, 本間希樹 （国立天文台）, 米倉覚則, 百瀬宗武 （茨城大学）, 蜂須賀一也 （上海天文台）, 稲吉恒平 (京都大学), 田中圭 (東北大学), 細川隆史 (東京大学), 内山瑞穂 (東京大学), S. Ellingsen (UTAS), J. A. Green (ATNF)

周期的なCH3OHメーザー強度変動	

6.7 GHz CH3OHメーザー: 周期変動	
q 大質量星周囲では珍しい現象
q 全スペクトル成分間で同期☞ 励起源近傍 or 星表面で生じる物理現象！？

B500日	CDHI
G331.13-0.24 のCH3OHメーザー周期強度変動 (Goedhart+ 04, 07)	

6.7 GHz CH3OHメーザー: 周期変動	
q 大質量星周囲では珍しい現象
q 全スペクトル成分間で同期☞ 励起源近傍 or 星表面で生じる物理現象！？
q 周期: 30-670日
B

500日	

C
D
H
I
G331.13-0.24 のCH3OHメーザー周期強度変動 (Goedhart+ 04, 07)	

6.7 GHz CH3OHメーザー: 周期変動	
q 大質量星周囲では珍しい現象
q 全スペクトル成分間で同期☞ 励起源近傍 or 星表面で生じる物理現象！？
q 周期: 30-670日
q 傾向は連続的 or 間欠的 の両方存在
A

300日	

A
B

B

G009.62+0.20 E のCH3OHメーザー周期強度変動 (Goedhart+ 03, 04)	

周期変動天体： これまでのまとめ	
q 周期変動天体数– 11天体+ 1天体 (山口大: 高瀬, 藤沢)q 周期: 30-670 日q “YSO”に多い (8/11)
q “連続的”が多い (8/11)
q 既存連星モデル CWB(van der Walt 11)では大半が説明困難– 周囲に卓越した電離領域(HII領域など) が必須

Period!

出現時期	

変動傾向	

009.62+0.20

244

HC HII

間欠的	

012.68-0.18

307

UC HII ?

連続的	

012.88+0.48

29.5

YSO

連続的	

022.35+0.06

179

YSO

間欠的	

037.55+0.20

237

YSO

間欠的	

188.95+0.88

404

HC HII

連続的	

196.45-1.67

668

YSO

連続的	

328.23-0.54

220

YSO

連続的	

331.13-0.24

504

YSO

連続的	

338.93-0.06

133

YSO ?

連続的	

339.62-0.12

201

YSO

連続的	IRAS 22198

34.5

中質量 ?

間欠的	Source!

Goedhart+ (04, 07, 09); Araya+ (10); Szymczak+ (11);Fujisawa+ (in prep).	

大質量原始星の脈動不安定モデル(Inayoshi et al. 2013)
The Astrophysical Journal Letters, 769:L20 (5pp), 2013 June 1
1000– 星内部構造モデルがベース

accretion rate

– 様々な進化段階、および質量降着率に対して実施q 膨張半径最大時に不安定帯が存在– κ機構– > 10-3 M◎/yr– ~1000 yr 滞在

R (Rsun)(Hosokawa & Omukai 09)
10010(Inayoshi+ 13)

S	ZAM
10100

M (Msun)Figure 1. Evolution of the protostellar radius with various accretion ratesṀ∗ = 10−4 , 10−3 , 3 × 10−3 , and 6 × 10−3 M$ yr−1 (taken from HO09). The
symbols indicate the stellar models for which we conduct the linear stability
analysis. The circles and stars represent the pulsationally stable and unstablemodels, respectively. The shaded layer denotes the instability strip where theprotostar becomes unstable.
(A color version of this figure is available in the online journal.)q CH3OHメーザー周期変動を説明可能– 原始星時代の変動– 連続的な変動– HII領域必要ナシ

