THE ORBIT, ROTATION, AND GRANULATION OF THE G7 GIANT β Her

Journal Article · Sun Nov 20 04:00:00 EST 2016 · Astrophysical Journal

DOI:https://doi.org/10.3847/0004-637X/832/1/68· OSTI ID:22667179

The G7 IIIa single-lined spectroscopic binary, β Her, is studied with high-resolution, high-signal-to-noise spectra taken over 10 seasons from 23MR2000 to 10MY2009. Absolute radial velocities, corrected for convective blueshifts, are determined and new orbital parameters are derived. Line-depth ratios are used to measure temperature variation ∼2 K. A Fourier analysis is done for the line broadening, yielding a projected rotation velocity of 3.27 ± 0.20 km s{sup -1} and a radial–tangential macroturbulence dispersion of 6.43 ± 0.08 km s{sup -1}. The “C” shaped bisector of Fe i λ 6253 has its blue-most point at a relative flux level of 0.52, consistent with what is expected from β Her’s absolute magnitude. The third-signature plot indicates granulation velocities 20% larger than the Sun’s. Mapping the λ 6253 line bisector onto the third-signature curve results in a flux deficit of 12.6 ± 1.0% that can be interpreted as arising from a temperature difference between granules and inter-granular lanes of 132 K. The flux deficit peaks near 5.5 km s{sup -1} from the line center, suggesting the velocity difference between granules and lanes is ∼20% larger than that found for recently analyzed K giants.

• OSTI ID: 22667179
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 832; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ATMOSPHERES
CONVECTION
DISPERSIONS
FOURIER ANALYSIS
GIANT STARS
GRANULATION
LINE BROADENING
ORBITS
RADIAL VELOCITY
RESOLUTION
ROTATION
SPECTRA