R
ES
Survey of the World’s Optical / IR Interferometers
Fourth Advanced Chilean School of Astrophysics
R
L
AT
A
NA V
OR Y
DE
PA
EN T OF TH
E
TM
VY
NA
R
EA
R C H LA
BO
A Survey of (Mostly) Current
Optical and Infrared Interferometers
Tom Armstrong
US Naval Research Laboratory
Navy Prototype Optical Interferometer
(NPOI)
tom.armstrong@nrl.navy.mil
December 4, 2006
1
R
ES
Survey of the World’s Optical / IR Interferometers
Fourth Advanced Chilean School of Astrophysics
R
L
AT
A
NA V
OR Y
DE
PA
EN T OF TH
E
TM
VY
NA
R
EA
R C H LA
BO
Michelson’s 20-foot interferometer, Mt. Wilson, California
(used mostly in 1921)
2
Survey of the World’s Optical / IR Interferometers
R
ES
Fourth Advanced Chilean School of Astrophysics
R
L
AT
A
NA V
OR Y
DE
PA
EN T OF TH
E
TM
VY
NA
R
EA
R C H LA
BO
Keck
SUSI
NPOI
Keck
PTI
VLTI
CHARA
3
Survey of the World’s Optical / IR Interferometers
R
R
L
ES
Fourth Advanced Chilean School of Astrophysics
AT
A
NA V
OR Y
DE
PA
EN T OF TH
E
TM
VY
NA
R
EA
R C H LA
BO
Interferometers currently in operation
Location
VLTI
www.eso.org
CHARA
www.chara.gsu.edu
NPOI
www.npoi.lowell.edu
PTI
www.pti.jpl.nasa.gov
Keck Interferometer
www.keck.cara.edu
SUSI
www.physics.usyd.au
ISI
www.isi.berkeley.edu
MIRA-I (under
development)
Apertures
Baselines
Wavelengths
Cerro Paranal, Chile
3 x 1.8 m
4 x 8.2 m
30 to 202 m
25 to 85 m
10 μm, 5 μm,
2 μm bands
Mt. Wilson, California, USA
6x1m
35 to 300 m
2 μm band
Anderson Mesa, Arizona, USA
6 x 12 cm
5 to 80 m
450 – 850 nm
Mt. Palomar, California, USA
3 x 12 cm
70 m, 100 m
2 μm band
Mauna Kea, Hawai`i, USA
2 x 10 m
70 m
10 μm, 5 μm,
2 μm bands
Narrabri, New South Wales,
Australia
2 x 12 cm
5 to 600 m
450 – 900 nm
Mt. Wilson, California, USA
3 x 1.65 m
5 to 80 m
10 μm band
Tokyo, Japan
2 x 25 cm
To 30 m
Visual band
4
Survey of the World’s Optical / IR Interferometers
R
R
L
ES
Fourth Advanced Chilean School of Astrophysics
AT
A
NA V
OR Y
DE
PA
EN T OF TH
E
TM
VY
NA
R
EA
R C H LA
BO
Interferometers currently in operation
Notes
VLTI
www.eso.org
CHARA
www.chara.gsu.edu
NPOI
www.npoi.lowell.edu
PTI
www.pti.jpl.nasa.gov
Keck Interferometer
www.keck.cara.edu
SUSI
www.physics.usyd.au
ISI
www.isi.berkeley.edu
Multiple backends. Largest telescope apertures in Southern Hemisphere. Adaptive optics.
FLUOR fiber beam combiner.
Two arrays: Wide-angle astrometry; Imaging. 35 cm and 1.4 m apertures in near future (3 years?)
Dual-star feed.
Largest telescope apertures in Northern Hemisphere. Aperture masking also available.
Outrigger array (1.8 m telescopes) cancelled.
Longest baselines.
Heterodyne detection.
5
R
ES
Survey of the World’s Optical / IR Interferometers
Fourth Advanced Chilean School of Astrophysics
R
L
AT
A
NA V
OR Y
DE
PA
EN T OF TH
E
TM
VY
NA
R
EA
R C H LA
BO
Interferometers under development
Location
MROI (under design)
www.mro.nmt.edu
LBT (under development)
www.lbt.uarizona.edu
`OHANA (under development)
www.ohana.eso.org
Apertures
Baselines
Wavelengths
Magdalena Ridge,
New Mexico, USA
4 to 10 x 1.5 m
To 500 m
2 μm, visual bands
Mt. Graham, Arizona,
USA
2x8m
14 m center-to-center
22 m edge-to-edge
2 μm band
Mauna Kea, Hawai`i,
USA
5: 4 m to 10 m
To 800 m
2 μm band
Recently closed interferometers
Location
IOTA (closed July ’06)
www.iota.cfa.org
COAST (MROI testbed after ’06)
www.coast.uc.uk
GI2T (closed June ’06)
www.gi2t.unice.fr
Apertures
Baselines
Wavelengths
Mt. Hopkins, Arizona,
USA
3 x 40 cm
5 to 38 m
2 μm band
Cambridge, UK
5 x 40 cm
3 to 100 m
500 – 800 nm
Obs. Côte d’Azur,
France
2x1m
To 50 m
2 μm, visual bands
6
R
ES
Survey of the World’s Optical / IR Interferometers
Fourth Advanced Chilean School of Astrophysics
R
L
AT
A
NA V
OR Y
DE
PA
EN T OF TH
E
TM
VY
NA
R
EA
R C H LA
BO
Interferometers under development
Notes
MROI (under design)
www.mro.nmt.edu
LBT (under development)
www.lbt.uarizona.edu
`OHANA (under development)
www.ohana.eso.org
Goal is ~ 100 AGNs.
