Polarimetric calibration of a spectropolarimeter instrument with high precision: Sunrise chromospheric infrared spectropolarimeter (SCIP) for the sunrise iii balloon telescope.

The Sunrise chromospheric infrared spectropolarimeter (SCIP) installed in the international balloon experiment sunrise iii will perform spectropolarimetric observations in the near-infrared band to measure solar photospheric and chromospheric magnetic fields simultaneously. The main components of SCIP for polarization measurements are a rotating wave plate, polarization beam splitters, and CMOS imaging sensors. In each of the sensors, SCIP records the orthogonal linearly polarized components of light. The polarization is later demodulated on-board. Each sensor covers one of the two distinct wavelength regions centered at 770 and 850 nm. To retrieve the proper circular polarization, the new parameter R, defined as the 45° phase shifted component of Stokes V in the modulation curve, is introduced. SCIP is aimed at achieving high polarization precision (1σ<3×10-4 of continuum intensity) to capture weak polarization signals in the chromosphere. The objectives of the polarization calibration test presented in this paper are to determine a response matrix of SCIP and to measure its repeatability and temperature dependence to achieve the required polarization precision. Tolerances of the response matrix elements were set after considering typical photospheric and chromospheric polarization signal levels. We constructed a feed optical system such that a telecentric beam can enter SCIP with the same f-number as the light distribution instrument of the sunrise iii telescope. A wire-grid linear polarizer and achromatic wave plate were placed before SCIP to produce the known polarization. The obtained response matrix was close to the values expected from the design. The wavelength and spatial variations, repeatability, and temperature dependence of the response matrix were confirmed to be smaller than tolerances.

Continuous plasma outflows from the edge of a solar active region as a possible source of solar wind.

The Sun continuously expels a huge amount of ionized material into interplanetary space as the solar wind. Despite its influence on the heliospheric environment, the origin of the solar wind has yet to be well identified. In this paper, we report Hinode X-ray Telescope observations of a solar active region. At the edge of the active region, located adjacent to a coronal hole, a pattern of continuous outflow of soft-x-ray-emitting plasmas was identified emanating along apparently open magnetic field lines and into the upper corona. Estimates of temperature and density for the outflowing plasmas suggest a mass loss rate that amounts to approximately 1/4 of the total mass loss rate of the solar wind. These outflows may be indicative of one of the solar wind sources at the Sun.

Chromospheric anemone jets as evidence of ubiquitous reconnection.

The heating of the solar chromosphere and corona is a long-standing puzzle in solar physics. Hinode observations show the ubiquitous presence of chromospheric anemone jets outside sunspots in active regions. They are typically 3 to 7 arc seconds = 2000 to 5000 kilometers long and 0.2 to 0.4 arc second = 150 to 300 kilometers wide, and their velocity is 10 to 20 kilometers per second. These small jets have an inverted Y-shape, similar to the shape of x-ray anemone jets in the corona. These features imply that magnetic reconnection similar to that in the corona is occurring at a much smaller spatial scale throughout the chromosphere and suggest that the heating of the solar chromosphere and corona may be related to small-scale ubiquitous reconnection.