Resolving the effects of rotation in altair with long-baseline interferometry

  title={Resolving the effects of rotation in altair with long-baseline interferometry},
  author={Deane M. Peterson and Christian A. Hummel and Thomas A. Pauls and John Thomas Armstrong and James A. Benson and Charmaine Gilbreath and Robert B. Hindsley and Donald Hutter and Kenneth J. Johnston and David Mozurkewich},
  journal={The Astrophysical Journal},
We report the successful fitting of a Roche model, with a surface temperature gradient following the von Zeipel gravity darkening law, to observations of Altair made with the Navy Prototype Optical Interferometer. We confirm the claim by Ohishi et al. that Altair displays an asymmetric intensity distribution due to rotation, the first such detection in an isolated star. Instrumental effects due to the high visible flux of this first magnitude star appear to be the limiting factor in the… Expand

Figures and Tables from this paper

Imaging the Effects of Rotation in Altair and Vega
After a brief review of rotation among upper main sequence stars and von Zeipel’s vZ24 theory for the interiors, we describe our interferometric measurements of two bright A stars, Altair and Vega.Expand
The Effect of Rotation on Calibrators for Ground-based Interferometry
We consider the problem introduced by rotation in the use of early-type stars as calibrators for optical interferometry. These objects have high surface brightnesses and hence are relatively bright,Expand
Tests of stellar model atmospheres by optical interferometry III: NPOI and VINCI interferometry of
Aims: We present a comparison of the visual and NIR intensity profile of the M0 giant gamma Sagittae to plane-parallel ATLAS 9 as well as to plane-parallel & spherical PHOENIX model atmospheres.Expand
A realistic two-dimensional model of Altair
Context. Fast rotation is responsible for important changes in the structure and evolution of stars and the way we see them. Optical long baseline interferometry now allows for the study of itsExpand
First Results from the CHARA Array. VII. Long-Baseline Interferometric Measurements of Vega Consistent with a Pole-On, Rapidly Rotating Star
We have obtained high-precision interferometric measurements of Vega with the CHARA Array and FLUOR beam combiner in the K’ band at projected baselines between 103m and 273m. The measured visibilityExpand
Early type stars as calibrators for ground-based interferometry
Visibility measurements with Michelson interferometers, particularly the measurement of fringe contrast, are affected by various atmospheric and instrumental effects, all of which reduce the measuredExpand
Navy Prototype Optical Interferometer Imaging of Line Emission Regions of beta Lyrae Using Differential Phase Referencing
We present the results of an experiment to image the interacting binary star β Lyrae with data from the Navy Prototype Optical Interferometer using a differential phase technique to correct for theExpand
Vega is a rapidly rotating star
Optical interferometric observations show that Vega has the asymmetric brightness distribution of the bright, slightly offset polar axis of a star rotating at 93 per cent of its breakup speed, which leads to the prediction of an excess of near-infrared emission compared to the visible, in agreement with observations. Expand
Do we see the simultaneous occurrence of stellar rotational effects and short-period pulsations in some A-type Kepler stars?
We used high-quality Kepler photometry and recent spectroscopic data to investigate the Kepler target KIC 005988140 considering three possible scenario’s: (1) binarity, (2) co-existence of δ Scuti-Expand
Gravity darkening in rotating stars
Context. Interpretation of interferometric observations of rapidly rotating stars requires a good model of their surface effective temperature. Until now, laws of the form Teff ∝ g βff have beenExpand


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 thisExpand
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 recordedExpand
Resolving the effects of rotation in early type stars
We review the theory of rotating stars, first developed 80 years ago. Predictions include a specific relation between shape and angular velocity and between surface location and effective temperatureExpand
Direct multi-wavelength limb-darkening measurements of three late-type giants with the Navy Prototype Optical Interferometer
We present direct measurements of the limb-darkened intensity proles of the late-type giant stars HR 5299, HR 7635, and HR 8621 obtained with the Navy Prototype Optical Interferometer (NPOI) at theExpand
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 forExpand
Altair's inclination from line profile analysis
We present a detailed spectroscopic study of line broadening in the A7IV-V star Altair. In a wavelength region covering 690 A we reconstruct the overall broadening profile taking into account moreExpand
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,Expand
Effects of gravitational darkening on the determination of fundamental parameters in fast-rotating B-type stars
In this paper we develop a calculation code to account for the effects carried by fast rotation on the observed spectra of early-type stars. Stars are assumed to be in rigid rotation, and the grid ofExpand
We have used the Goddard High-Resolution Spectrograph (GHRS) on the Hubble Space Telescope (HST) to search for chromospheric emission in the ultraviolet C II 1335 A lines of eight A-type stars. TheExpand
The effects of inclination, gravity darkening and differential rotation on absorption profiles of fast rotators
Mechanisms influencing absorption line profiles of fast rotating stars can be sorted into two groups; (i) intrinsic variations sensitive to temperature and pressure, and (ii) global eects common toExpand