Two telescopes on a single mount (no need for delay lines).
Fibers link existing telescopes. First fringes attained in ’06.
Recently closed interferometers
Notes
IOTA (closed July ’06)
www.iota.cfa.org
COAST (MROI testbed after ’06)
www.coast.uc.uk
GI2T (closed June ’06)
www.gi2t.unice.fr
First use of fiber beam combiner.
First image using closure phase.
High spectral resolution backend.
7
Survey of the World’s Optical / IR Interferometers
R
ES
Fourth Advanced Chilean School of Astrophysics
R
L
AT
A
NA V
OR Y
DE
PA
EN T OF TH
E
TM
VY
NA
R
EA
R C H LA
BO
2x1m
To 50 m baselines
2 μm, visual bands
High spectral resolution
GI2T, Observatoire de la Côte d’Azur
Photo: Peter Lawson
8
R
ES
Survey of the World’s Optical / IR Interferometers
Fourth Advanced Chilean School of Astrophysics
R
L
AT
A
NA V
OR Y
DE
PA
EN T OF TH
E
TM
VY
NA
R
EA
R C H LA
BO
3 x 0.40 m
5 m to 38 m baselines
2 μm band
Fiber beam combination
IOTA, Mt. Hopkins, Arizona
9
R
ES
Survey of the World’s Optical / IR Interferometers
Fourth Advanced Chilean School of Astrophysics
R
L
AT
A
NA V
OR Y
DE
PA
EN T OF TH
E
TM
VY
NA
R
EA
R C H LA
BO
5 x 0.40 m
3 m to 100m baselines
500—800 nm band
First closure phase image
COAST, Cambridge, England
10
R
ES
Survey of the World’s Optical / IR Interferometers
Fourth Advanced Chilean School of Astrophysics
R
L
AT
A
NA V
OR Y
DE
PA
EN T OF TH
E
TM
VY
NA
R
EA
R C H LA
BO
3 x 1.65 m apertures
5 to 80 m baselines
12 μm band
Heterodyne detection
ISI, Mt. Wilson, California
11
R
ES
Survey of the World’s Optical / IR Interferometers
Fourth Advanced Chilean School of Astrophysics
R
L
AT
A
NA V
OR Y
DE
PA
EN T OF TH
E
TM
VY
NA
R
EA
R C H LA
BO
3 x 0.18 m apertures
70, 100 m baselines
2 μm band
Dual-star feed for
small-angle astrometry
Palomar Testbed Interferometer (PTI), Mt. Palomar, California
12
Survey of the World’s Optical / IR Interferometers
R
ES
Fourth Advanced Chilean School of Astrophysics
R
L
AT
A
NA V
OR Y
DE
PA
EN T OF TH
E
TM
VY
NA
R
EA
R C H LA
BO
2 x 0.12 m apertures
5 to 80 m baselines
450—900 μm band
Longest baselines
SUSI, Narrabri, Australia
Photo: Karina Hall
13
R
ES
Survey of the World’s Optical / IR Interferometers
Fourth Advanced Chilean School of Astrophysics
R
L
AT
A
NA V
OR Y
DE
PA
EN T OF TH
E
TM
VY
NA
R
EA
R C H LA
BO
6 x 0.12 m apertures
5 to 80 m baselines
450—850 nm band
Astrometry and imaging
Largest number of apertures
Navy Prototype Optical Interferometer (NPOI), Anderson Mesa, Arizona
14
R
ES
Survey of the World’s Optical / IR Interferometers
Fourth Advanced Chilean School of Astrophysics
R
L
AT
A
NA V
OR Y
DE
PA
EN T OF TH
E
TM
VY
NA
R
EA
R C H LA
BO
3 x 1.8 m apertures
30 to 202 m baselines
and
4 x 8.2 m apertures
25 to 85 m baselines
2 μm, 5 μm,10 μm band
Multiple backends
Largest S. hemisphere apertures
Adaptive optics
VLTI, Cerro Paranal, Chile
15
R
ES
Survey of the World’s Optical / IR Interferometers
Fourth Advanced Chilean School of Astrophysics
R
L
AT
A
NA V
OR Y
DE
PA
EN T OF TH
E
TM
VY
NA
R
EA
R C H LA
BO
Keck Interferometer, Mauna Kea, Hawai`i
2 x 10 m apertures
70 m baseline
2 μm, 5 μm, 12 μm band
Largest N. hemisphere apertures
Also aperture masking
16
R
ES
Survey of the World’s Optical / IR Interferometers