6e-3
3e-3
1e-31e-44q 星の脈動解析◯: 安定モデル☆: 不安定モデル
脈動不安定帯	evolution is briefly summarized as follows (see HO09 fordetails). Initially, the stellar radius gradually increases withincreasing stellar mass. After this stage, e.g., M∗ ! 10 M$ forFig
thin
acc
Theeigshorelaope
witsouRei(A大質量原始星の脈動不安定モデル(Inayoshi et al. 2013)
The Astrophysical Journal Letters, 769:L20 (5pp), 2013 June 11000– 星内部構造モデルがベース

accretion rate

– 様々な進化段階、および質量降着率に対して実施q 膨張半径最大時に不安定帯が存在– κ機構– > 10-3 M◎/yr– ~1000 yr 滞在

R (Rsun)(Hosokawa & Omukai 09)
10010(Inayoshi+ 13)

S	ZAM
10100

M (Msun)Figure 1. Evolution of the protostellar radius with various accretion ratesṀ∗ = 10−4 , 10−3 , 3 × 10−3 , and 6 × 10−3 M$ yr−1 (taken from HO09). The
symbols indicate the stellar models for which we conduct the linear stability
analysis. The circles and stars represent the pulsationally stable and unstablemodels, respectively. The shaded layer denotes the instability strip where theprotostar becomes unstable.
(A color version of this figure is available in the online journal.)q CH3OHメーザー周期変動を説明可能– 原始星時代の変動– 連続的な変動– HII領域必要ナシ6e-33e-31e-3
1e-44q 星の脈動解析◯: 安定モデル☆: 不安定モデル
脈動不安定帯	evolution is briefly summarized as follows (see HO09 fordetails). Initially, the stellar radius gradually increases withincreasing stellar mass. After this stage, e.g., M∗ ! 10 M$ forFig
thinacc
Theeig
sho
rela
ope
wit
souRei(AWe see that the pulsation periods of the unstable modeare several 10 − 100 days, the same order of the observe
periods of the maser sources. Although the pulsation priod is shorter than 10 days with the low accretion ratṀ∗ ! 10−3 M# yr−1 , the instability strip does not cov
such cases as explained above. This explains well whthe maser sources which have such the short period
x 10-3	 not been observed.
variability6 have
Our calculations
predict that both the period and l
3 x 10-3	
minosity of the pulsationally unstable protostars increa
with the accretion rate. We thus predict a positive corr
1 x 10-3	
lation between the maser periodicity and the stellar lum
nosity. We fit the unstable models by a single power laand obtain the period-luminosity (P-L) relation (thiline in Fig. 2)

大質量原始星の周期-光度関係	

log(L/L# ) = 4.62 + 0.98 log(P/100 days),(which is similar to that of the Cepheids (L ∝ P 4/3
which is well-used as a cosmic distance ladder (e.g., Tam
予言される
relation: etInayoshi+13）	 The above P
mann周期-光度関係（P-Let al. 2003; Sandage
al. 2004).
relation and the instability strip can explain the di周期-光度関係の恩恵	q原始星表面の物理パラメータ（質量、光度、半径、質量降着率）が取得可能に！
– sub-AU スケール
• 現存装置(ALMA含む)ではおよそ観測不可能な領域– それを低空間分解能な単一鏡で実行可能！	
The Astrophysical Journal Letters, 769:L20 (5pp), 2013 June 1

Inayoshi et al.

Table 1
Methanol Maser Sources with Periodic Variability
SourcePmet

Dsrc(Galactic Name)(days)(kpc)

009.621+0.196
012.681−0.182
012.889+0.489
022.357+0.066
037.550+0.200
188.946+0.886
196.454−1.677
328.237−0.547
331.132−0.244
338.935−0.062
339.622−0.121

244
307
29.5
179.2
237
404
668
220
504
133
201

5.2
4.5
2.34
4.6
5.0
2.10
5.28
12.0
4.7
2.9
2.6

(Inayoshi+ 13)

LIRAS(104 L! )
30.0
4.2
2.0
2.4
4.5
1.2
10.2
117.26.23.81.6References
PD123451211116789910119799Notes. Column 1: name of the source; Column 2: variability period; Column 3:

周期-光度関係の恩恵	q原始星表面の物理パラメータ（質量、光度、半径、質量降着率）が取得可能に！
– sub-AU スケール
• 現存装置(ALMA含む)ではおよそ観測不可能な領域– それを低空間分解能な単一鏡で実行可能！	
The Astrophysical Journal Letters, 769:L20 (5pp), 2013 June 1

Inayoshi et al.

