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Author Gray, David F.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword ASTROPHYSICS, COSMOLOGY AND ASTRONOMY ♦ ATMOSPHERES ♦ DISPERSIONS ♦ FOURIER ANALYSIS ♦ GRANULATION ♦ LUMINOSITY ♦ RADIAL VELOCITY ♦ RED SHIFT ♦ ROTATION ♦ STARS
Abstract Eleven seasons of spectroscopic data comprised of 107 exposures for the stable G8 III standard star, ε Vir are analyzed for projected rotation rate and granulation parameters. A Fourier analysis of the line shapes yield v sin i = 3.06 ± 0.20 km s{sup −1} and a radial-tangential macroturbulence dispersion ζ {sub RT} = 5.16 ± 0.08 km s{sup −1}. The radial velocity over nine seasons is constant to 18 m s{sup −1}. The absolute radial velocity with granulation blueshifts (but not gravitational redshift) removed is −14120 ± 75 m s{sup −1}. Line-depth ratios show the temperature to be constant to 0.7 K over 11 years, although a small secular rise or cyclic variation ∼1 K cannot be ruled out. The third-signature plot shows that the star has granulation velocities 10% larger than the Sun's. Mapping the Fe i λ 6253 line bisector on to the third-signature plot indicates a normal-for-giants flux deficit area of 12.8%, indicating ∼134 K temperature difference between granules and lanes. Deficit velocities of GK giants are seen to shift to higher values with higher luminosity, ∼0.75 km s{sup −1} over Δ M {sub V} ∼ 1.5, indicating larger velocity differences between granules and lanes for giants higher in the HR diagram.
ISSN 0004637X
Educational Use Research
Learning Resource Type Article
Publisher Date 2017-08-10
Publisher Place United States
Journal Astrophysical Journal
Volume Number 845
Issue Number 1


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