ROTATION AND GRANULATION OF THE K2 GIANT α SER

Journal Article · Wed Jul 20 04:00:00 EDT 2016 · Astrophysical Journal

DOI:https://doi.org/10.3847/0004-637X/826/1/92· OSTI ID:22666028

The red giant α Ser was observed over 10 seasons, 2001–2010, at the Elginfield Observatory with the high-resolution coudé spectrograph. Season-mean radial velocities appear to show a small secular rise ∼11 ± 3 m s{sup 1} yr{sup 1}. The absolute spectroscopic radial velocity with convective blueshifts taken into account is 2730 m s{sup 1}. Ten line-depth ratios were investigated and show that the star's temperature is constant with any secular variation below 1.3 ± 1.0 K over the 11 years of observation. Fourier analysis of the line broadening yields v sin i = 2.0 ± 0.3 km s{sup 1} and a radial-tangential macroturbulence dispersion ζ {sub RT} = 4.50 ± 0.10 km s{sup 1}. The third-granulation-signature plot shows that the granulation velocities of α Ser are only 0.55 ± 0.10 as large as the Sun's. The line bisector of Fe i λ 6253 has the usual “C” shape and when mapped onto the third-signature plot results in a flux deficit that is slightly broader than seen in other measured K giants. The deficit fractional area of 12.3 ± 1.5% suggests a temperature difference between granules and lanes of 105 K as seen averaged over the stellar disk.

• OSTI ID: 22666028
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 826; 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
RADIAL VELOCITY
RESOLUTION
ROTATION
TURBULENCE