SIMBAD references

2006ApJ...637..494V - Astrophys. J., 637, 494-505 (2006/January-3)

First results from the CHARA array. III. Oblateness, rotational velocity, and gravity darkening of alderamin.

VAN BELLE G.T., CIARDI D.R., TEN BRUMMELAAR T., McALISTER H.A., RIDGWAY S.T., BERGER D.H., GOLDFINGER P.J., STURMANN J., STURMANN L., TURNER N., BODEN A.F., THOMPSON R.R. and COYNE J.

Abstract (from CDS):

We present observations of the A7 IV-V star Alderamin (α Cep, HR 8162, HD 203280) from the Georgia State University CHARA Array. These infrared interferometric angular size measurements indicate a noncircular projected disk brightness distribution for this known rapid rotator. The interferometric observations are modeled as arising from an elongated rigid atmosphere, with apparent polar and equatorial radii of rp=0.6753+0.0119–0.0135 and re=0.8767+0.0293–0.0183mas, respectively, for a difference of 201±32 µas, and with an axial ratio of re/rp=1.298±0.051. Using the Hipparcos distance of 14.96±0.11 pc, these angular measures translate to 2.18±0.05 and 2.82±0.10 R. The inclination of Alderamin to the line of sight indicated by this modeling is effectively edge-on (i=88.2+1.8–13.3 deg). The star has a true rotational velocity of 283±10 km/s (∼83% of breakup velocity) and a polar temperature of roughly 8400 K. Significantly, a necessary aspect of this modeling is a determination of the gravity-darkening coefficient, which at a value of β=0.084+0.026–0.049is consistent with a convective photosphere, as expected for an A7 IV-V star. Our detailed characterization of this object allows us to investigate various scenarios for the angular momentum history of Alderamin and the appropriateness of certain stellar evolution models.

Abstract Copyright:

Journal keyword(s): Infrared: Stars - Stars: Fundamental Parameters - stars: individual (Alderamin) - Techniques: Interferometric

Simbad objects: 3

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