Table 1
Methanol Maser Sources with Periodic Variability
SourcePmet

Dsrc(Galactic Name)(days)(kpc)

009.621+0.196
012.681−0.182
012.889+0.489
022.357+0.066
037.550+0.200
188.946+0.886
196.454−1.677
328.237−0.547
331.132−0.244
338.935−0.062
339.622−0.121

244
307
29.5
179.2
237
404
668
220
504
133
201

5.2
4.5
2.34
4.6
5.0
2.10
5.28
12.0
4.7
2.9
2.6

(Inayoshi+ 13)

LIRAS(104 L! )
30.0
4.2
2.0
2.4
4.5
1.2
10.2
117.2
6.2
3.8
1.6

References
PD

12
345
12
1
111

6
78
9910119799Notes. Column 1: name of the source; Column 2: variability period; Column 3:

We see that the pulsation periods of the unstable modeare several 10 − 100 days, the same order of the observe
periods of the maser sources. Although the pulsation priod is shorter than 10 days with the low accretion rat
Ṁ∗ ! 10−3 M# yr−1 , the instability strip does not cov
such cases as explained above. This explains well wh
運動学的	the maser sources which have such theshort period
x 10-3	 not been observed.
variability6 have
年周視差	Our calculations
predict that both theperiod and l
3 x 10-3	
minosity of the pulsationally unstable protostars increa
with the accretion rate. We thus predict a positive corr
1 x 10-3	
lation between the maser periodicity and the stellar lumnosity. We fit the unstable models by a single power laand obtain the period-luminosity (P-L) relation (thiline in Fig. 2)

大質量原始星の周期-光度関係	

log(L/L# ) = 4.62 + 0.98 log(P/100 days),(which is similar to that of the Cepheids (L ∝ P 4/3
which is well-used as a cosmic distance ladder (e.g., Tam
予言される
relation: etInayoshi+13）	 The above P
mann周期-光度関係（P-Let al. 2003; Sandageal. 2004).
relation and the instability strip can explain the diWe see that the pulsation periods of the unstable modeare several 10 − 100 days, the same order of the observe
periods of the maser sources. Although the pulsation p
riod is shorter than 10 days with the low accretion rat
Ṁ∗ ! 10−3 M# yr−1 , the instability strip does not cov
such cases as explained above. This explains well wh
運動学的	the maser sources which have such theshort period
x 10-3	 not been observed.
variability6 have
年周視差	Our calculations
predict that both theperiod and l
3 x 10-3	
minosity of the pulsationally unstable protostars increa
with the accretion rate. We thus predict a positive corr
1 x 10-3	
lation between the maser periodicity and the stellar lumnosity. We fit the unstable models by a single power laand obtain the period-luminosity (P-L) relation (thiline inKinematicFig. 2)
distance な天体が多い（7/11）	

大質量原始星の周期-光度関係	

log(L/L# ) = 4.62 + 0.98 log(P/100 days),(which is similar to that of the Cepheids (L ∝ P 4/3
which is well-used as a cosmic distance ladder (e.g., Tam
予言されるrelation: etInayoshi+13）	 The above P
mann周期-光度関係（P-L
et al. 2003; Sandageal. 2004).
relation and the instability strip can explain the di本研究の目的	
q最終ゴール– 大質量原始星周囲で予言される脈動不安定現象を観測的に検証する① P-L relation の観測的検証・確立② 周囲の物理環境温度の変動モニターq本講演では– 最終ゴール① へのアプローチ• 問題点： kinematic distance 天体が多い• 解決法： parallax で高精度に距離計測☞

天体光度の見積もりに貢献	観測天体	

G12.681-0.182 (W33 B)	
q Dkin: 4.5 kpc (near kinematic @V lsr 56 km/s)q “準”周期的な強度変動 (Goedhart+ 04)– 周期： 307 (±60) 日, 全スペクトル成分で同期q IRAS Lbol: ~ 4 x 104 L◎	G12.681-0.182 のCH3OHメーザー周期強度変動 (Goedhart+ 04)	

