Stellar model chromospheres. X. High-resolution, absolute flux profiles of the Ca II H and K lines in stars of sepctral types FO--M2

Journal Article · Sat Sep 01 04:00:00 EDT 1979 · Astrophys. J., Suppl. Ser.; (United States)

DOI:https://doi.org/10.1086/190607· OSTI ID:5461722

Linsky, J L; Worden, S P; McClintock, V; Robertson, R M

We present 120 mA resolution spectra of the cores and wings of the Ca II H and K lines in 43 stars covering a wide range of spectral type and luminosity class. These spectra were obtained with the KPNO 4 m echelle spectrograph and blue image tube, and are calibrated in absolute suface flux units using Willstrop's narrow-band photometry and the Barnes and Evans relations for stellar angular diameters. We estimate an uncertainty of +- 15% in our flux scales. We derive chromospheric radiative loss rates in H and K lines, and discuss trenfs in these loss rates with effective temperature for dwarfs, giants and supergiants. We compare these loss rates with similar rates for the Mg II h and k lines, and discuss the doublet line ratios for H and K. The monochromatic surface fluxes for different features in the H and K lines are presented. From the surface fluxes at K/sub 1/ we derived the radiation temperature T/sub R/(K/sub 1/). The T/sub R/(K/sub 1/)/T/sub eff/ ratio is lower in giants than in dwarfs, as predicted by partial redistribution calculations, and this ratio appears to be an empirical age indicator among dwarfs. Asymmetries in the K line profile provide evidence for a solar-type supergranulation flow pattern in F5--K5 dwarfs and perhaps aslo in G and early K supergiants. Measurements of line widths at H/sub 1/, K/sub 1/, and K/sub 2/ are presented, together with FWHM data for the H and K lines. We find rough agreement between the measured K/sub 1/ widths and the gravity and chromospheric heating rate dependences in the scaling law proposed by Ayeres. Finally, we present data on emission lines in the wings of H and K, and discuss chromospheric radiative loss rates in the Hepsilon line compared with loss rates in the H and K lines.

• Research Organization: Joint Institute for Laboratory Astrophysics, National Bureau of Standards and University of Colorado
• OSTI ID: 5461722
• Journal Information: Astrophys. J., Suppl. Ser.; (United States), Journal Name: Astrophys. J., Suppl. Ser.; (United States) Vol. 41:1; ISSN APJSA
• 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
ATOMIC IONS
CALCIUM IONS
CHARGED PARTICLES
DWARF STARS
EMISSION SPECTRA
GIANT STARS
IONS
MAIN SEQUENCE STARS
MASS TRANSFER
MATHEMATICAL MODELS
RADIATION FLUX
SPECTRA
STAR ACCRETION
STAR EVOLUTION
STAR MODELS
STARS
STELLAR ATMOSPHERES
SUPERGIANT STARS