Fine Structures and Kinematics of an Intriguing Chromospheric Jet Observed by Hinode Solar Optical Telescope

Details Fine Structures and Kinematics of an Intriguing Chromospheric Jet Observed by Hinode Solar Optical Telescope Fine Structures and Kinematics of an Intriguing Chromospheric Jet Observed by Hinode Solar Optical Telescope

Dec 2009

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009agufmsh51a1266l&link_type=abstract

American Geophysical Union, Fall Meeting 2009, abstract #SH51A-1266

Astronomy and Astrophysics

Astrophysics

[7507] Solar Physics, Astrophysics, And Astronomy / Chromosphere, [7509] Solar Physics, Astrophysics, And Astronomy / Corona, [7546] Solar Physics, Astrophysics, And Astronomy / Transition Region

Scientific paper

Transient, small-scale ejections of plasma from the lower atmosphere are common manifestations of solar activity. Hinode, with its superior resolutions, has spurred renewed interest in solar jets since its launch. Here we report a chromospheric jet lasting for more than 1 hr on 2007 February 9 observed by the Hinode Solar Optical Telescope (SOT) in unprecedented detail. SOT Ca II H passband observations at high resolution of 0.2 arcsecond and cadence of 8 s allowed us to investigate the fine structures and kinematics of the jet. The ejection occurred in three episodes, rather than continuously, with the amount and velocity of material decreasing with time. The upward velocities along the jet range from ~440 to ~30 km/s, while the downward velocities of the material falling back have much smaller values (mean: -60 km/s) and a narrower distribution. Some tracks in the space-time plot clearly show parabolic shapes and the inferred acceleration is a fraction of the solar gravitational acceleration. The jet consists of fine threads (0.5-2 arcsecond wide), which exhibit coherent, oscillatory transverse motions perpendicular to the jet axis and about a common equilibrium position. These motions propagate upward, with the maximum phase speed of ~740 km/s found at the leading front of the jet. The transverse oscillation velocities range from 150 to 30 km/s, amplitudes from 6 to 2 Mm, and periods from 250 to 550 s. The oscillations slow down with time and cease when the material starts to fall back. The falling material travels along almost straight lines in the original direction of ascent, showing no transverse motions. These observations are consistent with the models suggested by Shibata & Uchida (1985) and Canfield et al. (1996). In this scenario, the jet involves untwisting helical threads, which rotate about the axis of a single large cylinder and shed magnetic helicity into the upper atmosphere. Implications of this event in the context of multiwavelength data in H-alpha, EUV, and X-rays will be discussed. A chromospheric jet observed by Hinode SOT in the Ca II H passband (T=1-2×10 4 K). Note the helical-like fine threads.

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