Astronomy and Astrophysics – Astrophysics
Scientific paper
2008-03-11
Astronomy and Astrophysics
Astrophysics
Accepted by MNRAS (9 pages, 3 figures, 6 tables)
Scientific paper
10.1111/j.1365-2966.2008.13167.x
We have used the Sydney University Stellar Interferometer (SUSI) to measure the angular diameter of alpha Cir. This is the first detailed interferometric study of a rapidly oscillating A (roAp) star, alpha Cir being the brightest member of its class. We used the new and more accurate Hipparcos parallax to determine the radius to be 1.967+-0.066 Rs. We have constrained the bolometric flux from calibrated spectra to determine an effective temperature of 7420+-170 K. This is the first direct determination of the temperature of an roAp star. Our temperature is at the low end of previous estimates, which span over 1000 K and were based on either photometric indices or spectroscopic methods. In addition, we have analysed two high-quality spectra of alpha Cir, obtained at different rotational phases and we find evidence for the presence of spots. In both spectra we find nearly solar abundances of C, O, Si, Ca and Fe, high abundance of Cr and Mn, while Co, Y, Nd and Eu are overabundant by about 1 dex. The results reported here provide important observational constraints for future studies of the atmospheric structure and pulsation of alpha Cir.
Bedding Tim R.
Brandao Isa Maria
Bruntt Hans
Cunha Margarida
Davis Jared
No associations
LandOfFree
The fundamental parameters of the roAp star alpha Circini does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The fundamental parameters of the roAp star alpha Circini, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The fundamental parameters of the roAp star alpha Circini will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-285590