We see that the pulsation periods of the unstable modeare several 10 − 100 days, the same order of the observe
periods of the maser sources. Although the pulsation priod is shorter than 10 days with the low accretion ratṀ∗ ! 10−3 M# yr−1 , the instability strip does not cov
such cases as explained above. This explains well wh
運動学的	the maser sources which have such theshort periodx 10-3	 not been observed.
variability6 have
年周視差	
Our calculations
predict that both theperiod and l
3 x 10-3	
minosity of the pulsationally unstable protostars increa
withthe accretion rate. We thus predictターゲット	a positive corr-3	1 x 10lation between the maser periodicity and the stellar lumnosity. We fit the unstable models by a single power laand obtain the period-luminosity (P-L) relation (thiline in Fig. 2)

大質量原始星の周期-光度関係	

log(L/L# ) = 4.62 + 0.98 log(P/100 days),(which is similar to that of the Cepheids (L ∝ P 4/3
which is well-used as a cosmic distance ladder (e.g., Tam
予言される
relation: etInayoshi+13）	 The above P
mann周期-光度関係（P-L
et al. 2003; Sandageal. 2004).
relation and the instability strip can explain the diVERA共同利用観測(VERA11-72)	

観測・解析概要	q 観測– アレイ： VERA (2ビーム)– 対象： H2O メーザー
– 時期： 2012/01-2013/04– 回数： 6 エポック
– 参照電波源: J1818-1705• 離角： 1.36°• 暗いので “逆”位相補償q 解析– 較正・イメージング： AIPS
– Parallax： VEDA

Epoch	 Obs. code	 yyyy/mm/dd	
1 st	r 12026b	

2012/01/26	

2 nd	r 12108b	2012/04/17	

3 rd	r 12206a	

2012/07/24	

4 th	r 12275a	

2012/10/01	

5 th	r 13028b	

2013/01/28	

6 th	r 13119b	

2013/04/29	

使用した スペクトル feature	
200

1 epoch2 epoch3 epoch
4 epoch5 epoch
6 epochFlux density [Jy]

150

100

50

050

52

5456

5860

62-1

LSR Velocity [km s ]646668使用した スペクトル feature	
200

1 epoch2 epoch3 epoch
4 epoch5 epoch
6 epochFlux density [Jy]

150

100

50

050

52

54

56

5860

62-1

LSR Velocity [km s ]

6466

68

V lsr 61.85 km/s: 使用メーザスポット	
200

CLEANed image
1st epoch (r12026b)	

1 epoch2 epoch3 epoch
4 epoch5 epoch
6 epochFlux density [Jy]1501005006161.5

6262.563

LSR Velocity [km s-1]

20 mas	q 強度変動小q 視線速度ドリフト小− 少なくとも速度分解能以内でq シングルスポット @ 1ch	

参照電波源の逆位相補償イメージ	
Dirty image
1st epoch (r12026b)	

CLEANed image
1st epoch (r12026b)	

~ 30 mJy beam-1	

20 mas	

20 mas	（暫定）結果	

-23.5

RA 方向q Dpara: 2.9+2.0	
−0.9	kpc– χ2 ~1 となるように各

Offset [mas]-24

計測点の誤差調整-24.5-25-25.5(e.g., Reid+ 09)• ~ 250 µas

21Offset [mas]– Dpara /Dkin ~ 0.6

Dec 方向

21.5

20.5

2019.51918.5180100200300400

DOY [day]

500600700

（暫定）結果	

-23.5

RA 方向

q Dpara: 2.9+2.0	−0.9	kpc– χ2 ~1 となるように各

Offset [mas]-24

計測点の誤差調整-24.5-25-25.5(e.g., Reid+ 09)• ~ 250 µas

しかし。。。
+0.17	
2.40 −0.15	 kpc
(VLBA: Immer+ 13)

21

Offset [mas]– Dpara /Dkin ~ 0.6

Dec 方向

21.5

20.5

2019.51918.5180100200300400

DOY [day]

