MK Spectral Types for Some Bright F Stars

Cowley, A. P.; Fraquelli, D. A.

doi:10.1086/129562

Cited by 16 publications

(13 citation statements)

References 4 publications

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“…In particular, the iron and calcium line strengths of both components are reproduced by stars with normal spectra, so neither component of this close binary is an Am star. This finding is consistent with classifications of the combined spectrum by expert classifiers (Abt & Bidelman 1969;Cowley & Fraquelli 1974;Abt & Morrell 1995). The effective temperatures of the components derived from the CfA spectra imply spectral classes of A9 and F2, according to Table B1 of Gray (1992), and so are in good agreement with our classifications.…”

Section: Spectroscopically-derived Propertiessupporting

confidence: 90%

“…Using five additional observations, acquired nearly a decade later, Harper (1935) revised the period to 12.216 days. The combined spectrum of the stars has been classified as F2 IV,V by W. Morgan (Abt & Bidelman 1969), F0 IV (Cowley & Fraquelli 1974), and F2 IVp (Abt & Morrell 1995). Petrie (1950) determined a visual magnitude difference of 0.67 for the components.…”

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confidence: 99%

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Hr 8257: A Three-Dimensional Orbit and Basic Properties

Fekel

Boden

Tomkin

et al. 2009

ApJ

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We have used interferometric and spectroscopic observations of HR 8257 to determine a three-dimensional orbit of the system. The orbit has a period of 12.21345 days and an eccentricity of 0.2895. The masses of the F0 and F2 dwarf components are 1.56 and 1.38 M , respectively, with fractional errors of 1.4%. Our orbital parallax of 13.632 ± 0.095 mas, corresponding to a distance of 73.4 ± 0.6 pc, differs from the Hipparcos result by just 2% and has a significantly smaller uncertainty. From our spectroscopic observations and spectral energy distribution modeling we determine the component effective temperatures and luminosities to be T eff (A) = 7030 ± 200 K and T eff (B) = 6560 ± 200 K and L A = 9.4 ± 0.3 L and L B = 4.7 ± 0.2 L . The primary rotates pseudosynchronously, while the secondary is not far from its pseudosynchronous rotational velocity. Although both early-F stars are slowly rotating, neither component of this close binary is an Am star. A comparison with evolutionary tracks indicates that the stars are slightly metal poor, and although the components have evolved away from the zero-age main sequence, they are both still dwarfs.

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Section: Spectroscopically-derived Propertiessupporting

confidence: 90%

mentioning

confidence: 99%

Hr 8257: A Three-Dimensional Orbit and Basic Properties

Fekel

Boden

Tomkin

et al. 2009

ApJ

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“…They derived the values of V eq sin i = 240 km s −1 and 241 km s −1 . The source δ Aquilae A (δ Aql, HR 7377, HD 182640) is a subgiant F0IV star (Cowley & Fraquelli 1974). Using a model atmosphere analysis of spectroscopic binaries and multiple star systems, Fuhrmann (2008) determined that the mass of this star is 1.65 M , and its radius is 2.04 R .…”