Fourth Advanced Chilean School of Astrophysics
R
L
AT
A
NA V
OR Y
DE
PA
EN T OF TH
E
TM
VY
NA
R
EA
R C H LA
BO
6 x 1 m apertures
35 to 330 m baselines
2 μm band
FLUOR fiber beam combiner
Longest baseline
Mt. Wilson, California: 100-inch & 60-inch telescopes,
solar towers—and CHARA
17
R
ES
Survey of the World’s Optical / IR Interferometers
Fourth Advanced Chilean School of Astrophysics
R
L
AT
A
NA V
OR Y
DE
PA
EN T OF TH
E
TM
VY
NA
R
EA
R C H LA
BO
Mauna Kea, Hawai`i
5 apertures, 4 to 10 m
To 800 m baselines
2 μm band
Fiber combination
18
Survey of the World’s Optical / IR Interferometers
R
ES
Fourth Advanced Chilean School of Astrophysics
R
L
AT
A
NA V
OR Y
DE
PA
EN T OF TH
E
TM
VY
NA
R
EA
R C H LA
BO
2 x 8 m apertures
14 m baseline center-to-center
22 m baseline edge-to-edge
2 μm band
Two telescopes on single mount
Large Binocular Telescope, Mt. Graham, Arizona
19
R
ES
Survey of the World’s Optical / IR Interferometers
Fourth Advanced Chilean School of Astrophysics
R
L
AT
A
NA V
OR Y
DE
PA
EN T OF TH
E
TM
VY
NA
R
EA
R C H LA
BO
4 to 10 x 1.4 m apertures
To 500 m baselines
2 μm, visual bands
Rapid imaging
Magdalena Ridge Observatory, New Mexico
20
R
ES
Survey of the World’s Optical / IR Interferometers
Fourth Advanced Chilean School of Astrophysics
R
L
AT
A
NA V
OR Y
DE
PA
EN T OF TH
E
TM
VY
NA
R
EA
R C H LA
BO
Sample results: Cepheid pulsations (PTI)
Diameter of η Aquilae vs. pulsation
phase.
Crosses: diameters from PTI
Line: diameter inferred from infrared
surface brightness method.
Combining change in angular diameter
(interferometry) with change in
physical diameter (radial-velocity data)
yields the distance.
Lane et al. 1999 Astrophys. J.
21
R
ES
Survey of the World’s Optical / IR Interferometers
Fourth Advanced Chilean School of Astrophysics
R
L
AT
A
NA V
OR Y
DE
PA
EN T OF TH
E
TM
VY
NA
R
EA
R C H LA
BO
Sample results: Cepheid pulsations (VLTI)
Diameter of ℓ Carinae vs. pulsation
phase.
Circles: diameters from VLTI with
VINCI
Line: diameter inferred from infrared
surface brightness method.
Predicted angular diameters from
infrared surface brightness methods
are in good agreement with measured
diameters, giving confidence in the
conversion from radial velocities to
physical diameter variations.
Kervella et al. 2003 Astron. Astrophys.
22
Survey of the World’s Optical / IR Interferometers
R
R
L
ES
Fourth Advanced Chilean School of Astrophysics
AT
A
NA V
OR Y
DE
PA
EN T OF TH
E
TM
VY
NA
R
EA
R C H LA
BO
Sample results: Vega is a rapid rotator (NPOI)
180
Vega is the major
photometric standard,
but model atmospheres
do not fit the spectrum.
IMAGE:
Off-center bright polar cap
shows rotation axis is tilted
~5° from the line of sight.
0
0.8
0.6
Wavelength (mm)
Phase anomalies indicate
slight asymmetry.
Low secondary maximum shows
significant limb darkening.
|V1 V2 V3|
0.08
Pole-to-equator temperature
contrast (2400° K) may
explain spectral anomalies.
2
Dec offset (mas)
Closure phase (deg)
DATA:
RESULTS:
0
• Vega is rotating at 93% of
breakup velocity.
-2
0.04
2
0
RA offset (mas)
-2
Peterson et al., Nature, 2006
0.00
0.8
0.6
Wavelength (mm)
• Its equator is distended by 25%
and is 2400° K cooler than the
pole.
• We see it nearly pole-on.
