XKCD:Time (frame 2395)
http://xkcd.com/1190/

Parallaxes at 1.6 GHz
OH maser and AGBs (:aka“why should we care about the SKA?”

Gabor Orosz
Kagoshima University
Kagoshima, Japan

2016.10.04.
“VERA”UM14
Mitaka, Tokyo, JapanThank you for thefinancial support!

XKCD: Astronomy
http://xkcd.com/1522/

Hiroshi Imai

Dieter Engels

Maria Rioja

Sandra Etoka

Richard Dodson

Steve Goldman

Sandor Frey

Ambra Nanni
Paola Marigo

Akiharu Nakagawa

Daniel Tafoya

Ross Burns

Yoshiharu Asaki
Hiroyuki NakanishiA motivational speech

Why care aboutlow frequencies?
Why care about
OH masers?
Why care about
old stars?

A motivational speech

Why care about
low frequencies?
Why care about
OH masers?
Why care about
old stars?

A motivational speech

Why care about
low frequencies?
Why care about
OH masers?
Why care about
old stars?

A motivational speech

Why care about
low frequencies?
Why care about
OH masers?
Why care about
old stars?

22 GHz – a dream realized
thanks to BeSSeL and VERA

Spiral arms of the MWG
water and methanol parallaxes
fitting log-periodic spiral forms
Reid et al 2016

The challenge of low frequency phase-referencing
The dispersive ionosphere!
PR 1º

PR 4º

⌧/

TECU
⌫2

Peterson et al 2011

1.6 GHz

ionosphere (5 TECU)
ionosphere (0.5 TECU)
troposphere (3 cm)

1.6

The challenge of low frequency phase-referencing
The dispersive ionosphere!
PR 1º

PR 4º

⌧/

TECU
⌫2

Peterson et al 2011

ionosphere (5 TECU)
ionosphere (0.5 TECU)
troposphere (3 cm)

1.6 GHz“Low Freq.”

1.6“High Freq.”

The challenge of low frequency phase-referencing
The dispersive ionosphere!
PR 1º

PR 4º

⌧/

TECU
⌫2

Peterson et al 2011

1.6 GHz

ionosphere (5 TECU)
ionosphere (0.5 TECU)
troposphere (3 cm)

1. reduce ΔTECU
1.6Multi-freq phase-ref (from Richard Dodson) – BL Lac
Solve for delays (per IF) across all frequencies

TEC from𝜏

Small errors in ΔTEC require
Inclusion of low frequency (L-band)

K band21.8-22 GHz
Wide C band
3.9 - 7.9 GHz
L band
1.4 -1.7 GHz
Errors in ΔTEC ~ 0.1 TECU
Low Frequency Astrometry School: Hobart June 2016

1712

The challenge of low frequency phase-referencing
The dispersive ionosphere!
PR 1ºPR 4º⌧/

TECU⌫2Peterson et al 2011

1.6 GHz

ionosphere (5 TECU)
ionosphere (0.5 TECU)
troposphere (3 cm)

2. reduce Θsep
1.6

Concept of multi-calibrator PR: MultiView
Calibrator

TargetCalibrator

adapted fromLonsdale 2004

FOV << SB >> S
Wavefront

Antenna Beam
Field of View (FOV)

Ionosphere
temporal and spatial variability

tcycleIonosphericIrregularity Scale (S)tcycleBaseline (B)“IONOSPHERIC WEDGE” ➔ Spatial structure (frequency/weather/direction)
MultiView models the phase-screen around the target: direction dependent calibration

Epoch II

Average of VTEC over mainland USA (TECU)

Epoch I

262422

Epoch I

201816

Epoch II

1412100

1234

Time from start of observation (hours)

150

BR-PT (1-9)

150

100

100

50

50

00-50-50-100-100-150-150
NL-PT (7-9)

150

100

Phase (deg)Phase (deg)150
500-50-100100
500-50-150
OV-PT (8-9)

150

100

OV-PT (8-9)

100

50

50

00-50-50-100

Epoch I

-150
12 00

NL-PT (7-9)-100-150
150

BR-PT (1-9)

13 00

14 00
15 00
Universal time (hours)

16 00-100-150
11 00

MultiView
12 00

PR (w/ C2, ~2º)PR (w/ C1, ~4º)

