LOCAL HELIOSEISMIC AND SPECTROSCOPIC ANALYSES OF INTERACTIONS BETWEEN ACOUSTIC WAVES AND A SUNSPOT

Journal Article · Fri Oct 01 00:00:00 EDT 2010 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/721/2/L86· OSTI ID:21452792

Rajaguru, S P ^[1]; Wachter, R; Couvidat, S ^[2]; Sankarasubramanian, K ^[3]

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1. Indian Institute of Astrophysics, Bangalore (India)
2. W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305 (United States)
3. Space Science Division, Space Astronomy Group, ISRO Satellite Centre, Bangalore (India)

Using a high-cadence imaging spectropolarimetric observation of a sunspot and its surroundings in magnetically sensitive (Fe I 6173 A) and insensitive (Fe I 7090 A) upper photospheric absorption lines, we map the instantaneous wave phases and helioseismic travel times as a function of observation height and inclination of magnetic field to the vertical. We confirm the magnetic inclination-angle-dependent transmission of incident acoustic waves into upward propagating waves and derive (1) proof that helioseismic travel times receive direction-dependent contributions from such waves and hence cause errors in conventional flow inferences, (2) evidences for acoustic wave sources beneath the umbral photosphere, and (3) significant differences in travel times measured from the chosen magnetically sensitive and insensitive spectral lines.

• OSTI ID: 21452792
• Journal Information: Astrophysical Journal Letters, Vol. 721, Issue 2; Other Information: DOI: 10.1088/2041-8205/721/2/L86; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
INCLINATION
MAGNETIC FIELDS
MAGNETISM
PHOTOSPHERE
RADIANT HEAT TRANSFER
SOUND WAVES
SUN
SUNSPOTS
ATMOSPHERES
ENERGY TRANSFER
HEAT TRANSFER
MAIN SEQUENCE STARS
SOLAR ACTIVITY
SOLAR ATMOSPHERE
STARS
STARSPOTS
STELLAR ACTIVITY
STELLAR ATMOSPHERES