J/MNRAS/386/2039 Elemental abundances of α Cir (Bruntt+, 2008)
The fundamental parameters of the roAp star α Circini.
Bruntt H., North J.R., Cunha M., Brandao 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.
<Mon. Not. R. Astron. Soc., 386, 2039-2046 (2008)>
=2008MNRAS.386.2039B 2008MNRAS.386.2039B
ADC_Keywords: Stars, variable ; Spectroscopy ; Abundances
Keywords: techniques: interferometric - stars: chemically peculiar -
stars: fundamental parameters - stars: individual: alpha Cir
Abstract:
We have used the Sydney University Stellar Interferometer 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±0.066R☉. We have constrained the bolometric flux from
calibrated spectra to determine an effective temperature of
7420±170K . 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 1000K 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.
Description:
The Sydney University Stellar Interferometer (SUSI) was used to
measure the squared visibility, i.e. the normalized squared modulus of
the complex visibility or V2, on a total of eight nights, from 2007
April 18 to August 4.
Objects:
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RA (2000) DE Designation(s)
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14 42 30.4 -64 58 30 alpha Cir = HR 5463
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table5.dat 27 308 *The atomic number, element name, wavelength,
and oscillator strength from the VALD database
for lines used in the abundance analysis
table6.dat 36 23 Abundance of alpha Cir relative to the Sun based
on the analysis of the spectrum from 2004
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Note on table5.dat: VALD database, Kupta et al., 1999A&AS..138..119K 1999A&AS..138..119K
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Z Atomic number
4- 9 A6 --- Ion Element and Ionization level
13- 20 F8.3 0.1nm lambda Wavelength
22- 27 F6.3 [-] loggf Oscillator strength
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- El Element
4 A1 --- n_El [a] Note on Nd (1)
7- 11 F5.2 [Sun] A0 ? Mean abundance of neutral line (2)
13- 16 F4.2 [Sun] e_A0 ? rms uncertainty on AI
19- 21 I3 --- N0 ? Number of neutral lines
23- 27 F5.2 [Sun] A+ ? Mean abundance of ionized line (2)
29- 32 F4.2 [Sun] e_A+ ? rms uncertainty on AII
35- 36 I2 --- N+ ? Number of ionized lines
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Note (1): From three Nd III lines we find [Nd]=+2.06±0.12
Note (2): abundances are relative to the Sun, on a log scale.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 15-Jun-2009