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IAU Symposium 242, Alice Springs, March 2007

SiO Maser Observations of a Wide Dust-Temperature Range Sample

Jun-ichi Nakashima
Academia Sinica Institute of Astronomy & Astrophysics, Taiwan

Shuji Deguchi
Nobeyama Radio Observatory, Japan

Outline of the Project
Aims: Investigating the correlation between IR colors and the SiO maser intensity ratios n Methods: Observing a wide Tdust (color) range sample in multiple SiO lines n Result 1: Confirmed the correlation between IR colors and J=1-0 [v=2]/[v=1] n Result 2: Found possible correlation between IR colors and J=1-0 [v=3]/[v=1&2]
n

Background and Motivation
SiO 43 GHz (v=2)/(v=1) ratio
6 5 4 3 2 1 0 1 2 3 4 5 6 7 8

OH/IR stars

K-L > 4 K-L < 4

Reproduced from Nyman et al. 1993

K-L

Approach
n
Deguchi 2003)

Found ~40 SiO maser sources below Tdust=250 K (Nakashima &

n

Key point: Sample covers a wide Tdust (color) range:
150 K < T
dust

< 2000 K

n

1 v=1&2, 29SiO J=1-0&2-1 v=0, 30SiO J=1-0 v=0, H2O 61,6-52,3

Observed simultaneously in the multiple SiO transition lines: SiO J=1-0 v=0, 1, 2, 3, 4, SiO J=2Observed with the NRO 45m telescope (May 2004, Feb. 2006)

n
NRO 45m telescope

log(F25/F12) vs. SiO Line Ratios
log([J=1-0 v=3]/[J=1-0 v=2]) log([J=1-0 v=2]/[J=1-0 v=1])
1.6 1.2 0.8 0.4 0

log([J=1-0 v=3]/[J=1-0 v=1])

corr: 0.59

A

1

corr: 0.40

C

0

-1

-0.4 -0.8 -1.2 -0.6 0.5 0

-2

-0.4

-0.2

0

0.2

0.4

0.6

0.8

-3 -0.6

-0.4

-0.2

log(F25/F12)

0

0.2

0.4

0.6

0.8

corr: 0.35

B

-0.5 -1

-1.5 -2

l Detections in both lines s Upper limits r Lower limits
0.8

-2.5 -0.6 -0.4 -0.2 0 0.2 0.4 0.6

log(F25/F12)

log(F25/F12) vs. Absolute Int.
4 3 4

SiO J=1-0 v=1 [Jy km s-1]) log(F
abs

3 2 1 0 -1 -2 -3

SiO J=1-0 v=3

[Jy km s-1]) log(F
abs

2 1 0 -1 -2 -3 4

A

1.710.26

C

2.470.25

2 1 0 -1 -2 -3 -0.6

log(8 micron flux [Jy])
0.8

3

SiO J=1-0 v=2

3.2 2.4 1.6 0.8 0 -0.8 -0.6

8 micron flux (MSX)

log(F

a bs

[Jy km s-1])

B
-0.4 -0.2

2.120.20
0 0.2 0.4 0.6

D
-0.4 -0.2 0 0.2 0.4 0.6 0.8

log(F /F )
25 12

log(F25/F12)

Discussion
n

Overlap line of H2O

(e.g., Olofsson et al. 1981, 1985; ApJ 2007 March 1) Nyman et al. 1986, 1993; Bujarrabal 1987, 1996)

Cyg (C

ho et al.

Energy Levels of SiO

J=0 v=3

J=1 v=3
C
v=1.5 km/s

J=2 v=3

H2O v2=2 505Хv2= 1 634

Overlap

J=0 v=2

J=1 v=2
B
v=1 km/s

J=2 v=2
weak
Strong in S-type stars

Overlap

H2O v2=0 1275Хv2= 1 1166

J=0 v=1

J=1 v=1
A

J=2 v=1
Soria Ruiz et al. Poster# 5.16

Summary and Future Work
n Observed a wide dust-temperature range sample in the multiple SiO lines n Confirmed:
Correlation between J=1-0 [v=2]/[v=1] and IR colors

n Found:
Possible correlation between J=1-0 [v=3]/[v=1&2] vs. IR colors

n Conclusion: Additional overlap line of H2O? n Future work:
Monitoring observations (IR and/or Radio) VLBI observations in the J=1-0 v=3

Q&A Slide: MSX Color versus SiO Intensity Ratios
log([J=1-0 v=3]/[J=1-0 v=2]) log([J=1-0 v=2]/[J=1-0 v=1])
1.6 1.2 0.8 0.4 0 -0.4 -0.8 -1.2 -0.6 0.5 0 -0.5 -1 -1.5 -2 -2.5 -0.6 -0.4 -0.2 0 0.2 -0.4 -0.2 0 0.2

A

log([J=1-0 v=3]/[J=1-0 v=1])

1

C

0

-1

-2

corr: 0.69
0.4 0.6 0.8

corr: 0.16
-3 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8

B

l Detections in both lines sUpper limits rLower limits
0.8

corr: -0.05
0.4 0.6

log(F2

1.3

/F12.1)

Q&A Slide:

8 micron flux versus absolute Int.
3

SiO J=1-0 v=1 [ J y km s - 1 ] )
bs

3

SiO J=1-0 v=3

[Jy km s-1 ])

2

2

1

1

bs

log(Fa

-1

A
SiO J=1-0 v=2

log(Fa

0

0

-1

C
0 0.5 1 1.5 2 2.5 3

-2 3

-2 -0.5

log(F8

.28

[Jy])

[Jy km s-1])

2

1

log(Fa

0

l log(F25m/F12m)>0.2 u log(F25m/F12m)<0.2

bs

-1

B
0 0.5

-2 -0.5

log(F8

1

1.5

.28

[Jy])

2

2.5

3

Q&A Slide:

IR Color vs. SiO Line Ratio:
[J=2-1 v=1]/[J=1-0 v=1]
log([J=2-1 v=1]/[J=1-0 v=1]) log([J=2-1 v=1]/[J=1-0 v=1])
0.5 0.5 0

A

0

B

-0.5

-0.5

-1

-1

-1.5

-1.5

-2

-0.2

0

log(F25/F12)

0.2

0.4

0.6

-2 -0.1 -0.05

0

log(F2

0.05

0.1

1.3

/F12.1)

0.15

0.2

0.25

0.3

IRAS Color

MSX Color