Photoelectric observations of propagating sunspot oscillations

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

DOI:https://doi.org/10.1086/159642· OSTI ID:5169787

Lites, B W; White, O R; Packman, D

The Sacramento Park Observatory Vacuum Tower Telescope and diode array were used to make repeated intensity and velocity images of a large, isolated sunspot in both a chromospheric (lambda8542 Ca II) and a photospheric (lambda5576 Fe I) line. The movie of the digital data for the chromospheric line shows clearly a relationship between the propagating umbral disturbances and the running penumbral waves. The velocities for transverse propagating of the umbral and penumbral disturbances are 60--70 km s/sup -1/ and 20--35 km s/sup -1/, respectively. Power spectra of the oscillations show a sharp peak at a period of about 170 s in both the velocity and intensity signals. The rms velocity fluctuation of this power peak is 0.26 km s/sup -1/. The oscillations at any given point in the sunspot are very regular, and the phase relationship between the velocity and intensity of the chromospheric oscillations is radically different than that for the quiet Sun. Our preliminary interpretation of the phase relationship involves acoustic waves with wave vector directed downwards along the magnetic field lines; however, this interpretation relies on assumptions involved in the data reduction scheme. The mechanical energy flux carried by the observed umbral disturbances does not appear to be a significant contributor to the overall energy budget of the sunspot or the surrounding active region.

• Research Organization: Sacramento Peak National Observatory
• OSTI ID: 5169787
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 253:1; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics & Cosmology-- Solar Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ACOUSTIC RADAR
ATMOSPHERES
CALCIUM IONS
CHARGED PARTICLES
FLUID FLOW
IONS
IRON IONS
MAGNETIC FIELDS
MEASURING INSTRUMENTS
OSCILLATIONS
PHASE VELOCITY
RADAR
RANGE FINDERS
SOLAR ACTIVITY
SOLAR ATMOSPHERE
SUNSPOTS
SUPERSONIC FLOW
VELOCITY
WAVE PROPAGATION