The Capella Giants and Coronal Evolution across the Hertzsprung Gap

2002 ◽  
Vol 565 (2) ◽  
pp. L97-L100 ◽  
Author(s):  
O. Johnson ◽  
J. J. Drake ◽  
V. Kashyap ◽  
N. S. Brickhouse ◽  
A. K. Dupree ◽  
...  
Keyword(s):  
Hertzsprung Gap

scholarly journals AE Ursae Majoris – a δ Scuti Star in the Hertzsprung Gap

2017 ◽  
pp. stx125 ◽  
Author(s):  
Jia-Shu Niu ◽  
Jian-Ning Fu ◽  
Yan Li ◽  
Xiao-Hu Yang ◽  
Weikai Zong ◽  
...  
Keyword(s):  
Scuti Star ◽  
Hertzsprung Gap

scholarly journals Fossil Magnetospheres Confront Newborn Dynamos in the Rapid Braking Zone

2004 ◽  
Vol 215 ◽  
pp. 280-286
Author(s):  
Thomas R. Ayres
Keyword(s):  
Surface Field ◽  
New Type ◽  
Hertzsprung Gap

Fast spinning Hertzsprung gap giants display super-rotational broadening of UV “hot” lines like Fe XXI λ1354 and C IV λ1548, with FWHM's up to twice that expected from the photospheric v sin i. This possibly is the result of extended fossil magnetospheres enveloping the gap giants, a new type of stellar corona. The magnetospheric phase is short-lived, however, as the rapidly evolving giants develop a competing dynamo-generated surface field in the so-called Rapid Braking Zone.

Some aspects of the spectroscopic behavior of the stars of highest luminosity in the region of the Hertzsprung gap

1981 ◽  
Vol 243 ◽  
pp. 894 ◽  
Author(s):  
W. W. Morgan ◽  
P. C. Keenan ◽  
H. A. Abt ◽  
J. W. Tapscott
Keyword(s):  
Hertzsprung Gap ◽  
Spectroscopic Behavior

scholarly journals The Hertzsprung-gap giant 31 Comae in 2013: Magnetic field and activity indicators

2013 ◽  
Vol 9 (S302) ◽  
pp. 365-366
Author(s):  
Ana P. Borisova ◽  
Renada Konstantinova-Antova ◽  
Michel Aurière ◽  
Pascal Petit ◽  
Corinne Charbonnel
Keyword(s):  
Magnetic Field ◽  
Longitudinal Magnetic Field ◽  
Imaging Study ◽  
Doppler Imaging ◽  
Evolutionary Status ◽  
Rotational Period ◽  
Giant Star ◽  
Spectral Activity ◽  
Hertzsprung Gap

AbstractWe have observed the giant star 31 Comae in April and May 2013 with the spectropolarimeter Narval at Pic du Midi Observatory, France. 31 Comae is a single, rapidly rotating giant with rotational period ~6.8 d and vsini ~ 67 km/s. We present measurements and discuss variability of the longitudinal magnetic field (Bl), spectral activity indicators Hα, CaII H&K, Ca II IR triplet and evolutionary status. Our future aim is to perform a Zeeman-Doppler imaging study for the star.

scholarly journals Beryllium abundances along the evolutionary sequence of the open cluster IC 4651

2009 ◽  
Vol 5 (S268) ◽  
pp. 357-358 ◽  
Author(s):  
Rodolfo Smiljanic ◽  
L. Pasquini ◽  
C. Charbonnel ◽  
N. Lagarde
Keyword(s):  
Main Sequence ◽  
Open Cluster ◽  
High Signal ◽  
Evolutionary Sequence ◽  
Main Sequence Stars ◽  
Signal To Noise ◽  
Mixing Processes ◽  
Hydrodynamical Models ◽  
Spectrum Synthesis ◽  
Hertzsprung Gap

AbstractThe simultaneous investigation of Li and Be in stars is a powerful tool in the study of the evolutionary mixing processes. Here, we present beryllium abundances in stars along the whole evolutionary sequence of the open cluster IC 4651. This cluster has a metallicity of [Fe/H] = +0.11 and an age of 1.2 or 1.7 Gyr. Abundances have been determined from high-resolution, high signal-to-noise UVES spectra using spectrum synthesis and model atmospheres. Lithium abundances for the same stars were determined in a previous work. Confirming previous results, we find that the Li dip is also a Be dip. For post-main-sequence stars, the Be dilution starts earlier within the Hertzsprung gap than expected from classical predictions, as does the Li dilution. Theoretical hydrodynamical models are able to reproduce well all the observed features.

scholarly journals Magnetic fields in single late-type giants in the Solar vicinity: How common is magnetic activity on the giant branches?

2013 ◽  
Vol 9 (S302) ◽  
pp. 373-376 ◽  
Author(s):  
Renada Konstantinova-Antova ◽  
Michel Aurière ◽  
Corinne Charbonnel ◽  
Natalia Drake ◽  
Gregg Wade ◽  
...  
Keyword(s):  
Large Scale ◽  
Mass Range ◽  
Magnetic Activity ◽  
Asymptotic Giant Branch ◽  
Evolutionary Status ◽  
Fundamental Parameters ◽  
First Results ◽  
Red Giant ◽  
Hertzsprung Gap ◽  
The Magnetic Field

AbstractWe present our first results on a new sample containing all single G, K and M giants down to V = 4 mag in the Solar vicinity, suitable for spectropolarimetric (Stokes V) observations with Narval at TBL, France. For detection and measurement of the magnetic field (MF), the Least Squares Deconvolution (LSD) method was applied (Donati et al. 1997) that in the present case enables detection of large-scale MFs even weaker than the solar one (the typical precision of our longitudinal MF measurements is 0.1-0.2 G). The evolutionary status of the stars is determined on the basis of the evolutionary models with rotation (Lagarde et al. 2012; Charbonnel et al., in prep.) and fundamental parameters given by Massarotti et al. (1998). The stars appear to be in the mass range 1-4 M⊙, situated at different evolutionary stages after the Main Sequence (MS), up to the Asymptotic Giant Branch (AGB).The sample contains 45 stars. Up to now, 29 stars are observed (that is about 64% of the sample), each observed at least twice. For 2 stars in the Hertzsprung gap, one is definitely Zeeman detected. Only 5 G and K giants, situated mainly at the base of the Red Giant Branch (RGB) and in the He-burning phase are detected. Surprisingly, a lot of stars ascending towards the RGB tip and in early AGB phase are detected (8 of 13 observed stars). For all Zeeman detected stars v sin i is redetermined and appears in the interval 2-3 km/s, but few giants with MF possess larger v sin i.

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