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Title: A Spectral-line Analysis of the G8 III Standard ε VIR

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 formore » giants higher in the HR diagram.« less

Authors:
 [1]
  1. Department of Physics and Astronomy University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 3K7 (Canada)
Publication Date:
OSTI Identifier:
22663260
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 845; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ATMOSPHERES; DISPERSIONS; FOURIER ANALYSIS; GRANULATION; LUMINOSITY; RADIAL VELOCITY; RED SHIFT; ROTATION; STARS

Citation Formats

Gray, David F., E-mail: dfgray@uwo.ca. A Spectral-line Analysis of the G8 III Standard ε VIR. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA7F77.
Gray, David F., E-mail: dfgray@uwo.ca. A Spectral-line Analysis of the G8 III Standard ε VIR. United States. doi:10.3847/1538-4357/AA7F77.
Gray, David F., E-mail: dfgray@uwo.ca. Thu . "A Spectral-line Analysis of the G8 III Standard ε VIR". United States. doi:10.3847/1538-4357/AA7F77.
@article{osti_22663260,
title = {A Spectral-line Analysis of the G8 III Standard ε VIR},
author = {Gray, David F., E-mail: dfgray@uwo.ca},
abstractNote = {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.},
doi = {10.3847/1538-4357/AA7F77},
journal = {Astrophysical Journal},
number = 1,
volume = 845,
place = {United States},
year = {Thu Aug 10 00:00:00 EDT 2017},
month = {Thu Aug 10 00:00:00 EDT 2017}
}