The X-ray Telescope (XRT) of the Hinode mission provides an unprecedented combination of spatial and temporal resolution in solar coronal studies. The high sensitivity and broad dynamic range of XRT, coupled with the spacecraft’s onboard memory capacity and the planned downlink capability will permit a broad range of coronal studies over an\ud extended period of time, for targets ranging from quiet Sun to X-flares. This paper discusses in detail the design, calibration, and measured performance of the XRT instrument up to the focal plane. The CCD camera and data handling are discussed separately in a companion paper

Coronal magnetic fields are dynamic, and field lines may misalign, reassemble, and release energy by means of magnetic reconnection. Giant releases may generate solar flares and coronal mass ejections and, on a smaller scale, produce x-ray jets. Hinode observations of polar coronal holes reveal that x-ray jets have two distinct velocities: one near the Alfvén speed ( approximately 800 kilometers per second) and another near the sound speed (200 kilometers per second). Many more jets were seen than have been reported previously; we detected an average of 10 events per hour up to these speeds, whereas previous observations documented only a handful per day with lower average speeds of 200 kilometers per second. The x-ray jets are about 2 x 10(3) to 2 x 10(4) kilometers wide and 1 x 10(5) kilometers long and last from 100 to 2500 seconds. The large number of events, coupled with the high velocities of the apparent outflows, indicates that the jets may contribute to the high-speed solar wind.

Hinode/SOHO campaign 7197 is the most extensive study of polar jet formation and evolution from within both the north and south polar coronal holes so far. For the first time, this study showed that the appearance of X-ray jets in the solar coronal holes occurs at very high frequency-about 60 jets d 1 on average. Using observations collected by the X-Ray Telescope on Hinode, a number of physical parameters from a large sample of jets were statistically studied. We measured the apparent outward velocity, the height, the width and the lifetime of the jets. In our sample, all of these parameters show peaked distributions with maxima at 160 km s 1 for the outward velocity, 5 10 4 km for the height, 8 10 3 km for the width, and about 10 min for the lifetime of the jets. We also present the first statistical study of jet transverse motions, which obtained transverse velocities of 0-35 km s 1. These values were obtained on the basis of a larger (in terms of frequency) and better sampled set of events than what was previously statistically studied (Shimojo et al. 1996, PASJ, 48, 123). The results were made possible by the unique characteristics of XRT. We describe the methods used to determine the characteristics and set some future goals. We also show that despite some possible selection effects, jets preferably occur inside the polar coronal holes.

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.