500600700

We see that the pulsation periods of the unstable modeare several 10 − 100 days, the same order of the observe
periods of the maser sources. Although the pulsation priod is shorter than 10 days with the low accretion rat
Ṁ∗ ! 10−3 M# yr−1 , the instability strip does not cov
such cases as explained above. This explains well wh
運動学的	the maser sources which have such theshort period
x 10-3	 not been observed.
variability6 have
年周視差	
Our calculations
predict that both theperiod and l
3 x 10-3	
minosity of the pulsationally unstable protostars increawiththe accretion rate. We thus predictターゲット	
a positive corr-3	
1 x 10lation between the maser periodicity and the stellar lumnosity. We fit the unstable models by a single power laand obtain the period-luminosity (P-L) relation (thiline in Fig. 2)

大質量原始星の周期-光度関係	

log(L/L# ) = 4.62 + 0.98 log(P/100 days),(which is similar to that of the Cepheids (L ∝ P 4/3
which is well-used as a cosmic distance ladder (e.g., Tam
予言されるrelation: etInayoshi+13）	 The above P
mann周期-光度関係（P-L
et al. 2003; Sandageal. 2004).
relation and the instability strip can explain the diWe see that the pulsation periods of the unstable modeare several 10 − 100 days, the same order of the observe
periods of the maser sources. Although the pulsation priod is shorter than 10 days with the low accretion ratṀ∗ ! 10−3 M# yr−1 , the instability strip does not cov
such cases as explained above. This explains well wh
運動学的	the maser sources which have such theshort period
x 10-3	 not been observed.
variability6 have
年周視差	
Our calculations
predict that both theperiod and l
3 x 10-3	
minosity of the pulsationally unstable protostars increa
withthe accretion rate. We thus predict今回の計測	
a positive corr-3	
1 x 10lation between the maser periodicity and the stellar lumnosity. We fit the unstable models by a single power laand obtain the period-luminosity (P-L) relation (thi理論線から遠ざかる方向へ改定	
line in Fig.
2)

大質量原始星の周期-光度関係	log(L/L# ) = 4.62 + 0.98 log(P/100 days),(which is similar to that of the Cepheids (L ∝ P 4/3
which is well-used as a cosmic distance ladder (e.g., Tam
予言されるrelation: etInayoshi+13）	 The above P
mann周期-光度関係（P-Let al. 2003; Sandageal. 2004).
relation and the instability strip can explain the di考察	
q準周期で連続的な変動ではない？
– 307 (±60) 日 周期と誤差が大きい– “間欠的”な変動は脈動モデルでは説明困難

q赤外線フラックスの見積もりの誤差大きい？
– IRASは空間分解能が不足• 各YSOへの分離困難– SEDモデル (Robitaille+ 06) 自体の改善・利用が必要

q理論予言線の傾きが異なる？
– 今後の観測成果を踏まえたフィードバックが必要まとめ・展望	まとめ	
q大質量原始星の脈動不安定モデルの出現– CH3OHメーザー周期変動の要因として適当– 原始星表面の物理パラメータ取得に大きく貢献！？

qP-L relation の観測的検証・確立を目指して– 周期変動天体の年周視差計測• G12.681-0.182： Dpara = 2.9 +2.0	−0.9	 kpc
– Dpara /Dkin ~ 0.6• 理論予言線から遠ざかる方向へ改定– 間欠的？ 赤外線フラックスの見積もり不足？
– 理論モデルへのフィードバックも大いに必要

今後の展望	q 個別：G12.681-0.182– 他に使用可能なスポットサーベイ– 参照電波源に対するセルフキャルで構造の有無を調査

q 全体– P-L relation の観測的検証・確立• 南半球でも同様な年周視差計測を計画・実施• サンプル数の増加を目指した、大規模な長期高頻度単一鏡モニター （日立32-m @茨城大学 で実施継続中）– 周囲の物理環境温度の変動モニター• 円盤由来の温度変動を近・中赤外線モニターで観測 （PI: 内山）• ALMAでダスト温度変動モニター！？