1 T O C H Y Survey of the World’s Optical / IR Interferometers Fourth Advanced Chilean School of Astrophysics A Survey of (Mostly) Current Optical and Infrared Interferometers Tom Armstrong US Naval Research Laboratory Navy Prototype Optical Interferometer (NPOI) [email protected]December 4, 2006
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1 Survey of the World’s Optical / IR Interferometers Fourth Advanced Chilean School of Astrophysics A Survey of (Mostly) Current Optical and Infrared Interferometers.
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Survey of the World’s Optical / IR InterferometersFourth Advanced Chilean School of Astrophysics
Survey of the World’s Optical / IR InterferometersFourth Advanced Chilean School of Astrophysics
GI2T, Observatoire de la Côte d’Azur Photo: Peter Lawson
2 x 1 mTo 50 m baselines2 μm, visual bandsHigh spectral resolution
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Survey of the World’s Optical / IR InterferometersFourth Advanced Chilean School of Astrophysics
3 x 0.40 m5 m to 38 m baselines2 μm bandFiber beam combination
IOTA, Mt. Hopkins, Arizona
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Survey of the World’s Optical / IR InterferometersFourth Advanced Chilean School of Astrophysics
5 x 0.40 m3 m to 100m baselines500—800 nm bandFirst closure phase image
COAST, Cambridge, England
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Survey of the World’s Optical / IR InterferometersFourth Advanced Chilean School of Astrophysics
3 x 1.65 m apertures5 to 80 m baselines12 μm bandHeterodyne detection
ISI, Mt. Wilson, California
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Survey of the World’s Optical / IR InterferometersFourth Advanced Chilean School of Astrophysics
Palomar Testbed Interferometer (PTI), Mt. Palomar, California
3 x 0.18 m apertures70, 100 m baselines2 μm bandDual-star feed forsmall-angle astrometry
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Survey of the World’s Optical / IR InterferometersFourth Advanced Chilean School of Astrophysics
SUSI, Narrabri, Australia Photo: Karina Hall
2 x 0.12 m apertures5 to 80 m baselines450—900 μm bandLongest baselines
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Survey of the World’s Optical / IR InterferometersFourth Advanced Chilean School of Astrophysics
Navy Prototype Optical Interferometer (NPOI), Anderson Mesa, Arizona
6 x 0.12 m apertures5 to 80 m baselines450—850 nm bandAstrometry and imagingLargest number of apertures
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Survey of the World’s Optical / IR InterferometersFourth Advanced Chilean School of Astrophysics
3 x 1.8 m apertures30 to 202 m baselinesand4 x 8.2 m apertures25 to 85 m baselines2 μm, 5 μm,10 μm bandMultiple backendsLargest S. hemisphere aperturesAdaptive optics VLTI, Cerro Paranal, Chile
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Survey of the World’s Optical / IR InterferometersFourth Advanced Chilean School of Astrophysics
Keck Interferometer, Mauna Kea, Hawai`i
2 x 10 m apertures70 m baseline2 μm, 5 μm, 12 μm bandLargest N. hemisphere aperturesAlso aperture masking
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Survey of the World’s Optical / IR InterferometersFourth Advanced Chilean School of Astrophysics
Mt. Wilson, California: 100-inch & 60-inch telescopes, solar towers—and CHARA
6 x 1 m apertures35 to 330 m baselines2 μm bandFLUOR fiber beam combinerLongest baseline
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Survey of the World’s Optical / IR InterferometersFourth Advanced Chilean School of Astrophysics
Mauna Kea, Hawai`i5 apertures, 4 to 10 mTo 800 m baselines2 μm bandFiber combination
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Survey of the World’s Optical / IR InterferometersFourth Advanced Chilean School of Astrophysics
2 x 8 m apertures14 m baseline center-to-center22 m baseline edge-to-edge2 μm bandTwo telescopes on single mount
Large Binocular Telescope, Mt. Graham, Arizona
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Survey of the World’s Optical / IR InterferometersFourth Advanced Chilean School of Astrophysics
4 to 10 x 1.4 m aperturesTo 500 m baselines2 μm, visual bandsRapid imaging
Magdalena Ridge Observatory, New Mexico
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Survey of the World’s Optical / IR InterferometersFourth Advanced Chilean School of Astrophysics
Sample results: Cepheid pulsations (PTI)
Diameter of η Aquilae vs. pulsation phase.
Crosses: diameters from PTILine: 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.
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Survey of the World’s Optical / IR InterferometersFourth Advanced Chilean School of Astrophysics
Sample results: Cepheid pulsations (VLTI)
Diameter of ℓ Carinae vs. pulsation phase.
Circles: diameters from VLTI with VINCILine: 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.
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Survey of the World’s Optical / IR InterferometersFourth Advanced Chilean School of Astrophysics
RESULTS:
• Vega is rotating at 93% of breakup velocity.
• Its equator is distended by 25% and is 2400° K cooler than the pole.
• We see it nearly pole-on.
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.
Pole-to-equator temperature contrast (2400° K) may explain spectral anomalies.
Low secondary maximum shows significant limb darkening.
2
0
2
22 0RA offset (mas)
Dec
off
set
(mas
)
Wavelength (m)0.6 0.8
|V1 V
2 V
3|
0.08
0.04
0.00
Phase anomalies indicate slight asymmetry.
Wavelength (m)
Clo
sure
ph
ase
(deg
)
0
180
0.6 0.8
Peterson et al., Nature, 2006
DATA:
Sample results: Vega is a rapid rotator (NPOI)
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Survey of the World’s Optical / IR InterferometersFourth Advanced Chilean School of Astrophysics
Survey of the World’s Optical / IR InterferometersFourth Advanced Chilean School of Astrophysics
Sample results: Polarimetric interferometry with SUSI
Visibility vs. baseline length for R Carinae with SUSI at λ900 nmIreland et al. 2005, Monthly Notices R. A. S., 361, 337
Outflow model
Uniform stellar disk(no circumstellar dust)
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
0.06
0.04
0.02
0.00
-0,02
Δ V
isib
ilit
y
1.0
0.8
0.6
0.4
0.2
0,0
Vis
ibil
ity
0 2 4 6 8 10 12Baseline (m)
0 2 4 6 8 10 12Baseline (m)
Pulsation phase 0.08
Thin-shell model Note the visibility precision:± 1.5% to 2%
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Survey of the World’s Optical / IR InterferometersFourth Advanced Chilean School of Astrophysics
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 m2.15 μm wavelength, 0.30 μm bandwidth
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Survey of the World’s Optical / IR InterferometersFourth Advanced Chilean School of Astrophysics
Boden et al. 2005, ApJ, 635, 442
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.
Effective temperatureEffective temperature
Lu
min
osi
ty (
Lsu
n)
Lu
min
osi
ty (
Lsu
n)
Lu
min
osi
ty (
Lsu
n)
Lu
min
osi
ty (
Lsu
n)
Solar metallicity Sub-solar metallicity
Sie
ss
et
al.
(2
00
0)
mo
de
lsB
ara
ffe
et
al.
(1
99
8)
mo
de
ls
Sample results: Low-mass pre-main-sequence stars with the Keck Interferometer
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Survey of the World’s Optical / IR InterferometersFourth Advanced Chilean School of Astrophysics