The fundamental parameters of the roAp star α Circini

H. Bruntt; J. R. North; M. Cunha; I. M. Brandão; V. G. Elkin; D. W. Kurtz; J. Davis; T. R. Bedding; A. P. Jacob; S. M. Owens; J. G. Robertson; W. J. Tango; J. F. Gameiro; M. J. Ireland; P. G. Tuthill

doi:10.1111/j.1365-2966.2008.13167.x

The fundamental parameters of the roAp star α Circini

H. Bruntt^*, J. R. North, M. Cunha, I. M. Brandão, V. G. Elkin, D. W. Kurtz, J. Davis, T. R. Bedding, A. P. Jacob, S. M. Owens, J. G. Robertson, W. J. Tango, J. F. Gameiro, M. J. Ireland, P. G. Tuthill

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

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Abstract

We have used the Sydney University Stellar Interferometer to measure the angular diameter of α Cir. This is the first detailed interferometric study of a rapidly oscillating A (roAp) star, α 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 R_⊙. 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 α 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 α Cir.

Original language	English
Pages (from-to)	2039-2046
Number of pages	8
Journal	Monthly Notices of the Royal Astronomical Society
Volume	386
Issue number	4
DOIs	https://doi.org/10.1111/j.1365-2966.2008.13167.x
Publication status	Published - Jun 2008
Externally published	Yes

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Bruntt, H., North, J. R., Cunha, M., Brandão, I. M., Elkin, V. G., Kurtz, D. W., Davis, J., Bedding, T. R., Jacob, A. P., Owens, S. M., Robertson, J. G., Tango, W. J., Gameiro, J. F., Ireland, M. J., & Tuthill, P. G. (2008). The fundamental parameters of the roAp star α Circini. Monthly Notices of the Royal Astronomical Society, 386(4), 2039-2046. https://doi.org/10.1111/j.1365-2966.2008.13167.x

@article{bb291f48c49e4e12aeb7c805a296795a,

title = "The fundamental parameters of the roAp star α Circini",

abstract = "We have used the Sydney University Stellar Interferometer to measure the angular diameter of α Cir. This is the first detailed interferometric study of a rapidly oscillating A (roAp) star, α 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 R⊙. 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 α 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 α Cir.",

keywords = "Stars: chemically peculiar, Stars: fundamental parameters, Stars: individual: α Cir, Techniques: interferometric",

author = "H. Bruntt and North, {J. R.} and M. Cunha and Brand{\~a}o, {I. M.} and Elkin, {V. G.} and Kurtz, {D. W.} and J. Davis and Bedding, {T. R.} and Jacob, {A. P.} and Owens, {S. M.} and Robertson, {J. G.} and Tango, {W. J.} and Gameiro, {J. F.} and Ireland, {M. J.} and Tuthill, {P. G.}",

year = "2008",

month = jun,

doi = "10.1111/j.1365-2966.2008.13167.x",

language = "English",

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pages = "2039--2046",

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Bruntt, H, North, JR, Cunha, M, Brandão, IM, Elkin, VG, Kurtz, DW, Davis, J, Bedding, TR, Jacob, AP, Owens, SM, Robertson, JG, Tango, WJ, Gameiro, JF, Ireland, MJ & Tuthill, PG 2008, 'The fundamental parameters of the roAp star α Circini', Monthly Notices of the Royal Astronomical Society, vol. 386, no. 4, pp. 2039-2046. https://doi.org/10.1111/j.1365-2966.2008.13167.x

TY - JOUR

T1 - The fundamental parameters of the roAp star α Circini

AU - Bruntt, H.

AU - North, J. R.

AU - Cunha, M.

AU - Brandão, I. M.

AU - Elkin, V. G.

AU - Kurtz, D. W.

AU - Davis, J.

AU - Bedding, T. R.

AU - Jacob, A. P.

AU - Owens, S. M.

AU - Robertson, J. G.

AU - Tango, W. J.

AU - Gameiro, J. F.

AU - Ireland, M. J.

AU - Tuthill, P. G.

PY - 2008/6

Y1 - 2008/6

N2 - We have used the Sydney University Stellar Interferometer to measure the angular diameter of α Cir. This is the first detailed interferometric study of a rapidly oscillating A (roAp) star, α 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 R⊙. 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 α 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 α Cir.

AB - We have used the Sydney University Stellar Interferometer to measure the angular diameter of α Cir. This is the first detailed interferometric study of a rapidly oscillating A (roAp) star, α 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 R⊙. 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 α 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 α Cir.

KW - Stars: chemically peculiar

KW - Stars: fundamental parameters

KW - Stars: individual: α Cir

KW - Techniques: interferometric

UR - http://www.scopus.com/inward/record.url?scp=43749088898&partnerID=8YFLogxK

U2 - 10.1111/j.1365-2966.2008.13167.x

DO - 10.1111/j.1365-2966.2008.13167.x

M3 - Article

SN - 0035-8711

VL - 386

SP - 2039

EP - 2046

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

IS - 4

ER -

The fundamental parameters of the roAp star α Circini

Abstract

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