Solar luminosity variation. IV. The photospheric lines, 1976--1980

Journal Article · Fri Jan 01 04:00:00 EST 1982 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/159564· OSTI ID:5526888

Livingston, W; Holweger, H

Kitt Peak full disk spectrophotometric records covering the period 1976--1980 have been analyzed to study the behavior of seven spectrum lines sensitive to photospheric parameters. A secular decrease of equivalent widths ranging from 0 to 2.3% is observed. From the lack of correlation with localized, short-lived features like sunspots and plages we conclude that the line weakenings are due to global variations of surface properties. Model atmosphere analysis suggests that the observed response patterns reflects a slight flattening of the lower photospheric temperature gradient, corresponding to a 15% increase in mixing length, at constant, effective temperature. The associated increase in the efficiency of convection can be reconciled with a constant luminosity if the change is assumed to occur only in the outer approx.100 km of the convection zone.

• Research Organization: Kitt Peak National Observatory
• OSTI ID: 5526888
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 252:1; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics & Cosmology-- Solar Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
CONVECTION
FACULAE
FRAUNHOFER LINES
LUMINOSITY
MATHEMATICAL MODELS
MEASURING INSTRUMENTS
OPTICAL PROPERTIES
PHOTOSPHERE
PHYSICAL PROPERTIES
PLAGES
RADIATION DETECTORS
SOLAR ACTIVITY
SOLAR ATMOSPHERE
SPECTRA
STAR MODELS