Diagnostics of Ellerman bombs with high-resolution spectral data

Document Type

Article

Publication Date

9-1-2015

Abstract

Ellerman bombs (EBs) are tiny brightenings often observed near sunspots. The most impressive characteristic of EB spectra is the two emission bumps in both wings of the H and Ca II 8542Å lines. High-resolution spectral data of three small EBs were obtained on 2013 June 6 with the largest solar telescope, the 1.6 m New Solar Telescope at the Big Bear Solar Observatory. The characteristics of these EBs are analyzed. The sizes of the EBs are in the range of 0.3′ - 0.8′ and their durations are only 3-5 min. Our semi-empirical atmospheric models indicate that the heating occurs around the temperature minimum region with a temperature increase of 2700-3000 K, which is surprisingly higher than previously thought. The radiative and kinetic energies are estimated to be as high as 51025 - 3.01026 erg despite the small size of these EBs. Observations of the magnetic field show that the EBs just appeared in a parasitic region with mixed polarities and were accompanied by mass motions. Nonlinear force-free field extrapolation reveals that the three EBs are connected with a series of magnetic field lines associated with bald patches, which strongly implies that these EBs should be produced by magnetic reconnection in the solar lower atmosphere. According to the lightcurves and the estimated magnetic reconnection rate, we propose that there is a three phase process in EBs: pre-heating, flaring and cooling phases.

Identifier

84940507062 (Scopus)

Publication Title

Research in Astronomy and Astrophysics

External Full Text Location

https://doi.org/10.1088/1674-4527/15/9/008

ISSN

16744527

First Page

1513

Last Page

1524

Issue

9

Volume

15

Grant

1250818

Fund Ref

National Science Foundation

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