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HINODE Operation Plan (HOP)

accepted on


 HOP No.

 HOP title

HOP 0124

Time-varying Doppler velocity diagnosis of X-ray Bright Points

plan term


@ @


 name : Zhang, Guo, Chen, Ding @  e-mail : chenpf[at]nju.edu.cn

contact person in HINODE team

 name : Shimizu @  e-mail : shimizu[at]solar.isas.jaxa.jp

 abstract of observational proposal
Since the discovery of X-ray bright points (XBP, Vaiana et al. 1970; Krieger et al. 1971), extensive studies have been performed and many theoretical models have been proposed (e.g., Priest et al. 1994; Yokoyama et al. 1996; Longcope et al. 1998). Approximately 1500 such small-scale point-like brightenings are born over the entire Sun every day. The average lifetime of XBPs reaches up to 8 hours (Golub et al. 1974). Magnetic reconnection is widely accepted as the heating mechanism of XBPs. If so, it is expected to observe large Doppler velocity, comparable to the coronal Alfven speed, in the reconnection outflow region. However, reported Doppler velocities of XBPs are typically ~10 km/s (e.g., Vilhu et al. 2002; Madjarska et al. 2003; Popesou et al. 2004; Xia et al. 2004), with the maximum of 35 km/s (Brosius et al. 2007), which is contradictory to the magnetic reconnection model. We intend to carry out a thorough investigation on the magnetic field, density and Doppler velocity of XBPs using HINODE observations in order to clarify the working mechanism of XBPs and solve the big puzzle.

 request to SOT
3 days – NFI: Stokes I/V Na 589.6 nm
  FOV: 164"~164", 0.16" pix
  Cadence: 64 seconds
  Telemetry: 255Mbits/hr, 1530Mbits/6hours
Another 3 days – SP: Stokes I, Q, U, V
  FOV: 41"~123"
  Cadence: 8 min (Fast Map Mode)
  Telemetry:57Mbits/map,one map/10minutes,342Mbits/hr,2052Mbits/6hours

 request to XRT
Filters: Al/mesh; Ti/poly
FOV: 384"~384"
Cadence: 1 – 2 min

 request to EIS
EIS study 251: tr_bright_lo
Slit/slot: 2h
Scan step size (arcsec): 2
Line list:
FeXII 186.88
OV 192.90
FeXII 195.12
HeII 256.32
SiVII 275.35
FeXV 284.16
FeX 257.26
Window width (pixel): 24,24,32,32,24,24,24
Exposure time: 30 seconds

 other participating instruments
Hida Observatory
Domeless Solar Telescope (DST):
 * Ca-line (K or H) spectro-heliograph:
   Slit length: 145 arcsec
   Scan width: about 120 arcsec
   Time cadence: about 15 sec
 * H-alpha 5 or 7 wavelengths filtergraph:
   Wavelength: -0.8, -0.5, (-0.25,) 0.0, (+0.25,) +0.5, +0.8 A
   Time cadence: about 15 sec
   FOV: 300 x 300 arcsec
Solar Magnetic Activity Research Telescope (SMART):
 * H-alpha 5 wavelengths full-disk filtergraph
   Wavelength: -0.8, -0.5, 0.0, +0.5, +0.8 A
   Time cadence: 2 min

In order to get the high-cadence spectral observation of XBPs, we select narrow field of views near the solar disk center (with the heliocentric angle less than 30 degrees) to scan with HINODE/EIS. Generally an XBP shows a periodic light curve (with a period ~1hr). Therefore, we need 6 hours of continuous observations every day.

1) Highest priority: to observe newly-formed XBPs.
2) Second priority: to observe existing XBPs.

The plan term is flexible. We require 6 days of observations and do not care whether it is consecutive or not.

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