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Internal structure and rotation of the Sun: First results from the MDI data

Published online by Cambridge University Press:  25 May 2016

A.G. Kosovichev ,
J. Schou ,
P.H. Scherrer ,
R.S. Bogart ,
R.I. Bush ,
J.T. Hoeksema ,
J. Aloise ,
L. Bacon ,
A. Burnette  and
C. De Forest
...Show all authors
A.G. Kosovichev
Affiliation:
W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305, USA
J. Schou
Affiliation:
W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305, USA
P.H. Scherrer
Affiliation:
W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305, USA
R.S. Bogart
Affiliation:
W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305, USA
R.I. Bush
Affiliation:
W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305, USA
J.T. Hoeksema
Affiliation:
W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305, USA
J. Aloise
Affiliation:
W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305, USA
L. Bacon
Affiliation:
W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305, USA
A. Burnette
Affiliation:
W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305, USA
C. De Forest
Affiliation:
W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305, USA
P.M. Giles
Affiliation:
W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305, USA
K. Leibrand
Affiliation:
W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305, USA
R. Nigam
Affiliation:
W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305, USA
M. Rubin
Affiliation:
W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305, USA
K. Scott
Affiliation:
W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305, USA
S.D. Williams
Affiliation:
W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305, USA
Sarbani Basu
Affiliation:
Theoretical Astrophysics Center, Danish National Research Foundation, and Institute of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, Denmark
J. Christensen-Dalsgaard
Affiliation:
Theoretical Astrophysics Center, Danish National Research Foundation, and Institute of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, Denmark
W. Däppen
Affiliation:
Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089, USA
E.J. Rhodes Jr.
Affiliation:
Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089, USA
T.L. Duvall Jr.
Affiliation:
Laboratory for Astronomy and Solar Physics, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
R. Howe
Affiliation:
Astronomy Unit, Queen Mary and Westfield College, London, El 4NS, UK
M.J. Thompson
Affiliation:
Astronomy Unit, Queen Mary and Westfield College, London, El 4NS, UK
D.O. Gough
Affiliation:
Institute of Astronomy, and Department of Applied Mathematics and Theoretical Physics, Madingley Road, Cambridge, CB3 0HA, UK
T. Sekii
Affiliation:
Institute of Astronomy, and Department of Applied Mathematics and Theoretical Physics, Madingley Road, Cambridge, CB3 0HA, UK
J. Toomre
Affiliation:
JILA, University of Colorado, CO 80309, USA
T.D. Tarbell
Affiliation:
Lockheed-Martin Advanced Technology Center, 91-30/252, 3251 Hanover St., Palo Alto, CA 94304.
A.M. Title
Affiliation:
Lockheed-Martin Advanced Technology Center, 91-30/252, 3251 Hanover St., Palo Alto, CA 94304.
D. Mathur
Affiliation:
Lockheed-Martin Advanced Technology Center, 91-30/252, 3251 Hanover St., Palo Alto, CA 94304.
M. Morrison
Affiliation:
Lockheed-Martin Advanced Technology Center, 91-30/252, 3251 Hanover St., Palo Alto, CA 94304.
J.L.R. Saba
Affiliation:
Lockheed-Martin Advanced Technology Center, 91-30/252, 3251 Hanover St., Palo Alto, CA 94304.
C.J. Wolfson
Affiliation:
Lockheed-Martin Advanced Technology Center, 91-30/252, 3251 Hanover St., Palo Alto, CA 94304.
I. Zayer
Affiliation:
Lockheed-Martin Advanced Technology Center, 91-30/252, 3251 Hanover St., Palo Alto, CA 94304.
P.N. Milford
Affiliation:
Parallel Rules, Inc. 41 Manzanita Ave., Los Gatos, CA 95030

Abstract

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The Medium-l Program of the Michelson Doppler Imager (MDI) instrument on board SOHO provides continuous observations of oscillation modes of angular degree, l, from 0 to ∼ 300. The initial results show that the noise in the Medium-l oscillation power spectrum is substantially lower than in ground-based measurements. This enables us to detect lower amplitude modes and, thus, to extend the range of measured mode frequencies. The MDI observations also reveal the asymmetry of oscillation spectral lines. The line asymmetries agree with the theory of mode excitation by acoustic sources localized in the upper convective boundary layer. The sound-speed profile inferred from the mean frequencies gives evidence for a sharp variation at the edge of the energy-generating core. In a thin layer just beneath the convection zone, helium appears to be less abundant than predicted by theory. Inverting the multiplet frequency splittings from MDI, we detect significant rotational shear in this thin layer.

Type
Part II: Internal structure and rotation. Seismic inversions
Information
Symposium - International Astronomical Union , Volume 181: Sounding Solar and Stellar Interiors , 1997 , pp. 203 - 210
Copyright
Copyright © Kluwer 1997 

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