Hinode

List all Hinode datasets

Hinode (SOLAR-B)

Mission Descriptions

Overview

"Hinode (SOLAR-B)" is a Japanese satellite launched on September 23, 2006, dedicated to solar observation. The mission aims to elucidate the physical mechanisms of solar activity and heating phenomena. It focuses on:

  1. Understanding the processes of solar magnetic field generation and evolution.
  2. Unraveling the mechanisms of magnetic energy transport that cause high-temperature corona and coronal activity.
  3. Understanding the energy release in explosive phenomena such as flares and coronal mass ejections (CME).

This mission is conducted through international collaboration involving Japan's Institute of Space and Astronautical Science/Japan Aerospace Exploration Agency (ISAS/JAXA), the National Astronomical Observatory of Japan (NAOJ), NASA, and the UK's Particle Physics and Astronomy Research Council (PPARC; now STFC).

The satellite is a rectangular box weighing about 900 kg and measuring approximately 1.6 m × 1.6 m × 4 m. It orbits in a sun-synchronous circular orbit at an altitude of about 680 km, with an inclination of 98 degrees and an orbital period of 98 minutes. It carries three main observation instruments and conducts observations based on proposals from international researchers.

Observation Instruments

Solar Optical Telescope (SOT)

SOT is a Gregory-type telescope with a 0.5 m aperture. The observation equipment of SOT includes the Filtergraph (FG) and Spectro-polarimeter (SP), along with the Correlation Tracker (CT) for image stabilization. It can continuously observe in the visible light wavelength range (388-668 nm) at a very high resolution of 0.2-0.3 arcseconds (equivalent to about 140-210 km on the solar surface). It captures visible light images of the solar surface (photosphere) at about 6000 degrees and the chromosphere at about 10,000 degrees up to 1000 km above. Using polarization, it provides high-precision images of the three components of the magnetic field vector.

Filtergraph (FG)

The FG is an instrument for capturing images of the solar photosphere and chromosphere through filters corresponding to specific wavelengths. It has two modes: Broadband Filter Imager (BFI) and Narrowband Filter Imager (NFI), sampling different fields of view, passbands, and spectral regions. High-resolution images taken with the FG reveal fine structures on the solar surface, such as plages and sunspots. However, it stopped observations due to an overcurrent failure in February 2016.

Spectro-Polarimeter (SP)

The SP is an instrument for polarized light observation of the solar surface's magnetic field. It uses the iron atom (Fe I) absorption line near a wavelength of 630.2 nanometers to analyze local magnetic field strength and direction with very high precision. The SP's observation results provide crucial data on the temporal changes in the solar magnetic field and the generation and disappearance of local magnetic fields.

Correlation Tracker (CT)

The CT is a system to correct for the Sun's rotation and the observation instrument's slight movements. It continuously tracks the position of the observation target, ensuring stable images. The CT maintains high observation accuracy, enhancing the data quality obtained by the SP and FG.

X-Ray Telescope (XRT)

The XRT is an off-axis X-ray reflection telescope with a 0.35 m aperture, designed to observe X-rays emitted by the corona and flares at temperatures from 1 million to 10 million degrees. It captures X-ray images in the wavelength range of 0.2-20 nm with a resolution of about 2 arcseconds and has a field of view of 34 arcminutes, covering the entire Sun. Its goal is to analyze the characteristics of active regions and coronal holes and contribute to solving the coronal heating problem.

Extreme Ultraviolet Imaging Spectrometer (EIS)

The EIS is an instrument for spectroscopic observation of emission lines from coronal plasma. It observes two wavelength ranges, 17-21 nm and 25-29 nm, using two large CCDs simultaneously. By analyzing spectral lines emitted by different ions in the extreme ultraviolet range, it measures physical quantities such as temperature, density, and motion velocity of the corona and transition region. This contributes to understanding the heating mechanisms and energy transport processes in the solar atmosphere.

Achievements

Early data from Hinode revealed several important discoveries for understanding various physical phenomena occurring in the solar atmosphere, such as the detection of Alfvén waves, the dynamics of the chromosphere and photosphere, identification of solar wind sources, and the fine magnetic structures in sunspots and quiet regions.

Data obtained by Hinode have significantly contributed to understanding solar activity and space weather. In particular, new insights into the mechanisms of solar flares and coronal mass ejections (CME) have improved the ability to predict the impact of these phenomena on Earth's space environment.

Researchers integrate Hinode's observation data with other ground-based and space-based instruments for more detailed analysis. This integration deepens the understanding of solar magnetic activity and its variations, contributing to future space missions and the improvement of space weather forecasting accuracy.

Refereneces

Instrument paper