13 00
14 00
Universal time (hours)

Epoch II
15 00

MV Demo: Quasar astrometry1

Repeatability between Epochs ➔ Systematics

Astrometry atthermal noiselevel!
16

Flux recovered

C3.I

14

Dec. offset (mas)

1210

C3

0.9
0.8
0.7

σpos

6

per measurement~ 100 µas

20

MV.II
MV.I-2C2.I-4

sep

5C2
126

4

20-2

R.A. offset (mas)345~ 120 μas

C2.II-4

MV.I

0.6-67

MV.II

0.8

C1.I

6010.78C1Separation angle (deg)

0.9

C1.II

100.5

84

∝θ

0.6

0.4 MV
0.3
Astrometric Error
0C3.II

15

MultiView vs. PR 2º, 4º, 6º: Position Accuracy

Positional error (mas)180.5-3.3 -3.4 -3.5 -3.6

The challenge of low frequency phase-referencing
The dispersive ionosphere!
2flagged MKBR-HN

Dec. offset (mas)1.5

flagged KP
PT

flagged KP

flagged SC
FD-KP

10.5
0-0.5-1-1.5(a) OH138, epoch I-2

10.5

0 -0.5 -1

R.A. offset (mas)all systematicallyshifted positions
include data fromSAME ANTENNA(b) OH138, epoch II
10.5

0 -0.5 -1

R.A. offset (mas)(c) OH138, epoch III
10.5

0 -0.5 -1

R.A. offset (mas)(d) OH138, epoch IV10.5

0 -0.5 -1

R.A. offset (mas)

3. flag data showing
systematic errors

Trig. distances to OH/IR stars using 1612 MHz masers
Frequency (MHz)1612.31612.250.9

1612.2Frequency (MHz)1612.151612.11612.051612.50.9

Stokes I
Stokes V(a) OH128.6-50.1

1612.40.7
August 1, 2014
0.6
0.5
February 17, 2015
0.4
0.3
June 8, 2015
0.2
0.1

0.7
February 16, 2014
0.6
0.5
May 7, 2014
0.4
0.3
August 7, 20140.2
0.1

July 7, 2015

February 22, 201500-10-5

05

1015

20-1

25

30

35-50

-45-40

LSR velocity (km s )

44

2

032-4

R.A.

-6-8

10-10-1

2015 Jul. 7-1-2 -3 -4 -5 -6
R.A. offset (mas)

-7

R.A.

-2-4

R.A.

-3-4-2-4-5-6

Dec.
-6-12-20Dec. offset (mas)Offset (mas)

4Offset (mas)

-2

50-2

6
Dec. offset (mas)R.A.
2014 Feb. 16

Offset (mas)2014 Aug. 1

1-1
2

7-25

0.49 ± 0.14 mas (29%)

28-30-1

LSR velocity (km s )2.74 ± 0.39 mas (14%)
9-35

2014.52015.02015.5Epoch (years)

Dec.
2014.52015.02015.5Epoch (years)

0-1
-2-3
R.A. offset (mas)

-1

Dec.
-2

2015 Feb. 22-60
Offset (mas)-150

Stokes I
Stokes V(b) OH138.0-7.2

0.8

Correlated flux density (Jy beam-1)

Correlated flux density (Jy beam-1)

0.8

1612.45-8
2014.02014.52015.0Epoch (years)

2014.0Dec.
2014.52015.0Epoch (years)

So we have our trigonometricdistances to old stars
The question remains:
Why care about old stars?
gori gori gori goriStellar evolution and physics
1st overtone (C')

Semiregular (SRa & SRb, giants) OH maser H2O maser
Semiregular (SRc, supergiants) H2O maser-11

Mira (giants) OH maser H2O maser SiO maser
OH/IR (giants) OH maser (solid) phase-lag (open)
Ita et al. 2004 (C & C')
Whitelock et al. 2008-10

Nakagawa et al. 2014

MKNakagawa et al. 2016

-9OH128

OH138-8-7
fundamental mode (C)

2.1

2.2

2.3

2.4

2.5

2.6

2.7Log P

2.8

2.93

3.1

3.2

3.3

Stellar evolution and physics
1st overtone (C')

