Spatial variation and evolution of heliospheric sector structure

Journal Article · Wed Feb 01 04:00:00 EST 1989 · Journal of Geophysical Research; (USA)

DOI:https://doi.org/10.1029/JA094iA02p01245· OSTI ID:6052428

Behannon, K W; Burlaga, L F ^[1]; Hoeksema, J T ^[2]; Klein, L W ^[3]

---

1. NASA Goddard Space Flight Center, Greenbelt, MD (USA)
2. Stanford Univ., CA (USA)
3. Applied Research Corp., Landover, MD (USA)

The magnetic sector polarity at the Sun and in interplanetary space has been surveyed during approximately three quarters of sunspot cycle 21 using photospheric magnetic field observations from the Wilcox Solar Observatory at Stanford University and spacecraft observations by Voyagers 1 and 2, Pioneer Venus Orbiter, and, to a lesser extent, Helios A, IMP 8, and ISEE 3. During the more than 8-year period of the study, late 1977-1985, the Voyagers measured the interplanetary magnetic field (IMF) over a heliocentric distance range of 1-25 AU and a heliolatitude range of {minus}5{degree}-27{degree}. The photospheric data were used together with a potential field (PF) model to calculate the location of the heliospheric current sheet near the Sun throughout the same period, which included sunspot maximum and much of the declining phase. The large-scale magnetic polarity structure was found to be in almost continuous evolution throughout the period of study. Although the azimuth of the IMF was found by the Voyager spacecraft to be oriented more than 60{degree} from the theoretical Parker spiral angle 20% of the time, application of smoothing techniques produced IMF polarity patterns which could be compared with the pattern derived at the Sun. Such comparisons revealed very good agreement (82%) between solar and IMF sector patterns observed by Pioneer Venus in the inner heliosphere and significantly poorer agreement (61-64%) between solar and outer heliosphere patterns observed by Voyagers 1 and 2. This may be the result of dynamical processes in the solar wind which alter the position and shape of the current sheet beyond a few astronomical units.

• OSTI ID: 6052428
• Journal Information: Journal of Geophysical Research; (USA), Journal Name: Journal of Geophysical Research; (USA) Vol. 94:A2; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics & Cosmology-- Solar Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
DYNAMICS
HELIOSPHERE
INTERPLANETARY MAGNETIC FIELDS
INTERPLANETARY SPACE
MAGNETIC FIELD CONFIGURATIONS
MAGNETIC FIELDS
MAIN SEQUENCE STARS
MECHANICS
ORIGIN
PHOTOSPHERE
SOLAR ACTIVITY
SOLAR ATMOSPHERE
SOLAR CYCLE
SOLAR WIND
SPACE
STARS
SUN