Section: The Sample Starsmentioning

confidence: 99%

Beyond the diffraction limit of optical/IR interferometers

Hadjara

Souza

Vakili

et al. 2014

A&A

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Context. As previously demonstrated on Achernar, one can derive the angular radius, rotational velocity, axis tilt, and orientation of a fast-rotating star from the differential phases obtained by spectrally resolved long baseline interferometry using earth-rotation synthesis.Aims. We applied this method on a small sample of stars for different spectral types and classes, in order to generalize the technique to other rotating stars across the H-R diagram and determine their fundamental parameters. Methods. We used differential phase data from the AMBER/VLTI instrument obtained prior to refurbishing its spectrometer in 2010. With the exception of Fomalhaut, which has been observed in the medium-resolution mode of AMBER (λ/δλ ≈ 1500), our three other targets, Achernar, Altair, and δ Aquilae offered high-resolution (λ/δλ ≈ 12 000) spectro-interferometric data around the Brγ absorption line in K band. These data were used to constrain the input parameters of an analytical, still realistic model to interpret the observations with a systematic approach for the error budget analysis in order to robustly conclude on the physics of our 4 targets. We applied the super resolution provided by differential phases φ diff to measure the size (equatorial radius R eq and angular diameter / eq ), the equatorial rotation velocity (V eq ), the inclination angle (i), and the rotation axis position angle (PA rot ) of 4 fast-rotating stars: Achernar, Altair, δ Aquilae, and Fomalhaut. The stellar parameters of the targets were constrained using a semi-analytical algorithm dedicated to fast rotators SCIROCCO. Results. The derived parameters for each star were R eq = 11.2 ± 0.5 R , V eq sin i = 290 ± 17 km s −1 , PA rot = 35.4• ± 1.4• , for Achernar; R eq = 2.0 ± 0.2 R , V eq sin i = 226 ± 34 km s −1 , PA rot = −65.5 • ± 5.5• , for Altair; R eq = 2.2 ± 0.3 R , V eq sin i = 74 ± 35 km s −1 , PA rot = −101.2• ± 14 • , for δ Aquilae; and R eq = 1.8 ± 0.2 R , V eq sin i = 93 ± 16 km s −1 , PA rot = 65.6 • ± 5 • , for Fomalhaut. They were found to be compatible with previously published values from differential phase and visibility measurements, while we were able to determine, for the first time, the inclination angle i of Fomalhaut (i = 90• ± 9 • ) and δ Aquilae (i = 81 • ± 13 • ), and the rotation-axis position angle PA rot of δ Aquilae. Conclusions. Beyond the theoretical diffraction limit of an interferometer (ratio of the wavelength to the baseline), spatial super resolution is well suited to systematically estimating the angular diameters of rotating stars and their fundamental parameters with a few sets of baselines and the Earth-rotation synthesis provided a high enough spectral resolution.

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“…6.6. HD 45638 = HR 2351 Cowley & Fraquelli (1974) called HD 45638 an A9 IV star, while Abt & Morrell (1995) similarly classified the star as F0 IV. Gray & Garrison (1989) designated it a mild Am star with spectral classes of A9/F0/F2 for the Ca K line, hydrogen lines, and metal lines, respectively.…”

Section: Hd 38309 = Hr 1978 = Ads 4333a = Hip 27118mentioning

confidence: 99%

A Volume-Limited Photometric Survey of 114 Γ Doradus Candidates

Henry¹,

Fekel²,

Henry³

2011

The Astronomical Journal

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We have carried out a photometric survey of a complete, volume-limited sample of γ Doradus candidates. The sample was extracted from the Hipparcos catalog and consists of 114 stars with colors and absolute magnitudes within the range of known γ Doradus stars and that also lie within a specified volume of 266,600 pc 3 . We devoted one year of observing time with our T12 0.8 m automatic photometric telescope to acquire nightly observations of the complete sample of stars. From these survey observations, we identify 37 stars with intrinsic variability of 0.002 mag or more. Of these 37 variables, eight have already been confirmed as γ Doradus stars in our earlier papers; we scheduled the remaining 29 variables on our T3 0.4 m automatic telescope to acquire more intensive observations over the next two years. As promising new γ Doradus candidates were identified from the photometry, we obtained complementary spectroscopic observations of each candidate with the Kitt Peak coudé feed telescope. Analysis of our new photometric and spectroscopic data reveals 15 new γ Doradus variables (and confirms two others), eight new δ Scuti variables (and confirms one other), and three new variables with unresolved periodicity. Therefore, of the 114 γ Doradus candidates

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MK Spectral Types for Some Bright F Stars

Abstract: MK spectral types are presented for 100 stars previously classified F0. This comprises a portion of a larger project to assign accurate spectral types to the stars in the Bright Star Catalogue.

Cited by 16 publications

References 4 publications

Hr 8257: A Three-Dimensional Orbit and Basic Properties

Hr 8257: A Three-Dimensional Orbit and Basic Properties

Beyond the diffraction limit of optical/IR interferometers

A Volume-Limited Photometric Survey of 114 Γ Doradus Candidates

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