23
Survey of the World’s Optical / IR Interferometers
R
R
L
ES
Fourth Advanced Chilean School of Astrophysics
AT
A
NA V
OR Y
DE
PA
EN T OF TH
E
TM
VY
NA
R
R C H LA
BO
Sample results: High-precision binary astrometry (PTI)
ΔDec (arcsec)
EA
HD 171779
0.120
0.119
-0.230
-0.228
-0.226
-0.224
ΔRA (arcsec)
-0.222
-0.220
-0.218
Lane 2005 PTI
Position differences between components in right
ascension and declination (crosses), with 1-σ error
ellipses. Orbital motion is from south to north.
24
R
EA
R C H LA
Fourth Advanced Chilean School of Astrophysics
BO
Sample results: High-precision binary astrometry (PTI)
HD 171779
0.1199
The goal is to detect perturbations in the orbit
of a binary component due to an unseen
companion (possibly a planet).
Typical formal error ellipse is 5 x 100 microarcseconds.
0.1198
0.1197
ΔDec (arcsec)
ES
Survey of the World’s Optical / IR Interferometers
R
L
AT
A
NA V
OR Y
DE
PA
EN T OF TH
E
TM
VY
NA
R
0.1196
0.1195
0.1194
0.1193
Fit to linear trend yields an implied repeatability
of ~ 15 x 300 micro-arcseconds.
0.1192
0.1191
-0.230
-0.228
-0.226 -0.224 -0.222 -0.220
ΔRA (arcsec)
-0.218
Lane 2005 PTI
Position differences between components in right
ascension and declination (crosses), with 1-σ error
ellipses. Orbital motion is from south to north.
25
Survey of the World’s Optical / IR Interferometers
R
R
L
ES
Fourth Advanced Chilean School of Astrophysics
AT
A
NA V
OR Y
DE
PA
EN T OF TH
E
TM
VY
NA
R
EA
R C H LA
BO
Sample results: Polarimetric interferometry with SUSI
R Carinae is a Mira, a pulsating late-type giant surrounded by dust.
Light reflected by the dust is polarized. SUSI data fit a model with a thin shell of dust better than a model
with a thicker shell created by steady outflow.
Visibility difference between polarizations
Visibility for both polarizations
0.08
1.0
Thin-shell model
0.8
Visibility
Δ Visibility
0.06
Note the visibility
precision:
± 1.5% to 2%
0.04
0.02
0.6
0.4
Outflow model
Uniform stellar disk
(no circumstellar dust)
0.00
0.2
-0,02
0,0
0
2
4
6
8
Baseline (m)
10
12
Pulsation phase 0.08
0
2
4
6
8
Baseline (m)
10
12
Visibility vs. baseline length for R Carinae with SUSI at λ900 nm
Ireland et al. 2005, Monthly Notices R. A. S., 361, 337
26
R
ES
Survey of the World’s Optical / IR Interferometers
Fourth Advanced Chilean School of Astrophysics
R
L
AT
A
NA V
OR Y
DE
PA
EN T OF TH
E
TM
VY
NA
R
EA
R C H LA
BO
Sample results: Rotational distortion of Alderamin (α Cep) with CHARA
van Belle et al. 2006, Astrophys. J., 637, 494
Rotational velocity: 280 km/s (83% of breakup velocity)
Teff = 8440 K (poles) to 7600 K (equator)
Temperature contrast implies that the photosphere is convective.
Projected baseline lengths: 250 m to 312 m
2.15 μm wavelength, 0.30 μm bandwidth
27
Fourth Advanced Chilean School of Astrophysics
BO
Sample results:
Low-mass pre-mainsequence stars with
the Keck Interferometer
HD 98800 B:
Double-lined spectroscopic binary,
member of a four-star system.
Pre-main-sequence stars.
Combine Keck Interferometer data
with radial-velocity data and Hubble
Fine Guidance Sensor data to find:
M = 0.70 Msun and 0.58 Msun.
Masses and luminosities do not fit
models.
Solar metallicity
Sub-solar metallicity
Luminosity (Lsun)
R C H LA
Luminosity (Lsun)
EA
Baraffe et al. (1998) models Siess et al. (2000) models
Luminosity (Lsun)
Luminosity (Lsun)
R
ES
Survey of the World’s Optical / IR Interferometers
R
L
AT
A
NA V
OR Y
DE
PA
EN T OF TH
E
TM
VY
NA
R
Effective temperature
Effective temperature
Boden et al. 2005, ApJ, 635, 442
28
R
ES
Survey of the World’s Optical / IR Interferometers
Fourth Advanced Chilean School of Astrophysics
R
L
AT
A
NA V
OR Y
DE
PA
EN T OF TH
E
TM
VY
NA
R
EA
R C H LA
BO
Sample result: Colliding-wind binary WR 98
with Keck aperture masking
Image
Model
Monnier et al. 2000 Astrophys. J.
29