Short time-scale variability of chromospheric Ca II in late-type stars

Journal Article · Mon Jun 01 04:00:00 EDT 1981 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/158946· OSTI ID:6184888

Baliunas, S L; Hartmann, L; Waughan, A H; Liller, W; Dupree, A K

We have investigated short time-scale variability of singly ionized calcium chromospheric emission in a few late-type stars. Emission-line variations with time scales of a few minutes to hours are seen in ..cap alpha.. Tau (K5 III), lambda and (G8 III--IV), and epsilon Eri (K2 V). The existence of substantial chromospheric flux changes (10/sup 30/--10/sup 32/ ergs) over short periods of time suggests that the calcium emission arises from a few small, coherent regions. Frequencies present in the data are discussed in the context of acoustic wave predictions and estimated acoustic cutoff frequencies for giants and dwarfs.

• Research Organization: Harvard-Smithsonian Center for Astrophysics
• OSTI ID: 6184888
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 246:2; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
CARBON IONS
CHARGED PARTICLES
EMISSION
EMISSION SPECTRA
FOURIER ANALYSIS
GIANT STARS
IONS
MAIN SEQUENCE STARS
SPECTRA
SPECTROPHOTOMETRY
STARS
STELLAR ATMOSPHERES
VARIATIONS