Semiregular (SRa & SRb, giants) OH maser H2O maser
SED from Steve Goldman
Semiregular (SRc, supergiants) H2O maser-11
Mira (giants) OH maser H2O maser SiO maser
OH/IR (giants) OH maser (solid) phase-lag (open)
Ita et al. 2004 (C & C')
Whitelock et al. 2008-10

Nakagawa et al. 2014

MK

getluminosity
Nakagawa
et al. 2016
-9

OH128

OH138

-8

corrected for extinction-7
fundamental mode (C)

2.1

2.2

2.3

2.4

2.5

2.6

2.7

Log P

2.8

2.9

3

3.1

3.2

3.3

Stellar evolution and physics
1st overtone (C')

Semiregular (SRa & SRb, giants) OH maser H2O maser
get luminosity,opacity
Semiregular (SRc,supergiants) H2O maser-11
Mira (giants) OH maser H2O maser SiO maser
OH/IR (giants) OH maser (solid) phase-lag (open)
Ita et al. 2004 (C & C')
Whitelock et al. 2008-10

Nakagawa et al. 2014
Nakagawa et al. 2016

MKSED from Steve Goldman-9from Paola Marigo and Ambra Nanni

OH128

OH138

-8

corrected for extinction-7

2.1

fundamental
mode (C)get Massand mass
loss
expected
2.2 luminosity
2.3
2.4 below
2.5
2.6
2.7
2.8

Log P

2.9

3

3.1

3.2

3.3

(17 kpc)
Semiregular (SRa & SRb, giants)
Semiregular (SRc, supergiants)
Mira (giants)

OH/IR (giants)
1612 MHz OH maser (solid)
phase-lag (open)
Maser molecule used for parallax:
OH maser (1665 & 1667 MHz)H2O maser
SiO maser

Reid et al 2016
32

Zoomed-in view of Solar region(with parallactic distances only)
3 kpc

Per2 kpc

1 kpc

1Loc

0

-1

0SgN
1

2

S-2

CrN

Lo-1

AqR

from Daniel Tafoya

3

Galactic dynamics using AGBs

(17 kpc)

Phase-lag distance calibration

Engels et al 2015

Semiregular (SRa & SRb, giants)
Semiregular (SRc, supergiants)
Mira (giants)

φ-lag distances don’t need VLBI!
single dish for OH phase-lag
interferometry
for size of OH shellMaser molecule used
for parallax:
OH maser (1665 & 1667 MHz)
ideal SKA surveys!!!
H O maser
OH/IR (giants)
1612 MHz OH maser (solid)
phase-lag (open)

2

SiO maser

van Langevelde et al 1990
Reid et al 2016
32

Zoomed-in view of Solar region(with parallactic distances only)
3 kpc

Per2 kpc

1 kpc

1Loc

0-1

0SgN
1

2

S

-2

CrN

Lo-1

AqR

from Daniel Tafoya

3

Galactic dynamics using AGBs

Science #1 Stellar Evolution
Luminosity of our long-period variable AGBs are
low and don’t seem to depend on puls. period
Simulations can’t reproduce values for
M-type stars and Gal. metallicities
Calculated masses are also smaller than thought
Effect of metallicity on stellar evolution? Comparison with LMC
Science #2 Galactic dynamics
AGB stars can be new relaxed tracers of Galactic dynamics
Mapping the dynamics of evolved stars is important forunderstanding how matter circulates in the MWG/Local GroupWe need good distances to Galactic sources…A LOT
OH maser parallaxes + phase-lag distance calibration
SKA surveys to measure OH shell sizes and phase-lags

Pulsar astrometry (L-band VLBI and MultiView)
030 28 50.0

Hulse-Taylor
binary pulsar00

52.000Dec (J2000)

with Adam Deller
54.000Joel Weisberg

CX2
56.00058.000

CX3
290 00.000
47.60sTerzan 1

47.40s47.20sRA (J2000)

47.00s17h 35m 46.80s

with Vlad Tudor and James Miller-Jones

1993 Nobel prize in physics
proof of gravitational waves

Why should we care?
1. Japan and Korea is the center of AGB
astrometry: large KVN, KaVA, VERA projects
2. No one is doing low-frequency astrometryfor AGBs besides us (yet): VLBA, LBA, EVN
3. A huge interest from AGB astrophysics
community for distances: stellar evolution
4. Good follow-up projects when SKA comes