Asymmetric Surface Brightness Distribution of Altair Observed with the Navy Prototype Optical Interferometer

@article{Ohishi2004AsymmetricSB,
  title={Asymmetric Surface Brightness Distribution of Altair Observed with the Navy Prototype Optical Interferometer},
  author={Naoko Ohishi and Tyler E. Nordgren and Donald J. Hutter},
  journal={The Astrophysical Journal},
  year={2004},
  volume={612},
  pages={463 - 471}
}
An asymmetric surface brightness distribution of the rapidly rotating A7 IV-V star Altair has been measured by the Navy Prototype Optical Interferometer (NPOI). The observations were recorded simultaneously using a triangle with long baselines of 30, 37, and 64 m, on 19 spectral channels, covering the wavelength range of 520-850 nm. The outstanding characteristics of these observations are (1) high resolution with the minimum fringe spacing of 1.7 mas, easily resolving the 3 mas stellar disk… 
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References

SHOWING 1-10 OF 21 REFERENCES
Altair’s Oblateness and Rotation Velocity from Long-Baseline Interferometry
We present infrared interferometric angular size measurements for the A7IV-V star Altair that indicate a noncircular projected disk brightness distribution. Given the known rapid rotation of this
On the Near-Infrared Size of Vega
Near-infrared (2.2 μm) long baseline interferometric observations of Vega are presented. The stellar disk of the star has been resolved, and the data have been fitted with a limb-darkened stellar
Navy Prototype Optical Interferometer Observations of the Double Stars Mizar A and Matar
We present a detailed analysis of two spectroscopic binaries based on new observations obtained with the Navy Prototype Optical Interferometer (NPOI). While the data calibration needs refinement,
Stellar Angular Diameters of Late-Type Giants and Supergiants Measured with the Navy Prototype Optical Interferometer
We have measured the angular diameters of 50 F, G, K, and M giant and supergiant stars using the Navy Prototype Optical Interferometer at wavelengths between 649 and 850 nm and using three baselines
Comparison of Stellar Angular Diameters from the NPOI, the Mark III Optical Interferometer, and the Infrared Flux Method
The Navy Prototype Optical Interferometer (NPOI) has been used to measure the angular diameters of 41 late-type giant and supergiant stars previously observed with the Mark III optical
The spinning-top Be star Achernar from VLTI-VINCI
We report here the first observations of a rapidly rotating Be star, Eridani, using Earth-rotation synthesis on the Very Large Telescope (VLT) Interferometer. Our measures correspond to a 2a=2b= 1:56
The Navy Prototype Optical Interferometer
We describe the Navy Prototype Optical Interferometer (NPOI), a joint project of the Naval Research Laboratory (NRL) and the US Naval Observatory (USNO) in cooperation with Lowell Observatory. The
The Palomar Testbed Interferometer
The Palomar Testbed Interferometer (PTI) is a long-baseline infrared interferometer located at Palomar Observatory, California. It was built as a testbed for interferometric techniques applicable to
Modelling rapid rotators for stellar interferometry
Optical long baseline interferometry is a powerful tool to study detailed stellar structures. In particular, rapid rotation induces interferometric signatures requiring a detailed modelling for
New limb-darkening coefficients for modeling binary star light curves
We present monochromatic, passband-specific, and bolometric limb-darkening coefficients for a linear as well as nonlinear logarithmic and square root limb-darkening laws. These coefficients,
...
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