SMALL MAGNETIC LOOPS CONNECTING THE QUIET SURFACE AND THE HOT OUTER ATMOSPHERE OF THE SUN

Journal Article · Sat May 01 04:00:00 EDT 2010 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/714/1/L94; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21305006

Martinez Gonzalez, M J; Manso Sainz, R; Asensio Ramos, A ^[1]

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1. Instituto de Astrofisica de Canarias, C/VIa Lactea s/n, 38200 La Laguna, Tenerife (Spain)

Sunspots are the most spectacular manifestation of solar magnetism, yet 99% of the solar surface remains 'quiet' at any time of the solar cycle. The quiet sun is not void of magnetic fields, though; they are organized at smaller spatial scales and evolve relatively fast, which makes them difficult to detect. Thus, although extensive quiet Sun magnetism would be a natural driver to a uniform, steady heating of the outer solar atmosphere, it is not clear what the physical processes involved would be, due to lack of observational evidence. We report on the topology and dynamics of the magnetic field in very quiet regions of the Sun from spectropolarimetric observations of the Hinode satellite, showing a continuous injection of magnetic flux with a well-organized topology of {omega}-loop from below the solar surface into the upper layers. At first stages, when the loop travels across the photosphere, it has a flattened (staple-like) geometry and a mean velocity ascent of {approx}3 km s{sup -1}. When the loop crosses the minimum temperature region, the magnetic fields at the footpoints become almost vertical and the loop topology resembles a potential field. The mean ascent velocity at chromospheric height is {approx}12 km s{sup -1}. The energy input rate of these small-scale loops in the lower boundary of the chromosphere is (at least) of 1.4 x 10{sup 6}-2.2 x 10{sup 7} erg cm{sup -2} s{sup -1}. Our findings provide empirical evidence for solar magnetism as a multi-scale system, in which small-scale low-flux magnetism plays a crucial role, at least as important as active regions, coupling different layers of the solar atmosphere and being an important ingredient for chromospheric and coronal heating models.

• OSTI ID: 21305006
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 1 Vol. 714; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
99 GENERAL AND MISCELLANEOUS
CHROMOSPHERE
MAGNETIC FIELDS
MAGNETIC FLUX
MAGNETISM
PHOTOSPHERE
POLARIZATION
SATELLITES
SOLAR CYCLE
SUN
SUNSPOTS